Green-tailed Towhee Pipilo chlorurus
The few Green-tailed Towhees breeding high in the Cuyamaca Mountains represent an outpost well isolated from the nearest other populations, in the San Jacinto and Santa Rosa mountains to the north and in the Sierra San Pedro Mártir to the south. Like that of the Yellow-rumped Warbler, Dusky Flycatcher, and Fox Sparrow, the Green-tailed Towhee’s preferred habitat of montane chaparral and young conifers is barely touched by San Diego County’s highest mountains. Just as the county lies near the southern margin of the species’ breeding range, it lies near the northern margin of the winter range, so the Green-tailed Towhee is rare in winter. Even in migration the species largely skips over San Diego County.
Breeding distribution: During the atlas period, breeding Green-tailed Towhees were seen only near the summits of Cuyamaca and Middle peaks (M20). Their distribution thus closely resembles that of the Fox Sparrow, with which they share the same habitat. On Cuyamaca Peak Green-tailed Towhees occur along the fire road above 5700 feet elevation in chaparral and bracken fern. From 1997 to 2001, the high count there was of five on 5 June 2001 (M. B. Mulrooney). On Middle Peak, the towhees have been seen on the west slope between 4600 and 5000 feet elevation, with a high count of three, including two singing males, 2 July 2000 (R. E. Webster)
The observations of up to two on Hot Springs Mountain in June 1980 (E20/E21; Unitt 1981) and one at the Palomar Observatory (D15) 24 August 1981 (C. G. Edwards) have not been repeated since.
Nesting: During the atlas period, the only confirmations of Green-tailed Towhee breeding were observations of birds building nests on Cuyamaca Peak 22 May 1998 (G. L. Rogers) and 5 June 2001 (M. B. Mulrooney). A juvenile was accompanying adults there 29 July 1978 (AB 32:1210, 1978). The nest is usually well hidden within a dense-foliaged shrub or small tree. On the Mogollon Rim of Arizona, Dobbs et al. (1998) found nests predominantly in white firs, also available in the Green-tailed Towhee’s habitat in San Diego County.
Migration: The Green-tailed Towhee is recorded in its breeding habitat in the Cuyamaca Mountains from 19 May (1998, R. E. Webster) to 27 August (1978, D. Povey, Unitt 1984); records from elsewhere in the Green-tailed Towhee’s breeding range suggest these dates could be extended three or four weeks in both directions.
In spite of breeding commonly in the Sierra Nevada and Transverse Ranges and wintering commonly in southern Baja California, the Green-tailed Towhee is rare as a migrant through San Diego County, suggesting most birds fly nonstop over southern California. Fall migration extends from early September to mid November, spring migration from early April to mid May. From 1997 to 2001 spring dates extended from 4 April (1999, one at the Paradise Creek marsh, National City, T10, W. E. Haas; 1998, two in a cowbird trap in Goat Canyon, W10, J. M. Wells) to 14 May (1998, one near Scissors Crossing, E. C. Hall). Of the 31 spring records during this period, the only ones of more than a single individual were of four at Vallecito (M25) 12 May 1999 (M. C. Jorgensen) and the two in the cowbird trap (one of which was trapped again four days later). Spring migrants appear somewhat more numerous in the eastern half of the county than in the western half: 14 records in the west versus 17 in the east, in spite of nearly 50% more observer-hours in the field in the west. Massey (1998) also reported several April records in the Anza–Borrego Desert. Near the coast, an unseasonal straggler was in a condominium complex just northeast of Kate Sessions Park (P8) 10 June 1999 (J. Moore).
Winter: The Green-tailed Towhee is rare in San Diego County at this season, though hardly more so than in migration. It does not have a clear habitat preference in winter, other than dense low shrubbery, often near water. From 1997 to 2002 we recorded about 21 individual wintering Green-tailed Towhees, 15 in the coastal lowland. Only one record is of more than a single bird: two were at Lake Hodges (K10) 23 December 1998 (R. T. Patton). Some individuals were observed repeatedly through the winter, and at least two, at Point Loma Nazarene University (S7) and the Chula Vista Nature Center (U10), returned for three consecutive years. We noted six Green-tailed Towhees farther inland, where there are only a couple of earlier records, on Lake Henshaw and Anza–Borrego Christmas bird counts. Three were in canyons draining into the desert, while three were scattered in chaparral-dominated landscapes at higher elevations: one at 2800 feet elevation near La Posta microwave tower (T23) 22 January 2000 (G. Rebstock), one at 3600 feet at Indian Flats (D19) 6 January 1999 (K. J. Burns), and one at 3700 feet at a bird feeder in Pine Valley (P21) 24 December 1998 (J. K. Wilson).
Conservation: On the scale of the species’ entire range, there is no clear evidence of population change (Dobbs et al. 1998). As a bird of undergrowth and second growth, the Green-tailed Towhee colonizes logged forest (Franzreb and Ohmart 1978). Persisting continuously since its discovery on Cuyamaca Peak in 1974, the Green-tailed Towhee seems well established there, though populations so small are vulnerable to extirpation. In winter, the Green-tailed Towhee has become less frequent since the 1960s and 1970s, at least around metropolitan San Diego, the region of most early records. The maximum on a San Diego Christmas bird count, eight on 20 December 1969, is implausible today. From 1980 to 1992, the Green-tailed Towhee was recorded on 8 of 13 counts, but from 1993 to 2001 it was recorded on only one. Most likely the decrease is a result of the elimination of weedy thickets as more and more of the count circle was urbanized.
Spotted Towhee Pipilo maculatus
The Spotted Towhee is one of the most common birds—perhaps the most common bird—of chaparral. A study near Pine Valley comparing bird abundance in mature and recovering chaparral found the Spotted Towhee the most numerous species in stands averaging both 30 and 6 years after a fire, though the Wrentit was a close second (Cleveland National Forest data). A year-round resident, the towhee is just as common in the understory of riparian, oak, and coniferous woodland but much sparser where the shrubs are sparser, as in coastal sage scrub and desert-edge scrub. Poorly adapted to urbanization, the Spotted Towhee is beginning to see its range erode as a result of habitat fragmentation.
Breeding distribution: The Spotted Towhee occurs almost uniformly over the coastal slope. High numbers have been recorded in both the mountains (up to 170 in Matagual Valley, H19, 18 June 2000, S. E. Smith, B. E. Bell) and the coastal lowland (up to 115 along the Santa Margarita River north of Fallbrook, C8, K. L. Weaver). The Spotted Towhee is somewhat less numerous along the central and southern coast of San Diego County, dominated by developed areas and sage scrub. The remnant patches of native habitat in the 11 atlas squares around San Diego where breeding Spotted Towhees are lacking have almost no chaparral—though some have appreciable sage scrub. The Spotted Towhee generally inhabits sage scrub only if it contains lemonadeberry or laurel sumac shrubs, in whose leaf litter the birds forage (M. A. Patten pers. comm.). On the east slopes of the mountains, the Spotted Towhee inhabits desert-edge scrub with shrubs like desert scrub oak and sugarbush and descends in riparian scrub to Lower Willows, Coyote Creek Canyon (D23; up to four on 24 May 2000, J. R. Barth) and Sentenac Canyon (J23; up to seven on 7 June 2000, R. Thériault). At some points on the eastern margin of the range the Spotted Towhee is apparently irregular: mesquite thicket near east end of Vallecito Valley (M24), two on 9 May 2001 (P. K. Nelson); Inner Pasture (N25), one on 6 April 2000 (M. B. Mulrooney); and upper end of Indian Valley (P26), one on 9 May 1998 and 30 April 2000 (P. R. Pryde). In high-desert scrub, junipers, and pinyons, the Spotted Towhee extends into San Diego County along the spine of the Santa Rosa Mountains from Rabbit to Villager Peak (C27; up to nine on 17 June 2001, R. Thériault); a few birds are isolated east of a deep chasm in the pinyon grove near benchmark Rosa (D28; up to two on 2 May 2000, L. J. Hargrove). Another isolated population lives in similar habitat in the upper elevations of the Vallecito Mountains (K25/L25/L26; maximum count seven on the east slope of Whale Peak, L26, 12 April 2000, J. R. Barth).
Nesting: The Spotted Towhee usually nests on the ground, concealing the nest in leaf litter or under low-growing plants like snowberry, skunkbrush, mugwort, California rose, or clumps of grass. Nests as high as 12 feet have been reported in Alameda County (Cohen 1899), but San Diego County bird atlas observers described no nest higher than 1 foot off the ground. Of 45 nests studied by M. A. Patten (pers. comm.) around San Diego 2001–02, 44 were on the ground, one 36 cm above the ground in a white sage. Patten found the nests under a variety of plants, including dead wood, but noted the birds avoided nesting deep within the cover of large shrubs, choosing instead small shrubs, herbs, grass, or the outer edge of a large shrub, where its branches hang near the ground.
Our observations suggest the Spotted Towhee begins laying around the end of March or first of April; Patten’s egg dates extended from 2 April to 26 June. An egg set collected at Escondido 11 March 1900 (C. S. Sharp, WFVZ 86710) was exceptionally early. The nesting season continues into July; a nest with three eggs along Pilgrim Creek, Oceanside (F6), 8 July 2000 (B. Peterson) was slightly later than the 4 July date of the latest of 31 egg sets collected in San Diego County 1898–1940.
Migration: There is little evidence of Spotted Towhee migration in San Diego County. The only spring record clearly outside the breeding range is of one at Palm Spring (N27) 24–27 April 1998 (D. C. Seals, S. Peters).
Winter: The Spotted Towhee remains year round even at high elevations. In winter, a few birds disperse a short distance, resulting in records from most of the urban squares in San Diego where the species does not breed. None of these records is more than 4 miles from breeding habitat; two at the Chula Vista Nature Center (U10) 8 December 2001 (B. C. Moore) had moved the farthest. Similarly, the Spotted Towhee is a rare winter visitor to the Anza–Borrego Desert outside the breeding range. The 11 such records 1997–2002 were all of one or two individuals, and none was farther than 6 miles from breeding habitat (one at Ellis Farms nursery, F25, 17 December 2000, L. J. Hargrove, P. Unitt).
Conservation: As a ground nester, the Spotted Towhee is ill equipped to survive in the urban environment, and it is absent from heavily developed areas. Crooks et al. (2001) investigated its response to habitat fragmentation in San Diego in 1997, finding it in 17 of 30 urban canyons, consistently only in the six fragments of greater than 30 hectares. The towhee occurred in 11 of 24 fragments of 2 to 15 hectares. Two of these had been recolonized since 1987, and the towhee had disappeared from none of the fragments where it had been noted at the time of that initial study. Crooks et al. reported two Spotted Towhees in residential development 250–750 meters from Mission Trails Regional Park, revealing some capability for dispersal across unsuitable habitat, and they suggested that recolonization of habitat fragments could take place during the nonbreeding season—as attested by atlas results. Their analysis suggested that the size of a habitat fragment is the most important factor governing the likelihood of the Spotted Towhee inhabiting it, but that the time since the fragment was isolated plays a role as well. Crooks et al. did not consider, however, another likely factor: the type of habitat within a fragment. Bolger et al. (1997), addressing the question at a somewhat coarser scale, did not identify the Spotted Towhee as strongly affected by fragmentation but did find that its abundance increased significantly with distance from development. Sensitivity to fragmentation can be measured in various ways, but the results of Crooks et al. and Bolger et al. imply that the Spotted Towhee is moderately sensitive—less so than the California Quail, Greater Roadrunner, and Rufous-crowned, Sage, and Lark Sparrows, more so than the Wrentit, Bewick’s Wren, and California Towhee. Lovio (1996), studying less-isolated fragments in the Spring Valley/Jamacha region (R12/R13/R14/S12/S13), found the Spotted Towhee in 29 of 36 habitat fragments, including all nine greater than 15 hectares.
Taxonomy: Only coastal southern California’s resident subspecies of Spotted Towhee, P. m. megalonyx Baird, 1858, is known from San Diego County. It is boldly spotted with white but otherwise represents the dark extreme of the species: the blackish parts of the female’s plumage are almost as black as the male’s; even her rump is almost black. The paler (female especially) subspecies P. m. curtatus Grinnell, 1911, from the northern Great Basin and intermountain region reaches the Salton Sink and lower Colorado River as a rare winter visitor. It is so far unknown from San Diego County but could reach the Anza–Borrego Desert; a specimen would be needed to confirm it.
California Towhee Pipilo crissalis
The California Towhee is one of the dominant birds of coastal sage scrub. It is also common in chaparral (especially where broken by openings), riparian scrub, high-desert scrub, and the undergrowth of riparian and oak woodland. It is famed for its sedentary nature, mated pairs remaining for life in one territory. The California Towhee adapts fairly well to urban life, readily moving into parks and residential areas wherever these offer a certain density of shrubbery for nesting and unpaved ground surface for foraging.
Breeding distribution: The California Towhee covers almost the entire coastal slope of San Diego County except the Coronado peninsula, the most densely built parts of cities, and the forested summits of the highest mountains. Even in the long-developed parts of San Diego, there remains enough habitat for the towhee in every atlas block except R7 and S8, incomplete squares that lack any native scrub. The species is distinctly more numerous in the coastal lowland than at higher elevations, but it was still found in every foothill and mountain square surveyed except D14 (Palomar Mountain), E20 (summit of Hot Springs Mountain), M20 (Cuyamaca Peak), and O23 (Mount Laguna).
On the east slopes of the mountains the California Towhee is uncommon but widespread even in sparse desert-edge scrub. Only in creosote bush scrub on the desert floor does it drop out completely. Mesquite thickets offer it good habitat in canyons (maximum 25 at Vallecito, M25, 27 April 1998, M. C. Jorgensen), yet it is absent from the mesquite bosque on the floor of the Borrego Valley. The birds also range into the Santa Rosa Mountains (maximum three on the east slope, C28, 2 May 2000, R. Thériault) and Vallecito Mountains (maximum seven on the east slope of Whale Peak, L26, 12 April 2000, J. R. Barth).
Nesting: Unlike the Spotted Towhee, the California Towhee seldom places its nest on the ground; more usually it builds in low shrubs, sometimes even in the outer canopy of coast live oaks. The birds commonly use ornamental shrubs and fruit trees as well as native plants. Like many other resident birds, most California Towhees begin laying in the third week of March; 31 egg sets collected 1891–1953 range from 16 March to 12 July. During the atlas period, we found a few birds starting two to three weeks earlier, especially in the wet year of 1998. Our earliest observations of courtship behavior were 8 February 1998 (a rainy day—female soliciting copulation in Rancho Cuca, F14, P. Unitt), of nest building 16 February 2001 (near Puerta La Cruz, E18, K. J. Winter), and of fledglings 22 March 1998 (Encanto, S11, P. Unitt).
Winter: Only two records imply winter dispersal of California Towhees out of their breeding range by the width of even one atlas square: two at Borrego Springs (F24) 19 December 1999 (P. K. Nelson) and one in Carrizo Valley east of Highway S2 (O28) 7 February 2002 (P. D. Jorgensen). There is only one record from the Salton Sink (Patten et al. 2003).
Conservation: With its ability to use nonnative habitats, the California Towhee has largely avoided the negative effects of urban sprawl that afflict many other birds that prefer sage scrub. Bolger et al. (1997) identified it as a species insensitive to habitat fragmentation in San Diego, and this is corroborated by our atlas results. High-density development can eliminate the towhee, as it has in some neighborhoods of inner-city San Diego. At the scale of our atlas grid, though, this effect is visible only in the species’ absence from Ocean Beach (R7).
Taxonomy: The subspecies of the California Towhee found in coastal southern California and northern Baja California, P. c. senicula Anthony, 1895, is a prime example of the subspecies whose ranges define the San Diegan district of the California Floristic Province. Like the Rufous-crowned Sparrow, Bewick’s Wren, Oak Titmouse, and others in this area, it is distinguished by its darker color in comparison to the other subspecies both farther north and farther south.
Cassin’s Sparrow Aimophila cassinii
Cassin’s Sparrow normally ranges from southeastern Arizona and the southwestern Great Plains south into mainland Mexico. Though there were small influxes to the Mojave Desert in spring 1978 and 1993, following wet winters, the species is a rare vagrant to California. The three records for San Diego County are likely of a single bird returning to the same site.
Migration: San Diego County’s one location for Cassin’s Sparrow was open sage scrub along Dehesa Road 1 mile east of Granite Hills Drive, El Cajon (Q14). Here a singing male appeared 15–30 May 1970, 8–11 May 1976, and 10–12 June 1978, to be photographed and tape-recorded (S. Oberbauer, M. U. Evans, Roberson 1993). The habitat has since been replaced with a housing development.
Rufous-crowned Sparrow Aimophila ruficeps
The Rufous-crowned Sparrow is one of the characteristic birds of coastal sage scrub. Preferring this threatened habitat and sensitive to habitat fragmentation, the sparrow has seen its numbers and range reduced over much of coastal San Diego County. Yet it remains fairly common over wide areas, as it can use steep slopes that discourage development, readily colonizes burned chaparral, and persists in openings in mature chaparral. A year-round resident, the Rufous-crowned Sparrow is rarely seen even a short distance away from the habitat where it breeds.
Breeding distribution: The Rufous-crowned Sparrow is widespread over the coastal lowland and foothills of San Diego County in sage scrub, broken or burned chaparral, and grassland with scattered shrubs. Collins (1999) found that its average habitat in northwestern Santa Barbara County is fairly steep south-facing slopes with about 50% cover of low shrubs, and this represents the current situation in San Diego County as well. Sage scrub on gentle rolling hillsides is even more favorable but now greatly reduced and fragmented. The Rufous-crowned Sparrow avoids flat valley floors and floodplains, impenetrable chaparral, woodland, and developed areas. It ranges down to the coast where suitable habitat remains, as in Camp Pendleton, Torrey Pines State Reserve, and Point Loma. The denser populations are at low elevations, as in eastern Camp Pendleton and the Fallbrook Naval Weapons Station (D7, 36 on 4 April 2000, W. E. Haas), from Mission Trails Regional Park and Miramar east to San Vicente Reservoir (N13, 22 on 22 March 1998, C. G. Edwards) and Lake Jennings, and from Sweetwater Reservoir east to Rancho Jamul (T15, 18 on 5 April 2000, P. Unitt). The local distribution shifts with time, though, because the Rufous-crowned Sparrow quickly invades recovering burned chaparral while it is still dominated by grasses and herbs, then drops out as the chaparral matures. At higher elevations, largely covered with thick chaparral, the species is linked to microhabitats such as rock outcrops or gabbro soil that make for openings or sparser growth. Rocks surrounded by clumps of the giant needlegrass are a frequent clue for the Rufous-crowned Sparrow in San Diego County’s foothills. Man-made openings like firebreaks and small abandoned clearings also attract the species. The Rufous-crowned Sparrow largely avoids the mountain zone, being rare above 4000 feet elevation, but occurs almost continuously, though in low density, along the mountains’ steep east slope. In the Anza–Borrego Desert it is a rare resident in the Vallecito Mountains (K26, pair on 3 May 2001; L26, two on 10 May 2000, J. R. Barth) and possibly the Santa Rosa Mountains, though all records in the latter are for winter.
Nesting: The Rufous-crowned Sparrow nests primarily on the ground, only rarely in low shrubs. Of 304 nests studied around San Diego by Morrison and Bolger (2002) and M. A. Patten (pers. comm.), 42% were on the ground at the base of a bunchgrass, typically the native purple needlegrass or giant needlegrass, but one pair used an exotic African fountain grass. Other nests (32%) were at the bases of small shrubs like flat-top buckwheat, white sage, and California sagebrush, and most others were among rocks or dirt clods. Only 4% of nests were above ground in low shrubs. Like most resident birds of its habitat, the Rufous-crowned Sparrow usually begins nesting in the third week of March; collected egg sets range from 11 March to 7 June. In 2001, M. A. Patten found 26 nests with eggs between 3 April and 15 June, with nestlings between 6 April and 25 June. A few individuals start earlier: pairs seen carrying insects near the Highway 94 crossing of the Sweetwater River (R13) 17 March 1997 (D. and M. Hastings) and at the De Luz Road crossing of the Santa Margarita River (C7) 19 March 1997 (K. L. Weaver) must have laid in the first week of March, slightly earlier than previously reported. Likewise, a nest with eggs in Pueblitos Canyon (F5) 17 June 1999 (C. Reynolds) and one with nestlings near the summit of Mt. Woodson (L13) 16 July 1997 (P. von Hendy) demonstrate nesting somewhat later than previous records.
Migration: The Rufous-crowned Sparrow is sedentary. Studies with banded birds addressing this issue directly are lacking, but probably juveniles disperse only a few miles from the place where they hatched and adults remain in their established territories for life.
Winter: Few records of the Rufous-crowned Sparrow suggest even short-distance shifting in winter outside its breeding habitat. The birds at higher elevations remain there through the winter, e.g., one at 4290 feet on the ridge 0.5 mile north of the Indian exhibit, Cuyamaca Rancho State Park (N21), 10 February 2000 (J. Fitch) and one at 4640 feet in Scove Canyon (P22) 31 December 1998 (P. Unitt). A couple of records from isolated urban canyons in Pacific Beach (Q7, one on 22 January 2000, L. Polinsky) and East San Diego (R10, one on 20 December 1997, J. A. Dietrick) suggest occasional birds still reach habitat fragments where the species is unable to sustain itself. Other locations where the Rufous-crowned Sparrow was recorded in the winter but not the breeding season are mostly in marginal habitat where the species probably occurs in low density year round. Possible exceptions are in the northeast-draining canyons of the Santa Rosa Mountains (C27/C28/D28) and in the Alma Wash/Starfish Cove area at the east end of the Vallecito Mountains (K28). Winter visits to these areas yielded daily counts of up to five at the east base of the Santa Rosa Mountains (C28) 20 January 2000 (R. Thériault) and four near Starfish Cove 5 December 1999 (L. J. Hargrove, J. O. Zimmer), but an equal level of effort during the breeding season yielded none. In these very marginal habitats the Rufous-crowned Sparrow may be irregular.
Conservation: The Rufous-crowned Sparrow’s susceptibility to habitat fragmentation is attested by multiple studies (e.g., Lovio 1996, Bolger et al. 1997, K. L. Weaver unpubl. data) and is clear in the distribution we observed 1997–2002. The native maritime scrub on Point Loma (S7) is the only site where the species survives far isolated by development. If this is a minimum, and the population is viable indefinitely, it implies that nearly 400 hectares of habitat are necessary to support a self-sustaining population. Lovio (1996) found the Rufous-crowned Sparrow consistently only in tracts of scrub of 17 hectares or greater; the habitat fragments he studied were less isolated in both space and time than Point Loma. Morrison and Bolger (2002) reported the sparrow’s abundance in small, isolated habitat fragments (1–100 hectares) to be only 2% of that in expanses over 1000 hectares. The Rufous-crowned Sparrow’s apparent absence from patches of sage scrub in Oceanside and Encinitas also implies loss due to habitat fragmentation. The outlook is therefore not good for the birds persisting in smaller isolated patches like Soledad Natural Park in La Jolla (P7). The Rufous-crowned Sparrow’s survival over much of the coastal lowland of San Diego County may depend on how well multiple-species conservation plans succeed in linking patches of sage scrub. Because the process of piecing together habitat reserves under these plans is gradual, their success with the Rufous-crowned Sparrow cannot yet be predicted. Even if this success is poor, and the species disappears from large areas west of Interstate 15, the Rufous-crowned Sparrow is likely to survive farther inland. Although the Rufous-crowned Sparrow is sparser here than at lower elevations, its adaptability as a fire follower seems certain to ensure its place in San Diego County’s biota.
Taxonomy: The Ashy Rufous-crowned Sparrow, A. r. canescens Todd, 1922, is the subspecies occurring in San Diego County. It is restricted to the San Diegan District of the California Floristic Province, and its characters typify the pattern of this area’s endemic birds: it is darker both above and below than the subspecies to both the north and the south, and the underparts differ from those of the other subspecies in having a gray wash.
American Tree Sparrow Spizella arborea
The American Tree Sparrow is a bird of the arctic and subarctic. Even in northernmost California it is a rare winter visitor. The 12 records for San Diego County are the southernmost along the Pacific coast.
Migration: All sightings of the American Tree Sparrow in San Diego County have been at Point Loma (S7), except for one in southwestern Balboa Park (S9) 13–21 December 1975 and one in Presidio Park (R8) 13 November 1976 (AB 31:225, 1977). All have been of single individuals (usually flocked with other sparrows), except for two at Point Loma 28–31 October 1982 (R. E. Webster, AB 37:226, 1983). The only one during the atlas period was there 4–5 November 1999 (J. C. Worley, NAB 54:107, 2000). The species’ dates range from 11 October (1970, McCaskie 1973) to 21 December.
Taxonomy: No specimen has been collected in San Diego County, but specimens from elsewhere in California are S. a. ochracea Brewster, 1882 (McCaskie 1973).
Chipping Sparrow Spizella passerina
Though the Chipping Sparrow takes to man-made habitats like orchards, cemeteries, and landscaped parks, it is at best locally common in San Diego County. Its distribution is complex: it breeds primarily in the mountains among the pines, only sparingly elsewhere. In winter it is even less predictable, fluctuating with the supply of seeds in natural habitats and being most consistent in irrigated parks. The Chipping Sparrow is most widespread as a spring migrant, at this season concentrating at the east base of the mountains.
Breeding distribution: The Chipping Sparrow’s distribution in San Diego County is curious and unique. Open pine/oak woodland with a grassy understory is the species’ principal breeding habitat, so the higher mountain ranges constitute the core of the sparrow’s range. Yet even here the distribution is patchy: the Chipping Sparrow is uncommon and local on Palomar Mountain and now absent from Hot Springs Mountain (previously, only a single bird seen on two of three visits in summer 1980, Unitt 1981). It is most numerous in the Julian area, with up to 20 at Wynola 17 April 1999 (S. E. Smith), 18 (all singing males) between Julian and William Heise County Park (K20) 10 June 1998 (E. C. Hall), and 12 on Volcan Mountain (I20) 28 June 2000 (A. P. and T. E. Keenan).
In oak woodland without conifers the Chipping Sparrow is very local and usually rare, with only scattered pairs. It occurs at several sites from near Santa Ysabel northwest through Mesa Grande to Pine Mountain (G15), a region also occupied by several other birds more typical of coniferous woodland. Eight in the Edwards Ranch (J18) near Santa Ysabel 25 June 2000 (S. E. Smith) was the highest count in this area. The only other substantial population in natural habitat—open Engelmann oak woodland—is in Camp Pendleton at the south end of the Santa Margarita Mountains between Roblar Creek and Case Spring (B4, C5). From 1998 to 2001 the species was consistent there, unlike the scattered ephemeral pairs or individuals at most other oak woodland sites, in numbers ranging up to 16 on 27 May 2001 (C5; L. J. Hargrove).
The Chipping Sparrow is also an uncommon and localized breeding bird in avocado and citrus orchards, mainly around Pauma Valley, Valley Center, and San Pasqual. The highest count in this habitat was of six 1.5 miles northeast of Weaver Mountain (E11) 27 May 1999 (D. C. Seals), and most reports are of scattered individuals or pairs. Yet another isolated colony, known since the 1970s, is at Point Loma (S7), where the birds occur fairly commonly both around the edges of native scrub and in the ornamental plantings of Cabrillo National Monument and Fort Rosecrans Cemetery. The Chipping Sparrow may be colonizing La Jolla (P7) as well, where L. and M. Polinsky noted six and two on 16 and 27 May 1999, respectively.
Nesting: The Chipping Sparrow prefers to nest in conifers (Middleton 1998), a preference that may account for its concentrating in San Diego County’s mountain forests. There is little information about the species’ nesting in the county, though. On Point Loma the birds nest in shrubs, at least; one early collected egg set from Palomar Mountain was in a wild rose. The schedule of breeding activity we observed was consistent with the eight egg sets collected 1895–1920, whose dates ranged from 29 April to 21 June. Any differences in nesting schedule among the Chipping Sparrow’s diverse habitats remain unknown.
Migration: Over much of San Diego County the Chipping Sparrow occurs only as a migrant. Records far from wintering and breeding localities suggest that spring migration extends mainly from late March to mid May, with extreme dates 16 March (1998, one in Travertine Palms Wash, C29, R. Thériault) and 24 May (1999, 10 at Yaqui Well, I24, P. K. Nelson). Spring migrants are most numerous in the Anza–Borrego Desert along the east base of the mountains, with up to 59 in Blair Valley (L24) 3 April 1998 (R. Thériault), 30 near Scissors Crossing (J22) 26 April 1999 (E. C. Hall), and 30 near San Felipe Narrows (I25) 10 April 1999 (P. K. Nelson). Twenty-five at Sunshine Summit (D17) 1 May 1999 (A. Mauro) were at a concentration point for migrants crossing the mountains. Numbers of migrants elsewhere on the coastal slope were small—all counts of over 10 in a day were from sites where the species winters. Fall migration begins in late August or early September.
Winter: At this season the Chipping Sparrow is widespread but patchy. The species can be seen almost anywhere where bare ground or short grass for foraging lies near dense shrubs or trees for refuge from predators. Wintering birds range from the coast to the low desert and up to at least 4700 feet in the mountains (15 northeast of Lake Cuyamaca, L21, 5 January 1999, J. K. Wilson). They appear to be most numerous, though, in the inland valleys. They typically flock with other wintering sparrows, especially the White-crowned and, in the desert, Brewer’s. Lawns and open ground with scattered trees attract wintering Chipping Sparrows, so parks and cemeteries are the most consistent sites for them. In natural habitats, especially desert, the species is irregular, presumably according to the food supply. The numbers reported in the eastern two-thirds of San Diego were at least twice as high in 1998–99 (the winter following the wet one) than in any other of the five. By 2001–02, an exceptionally dry winter, numbers of Chipping Sparrows reported from this region were only 12% of those three years earlier.
Conservation: Although the Chipping Sparrow uses artificial landscaping, and has become a suburban bird in the eastern United States (Middleton 1998), it has not taken to residential areas in San Diego County. Breeding birds have benefited to a modest extent from the planting of orchards—and have suffered from their replacement by urban sprawl. Anecdotal observations do not imply a conspicuous change in the status of the Chipping Sparrow in San Diego County over the last third of the 20th century, but the Breeding Bird Survey implies a significant decrease in California as a whole over this period (Sauer et al. 2003). Stephens (1919a) called the species a “rather common summer resident” in San Diego County, Willett (1912) a “common resident of orchards, gardens, and parks in the foothill and mesa region, abundant in summer in coniferous forests of the mountains” of coastal southern California as a whole—evaluations that no longer apply. Brown-headed Cowbird parasitism is likely a factor in this decrease; the cowbird parasitizes the sparrow heavily, reducing its nest success (Middleton 1998).
Taxonomy: Chipping Sparrows of the western United States are now generally all listed as the pale S. p. arizonae Coues, 1872. Kenneth C. Parkes identified two fall specimens from San Diego County as probably S. p. boreophila Oberholser, 1955, a far-northern darker-backed subspecies of uncertain validity (Unitt 1984).
Clay‑colored Sparrow Spizella pallida
Even though it nests in eastern British Columbia and winters in Baja California Sur, the Clay-colored Sparrow is rare in San Diego County. It occurs mainly as a fall migrant, flocking with its close relative the Chipping Sparrow and seen most frequently at Point Loma.
Migration: Four or five per fall is an average number of sightings of the Clay-colored Sparrow in San Diego County. The species occurs mainly from mid September to mid November; 28 August (1968, one in the Tijuana River valley, AFN 23:112, 1969) is the earliest date. All reports are from the coastal lowland, overwhelmingly from Point Loma and the Tijuana River valley.
There are only three records of spring migrants, all from Point Loma, 19 May 1980 (AB 34:817, 1980), 29 April–1 May 2001 (J. Abernathy, P. A. Ginsburg, NAB 55:358, 2001), and 5 May 2002 (J. C. Worley).
Winter: The seven winter records, all from the coastal lowland, include five listed by Unitt (1984), one at Point Loma 10 January–10 April 1992 (G. McCaskie, AB 46:316, 1992), and one that returned for two years to Oak Hill Cemetery, Escondido (I12) 20–22 February 2001 and 16–24 February 2002 (M. B. Mulrooney, NAB 55:229, 2001).
Brewer’s Sparrow Spizella breweri
Brewer’s Sparrow may not be much to look at, but its song is a show-stopper: a series of trills at varying high pitches and tempos, continued at length. The birds often sing in chorus, creating a surreal sound. They sing even in their winter range—fortunately for San Diegans, because it is as a winter visitor and migrant that Brewer’s Sparrow occurs primarily in San Diego County. It is overwhelmingly a bird of the Anza–Borrego Desert but occurs locally in small numbers on the coastal slope, mainly in habitats mimicking desert scrub. Field work for this atlas generated much new data on Brewer’s Sparrow, recording a winter invasion on an unprecedented scale and the first confirmed breeding of the species in San Diego County.
Winter: As a winter visitor, Brewer’s Sparrow is widespread in the Anza–Borrego Desert, especially in broad washes and on valley floors where there are good numbers of shrubs as well as open sandy ground. The species’ abundance, though, varies greatly with rainfall. The numbers reported in the winter of 1998–99, the year after a wet El Niño, were 20 times higher than in any of the three following dry winters. The difference even from 1997–98 would have been almost as great if not for the flock of 300 northwest of Carrizo Marsh (O29) 21 January 1998 (M. C. Jorgensen). In the peak year concentrations ranged up to 231 at Borrego Springs (G24) 20 December 1998 (P. D. Ache) and 200 near Yaqui Well (I24) 31 January 1999 (R. Thériault). The Anza–Borrego Christmas bird count implies substantial year-to-year variation in numbers of the Brewer’s Sparrow, but the figure in 1998–99 was still at least 15 times higher than in any year back to the count’s inception in 1984. In most years the species is seen inconsistently at any given site; it probably wanders nomadically.
Brewer’s Sparrow also occurs in semidesert scrub on the south-facing slopes of Dameron and Oak Grove valleys, in the coastal drainage basin of the Santa Margarita River. The species was common there in 1998–99 (up to 34 in Dameron Valley, C16, 12 December 1998, K. L. Weaver) and still occurred in small numbers in later years. The only report of a large number elsewhere on the coastal slope was from near Campo (U22), site of 20 on 23 January 1999 (C. R. Mahrdt). Locations of scattered Brewer’s Sparrows elsewhere on the coastal slope were mostly from pockets of exceptionally arid scrub on south-facing slopes, such as Pamo Valley (I15, three on 10 December 1998, O. Carter) and the region of Otay Lakes (four records of single birds, P. Unitt, S. Buchanan).
Migration: As a migrant, Brewer’s Sparrow is as widespread in the Anza–Borrego Desert as in winter but more numerous. Exceptionally high concentrations occurred in both 1998 (up to 600 on Mescal Bajada, J25, 26 April, M. and B. McIntosh) and 1999 (up to 440 in the Borrego Valley’s mesquite bosque, G25, 16 March, R. Thériault). Even in “normal” years large flocks of spring migrants are seen occasionally, such as 70 near Whitaker Horse Camp (D24) 4 April 2001 (J. O. Zimmer) and 50 along Rockhouse Trail (D25) 15 April 2000 (K. J. Winter). Also, a few are seen in spring at the places on the coastal slope where the species winters (six in Dameron Valley, C16, 10 April 1999, K. L. Weaver; two in Proctor Valley, T14, 29 April 1998, P. Unitt). Coastal migrants away from wintering areas are rare (maximum four in Rancho Jamul, S15, 21 April 2001, P. Unitt, C. Woodruff) but scattered as far northwest as Las Pulgas Canyon, Camp Pendleton (E4, one on 26 April 2001, S. Brad). Numbers decline through the first half of May; 15 May 1999 (two in Indian Gorge, O27, P. R. Pryde) may be the latest date for a migrant, close to the species’ latest date of 11 May for the Imperial Valley (Patten et al. 2003). Two in Miller Valley (S24) 22 May 1999 (L. J. Hargrove) and two near Sentenac Ciénaga (J23) 28 May 1998 (R. Thériault) may have been prospective breeders, in light of the discovery of the species’ nesting in 2001.
In fall, Brewer’s Sparrow begins arriving in early September (4 September 1988, one along Carrizo Creek near Arsenic Spring, T28, P. Unitt). It is most frequent along the coast at this season, sometimes associating with flocks of Chipping Sparrows.
Breeding distribution: Though Stephens (1919a) wrote that a few Brewer’s Sparrows breed on the eastern slope of San Diego County’s mountains, and collected a specimen at 6000 feet elevation in the Cuyamaca Mountains 21 May 1893 (SDNHM 1012), the first confirmation of the species’ nesting in the county came in 2001. On 13 May 2001, in a stand of the big sagebrush in Montezuma Valley just southwest of Ranchita (H21), B. E. Bell, G. Rebstock, and I found a singing male, a highly agitated presumed female, and her completed but still empty nest, 1–2 feet above the ground in sagebrush. A follow-up visit on 31 May revealed the nest deserted and the birds gone from the area. Less than 1 mile to the east, in sagebrush just southeast of Ranchita, Brewer’s Sparrows occurred in late April 1999, 2000, and 2001, with up to six, including two singing males, 29 April 2001 (P. D. Jorgensen). In the Manzanita Indian Reservation (R25), G. Rebstock and J. Determan noted a single agitated Brewer’s Sparrow 6 May 2001. Less than 2 miles to the east in upper McCain Valley (R26), J. R. Barth found one carrying an insect 17 May 2001, then found two juveniles at the same site 11 and 13 June 2001. Finally, M. B. Mulrooney reported a singing male in a large patch of big sagebrush along Indian Creek in the Laguna Mountains (N22) 21 May 2002. Over 80 years later, Stephens’ assessment of the Brewer’s Sparrow’s breeding in San Diego County has been verified, extending the species’ breeding range significantly south of its previously established limit in the San Bernardino Mountains.
The only previous summer record of Brewer’s Sparrow in San Diego County is of one singing at 850 feet elevation along Marron Valley Road (V17) 7 August 1991 (C. G. Edwards).
Nesting: The one Brewer’s Sparrow nest known from San Diego County was typical for the species in being placed under the crown of a big sagebrush.
Conservation: Brewer’s Sparrow is suffering a decline in its core breeding range in the Great Basin (Rotenberry et al. 1999) and has been extirpated from former breeding sites in the Los Angeles region (Garrett and Dunn 1981). No change is evident in the Anza–Borrego Desert, however, where the species’ winter habitat is little modified and the historical record is slight. Brewer’s Sparrow has been known in winter on the coastal slope since L. M. Huey collected two at San Diego 15 January 1914 (SDNHM 34563–4) but has apparently always been rare. Nevertheless, runaway urbanization threatens the sage scrub used by wintering Brewer’s Sparrows both in the Proctor Valley/Otay Lakes area and in Dameron Valley.
Taxonomy: All specimens from San Diego County are S. b. breweri Cassin, 1856, except for one from San Luis Rey (G6) 14 February 1962 (Rea 1967, DEL 27230), the only reported California specimen of S. b. taverneri Swarth and Brooks 1925. This larger, darker, grayer, more heavily streaked form breeds north of nominate breweri, largely in northwestern Canada, and apparently winters primarily in the Chihuahuan Desert of mainland Mexico.
Black-chinned Sparrow Spizella atrogularis
The Black-chinned Sparrow is one of North America’s least-studied birds, yet it is one of the commonest species on the steep chaparral-covered slopes so widespread in San Diego County’s foothills and mountains. Rugged topography seems to be nearly as much a feature of the Black-chinned Sparrow’s habitat as chaparral. The birds are inconspicuous except for the male’s song, an accelerating trill with a mechanical quality unique among California’s breeding birds. The Black-chinned Sparrow is a summer visitor almost exclusively, being very rare in winter and even as a migrant away from its breeding habitat.
Breeding distribution: The Black-chinned Sparrow occurs widely in San Diego County’s foothills and mountains above 1500 feet elevation. Gaps are due to extensive grassland, as in Warner Valley, or forest, as in the Cuyamaca Mountains. The largest concentrations appear to be between 2500 and 5500 feet elevation on south-facing slopes, e.g., 60 in Noble Canyon (O22) 6 June 1997 (R. A. Hamilton), 48 on Otay Mountain (V15) 25 May 1999 (D. C. Seals), and 46 along the Pacific Crest Trail from Kitchen Creek to Fred Canyon (R23) 17 May 1998 (L. J. Hargrove). In prime habitat the population is so dense that up to four territorial males are within earshot of each other and sing in rotation (L. J. Hargrove). Though the big sagebrush is not typically defined as chaparral, and the Black-chinned Sparrow is absent from the Great Basin where this shrub dominates, in San Diego County the sparrow uses this plant commonly. The Black-chinned Sparrow’s use of coastal sage scrub, though, is only marginal. Outlying sites nearer the coast correspond to more isolated chaparral-covered hills, such as San Onofre Mountain (D3; one on 3 June 2000, R. and S. L. Breisch), the San Marcos Mountains (G8/H8; up to three on 31 May 1999, J. O. Zimmer), Frank’s Peak/Mt. Whitney (J9; one on 25 May 1998, J. O. Zimmer), Black Mountain (M10; three on 9 May 1999, K. J. Winter), the western edge of steep hills on Miramar (O10; feeding young on 10 June 1998, G. L. Rogers), and Cowles Mountain (Q11; up to four on 7 and 29 April 1997, N. Osborn). The lowest elevation to which breeding Black-chinned Sparrows descend appears to be about 500 feet, as in Sycamore Canyon (O12; seven on 6 May 1999, G. L. Rogers). A few pairs edge into coastal sage scrub, occupying small patches of chamise within the sage scrub or stands of denser, leafier shrubs like redberry and laurel sumac (M. A. Patten).
Along the desert slope the edge of the Black-chinned Sparrow’s breeding range tracks the edge of the chaparral closely. The notable exception is in the stunted pinyon woodland of the Santa Rosa Mountains, where the species is rare and possibly sporadic. There is one record, of a pair with three fledglings at 5700 feet elevation 1.25 miles south-southeast of Rabbit Peak (C27) 4 June 2001 (R. Thériault).
Nesting: The Black-chinned Sparrow conceals its small cup nest in the middle level of shrubs. The species of shrub appears immaterial: in San Diego County, chamise, big sagebrush, manzanita, and flat-top buckwheat have all been noted as nest sites. The nesting schedule we observed during the atlas period agrees with published data (91 California egg dates 21 April–7 July, J. D. Newman in Austin 1968), but the species’ breeding season can extend slightly later: a clutch near Guatay (P21) hatched between 17 and 19 July 1995 (Cleveland National Forest data).
Migration: During the atlas’ term, first spring dates for the Black-chinned Sparrow ranged from 16 March (1997, two at Cowles Mountain, N. Osborn) to 26 March. The earliest date ever reported is 10 March (1983, near San Diego, AB 37:911, 1983). Since 1980 spring arrival appears to have shifted a few days earlier than previously (cf. Unitt 1984). The Black-chinned Sparrow is seldom seen in migration away from its breeding habitat, but we recorded the species 12 times in spring in the Anza–Borrego Desert, mainly along the east base of the mountains, between 26 March (2001, two in Inner Pasture, N25, A. P. and T. E. Keenan) and 24 May (1997, one in Bow Willow Canyon, D. G. Seay). Though some of these birds were singing, the observations were not repeated later in the season and were not concentrated in 1998, as would be expected if the species expanded its range during a wet year. Therefore I infer that these birds were migrants. Along the coast, the only records of migrants are of one in San Clemente Canyon (P8) 27 April 1999 (M. B. Stowe) and one at Point Loma (S7) on the very late date of 5 June 2001 (R. E. Webster, NAB 55:484, 2001). As a fall migrant the Black-chinned Sparrow is equally rare, reported away from breeding habitat from 12 August to 21 October (both records from Point Loma in 1984, R. E. Webster, AB 39:104, 1985); an even later one was at Point Loma 6–28 November 1965 (AFN 20:93, 1966).
Winter: Though the Black-chinned Sparrow winters commonly in central Baja California, it is very rare at this season in San Diego County. Before 1997, there were only nine records, all from Christmas bird counts; one of the birds was collected (2 miles west of Bonita, 26 December 1940, SDNHM 18245, Huey 1954). Four of the records are from the San Diego circle, one from Oceanside, two from Escondido, one from Lake Henshaw, and one from Borrego Springs. During the atlas period, we added five records, three from the foothills of central San Diego County in 1999: two in the gorge of the San Diego River above El Capitan Reservoir (M17) 23 January (R. C. Sanger), one at 2200 feet elevation on the steep west slope of Lillian Hill (M18) 7 February (P. Unitt, L. J. Hargrove, NAB 53:210, 1999), and the third 1 mile southwest of El Capitan Dam (O16) 3 January (S. Kingswood). Two records were from rugged regions of the Anza–Borrego Desert in 1998: one above Angelina Spring (I22) 21 January (P. K. Nelson), the other from 2200 feet elevation 1.1 miles south of Sunset Mountain (J26) 11 January (J. Determan, FN 52:259, 1998). The last two records, in a wet winter, recall the “extraordinary flight” of the Black-chinned Sparrow to the Kofa Mountains of southwestern Arizona in 1955–56, “a time of unusually beneficial rain” (Phillips et al. 1964).
Conservation: The Black-chinned Sparrow does not adapt to urbanization, but its rugged habitat is unattractive to development, and much is conserved in areas under the jurisdiction of the Cleveland National Forest, Bureau of Land Management, and California State Parks. The sparrow readily recolonizes recovering burned chaparral. A study on national forest land near Pine Valley found no difference in Black-chinned Sparrow abundance between chaparral averaging 31 and that averaging six years since burning (Cleveland National Forest data). It is in thick old chaparral on north-facing slopes where the species is scarce or absent. Cowbird parasitism of the Black-chinned Sparrow occurs but appears light (Friedmann 1963). Of 31 Black-chinned Sparrow nests found around Pine Valley 1994–97 only one was parasitized (Cleveland National Forest data).
Bolger et al. (1997) listed the Black-chinned Sparrow as the most sensitive to habitat fragmentation of 20 species studied in northern San Diego. Their study design, though, assumed that the species addressed were uniformly distributed over the study area before urbanization, certainly not the case with the Black-chinned Sparrow. The sparrow’s absence or scarcity along the coast is well attested by both historical data and its current anticoastal distribution in little-developed areas like Camp Pendleton.
Taxonomy: Spizella a. cana Coues, 1866, distinguished by its combination of dark plumage and small size, is the only subspecies of the Black-chinned Sparrow occurring in San Diego County. Indeed, San Diego County constitutes the core of this subspecies’ range. The inland subspecies S. a. evura Coues, 1866, is not confirmed by specimens as a vagrant to the coast, but the individual seen on Point Loma in June may have been evura, which migrates later than cana.
Vesper Sparrow Pooecetes gramineus
Open grassland and sparse scrub in the inland valleys and desert sinks are home to the Vesper Sparrow during its winter stay in San Diego County. Generally uncommon, the Vesper Sparrow can be overlooked among the Savannah Sparrows that often outnumber it, but it is locally common in the most favorable places, Warner and San Felipe valleys. The Vesper Sparrow’s restriction to only large tracts of its habitat suggests that birds can suffer the effects of habitat fragmentation in their winter range as well as their breeding range.
Winter: The Vesper Sparrow avoids a narrow strip along the coast but otherwise occurs widely in the largest tracts of its habitats: grassland, stands of the big sagebrush, and halophytic scrub on valley floors in the Anza–Borrego Desert. In San Diego County these habitats are patchy, giving the Vesper Sparrow a patchy distribution. Sparse semidesert sage scrub was once also Vesper Sparrow habitat, but stands of this large enough to attract the birds remain only in Dameron Valley (C15; up to 10 on 6 February 1999, K. L. Weaver) and around the upper end of El Capitan Reservoir (M17/N17; up to 25 on 16 January 2002, J. R. Barth). Warner Valley and San Felipe Valley (I21/J21) offer the most Vesper Sparrow habitat, and the birds are most numerous there, with up to 35 north of Lake Henshaw (F17) 8 December 2001 (P. Unitt), 27 in the east arm of Warner Valley (G19) 10 December 2000 (R. and S. L. Breisch), and 79 in San Felipe Valley 18 December 2000 (W. E. Haas).
In the northwestern part of the county Camp Pendleton (up to 12 in San Onofre Canyon, C3, 19 January 2002, J. R. Barth), the Fallbrook Naval Weapons Station (E6, up to 12 on 11 December 1998, P. A. Ginsburg), and grassland around Willow Spring (A5, up to 20 on 12 December 2001, K. J. Winter) are the only areas where the Vesper Sparrow occurs currently. Other places where Vesper Sparrows concentrate are broad inland valleys like Oak Grove (C17; 15 on 9 December 2001, J. M. and B. Hargrove), Montezuma (Ranchita; H21/H22; 20 on 15 January 1999, P. Unitt), Santa Maria (Ramona; K13–15; 10 on 3 January 1998, E. C. Hall), Proctor (T13/T14; 30 on 5 December 1999, S. Buchanan), Rancho Jamul (S15/T15; 21 on 14 January 2001, P. Unitt), Marron (V16/V17; 15 on 22 January 2001, D. C. Seals), Campo (U22/U23; 16 on 3 February 1999, D. C. Seals), Hill (T25; 36 on 10 February 2001, E. C. Hall), and Jacumba (U28; 20 on 23 January 2001, F. L. Unmack). Another noteworthy site is the native grassland at Wright’s Field, Alpine (P17; 20 on 9 December 2001, K. J. Winter).
In the Anza–Borrego Desert the Vesper Sparrow is usually uncommon, though the Anza–Borrego Christmas bird count on 20 December 1998 produced 48 in north Borrego Springs (F24) and 56 in the entire count circle, the only record of more than eight individuals since the count’s inception in 1984. Recorded during the atlas period in the Borrego Valley and at Clark Dry Lake (D26), Little Clark Dry Lake (E27), Blair Valley (L24), and Vallecito Valley (M25), the species is localized in the Anza–Borrego Desert to poorly drained valley floors and sinks with scattered shrubs, especially saltbush.
Migration: The Vesper Sparrow begins arriving in late September and departs largely by early April. Interestingly, the six records later than 15 April are from elevations between 2500 and 4200 feet, most from stands of big sagebrush recalling the species’ breeding habitat in the Great Basin. The Vesper Sparrow breeds around Baldwin Lake in the San Bernardino Mountains, 60 miles north of San Diego County, but this is an isolated colony separated by over 100 miles from the species’ main breeding range still farther north. The latest San Diego County records are of three between Ranchita and Camel Rock (H22) 27 April 1999 and one near Adobe Springs, Chihuahua Valley (C18), 2 May 1999 (P. Unitt).
Conservation: The Vesper Sparrow’s absence from small patches of grassland suggests it is susceptible to habitat loss through fragmentation. Specimens and published reports confirm it at places where it no longer occurs, such as National City, Lake Murray (SDNHM), Poway, and El Cajon (Belding 1890). Most grassland in the coastal lowland has already been urbanized, and what remains is fragmented and degraded by the proliferation of nonnative grasses and weeds. Heavy grazing and groundwater pumping affect the Warner Valley, but fortunately two other important Vesper Sparrow sites, San Felipe Valley and Rancho Jamul, have been acquired by the California Department of Fish and Game. Field work for the atlas revealed the Vesper Sparrow to be more common in San Diego County than I reported in 1984, but this is a result of better surveys of areas formerly poorly known. Christmas bird counts show no clear trend in Vesper Sparrow numbers, though this may be an artifact of coverage. In the San Diego count circle, the best habitat, in Rancho Otay (U12), was not consistently accessible before it was eliminated. The decline of the Oregon Vesper Sparrow, P. g. affinis, may also have contributed to a decline of the Vesper Sparrow as a whole in San Diego County (see Taxonomy).
Taxonomy: The subspecies of the Vesper Sparrow dominant in San Diego County is the pale grayish P. g. confinis Baird, 1858, which breeds widely in western North America east of the Cascade Range. The smaller, buffier P. g. affinis is known in San Diego County from two specimens from Jamacha (R14) 23 February and 1 March 1924 (SDNHM 9266 and 9270) and one from El Cajon (Belding 1890). Pooecetes g. affinis breeds largely in western Washington and western Oregon, where it has gone from “abundant” in the Willamette Valley (Gabrielson and Jewett 1940) to “locally uncommon to rare” (Gilligan et al. 1994). It is recognized as a bird of special concern by the California Department of Fish and Game. Though affinis has been collected as far south as Santo Domingo in northwestern Baja California, the San Joaquin Valley was apparently the core of its winter range (R. A. Erickson unpubl. data).
Lark Sparrow Chondestes grammacus
The Lark Sparrow is a characteristic bird of San Diego County’s inland valleys. It is a year-round resident, but in winter its numbers are augmented by migrants, most noticeably in the Borrego Valley. The Lark Sparrow is common where there is ample grassland, pasture, or bare ground for foraging, yet also scattered trees or shrubs for nesting. It adapts to agriculture but retreats from urbanization.
Breeding distribution: The Lark Sparrow offers one of the clearest examples of an “anticoastal” distribution: a bird that is widespread except in a narrow strip along the coast. It remains at least 5 miles from the beach throughout the county. The only coastal atlas square with a Lark Sparrow record during the breeding season was at the far north, along the Orange County line near San Onofre (C1), and there was only a single record even there (two on 14 June 1998, K. Lopina). Just 10 miles inland, though, the species can be common, as illustrated by 30 around lower Roblar Road in Camp Pendleton (D5) 2 July 2000 (R. E. Fischer) and 50 at Lower Otay Lake (U14) 3 July 1999 (S. Buchanan). The Lark Sparrow’s center of abundance in San Diego County is the county’s largest grassland, Warner Valley (G18, 107 on 19 March 1999, C. G. Edwards; G19, 65 on 25 June 2000, P. Unitt). The grasshoppers that swarm over Warner Valley in summer are the principal food Lark Sparrows feed their young.
The Lark Sparrow ranges up to San Diego County’s highest elevations; mountain meadows and broken coniferous forest offer it good habitat. On the desert slope, it ranges down into San Felipe, Earthquake, and Mason valleys, then occurs in scattered patches in the Anza–Borrego Desert. Most desert locations for the Lark Sparrow are in or near orchards (north Borrego Valley) or shade trees around buildings (e.g., Ocotillo Wells). Yet, during the atlas period, the Lark Sparrow did not occupy all such habitat. It is evidently a recent colonist in the low desert. Our eight confirmations of breeding in the Anza–Borrego Desert are the first for this area (cf. Massey 1998). The earliest was in 1998, and all but two were in 2001. In the Imperial Valley just east of San Diego County, the Lark Sparrow colonized as a new breeding species in the mid 1980s (Patten et al. 2003). Among the grapefruit orchards of the northern Borrego Valley (E24), the Lark Sparrow is already fairly common, with up to 10 on 25 May 2001 (P. D. Ache).
Nesting: The Lark Sparrow may nest in a tree, in a shrub, or on the ground, usually at the base of a shrub. Atlas observers reported four nests on the ground or in grass. When the Lark Sparrow nests above ground its choice of site is unspecialized; atlas observers noted laurel sumac, eucalyptus, and tamarisk, and egg collections from the county mention lemon trees.
Lark Sparrow eggs collected from San Diego County 1887–1935 range from 27 March to 6 July, and our atlas data reflect this same schedule almost exactly, with fledglings as early as 26 April (1998, Cuyamaca College, R13, J. R. Barth) and a nest with nestlings as late as 29 July (2001, Edwards Ranch, I19, D. W. Au). On 27 March in the wet spring of 1998, though, K. L. Weaver noted exceptionally early nesting in the semidesert scrub of Dameron Valley (C15): a pair of Lark Sparrows carrying off small caterpillars, evidently feeding young and implying egg laying at least 11 days earlier than the previous early nest date.
Migration: There are few data on Lark Sparrow migration in San Diego County. Away from known or probable nesting habitat in the Anza–Borrego Desert, the latest spring date is 24 April (1998, two at the east end of Clark Valley, E27, P. D. Jorgensen) or 1 May (1997, one at Tamarisk Grove—a plausible site for the species to pioneer, I24, P. K. Nelson). Near the coast our only spring records outside the breeding range were of one at Whelan Lake (G6) 18 March 1998 (D. Rorick) and one at Mt. Hope Cemetery (S10) 20 April 1997 (P. Unitt). Fall migration begins by 9 September (1977, one in the Tijuana River valley, J. L. Dunn).
Winter: In winter the number of Lark Sparrows in the Borrego Valley increases greatly. Daily counts for a single atlas square in that area run up to 75 in north Borrego Springs (F24) 17 December 2000 (N. Osborn). Totals for Anza–Borrego Christmas bird counts run as high as 154 on that same day. High numbers in the inland valleys of the coastal slope—up to 400 in a day, as in Pamo Valley (I15) 29 February 2000 (O. Carter) and at Puerta La Cruz (E18) 11 December 1999 (L. and M. Polinsky)—probably reflect both an influx of migrants from the north and the local population gathering in flocks. It seems that in winter the birds leave smaller patches of breeding habitat to flock in larger grasslands. Also, the Lark Sparrow largely vacates San Diego County’s higher elevations in winter; note the lack of winter records from the Palomar and Laguna mountains, where the species breeds. From 1997 to 2002 the Lark Sparrow occurred only rarely in the coastal strip where it is absent as a breeding species. The maximum in this area was only five, at Guajome Lake (G7) 23 December 2000 (K. L. Weaver). In the Tijuana River valley (V10), the sole winter record during the atlas period was of one 19 December 1998 (P. K. Nelson).
Conservation: The Lark Sparrow responds positively to agriculture and low-density rural development. Orchards, pastures, horse corrals, and firebreaks all offer expanses of bare dirt and low weeds where the sparrow can feed. Urban sprawl, though, eliminates the Lark Sparrow. Pavement, lawns, and landscaping disfavor it. The species’ disappearance from Escondido and El Cajon, for example, is clearly the result of cities replacing farms. More curious are the coastal localities where Lark Sparrow eggs were collected 1887–1935, such as Encinitas, La Jolla, and National City. Though these have been urbanized and no longer offer Lark Sparrow habitat, they contradict the anticoastal distribution observed in recent years, which appears unrelated to urbanization because it extends seamlessly through undeveloped areas of Camp Pendleton. Bolger et al. (1997), studying birds’ response to habitat fragmentation in San Diego, identified the Lark Sparrow as a species reduced in range by fragmentation. Even in winter the Lark Sparrow is retracting inland: during the atlas period it went unrecorded in Balboa Park, where it was a sporadic winter visitor until the early 1980s (D. Herron), and it is no longer seen regularly in the Tijuana River Valley, where counts once ranged as high as 100 (20 December 1975, C. Lyons).
Taxonomy: Only the paler western subspecies C. g. strigatus Swainson, 1827, is known from California.
Black-throated Sparrow Amphispiza bilineata
Few birds evoke the rugged beauty of the Anza–Borrego Desert more than the Black-throated Sparrow. Rocky bajadas graced with agaves, yuccas, cacti, and thorny shrubs are its prime habitat, and it is common there year round. It ranges upslope into the junipers and, in smaller numbers, down onto the valley floors. To the east its numbers diminish, until around the Salton Sea it is absent.
Breeding distribution: The Black-throated Sparrow occurs almost throughout the Anza–Borrego Desert but very little outside it. Its numbers are highest on well-drained slopes supporting a diversity of cacti and thorny shrubs. In such areas, searching for a day, one can reach counts as high as over 50 in Chuckwalla Wash (J24) 15 April 2001 (L. and M. Polinsky), 82 around Jacumba (U28) 20 March 1998 (C. G. Edwards), and 100, including 90 singing males, around Indian Hill (R28) 26 April 1999 (J. O. Zimmer). On valley floors, especially on alkaline soil sparsely grown with halophytic shrubs, the Black-throated Sparrow is quite uncommon. Only in the Ocotillo Wells off-road vehicle area, though, does the species appear absent from an entire atlas square. Altitudinally, Black-throated Sparrows range from under 200 feet near Ocotillo Wells to over 5000 feet along the ridgeline of the Santa Rosa Mountains.
Toward the west, the Black-throated Sparrow drops out as chamise crowds out desert shrubs along the divide. Along the Mexican border, the Black-throated Sparrow extends west as far as Lake Domingo (U26, 21 May 1997, F. L. Unmack), still east of the Tecate Divide. In the Ranchita area, a few range a short distance onto the coastal slope west to Cañada Buena Vista (G20, one singing male 12 May 2001, A. P. and T. E. Keenan). Also on the coastal slope, a population in the Aguanga region of Riverside County extends sparsely into San Diego County in semidesert scrub on the south-facing slopes of Dameron and Oak Grove valleys, e.g., one carrying food items northeast of Oak Grove (C17) 9 June 2001 (J. M. and B. Hargrove). A tenuous linkage between Oak Grove and Ranchita is possible, implied by a report of three Black-throated Sparrows on Aguanga Ridge near Sunshine Summit (E17) 25 April 2001 (J. D. Barr).
Elsewhere on the coastal slope, the only suggestion of Black-throated Sparrow breeding before or during the atlas period was a single singing male in a patch of native needlegrass on the south slope of Poser Mountain (P18) 18 June 1999, not relocated six days later (K. J. Winter). In the record dry year of 2002, however, two appeared in burned chaparral just east of Buckman Springs (R22) in mid May (M. Sadowski, J. K. Wilson), with one still singing territorially 15 June (M. B. Stowe), and yet another was reported from north of Pine Valley in July 2002 (N. Ferguson). On the Pacific slope of Baja California, the Black-throated Sparrow ranges north to Sangre de Cristo and San Rafael Valley, just east of Ensenada and only about 50 miles south of the international border.
Nesting: The Black-throated Sparrow builds its cup nest in a wide variety of desert shrubs and cacti. Nest plants reported by atlas observers, desert lavender, ocotillo, smoketree, and cholla, are all spiny enough to offer the nest substantial protection. Elsewhere Black-throated Sparrows commonly nest in nonthorny shrubs like the creosote bush (Johnson et al. 2002). Little was known of the schedule of Black-throated Sparrow nesting in San Diego County before our field work for the atlas. Rain stimulates this species to nest, and the birds may raise two broods in wetter years (Johnson et al. 2002). Our observations suggest that egg laying ranges from about 5 March to 8 July, making even three broods are possible. A nest with young 2–4 days old in Palo Verde Canyon (E28) 20 March 1998 (P. D. Jorgensen) implies eggs laid about 5 March. In dry years, though, there is little nesting activity before April. A pair was still building a nest near Sentenac Ciénaga (J23) 4 July 1999 (R. Thériault), and nestlings hatched—in a nest built in a hanging basket around a house—in Borrego Springs (G24) 20 July 2000 (P. D. Jorgensen).
Migration: San Diego County’s population of the Black-throated Sparrow is apparently resident, but that breeding in the northern part of the species’ range is migratory. Such migrants occur rarely near the coast, most frequently in fall. There are only six coastal records in spring, between 26 March (1995, Torrey Pines State Reserve, S. Summers, NASFN 49:311, 1995) and 30 May (1984, Point Loma, V. P. Johnson, AB 38:965, 1984). Black-throated Sparrows, still in juvenile plumage, are somewhat more frequent along the coast in the fall, with at least 21 individuals reported between 20 August (1984) and 11 October (1973 and 1984; AB 28:111, 1974; 39:104, 1985). An adult in downtown San Diego (S9) 10 July 1997 (R. Scalf, FN 51:1055, 1997) was perhaps an early fall migrant or postbreeding disperser.
Winter: The distribution and abundance of the Black-throated Sparrow in winter do not differ noticeably from those in the breeding season, though the birds flock more in winter. Maximum winter counts are similar, with up to 100 in Borrego Palm Canyon (F23) 19 December 1999 (A. DeBolt) and 72 in the Table Mountain/In-Ko-Pah area (T29) 2 February 1999 (L. J. Hargrove). Numbers increased following the wet winter of 1997–98 but far less dramatically than in some other species of sparrows. Small numbers still occur in winter on the north sides of Dameron and Oak Grove valleys (maximum winter count two northeast of Oak Grove, C17, 31 December 2000, L. J. Hargrove). There are two coastal winter records, of one near Sweetwater Dam 21 December 1969 (AFN 24:541, 1970) and one in Coronado 11 December 1988 (J. Oldenettel, AB 43:368, 1989).
Conservation: Living largely on land conserved by Anza–Borrego Desert State Park and the Bureau of Land Management, on terrain that isolates it from human disturbance, and adapted to a harsh climate, the Black-throated Sparrow seems insulated from man-made problems. Ever longer droughts, though, could depress its population and shift its range to the west.
Taxonomy: A. b. deserticola Ridgway, 1898, is the only subspecies known or expected in California.
Sage Sparrow Amphispiza belli
Two subspecies of the Sage Sparrow occur in San Diego County, so well differentiated in plumage, habitat, and seasonal status that they are more easily discussed separately. Bell’s Sparrow, the dark form, is a year-round resident in chaparral and sage scrub. The habitat must not be too dense or too encumbered by leaf litter to favor this bird that spends most of its time running on the ground. Thus chaparral partly recovered from a fire, stunted by growing on magnesium-laden gabbro soil, or growing on mesa tops or south-facing slopes most frequently offers the Sage Sparrow habitat. Though broad areas of its habitat persist in south-central San Diego County, it has been eliminated from most coastal areas—it is the shrubland bird most sensitive to habitat fragmentation. The pale subspecies, the Sage Sparrow proper, is a winter visitor to the Anza–Borrego Desert, where it seeks halophytic scrub on the valley floors.
Breeding distribution: The distribution of Bell’s Sparrow follows a unique pattern, though that pattern is now partly obscured by urbanization. Because its low, open habitat is rather specialized, and shifts with fire, it is naturally patchy. Even during the breeding season territories seem clumped, perhaps because of social interaction. The distribution is most continuous in the extensive chaparral of the Campo Plateau, north into the south-facing slopes of the Laguna Mountains. Farther to the northwest, it becomes progressively more localized, but there are sites of concentrated populations. Some of these correspond to peaks or outcrops of gabbro-based soil, as on Otay, McGinty, Sycuan, Viejas, and Guatay mountains. In north-central San Diego County, semidesert climates as well as recovering burns and gabbro soils appear to be responsible for the more open chaparral attracting concentrations of Sage Sparrows around Ranchita and in Dameron and Oak Grove valleys. Near Ranchita, subspecies belli nests in stands of the big sagebrush, the same habitat as subspecies nevadensis in the Great Basin. Along the crest of the mountains, the edge of the Sage Sparrow’s range follows the edge of the chaparral. In the wet spring of 1998, a pair edged slightly into the desert, seen with a fledgling at 2040 feet elevation 0.35 mile north-northeast of Indian Hill (R28) 6 May (J. O. Zimmer). Elevationally, the Sage Sparrow is not limited in San Diego County, breeding up to at least 5600 feet near High Point, Palomar Mountain (D15; pair with fledglings 12 July 2000, K. L. Weaver).
Toward the coast, Sage Sparrows are now localized. In the south county, west of Sweetwater and Otay reservoirs, where the species was once widespread, the only birds found 1997–2002 were one pair on the hill just east of San Ysidro Junior High School (V11, 10 April 1999, P. Unitt). There is a small number on Cowles Mountain, then a population in Mission Trails Regional Park merges with that in Marine Corps Air Station Miramar. The mesa of Miramar, its chaparral broken by vernal pools, supports the largest concentration of Sage Sparrows remaining near the coast. Urban sprawl has now broken the connection between this core and other sites to the north, where the sparrows survive in scattered undeveloped patches. The largest of these is on Black Mountain (M10), where Kirsten Winter counted 18, many paired, 18 April 1999 and estimated at least 50 pairs in the atlas square on the basis of the extent of burned chaparral. The vicinity of Lake Hodges (K10) offers substantial habitat and one of the few remaining sites where the Sage Sparrow occurs in sage scrub rather than chaparral (maximum count eight on 28 May 1999, R. L. Barber). A pair feeding young about 0.7 mile southwest of the San Marcos landfill (J8) 31 May 1997, a pair just southeast of Fuerte Park, Carlsbad (J8) 15 May 1999 (J. O. Zimmer), and six, including four singing males, in black sage just northeast of Palomar College, San Marcos (I9) 2 April 1997 (K. L. Weaver) were our northernmost in coastal San Diego County during the breeding season. Farther north, the Sage Sparrow is scarce, local, and restricted to the Fallbrook Naval Weapons Station and foothills of the Santa Margarita Mountains, well away from the coast.
Nesting: Sage Sparrows nest typically in shrubs, well below the canopy, occasionally on the ground. Nest sites atlas observers noted were chamise, Cleveland sage, big sagebrush, and on the ground amid broken-down branches of big sagebrush. Our observations of breeding activity were consistent with the 25 March–18 June spread of known San Diego County egg dates, except for nest building 1 March 1997 and feeding young 27 March 1997 in Dameron Valley (C15/C16, K. L. Weaver). The habitat here resembles that in western Riverside County, where Martin and Carlson (1998) reported nest building beginning in mid February and egg laying beginning 11 March.
Migration: Bell’s Sparrow is sedentary, though in the nonbreeding season the birds cease maintaining their territories and often form loose flocks. A juvenile in residential Fallbrook (D7) in early October 1992, at least 1 mile from breeding habitat in the Naval Weapons station, demonstrates some dispersal across unsuitable terrain by young birds (K. L. Weaver).
Subspecies nevadensis, by contrast, is largely migratory. Most arrive in San Diego County probably in September (earliest date around the Salton Sea 27 August, Patten et al. 2003) and depart around the first of March. The latest date is 17 March (2000, one south of Clark Dry Lake, E26, K. L. Weaver).
Winter: The few squares on the coastal slope and desert edge where we recorded the Sage Sparrow in winter but not the breeding season are presumably sites where the species is resident in small numbers but was missed during the spring and summer. A probable exception is at Torrey Pines State Reserve (N7; one on 7 February 1998, K. Estey), a site well isolated from known populations and well covered during the breeding season. One near Agua Hedionda Creek at the east edge of Carlsbad (I7) 22 December 2001 (E. Garnica, S. Walens) may represent another small remnant population in north coastal San Diego County.
The winter range of subspecies nevadensis is completely separated from the year-round range of belli by steep mountain slopes. Stands of saltbush and iodine bush on valley floors and in sinks are the Sage Sparrow’s most typical winter habitat, but the birds can also be common in broad sandy washes with more diverse shrubs. Unexpectedly, we found the Sage Sparrow as a rare winter visitor in the open pinyon woodland of the Santa Rosa Mountains (C27/D28; maximum count two, 20–21 January 2000, L. J. Hargrove). The blackbush, though, is more numerous than the pinyons on these mountains, and forms stands of a low open scrub recalling the Great Basin. The highest counts of nevadensis recorded during the atlas period, 127 in San Felipe Creek near San Felipe Narrows (I25) 10 January 1998 (A. Mauro) and 72 in the Borrego Sink (G25) 9 February 1998 (R. Thériault) coincided with rain in a wet year. Overall numbers of the Sage Sparrow in the Anza–Borrego Desert, though, varied less dramatically in response to rain than those of some other wintering sparrows. They remained fairly steady from 1997 to 2001 and plummeted only in the record dry winter of 2001–02.
Conservation: Lovio (1996) found Bell's Sparrow to be the most sensitive to habitat fragmentation of 31 species nesting in southwestern San Diego County. The smallest tract of habitat in which he found the species was 160 hectares. K. L. Weaver (unpubl. data) had similar results in the north county, though recording the species in one patch of only 13 hectares. He has found the birds persisting over time in a 26-hectare patch near Palomar College (I9). On the basis of a study ranging from Tecolote and Rose canyons to Miramar, Bolger et al. (1997) also found the Sage Sparrow highly sensitive to fragmentation. On the Fallbrook Naval Weapons Station Bell’s Sparrows occupy rather small patches of sage scrub amid a mosaic of grassland and weeds, so apparently they do not perceive the grassy areas between the scrub patches to be barriers like housing developments. In the coastal lowland they are now restricted to the last large blocks of brushland, and their prospects in this area are dubious since many of these areas are subject to further development. Smaller tracts may not accommodate enough opportunity for the birds to shift among recovering burned chaparral and older stands that have become too dense for them. Away from the Santa Margarita Mountains, Bell’s Sparrow could easily be eliminated west of Interstate 15. Even farther inland extensive habitat degradation through fragmentation is possible. Fire-management practices that lead to infrequent colossal fires instead of frequent small ones also likely disfavor the Sage Sparrow.
Taxonomy: Patten and Unitt (2002) found too much overlap between A. b. nevadensis (Ridgway, 1873) and A. b. canescens (Grinnell, 1905) for the latter to be distinguished. Synonymizing canescens leaves only one pale migratory subspecies and eliminates the apparent but unlikely scenario that these two subspecies have the same winter range. We found no significant difference in bill length between A. b. belli (Cassin, 1850) and the supposedly longer-billed A. b. clementae Ridgway, 1898, of San Clemente Island, so we synonymized the latter, leaving only one dark subspecies of the Sage Sparrow.
Lark Bunting Calamospiza melanocorys
Though the Lark Bunting migrates southwest from the northwestern Great Plains to winter commonly in Baja California, it is rare in Alta California. Historically, records for San Diego County were concentrated along the coast in the fall, though there were also several winter and spring records, some of the latter of flocks. The more uniform coverage of the county achieved by field work for this atlas, however, suggests the Lark Bunting’s primary role here is as a rare spring migrant through the Anza–Borrego Desert.
Migration: In fall, the Lark Bunting is reported in San Diego County less than annually, with no more than three birds together. Aside from one in Mason Valley (M23) 13 September 1913 (SDNHM 1851) and one at Lake Henshaw (G17) 18 November 1978 (P. Unitt), all have been in the coastal lowland, most in the Tijuana River valley. Fall dates are 6 September and later, except for 22 July 1996, when an exceptionally early migrant was at Chula Vista (U10; D. and M. Vanier, NASFN 50:998, 1996).
In spring the Lark Bunting is notably sporadic, occasionally occurring in small flocks. It is most likely in the Anza–Borrego Desert after wet winters, as illustrated in 1983 and 1998. In the latter year, one was near Seventeen Palm Springs (F29) 4 April (C. Hagen), 10 were near Five Palms Spring (G29) 11 April (G. Rebstock, K. Forney), 10 were near the Volcanic Hills (Q29) 25 April (R. Thériault), and five were near the Borrego Air Ranch (H27) 27 April (M. L. Gabel). The Lark Bunting has occurred in the desert in normal to dry years, too, for example, one or two at Agua Caliente Springs (M26) 4 April–1 May 1990 (R. Thériault, AB 44:498, 1990) and one at the north end of Clark Valley (C25) 7 May 2001 (D. C. Seals). Desert records extend from 30 March (1999, one at Ocotillo Wells, I29, P. Unitt) to 9 May (1983, one in Earthquake Valley, K23, R. L. McKernan, AB 37:914, 1983).
There are also a few spring records for the coastal slope, clumped in a few wet years, especially 1884 and 1978, following the wettest and third wettest winters in San Diego County history. In the former year, the birds were seen in flocks at Campo (U23) and National City (T10). On 25 May, from National City, Holterhoff (1884) wrote, “they are everywhere abundant on the mesas, and apparently breeding.” No proof of breeding followed, however. The Lark Bunting has been confirmed nesting in California only in the Lanfair Valley of the Mojave Desert in spring 1978 (AB 32:1210, 1978). The only spring Lark Bunting on the coastal slope during the atlas period was in Proctor Valley (T14) 29 April 1998 (P. Unitt). With 1884 excluded, spring records for the coastal slope extend from 4 April (1977, Campo, AB 31:1049, 1977) to 20 May (1978, Horno area, Camp Pendleton, D3, A. Fries).
Winter: There are 10 winter records of the Lark Bunting in San Diego County, all of one or two individuals and all from the coastal lowland. Since Unitt (1984) listed eight, the only ones have been at Chula Vista 5–24 March 1989 (R. Reinke, AB 43:368, 1989) and about 0.5 mile northwest of the mouth of Las Flores Creek (E3) 16 February 1998 (R. and S. L. Breisch).
Savannah Sparrow Passerculus sandwichensis
Belding’s Sparrow, the nonmigratory subspecies of the Savannah Sparrow endemic to the coast of southern California and northern Baja California, is narrowly restricted to coastal marshes dominated by pickleweed. Recognized as endangered by the California Department of Fish and Game, Belding’s Sparrow has been censused statewide five times, most recently in 2001. These results suggest that the bird is holding its own, with a county population of 1105 pairs, but many threats to its habitat persist. Three other subspecies of the Savannah Sparrow, breeding to the north, come to San Diego County as winter visitors only. These subspecies are locally common in open grassy or weedy areas throughout the county and invade the Belding’s Sparrow’s habitat. Small numbers of yet another subspecies, the Large-billed Sparrow, breeding around the head of the Gulf of California, visit the coast in fall and winter.
Breeding distribution: Thanks to the work of Richard Zembal and Barbara Massey, the distribution of Belding’s Sparrow in California is known exhaustively. Field work for the atlas did not reveal any sites beyond the ones they have surveyed. The most recent census is that for 2001 (Zembal and Hoffman 2002). It recorded one territory at the Aliso Creek mouth (F4), 172 at the Santa Margarita River estuary (G4), 6 at Buena Vista Lagoon (H6), 22 at Agua Hedionda Lagoon (I6), 66 at Batiquitos Lagoon (J6/J7), 75 at San Elijo Lagoon (L7), 40 at the San Dieguito River lagoon (M7), 129 at Los Peñasquitos Lagoon (N7), 38 at Kendall–Frost Reserve, Mission Bay (Q8), 4 at the FAA island in Mission Bay (Q8), 26 at the San Diego River flood-control channel (R8), 7 at the Paradise Creek marsh, National City (T10), 93 at the Sweetwater River marsh, Chula Vista (U10), 9 at the marsh on the south site of F Street (Lagoon Drive), Chula Vista (U10), 26 at the South Bay Marine Biology Study Area (U10/V10), 102 in the south San Diego Bay salt works (U10/V10), and 289 in the Tijuana River estuary (V10/W10).
Nesting: Belding’s Sparrow places its nest in dense marsh vegetation, on or near the ground, concealed from above. Pickleweed, shore grass, and saltwort are recorded as nest plants (Collier and Powell 1998). Nesting success is higher where the marsh plants are denser and taller (Powell and Collier 1998). With 221 sets taken from 1887 to 1952, Belding’s Sparrow was one of the species whose eggs were most avidly sought by the early collectors. The breeding activity we observed from 1997 to 2001 was entirely consistent with the dates of the collected sets, 15 March–2 July.
Migration: Belding’s Sparrow is sedentary; Collier and Powell (1998) did not find population exchange even between the F Street and Sweetwater marshes, separated by only a quarter mile. Habitat fragmentation is thus a serious concern for this subspecies.
The northern subspecies of the Savannah Sparrow occur in San Diego County mainly from mid or late August to late April. By the first week of May they are rare; the latest was one 0.3 mile north of Indian Hill (R28) 6 May 1998 (J. O. Zimmer). The Large-billed Sparrow’s season is shifted earlier. Its current seasonal status is still encompassed by the dates of older specimens, 8 August (1914, National City, SDNHM 34223) to 23 February (1930, Silver Strand, SDNHM 34215).
Winter: In winter the subspecies that come from the north spread widely over San Diego County in grassland (whether it retains any native plants or not), pastures, farmland, weedy open areas, and salt marshes. These visitors are common along the coast and in the inland valleys, with up to 285 in the San Dieguito River valley east of Lake Hodges 29 December 2001 (E. C. Hall) and 255 at Sweetwater Reservoir (S12) 18 December 1999 (P. Famolaro). The beds of reservoirs exposed by low water offer Savannah Sparrows habitat: e.g., 60 on the dry floor of upper El Capitan Reservoir (N17) 31 January 2001 (J. R. Barth). In the mountains the Savannah Sparrow is uncommon; maximum counts are only 12, 2–3 miles north of Julian (J20) 27 December 1999 (R. T. Patton), and 10 northeast of Lake Cuyamaca (L21) 27 January 2000 (J. K. Wilson). In the desert it is common only in the Borrego Valley, in agricultural areas or halophytic scrub, where it may flock with Sage, Brewer’s, and Vesper Sparrows. Numbers of Savannah Sparrows in the Anza–Borrego Desert did not swing so widely over the atlas’ five years as did those of some other sparrows, but they were higher in the first two years of the period than in the three dry later ones. High counts in the desert ranged up to 56 in north Borrego Springs (F24) 20 December 1998 (R. Thériault) and 50 in Sleepy Hollow (H26) 9 February 1998 (M. L. Gabel).
The Large-billed Sparrow is strictly coastal and often mixes in the salt marshes with Belding’s. But it occurs just as readily on jetties and beaches among driftwood and kelp. During the atlas period high counts were seven at the Del Mar jetty in Camp Pendleton (G4) 15 November 2001 (P. A. Ginsburg), six near Zuñiga Point on North Island (S8) 11 January 2002, six in the south San Diego Bay salt works (U10) 15 December 2001 (D. C. Seals), and nine at Imperial Beach (V10) 16 December 2000 (C. G. Edwards). Other reported locations include the San Luis Rey River mouth (H5) and the San Diego River flood-control channel (R8). The subspecies could be expected anywhere along the coast of San Diego County.
Conservation: With the elimination of at least 75% of southern California’s salt marshes, the range of Belding’s Sparrow contracted greatly, especially around Mission and San Diego bays. Only 1182 hectares of salt marsh are left in San Diego County, some of it seriously degraded, and the birds fill the remaining suitable habitat to capacity. Now, fortunately, most of the Belding’s Sparrow’s remaining sites are designated as wildlife refuges of various kinds. But, in the delicate balance of its habitat, Belding’s Sparrow still walks a tightrope. Nesting success in small, isolated marshes like that at F Street is low to none, so these sites probably act as population sinks (Powell and Collier 1998). The marshes must be flooded regularly enough to sustain the pickleweed and prevent the invasion of upland plants but not so deeply or for so long the birds are precluded from nesting. Belding’s Sparrow’s primary habitat is the upper marsh zone that is flooded by the tide only infrequently. The birds nest only in this zone (Powell 1993), though they range outside it to forage. Because this is the part of a marsh that is most easily filled and developed, the fraction of its habitat Belding’s Sparrow has lost is even greater than the fraction of total coastal wetland lost. Currently, at Santa Margarita, Buena Vista, and Los Peñasquitos, the lagoons’ mouths are often or continuously blocked from the tides. Thus the pickleweed may dry out for long periods, then be flooded for long periods by winter rain. Restoration of consistent tidal flow at Batiquitos and San Elijo allowed the numbers of Belding’s there to increase (Zembal and Hoffman 2002). Blockage of lagoon mouths comes with accelerated sedimentation of the lagoons, a consequence of their watersheds being stripped of vegetative cover during development. Another factor is that tidal flow into most lagoons is constricted by the berms built for roads and train tracks. Sedimentation converts salt marsh into nonsaline uplands, as has happened on a large scale at Los Peñasquitos. Sediment and debris washing in from Tijuana threaten the Tijuana River estuary, site of San Diego County’s largest Belding’s Sparrow colony. Techniques for salt-marsh restoration have been established but have not yet been carried out on a scale large enough to be of significant benefit to Belding’s Sparrow. Restored habitat takes over four years to reach a structure beneficial to the birds (Keer and Zedler 2002). The low numbers at several sites and the lack of dispersal between these sites raise concern for the long-term genetic viability of the population (Zembal et al. 1988). Finally, invasion of nonnative predators, disturbance by domestic dogs, and trampling of the marshes by people are continuing problems.
The career of the Large-billed Sparrow is one of the most interesting of California’s birds. It is all the more mysterious because it has been viewed largely in ignorance of what has happened in the subspecies’ breeding range. At the turn of the last century the Large-billed Sparrow was common in marshes and on beaches, wharves, and even city streets along the coast of San Diego County. By the 1940s it was on the decline, and 1954 saw the last report for 23 years (Unitt 1984). After one seen in 1977 and one in 1987, the Large-billed Sparrow invaded in fall 1988 (AB 43:170, 1989) and 1989; 37 were reported on the San Diego Christmas bird count, 17 December 1988, and over 50 were around south San Diego Bay in September 1989 (C. G. Edwards, AB 44:165, 1990). Subsequently the numbers have not been so large, but the subspecies has continued to occur as a rare but annual winter visitor. Presumably the fluctuations are due to habitat changes in the Colorado delta and possibly to changes in sparrow’s adaptability to them.
Even the northern subspecies of the Savannah Sparrow are not immune to habitat change. With the conversion of much farmland and grassland to urban development the habitat available to winter visitors has been reduced. The thousands recorded on San Diego Christmas bird counts in the 1960s and early 1970s, primarily in the Tijuana River valley, are no longer found.
Taxonomy: Belding’s Sparrow, P. s. beldingi Ridgway, 1885, is recognized by its heavily black-streaked underparts and dark olive-tinged upperparts. The three subspecies occurring as winter visitors from the north are paler above and have narrow crisp brown streaks on the underparts. Not safely distinguishable from each other in the field, the three comprise P. s. anthinus Bonaparte, 1853, rich brown above and breeding widely in Alaska and northwestern Canada, P. s. nevadensis Grinnell, 1910, grayer with broad silvery-white streaks on the back, breeding in the Rocky Mountains and Great Basin, and P. s. brooksi Bishop, 1915, similar in color to nevadensis but slightly smaller, breeding in the Pacific Northwest. Restudy of 178 San Diego County specimens of the Savannah Sparrow reveals that anthinus and nevadensis are about equally common, with 35 and 32 specimens, respectively (Tricia A. Campbell, P. Unitt). With only four specimens brooksi is much scarcer, as might be expected with San Diego near the southern tip of its winter range. On the basis of existing specimens, both anthinus and nevadensis are widespread in the county with no difference in seasonal status, though the earliest fall specimen was collected only on 6 October and by spring the plumage of some individuals is so badly worn as to leave them unidentifiable. The Large-billed Sparrow, P. s. rostratus (Cassin, 1852), differs grossly, in its large size, brown-streaked underparts, inconspicuously streaked gray upperparts, and thick bill. It looks almost as much like a female House Finch as a Savannah Sparrow.
Grasshopper Sparrow Ammodramus savannarum
The Grasshopper Sparrow is San Diego County’s bird most restricted to native grassland—one of southern California’s most threatened habitats. The habitat, dominated by bunchgrasses of the genus Nassella, was once widespread in the inland valleys. Now it has been much diminished and degraded by overgrazing, groundwater pumping, invasion of exotic plants, conversion to agriculture, and urban sprawl. As a result, the Grasshopper Sparrow is localized and generally uncommon; it has been designated a species of special concern by the California Department of Fish and Game. Yet at a few sites it persists in numbers even where the native grass has been replaced totally by nonnative species. Because the species is so difficult to find and identify except when singing (mainly March–July), its seasonal status is still not clear. Nevertheless, atlas observers generated enough winter records to demonstrate that in San Diego County the Grasshopper Sparrow is at most a partial migrant.
Breeding distribution: The Grasshopper Sparrow’s range in San Diego County is now reduced to five main blocks and a few other scattered colonies. Camp Pendleton supports the largest area of contiguous habitat and probably the largest population, with single-day counts of up to 20 around Case Spring (B4) 30 June 1998 (P. A. Ginsburg) and 18 in Piedra de Lumbre Canyon north of Pulgas Lake (D4) 29 May 1999 (P. Unitt, B. O’Leary, J. Asmus). Both the abundance of clay soil and frequent fires favor native grassland on the base. In central coastal San Diego County the original broad distribution of grassland is much fragmented, and most of what remains is threatened by urbanization. The sites of the largest counts in this region are from the only two large areas not subject to urban sprawl: Los Peñasquitos Canyon Preserve (N8; up to 20 on 3 June 2001, B. Siegel) and Marine Corps Air Station Miramar/Mission Trails Regional Park (up to 12 in West Sycamore Canyon, O12, 24 March 1999, P. Unitt). In the southern part of the county Grasshopper Sparrow habitat is now narrowly wedged between the cities of San Diego and Chula Vista and the higher chaparral-covered mountains, McGinty and Otay. Even though the site is former agricultural land, much of which is now vegetated with exotic grasses only, Rancho Jamul, now acquired by the California Department of Fish and Game, appears to host the key population in this region (S15/T15; up to 47 on 22 April 2001, M. and B. McIntosh, V. Marquez). The Ramona grasslands are also important to the Grasshopper Sparrow, though poor access impeded our quantifying this. The site of our largest count in this region, northeast of Ramona (K15; 23 on 25 May 1998, M. and B. McIntosh), had houses built on it the following year.
In the mountains, from Dyche and Love valleys (F16) southeast of Palomar Mountain to Lake Cuyamaca (M20), Grasshopper Sparrow habitat is discontinuous and the birds appear less numerous and more irregular than at lower elevations. The highest counts were of 16 at Wynola (J19) 2 July 1999 (S. E. Smith) and nine at Lake Henshaw (G17) 12 May 2001 (R. and S. L. Breisch). Of the more isolated colonies, by far the most important is that around Willow Spring (A5), with counts of up to 20 on 25 May and 10 June 1999 (K. J. Winter).
The Grasshopper Sparrow’s grassland habitat usually has some shrubs typical of coastal sage scrub, and some of its sites are shrubby enough to have been mapped as scrub rather than as grassland. Wet winters that stimulate the spread of grass stimulate the Grasshopper Sparrow to move into marginal habitat. Its sensitivity to rainfall variation is dramatized by figures from West Sycamore Canyon in Miramar, monitored annually 1997–2002. The same area that had up to 12 territorial males in 1998 and 1999 had no more than two during the drought of 2002 (P. Unitt). After the wet winter of 1983–84, Roger Higson reported up to 30 in summer 1984 at Lake Henshaw and one at the Palomar Observatory (D15) 5 May 1984 (AB 38:1063, 1984). An atypical site for the Grasshopper Sparrow is Border Field State Park (W10), where on 23 May 2000 three birds had established territories in former salt marsh still dominated by pickleweed, now degraded by silt washed in from Tijuana (W. E. Haas). Dawson (1923) mentioned a nest near Escondido in an alkaline meadow covered with saltgrass, but no significant stands of such habitat remain inland.
Nesting: Hidden on the ground under clumps of grass, screened from above by a dome, Grasshopper Sparrow nests are notoriously hard to find. Only three were reported during the atlas period. The dates of breeding behavior we observed imply egg laying from the second week of April to the last week of May.
Migration: Records of winter visitors south to Cabo San Lucas demonstrate that the Grasshopper Sparrow is migratory, but in San Diego County the species is very rarely seen away from its breeding habitat. There are no records of such migrants in spring. The three records from Point Loma coincide in late fall: 25 October–1 November 1984 (R. E. Webster, AB 39:104, 1985), 30–31 October 1986 (R. E. Webster, AB 41:146, 1987), 22 October 1989 (M. A. Patten, AB 44:165, 1990).
Winter: Our field work for this atlas generated 55 winter records of the Grasshopper Sparrow, far more than expected and far more than reported previously. Excluding eight records from the last week of February, when the birds may begin singing, still leaves 47. By the end of the project it became clear that the species could be found consistently in its summer habitat, at least at low elevations, with persistent searching. Winter counts, excluding those in late February, ranged up to six, near Pilgrim Creek, Camp Pendleton (E7), 4 December 1998 (P. A. Ginsburg). Even the birds at higher elevations may be resident, with three as high as 3430 feet in Love Valley (G16) 22 January 2001 (W. E. Haas). The most notable winter records were from San Felipe Valley (I21, one on 8 February 2000; J21, two on 14 December 1999, P. K. Nelson), in grassland but on the desert slope where the species is not known in summer. Two at Campo (U23) 14 January 2001 (D. S. and A. W. Hester) were also in suitable habitat but at a site where no breeding birds were found.
Conservation: Dependent on a threatened habitat, the Grasshopper Sparrow’s outlook in San Diego County is dim. Most habitat is privately owned and subject to intense pressure for development. Conservation of all grasslands under multiple-species conservation plans is relatively poor (around 31% under the plan for the north county), and little native grassland remains in the areas covered by these plans. As a result, the Grasshopper Sparrow was excluded from the list of species “covered” by San Diego’s plan.
Conservation of the Grasshopper Sparrow will require action on multiple fronts. Maintaining grassland’s value as habitat may require control of invasive weeds and enhancement, possibly through burning, to give native species an advantage over exotics. In Warner Valley, San Diego County’s largest grassland, where the birds are now confined to patches around seeps, recovery will require that grazing and groundwater pumping be reduced. The largest tracts of Grasshopper Sparrow habitat currently lie on military bases and water-district lands set aside for purposes other than wildlife conservation. It is far from certain that existing parks and reserves, mainly Los Peñasquitos, Mission Trails, and Rancho Jamul, covering only a small fraction of the Grasshopper Sparrow’s habitat, will suffice to ensure the species’ survival in San Diego County.
Taxonomy: Only the western subspecies A. s. perpallidus has been collected in California. It is paler and drabber than the other Grasshopper Sparrows of North America.
Baird’s Sparrow Ammodramus bairdii
A scarce and declining bird of the northern Great Plains, Baird’s Sparrow winters regularly as far west as southeastern Arizona. But there are only three records for California, two from Southeast Farallon Island and one from San Diego County.
Migration: Southern California’s single known Baird’s Sparrow was a juvenile photographed at Fort Rosecrans Cemetery, Point Loma (S7), 5–10 October 1981 (G. McCaskie, Binford 1985).
Nelson’s Sharp-tailed Sparrow Ammodramus nelsoni
Most of the population of Nelson’s Sharp-tailed Sparrow migrates from central Canada to the Gulf of Mexico, but a few birds reach the coast of California. Here they are found in coastal salt marshes almost invariably. The birds seldom expose themselves outside the cover of dense vegetation, especially pickleweed. Birders have learned to look for them as they look for rails, during the winter’s highest tides, when high water floods them out and forces them to the marsh’s edge.
Winter: There are just 13 records of Nelson’s Sharp-tailed Sparrow in San Diego County, and some of these likely represent the same individuals returning in successive years. Locations are a freshwater marsh near Oceanside (H5) 11 October 1992 (R. R. Veit, AB 47:151, 1993), Kendall–Frost Marsh, Mission Bay (Q8), 31 December 1986–27 February 1987 and 8 October 1987–18 January 1988 (E. Copper, AB 41:331, 1987; 42:139, 323, 1988), the Sweetwater River estuary, Chula Vista (U10) 8 December 1987 (S. J. Montgomery, AB 42:323, 1988) and 2–17 December 1994 (V. P. Johnson, NASFN 49:200, 1995), and the Tijuana River estuary (V10). The six records for the last site encompass the only specimen, collected 2 November 1963 (McCaskie et al. 1967c, SDNHM 30788), the highest count (three from 22 December 1991 to 16 February 1992, A. Mercieca, AB 46:316, 1992), and the only reports during the atlas period, of two 21–22 January 2000 (D. K. Adams, NAB 54:222, 2000) and 9 January 2001 (E. Wallace, NAB 55:229, 2001).
Migration: Extreme dates for this species in San Diego County are 8 October and 27 February.
Taxonomy: The split of the Sharp-tailed Sparrow into two species (AOU 1995) has still left Nelson’s with three component subspecies. Nominate A. n. nelsoni Allen, 1875, is the one occurring in California. See Sibley (1996) for details on its identification.
Fox Sparrow Passerella iliaca
The Fox Sparrow is a common winter visitor in the chaparral that blankets San Diego County’s foothills and mountains—one of the most common winter birds in this habitat. Yet it easily passes unnoticed, foraging quietly on the ground, screened from view by dense shrubbery. Only when the birder “squeaks” or “pishes” to stimulate the birds’ curiosity do Fox Sparrows reveal their true abundance, rising to the tops of the shrubs to look around and call, “smack” or “chink.” San Diego County appears central to the winter range of two or three subspecies of the Fox Sparrow, and it hosts at least eight subspecies—more than of any other species of bird. The county is marginal, though, to the Fox Sparrow’s breeding range. Only a few birds summer, near the summit of the county’s highest mountains.
Breeding distribution: Cuyamaca Peak (M20) is the Fox Sparrow’s principal breeding site in San Diego County, occupied annually since D. W. Povey first discovered the species there in 1978. Thickets of bracken fern and Palmer’s ceanothus between Deer Spring and Cherry Flat, 5600 to 6200 feet elevation, are the birds’ habitat. The maximum count in this area, 1997–2002, was five on 13 July 2000 (J. R. Barth), less than the high of 16 reported in 1980 (AB 34:931, 1980). Fox Sparrows have also colonized the west slope of nearby Middle Peak (M20), where Richard Webster had two singing males 11 June 2000 and an adult with a fledgling 2 July 2000.
During the first opportunity for an ornithologist to visit Volcan Mountain (I20) in many years, I found Fox Sparrows in small numbers (five singing males) 30–31 May 1993. During the atlas period, only a single individual was found there, 22 July 1999 (L. J. Hargrove). Summering Fox Sparrows were found for the first time in the Laguna Mountains in 2000. C. H. Reiser reported one on Garnet Peak (N23) 26 June 2000, then G. L. Rogers reported another near Pine Mountain (N22) 30 June 2001. Roger Higson located three or four pairs around the Palomar Observatory (D15) in summer 1979 (AB 33:898, 1979), but the birds have not returned there since.
Nesting: No nests of the Fox Sparrow have yet been found in San Diego County, and the observations of fledglings on Middle Peak 2 July 2000 (R. E. Webster) and on Cuyamaca Peak 8 and 13 July 2000 (G. L. Rogers, J. R. Barth) appear to be the first confirmation of the species’ nesting here. The nest may be either in or under dense shrubs; of eight nests Pierce (1921) described in the San Bernardino Mountains, three were on the ground, five were in ceanothus bushes.
Migration: Wintering Fox Sparrows depart gradually through March and April. No peaks or concentrations of migrants are known or expected, given that northwestern Baja California marks the southern end of the species’ winter range. By 1 May the Fox Sparrow is rare. The only records of spring migrants after 3 May during the atlas period were of one at Yaqui Well (I24) 24 May 1999 (P. K. Nelson) and one at Camp Horno, Camp Pendleton (D3), 27 May 2000 (P. A. Ginsburg), and these appear to be the latest ever. Fall migrants begin returning in the third week of September.
The migration schedule of the Fox Sparrows nesting in San Diego County’s mountains is still not known. The birds have been reported on Cuyamaca Peak only from 23 May to 6 August. Data from elsewhere in California suggest arrival in April and departure in September or early October.
Winter: The Fox Sparrow is widespread over the coastal slope of San Diego County, most concentrated in extensive stands of mature chaparral. In northern San Diego County the Santa Margarita Mountains, the north slope of Palomar Mountain, and the Indian Flats/Bucksnort Mountain region emerge as regions of greatest abundance. In central and southern San Diego County the Fox Sparrow is common almost continuously from Viejas (O17), McGinty (R15), and Sycuan (R16) Mountains east to the Lagunas. Our high counts, of up to 70 near Thing Valley (Q24) 7 January 2001 (J. R. Barth) and 55 along Miner’s Road (O21) 5 January 1999 (P. Unitt), could be duplicated easily in this region by an observer focusing his effort on Fox Sparrows.
The Fox Sparrow occurs in coastal sage scrub and riparian scrub but is uncommon in those habitats, and it is lacking in grassland and developed areas, making its distribution patchy. It can still be fairly common even right along the coast, though, where conditions are suitable, as around Onofre Hill (D2; 12 on 21 January 2002, P. Unitt) and Torrey Pines City Park (O7; 10 on 16 January 2002, D. G. Seay). At the desert’s edge, the Fox Sparrow drops out quickly as the chaparral begins to break up. On the desert floor the Fox Sparrow is very rare, recorded twice in Borrego Springs (G24, one on 14 January 1991, A. G. Morley; F24, one on 20 December 1998, R. Thériault) and seven times at Yaqui Well and Tamarisk Grove (I24; ABDSP database).
Conservation: Whether the small numbers of Fox Sparrows in San Diego County’s mountains represent a recent range extension or a discovery (as a result of better coverage) of birds long present remains unknown. Because the numbers are so small, the population is vulnerable to disruptions like fire or prolonged drought, but the Fox Sparrow’s chaparral habitat regenerates quickly after fire. Broad-scale climate change, though, could push the birds’ preferred habitat to an elevation zone above the county’s highest peaks. Urbanization has rendered a chunk of the Fox Sparrow’s winter range unusable, but the core of this range is inland from the coastal regions where the cities are spreading. The Cleveland National Forest encloses the areas of the Fox Sparrow’s greatest winter density, so it seems likely the species will remain common in winter indefinitely.
Taxonomy: The Fox Sparrow offers one of the prime examples of the application of subspecies, because its subspecies enable us to identify the regions where these winter visitors originate. The largest numbers come from the Sierra Nevada and Cascade Range, but other major sources are southwestern and/or south-central Alaska and the Rocky Mountains, in both Canada and the contiguous United States.
Swarth (1920) divided the Fox Sparrow into three groups of subspecies: the gray or schistacea group, with plain gray crown and back, the brown or unalaschcensis group, with plain brown crown and back, and the red or iliaca group, with a red-streaked gray crown and back. This arrangement has been supported by genetic studies, leading to the proposal that each group be considered a species in its own right (Zink 1986, 1994, Rising 1996). Nevertheless, there are specimens intermediate between the groups, whole subspecies intermediate between the gray and red groups, and no known differences in the birds’ winter ecology. The Fox Sparrows most common in San Diego County are of the schistacea group, having gray heads and backs contrasting with more rufous wings and tails and black spots on the underparts. This group can be divided into three subspecies on the basis of bill thickness. The heaviest-billed birds, the subspecies P. i. stephensi Anthony, 1895, are those breeding in the high mountains of southern California, including San Diego County. No specimens of the local breeding population, however, have been collected yet. Mailliard (1918) named the large-billed Fox Sparrows breeding in the inner Coast Ranges of northwestern California from the Trinity River to Snow Mountain as P. i. brevicauda, and Swarth (1920) supported this, distinguishing brevicauda from stephensi by its supposedly browner color, shorter tail, and more bulbous bill. The color difference is not evident in specimens now so was presumably based on comparison of specimens of different ages—the Fox Sparrow is a prime exemplar of foxing, the tendency of feather color to drift from gray to brown to rusty as a bird skin sits in the museum. The shorter tail is a poor character because these ground-dwelling birds’ tails wear so quickly; hardly any specimens collected during the breeding season have a tail intact enough to yield a valid measurement. There is a slight average difference, insufficient to diagnose a subspecies (male brevicauda mean 85.0, n = 20 in MVZ and CAS, standard deviation 4.01; male stephensi mean 89.2, n = 5 in MVZ and SDNHM, standard deviation 2.93). Zink (1986) found no difference between the populations in the length of the outermost rectrix. Bill shape varies much among individuals, and the width of the maxilla of stephensi actually averages greater than that of brevicauda (male brevicauda mean 9.47, n = 60; male stephensi mean 9.58, n = 38). Therefore, despite the two populations’ ranges being so disjunct, brevicauda cannot be distinguished from stephensi and must be considered a synonym of it. Including brevicauda, stephensi is uncommon as a winter visitor in San Diego, with six specimens (4 miles southwest of Ramona, L14; Old Mission Dam, P11; Flinn Springs, P15; 3 miles south of Alpine, Q17; Otay Mountain, V12).
The Fox Sparrows breeding in the southern Cascade Range and northern and central Sierra Nevada, P. i. megarhynchus Baird, 1858, are gray like stephensi but have a smaller bill, though the bill is still larger than in the remaining subspecies of the Fox Sparrow. The difference in bill thickness is adequate to support megarhynchus and stephensi as subspecies by the criteria of Patten and Unitt (2002) (Table 8). Fox Sparrows averaging smaller billed, intermediate toward the small-billed birds of the Great Basin, occur on the east slope of the Cascade Range in Oregon, on northeastern California’s Modoc Plateau (P. i. fulva Swarth, 1918), and in and near Mono County, California (P. i. monoensis Grinnell and Storer, 1917). These populations’ differences from megarhynchus, though, are insufficient to support their recognition as subspecies; both must be synonymized with megarhynchus (Table 8). Zink (1986) made the same recommendation. He proposed merging stephensi and brevicauda with megarhynchus as well, while saying “there might be a basis for recognizing two groups, stephensi plus brevicauda vs the other three” (i.e., megarhynchus, fulva, and monoensis). Data in Table 8 show that the Fox Sparrows in the largest-billed subspecies’ core ranges are adequately differentiated to merit another name. Defined to include fulva and monoensis, megarhynchus is the most numerous subspecies of the Fox Sparrow in San Diego County, represented by 83 of 124 SDNHM specimens (67%). These specimens range from La Jolla and Point Loma on the coast east to Oriflamme Canyon (M22) and the Laguna Mountains (P23), on dates extending from 7 October to 11 April.
Table 8 Bill depths of males of gray subspecies of the Fox Sparrowa
| Nominal subspecies |
N |
Mean |
Range |
Standard deviation |
|
stephensi |
50 |
14.14 |
12.8–15.2 |
0.53 |
|
brevicauda |
59 |
13.65 |
12.5–14.5 |
0.44 |
|
megarhynchus |
53 |
11.90 |
11.3–13.0 |
0.41 |
|
monoensis |
25 |
11.72 |
10.8–12.6 |
0.49 |
|
fulva |
98 |
10.83 |
9.1–12.2 |
0.59 |
| schistacea |
51 |
9.53 |
8.7–10.6 |
0.41 |
aAll specimens from the breeding range; bill depth measured by Swarth’s (1920:83) technique.
Passerella i. schistacea Baird, 1858, the Fox Sparrow of the Great Basin and Rocky Mountains north to southwestern Alberta is gray too but has a small bill, like that of the brown and rusty subspecies. It includes as synonyms P. i. canescens Swarth, 1918, and P. i. swarthi Behle and Selander, 1951. Specimens of schistacea from eastern Nevada are well differentiated from those of megarhynchus on the west slope of the Sierra Nevada (Table 8). P. i. schistacea is much less common than megarhynchus but appears more prevalent in semidesert chaparral. Of the 15 SDNHM specimens from San Diego County eight are from the east slope of the mountains at the edge of Fox Sparrow habitat. Others, though, are from as close to the coast as 4 miles north of San Marcos (H9) and Escondido (J10).
The Fox Sparrows of the Washington Cascades and south-central British Columbia are an intermediate step between schistacea and the browner subspecies altivagans to the north. This subspecies, P. i. olivacea Aldrich, 1943, appears to reach San Diego County in small numbers. Four specimens from San Diego County meet the description of olivacea or intergrades between olivacea and altivagans: Point Loma (S7), 16 December 1970 (SDNHM 37751), Highland Valley (K12), 9 October 1950 (SDNHM 29877), 1 mile north of Cibbets Flat (Q23), 11 December 1989 (SDNHM 46484), and 0.95 mile north of Los Pinos Mountain (R20), 13 March 1984 (SDNHM 42942).
All along the Pacific coast from Unalaska Island in the Aleutians to the Olympic Peninsula of Washington nest the seven brown or sooty subspecies of the Fox Sparrow. These subspecies have the entire upperparts almost uniform, the wings and tail hardly more rufous than the back, brown spots on the underparts, and a distinctly yellow base to the mandible. These subspecies are famed for their leapfrog pattern of migration: the southernmost migrating little or none, the northernmost migrating the farthest, that is, to San Diego. The three northernmost subspecies, P. i. unalaschcensis (Gmelin, 1789), breeding in the eastern Aleutian Islands and Alaska Peninsula, P. i. insularis Ridgway, 1901, breeding on Kodiak Island, and P. i. sinuosa Grinnell, 1910, breeding in south-central Alaska, are closely similar. Willett (1933) implied that they are better combined, but Gibson and Kessel (1997), with specimens from the breeding range, continued to recognize them. With 22 of 124 SDNHM specimens, unalaschcensis is less numerous in San Diego County than megarhynchus, but it is still common and widespread. The specimens range from Point Loma (S7) to the Cottonwood Campground in the In-Ko-Pah Mountains (Q25), near the east edge of the chaparral.
Coastal Fox Sparrows from farther southeast in Alaska reach San Diego County only rarely. Bishop (1905) reported that H. C. Oberholser identified three of 13 Fox Sparrows taken at Witch Creek (J18) on 12 December 1904 as P. i. annectens Ridgway, 1900, a somewhat darker brown subspecies breeding in the Yakutat area of Alaska. There is only one county specimen of annectens in the SDNHM collection (46485), from 1 mile north of Cibbets Flat (Q23) 11 December 1989 (T. Ijichi). Still darker birds, sooty brown on the upperparts and very thickly spotted on the underparts, breed in southeastern Alaska and on the Queen Charlotte Islands—P. i. townsendi (Audubon, 1838). One specimen of townsendi has been collected in San Diego County, 2 miles east of Descanso (P20) 16 November 1924 (M. Canfield). These are the southernmost specimens known of both annectens and townsendi—their main winter ranges lie farther north.
In interior British Columbia and the northern Rocky Mountains of Alberta breed Fox Sparrows that bridge the schistacea and iliaca groups, the subspecies P. i. altivagans Riley, 1911. It has brown spots on the underparts and brown upperparts, often with a hint of the rufous streaking characteristic of the iliaca group. Swarth grouped altivagans with iliaca; Zink (1994) and Rising (1996) grouped it with schistacea. Toward the coast of British Columbia it apparently intergrades with the dark subspecies of the unalaschcensis group as well (Swarth 1920). Specimens of altivagans lacking any back streaking resemble the geographically disjunct sinuosa, differing most clearly in their brighter rufous, more contrasting uppertail coverts. Distinguishing altivagans in the field from the paler subspecies of the unalaschcensis group may not be possible unless there are differences in calls or bill color, still inadequately explored. P. i. altivagans is an uncommon or fairly common winter visitor in San Diego County, with 13 SDNHM specimens scattered from Point Loma to the Laguna Mountains. Another specimen from Ames Valley in the Laguna Mountains (P23) 14 November 1983 (SDNHM 42692) appears to be an intergrade between altivagans and P. i. fuliginosa Ridgway, 1899, the darkest subspecies of the brown group.
Finally, P. i. zaboria Oberholser, 1946, the western representative of the boldly patterned rufous-and-gray iliaca group, reaches San Diego County very rarely. There is one specimen of zaboria, from Point Loma 18 November 1968 (SBCM 4423), and four sight records, from Agua Caliente Springs (M26) 25 February 1973 (G. McCaskie), Tijuana River valley 8 March 1974 (G. McCaskie), near Green Valley Falls Campground (N20) 11 January 1992 (K. L. Weaver), and Santee (P12) 12 February 2002 (M. B. Mulrooney, NAB 56:225, 2002).
Song Sparrow Melospiza melodia
The Song Sparrow is the most abundant bird in San Diego County’s riparian woodlands. Freshwater marshes, low rank vegetation in disturbed areas, shrubbery in parks, coastal chaparral, and any dense vegetation near water offer it habitat too. Though making little use of heavily built-up areas, the Song Sparrow on balance benefits from human modification of the southern California environment, taking advantage of agriculture, irrigated landscaping, and urban runoff. A year-round resident, it is seen only very rarely in desert areas outside its breeding range.
Breeding distribution: Though the Song Sparrow lives mainly around water, its habitat needs are generalized enough that on the scale of our atlas grid its distribution appears almost uniform over the coastal slope. The few gaps correspond to large stands of chaparral and/or coniferous forest. Concentrations correspond to squares with much riparian woodland (especially northwestern San Diego County), lagoons, and lakes. In prime habitat daily counts of Song Sparrows can be in triple digits, e.g., 226 in lower Los Peñasquitos Canyon (N8) 3 May 1997 (L. D. and R. Johnson et al.), 125 in Daley Ranch (H11) 31 May 1998 (C. G. Edwards).
On the desert slope the Song Sparrow occurs in all canyons where there is permanent water: Coyote Creek (C22/D23), Borrego Palm (F23), Hellhole (G23), Sentenac (J23), Vallecito Creek (M23–25), Canebrake (N27/O27), Bow Willow (P26), and Carrizo (Q27/R27). It also inhabits the oases of Agua Caliente Springs (M26, up to four on 4 June 1998, E. C. Hall) and Carrizo Marsh (O29, up to eight on 17 April 1998, M. C. Jorgensen). It has colonized plant nurseries on the floor of the northern Borrego Valley (maximum 16 at Ellis Farms, F25, 13 May 2001, P. D. Ache), outside its historic breeding range but in parallel with the spread of the coastal subspecies heermanni on the floor of the Coachella Valley in Riverside County (Patten 2001).
Nesting: Song Sparrows usually build their cup nest in or under dense low vegetation. The nest is occasionally higher, such as one 10 feet up in a saltcedar in Vallecito Valley (M24). It is often over or near water, as implied by atlas observers’ reports of nests in cattails, hedge nettle, and debris left by a flood. Some nests are in drier places, and some are in entirely man-made habitats, such as one in rosemary in a garden and another in a potted shrub in a nursery.
Song Sparrows are prolific, often raising three, rarely four broods per year (M. M. Nice in Austin 1968). In San Diego County they usually nest from March to July. A few birds begin even in mid February, as implied by two fledglings at the east end of Lake Hodges (K11) 17 March 1999 (E. C. Hall), adults carrying insects at Sentenac Ciénaga (J22) 3 March 1997 (L. Allen), and an egg set collected at Encinitas (K6) 16 February 1939 (WFVZ).
Migration: The local population of the Song Sparrow appears practically sedentary. In the Anza–Borrego Desert, migrants occur rarely away from sites where the species is resident: south Borrego Springs (G24), one on 7 March 1998 (P. D. Ache); Borrego sewage ponds (H25), one on 4 April 1997 (H. L. Young, M. B. Mosher); Yaqui Well (I24), one on 18 March 1997 (P. K. Nelson); Arroyo Seco del Diablo (N28), one on 14 March 1998 (R. and S. L. Breisch). Massey (1998) also reported single spring sightings from Clark Dry Lake (D26/E26) and Indian Valley (O27). These records more likely represent wanderers or pioneers of the local subspecies heermanni rather than migrants headed farther north: heermanni occasionally reaches the Imperial Valley (Patten et al. 2003).
Winter: In San Diego County, the only site outside the Song Sparrow’s breeding range where the species appears even somewhat regular in winter is the Borrego sewage ponds (H25), with three records 1997–2002, of up to two on 16 January 1999 (P. D. Jorgensen) and 16 December 2001 (L. D. and R. Johnson). The few other winter records from atlas squares where no Song Sparrows were noted during the breeding season are adjacent to squares where it breeds; they may represent sites where it is resident in small numbers.
Conservation: Although primarily a species of riparian woodland and scrub, many of whose birds have suffered declines, the Song Sparrow continues to thrive. Though a principal host for the Brown-headed Cowbird, the Song Sparrow remained common in San Diego County in spite of the cowbird’s invading. Importation of water and irrigation allowed the sparrow to colonize areas formerly unsuitable, compensating for loss of riparian habitat. Urban runoff yields enough water to turn small canyons within the cities into Song Sparrow habitat. Although sparse in older residential areas, the Song Sparrow colonizes the ornamental shrubbery around new office parks and in landscaped housing developments. Low rank weeds often suffice: after a restoration attempt at the San Dieguito River estuary (M7), a sandy island intended as a Least Tern site was soon overgrown with weeds, and Song Sparrows moved in. The amount of habitat needed to support a pair may be quite small—Song Sparrows can usually be found in the patch of ornamental shrubbery, measuring about 50 by 30 feet, on the northeast side of the San Diego Natural History Museum.
Taxonomy: Though the Song Sparrow has differentiated into a remarkable number of subspecies—25 even after Patten’s (2001) revision dispensed with some inadequately defined ones—only two of these are known from San Diego County. The resident subspecies, characterized by its heavy black streaking below and tricolor (black, brown, and olive gray) streaking above, is M. m. heermanni Baird, 1858, from which cooperi Ridgway, 1899 (type locality San Diego) is not well differentiated (Patten 2001). Although heermanni hybridizes with the small pale rusty fallax of the desert Southwest in the Coachella Valley of Riverside County (Patten 2001), the Song Sparrows at even the easternmost sites in San Diego County, Borrego Valley and Carrizo Marsh, appear typical of heermanni.
Some other subspecies breeding to the north of San Diego County are migratory, but their winter ranges do not extend quite this far south. The only specimen of one of these migrants is M. m. merrilli Brewster, 1896, collected by L. M. Huey at Yaqui Well (I24), where heermanni is absent, 13 October 1936 (SDNHM 17255). M. m. merrilli has moderate rufous streaking on its underparts and muted streaking on its upperparts—it would be readily noticed in the field as different from heermanni. The specimen from Yaqui Well is too pale and crisply streaked for subspecies morphna of the Pacific Northwest, as Huey (1954) reported it. M. m. merrilli originates in the intermountain area of eastern Washington, southeastern British Columbia, northern Idaho, and northwestern Montana. The next winter records north of San Diego County are from Los Angeles County (Grinnell and Miller 1944).
Lincoln’s Sparrow Melospiza lincolnii
Though often overlooked, hidden in dense, low vegetation, Lincoln’s Sparrow is not rare. It is uncommon, even fairly common, in riparian scrub, riparian edges, and damp weedy areas. One must learn its juncolike “tup” and buntinglike buzz calls to appreciate Lincoln’s Sparrow’s actual numbers. Lincoln’s Sparrow occurs in San Diego County as a migrant and winter visitor only. Though the southern tip of its breeding range is as close as the San Jacinto Mountains of Riverside County, there is only one summer record for San Diego County.
Winter: Lincoln’s Sparrow is widespread in the coastal lowland, where the damp thickets the birds prefer are most frequent. During the atlas period, daily counts ran to a maximum of 35 at the south base of Cerro de las Posas, San Marcos (J8), 24 December 1997 (J. O. Zimmer) and 26 in the San Pasqual Valley (K12) 2 January 2000 (C. G. Edwards). In wet years even higher numbers occur in the thick ruderal vegetation along Santa Ysabel Creek in the San Pasqual Valley (K. L. Weaver). Seldom, though, are more than 10 individuals counted in a day, even in good habitat. And the species was missed entirely in a few atlas squares with substantial riparian habitat where it should be expected. Other gaps at low elevations are due to dearth or lack of habitat. At higher elevations, in more rugged terrain, wintering Lincoln’s Sparrows become progressively scarcer and more localized. A few individuals occur as high as 5300 feet elevation, such as one near the Palomar Fire Station (D15) 4 December 1998 (K. L. Weaver) and two at Cuyamaca Lake (M20) 22 February 1999 (A. P. and T. E. Keenan).
In the Anza–Borrego Desert, Lincoln’s Sparrow is uncommon at oases and in developed areas with irrigated shrubbery. Desert numbers range up to 21 in Borrego Springs (F24) 20 December 1998 (R. Thériault), six at Lower Willows (D23) 19 December 1999 (P. R. Pryde), and five at Agua Caliente Springs (M26) 28 January 1998 (E. C. Hall). We noted only five scattered individuals in dry desert habitats, and three of these were in the wet winter of 1997–98.
Migration: Lincoln’s Sparrows arrive in mid to late September, then depart in April. Scattered birds are seen in late March and April at locations where the species does not winter, rarely even in sparsely vegetated desert. By the first of May the species is rare. The only spring records after 5 May are of single birds near Puerta La Cruz (E18) 12 May 2001 and near Angelina Spring (I22) 16 May 1999 (both P. K. Nelson). The single summer record is of one along Doane Creek, Palomar Mountain State Park (E14) 7 July 1986 (K. L. Weaver, E. J. McNeil)—the wet meadow at this site is the closest approximation to Lincoln’s Sparrow’s breeding habitat in San Diego County.
Conservation: No trend in Lincoln’s Sparrow numbers in San Diego County is obvious. Christmas bird count results suggest much variability from year to year, but, among the county’s six counts, these variations do not run in phase. Importation of water benefits Lincoln’s Sparrow; even the weedy dry beds of reservoirs exposed during droughts are good Lincoln’s Sparrow habitat. But the development of floodplains—channelizing, landscaping, paving—disfavors this bird so partial to uncontrolled dense undergrowth.
Taxonomy: Two subspecies of Lincoln’s Sparrows are generally recognized, M. l. gracilis (Kittlitz, 1858), breeding in southeastern Alaska and coastal British Columbia, and M. l. lincolnii (Audubon, 1834), breeding in the rest of the species’ transcontinental range. The two still need to be better defined; the characters of gracilis, small size and heavier black streaking on the upperparts, are not always correlated. As might be expected from its much wider range, nominate lincolnii is the common subspecies in San Diego County, but some examples of gracilis (core winter range central and northern California) reach us as well. Of the 30 Lincoln’s Sparrow specimens in the San Diego Natural History Museum, three appear to qualify as gracilis on both characters: National City (T10) 10 January 1924 (SDNHM 9216), Tijuana River valley 25 October 1974 (SDNHM 38983), and Point Loma (S7) 19 March 1990 (SDNHM 46540).
Swamp Sparrow Melospiza georgiana
The Swamp Sparrow lives mainly east of the Rocky Mountains but is a regular rare fall migrant and winter visitor to California. It is well named, for it seeks freshwater marshes and the undergrowth of riparian woodland.
Winter: The Swamp Sparrow is an annual visitor to San Diego County. The atlas period 1997–2002 was rather meager for the species, with only seven reported. Three per year is more typical. All wintering Swamp Sparrows have been found in the coastal lowland except for one at Lake Henshaw (G17) 20 February 1979 (AB 33:317, 1979). Typical sites are San Elijo Lagoon (L7; 1 April 2000, M. B. Mulrooney), San Dieguito Valley (M8; 28 December 1997, P. Unitt), Santee Lakes (P12; 9 February 2000, J. C. Worley), Lindo Lake (P14; 17 January–18 February 2002, M. B. Mulrooney), and the Dairy Mart Pond, Tijuana River valley (V11; 1–11 January 2000, G. McCaskie). The maximum seen in one area is four in the Tijuana River valley 18 January 1964 (G. McCaskie); nine were seen countywide that winter. December 1990 yielded two on the Oceanside Christmas bird count and five on the San Diego count.
Migration: Fall migrants have been noted a few times in atypical habitat such as Point Loma (S7). The only record for the Anza–Borrego Desert is of one at the Borrego sewage ponds (H25) 9 November 1997 (P. D. Jorgensen). Dates for the Swamp Sparrow in San Diego County extend from 13 October (1957, near Lakeside, P14, AFN 12:60, 1958) to 11 April (1975, O’Neill Lake, E6, A. Fries), except for the single known spring vagrant, singing along the San Diego River in Mission Valley (R9) 30 May 1992 (P. Unitt, AB 46:482, 1992).
Taxonomy: The two specimens from San Diego County, from the east end of Sweetwater Reservoir (S13) 4 November 1943 (SDNHM 18759) and the Tijuana River valley 12 February 1964 (SDNHM 35080), are M. g. ericrypta Oberholser, 1938, which breeds in the northern part of the species’ range, through the boreal forest of Canada.
White-throated Sparrow Zonotrichia albicollis
The White-throated Sparrow is a rare but regular winter visitor to San Diego County. The five-year atlas-study period generated about five sightings per year. The White-throated Sparrow is often found with the more common species of Zonotrichia but prefers the cover of dense vegetation, much like the Golden-crowned Sparrow. It avoids the open scrub and grassland where the White-crowned Sparrow is often abundant.
Winter: In San Diego County the White-throated Sparrow occurs widely through the coastal slope. Its locations during the atlas period were all at 2600 feet elevation or lower, but earlier records go as high as 4600 feet at Lake Cuyamaca (M20). There are only a few records from the Anza–Borrego Desert, of birds picked up dead at the Borrego airport (F25) 7 and 19 December 1984 (SDNHM 44445 and 44498), one in Borrego Springs (G24) 30 December 1990–16 March 1991 (A. G. Morley), and one at Agua Caliente Springs (M26) 28 January 1998 (E. C. Hall). Seldom is more than one White-throated seen at a time, though it flocks with other sparrows. The maximum is three, as at Fort Rosecrans Cemetery, Point Loma (S7), 2 March 2002 (D. V. Blue).
Migration: The White-throated Sparrow occurs in San Diego County mainly from November to March, but dates range from 10 October (1974, Point Loma, J. L. Dunn) to 12 May (1988, same location, R. E. Webster, AB 42:483, 1988).
Harris’ Sparrow Zonotrichia querula
Breeding in the central Arctic of Canada, Harris’ Sparrow winters mainly on the southern Great Plains of the United States. In California it is a rare winter visitor, and in San Diego County, through 2003, there are 24 records. When Harris’ Sparrow shows up in the county, it often flocks with the abundant White-crowned Sparrow.
Winter: Records of Harris’ Sparrow in San Diego County are well scattered through the coastal lowland from Fallbrook (D15; one from 16 December 1984 to 8 January 1985, L. Bevier, AB 39:211, 1985) to the Tijuana River valley (four records). Although the species commonly winters in regions with a climate far harsher than any San Diego County has to offer, only one Harris’ Sparrow has been seen in the county above 1500 feet elevation: at about 2500 feet in Dameron Valley (C15; 6 February 1999, K. L. Weaver). It was also the only one reported 1997–2001. Other recent sightings are from Guajome Lake (G7) 29 December 1996 (K. L. Weaver, Oceanside Christmas bird count), San Elijo Lagoon (L7) 28 November–13 December 2003 (J. Benton), and the Sweetwater County Park campground (T13) 14 December 2002 (S. Walens, NAB 57:259, 2003). All reports are of single individuals, except for one of two birds in the Tijuana River valley 16 December 1972–20 January 1973 (G. McCaskie).
Migration: San Diego County’s records of Harris’ Sparrow extend from 22 November (1970, Tijuana River valley, AB 25:112, 1971) to 10 May (1976, Coronado Cays, T9, AB 30:893, 1976).
White-crowned Sparrow Zonotrichia leucophrys
In winter, the White-crowned Sparrow is one of San Diego County’s most abundant birds. Some grass, weeds, or open ground for foraging, and nearby shrubbery or trees for refuge from predators, are all it needs for habitat at this season. Thus coastal sage scrub, broken chaparral, woodland edges, desert-edge scrub, desert washes and sinks, urban parks, and disturbed weedy areas all are home to the White-crowned Sparrow during its seven-month stay in San Diego County. White-crowned Sparrows often gather in large flocks and patronize bird feeders, making them seem even more numerous.
Winter: As an abundant winter visitor, the White-crowned Sparrow seems to be everywhere. On the coastal slope it is indeed almost ubiquitous, being scarce or lacking only at the highest elevations. The largest numbers are near the coast and in the inland valleys, with reports as high as 940 in the Tijuana River valley 18 December 1999 (W. E. Haas) and 700 at Sweetwater Reservoir (S12) 20 December 1997 (P. Famolaro). Large numbers sometimes occur even as high as 5000 feet (572 near Julian, J20, 27 December 1999, E. Post; 253 near San Ignacio, Los Coyotes Indian Reservation, E21, 11 December 1999, K. L. Weaver, C. R. Mahrdt). In the Anza–Borrego Desert the White-crowned Sparrow is abundant around oases and irrigated developed areas, with counts as high as 1053 in north Borrego Springs (F24) 20 December 1998 (R. Thériault et al.). In dry natural desert habitats, though, its numbers vary with rainfall. White-crowned Sparrow numbers in the desert outside Borrego Springs were greatest during the atlas’ first year, the wet winter of 1997–98. Daily counts in creosote bush scrub ran as high as 300 on Mescal Bajada (J25) 11 January 1998 (M. and B. McIntosh) and near Indian Hill (R28) 8 February 1998 (J. O. Zimmer). The following three years White-crowned Sparrows remained fairly steady at a level less than half that in the wet year. In the atlas’ final winter, the record dry winter of 2001–02, their numbers dropped even further. During the drought, the sparrows became so sparse over so much desert that they were missed in 16 atlas squares not covered in 1997–98.
Migration: In fall, the White-crowned Sparrow arrives punctually in the third week of September and is common by the end of that month. The earliest date is 7 September with one near Lake Murray (Q11; N. Osborn) and two near Los Peñasquitos Lagoon (N7; D. K. Adams) in 2003. In spring, the sparrow’s numbers decrease through April and early May. By the end of April the species is uncommon, though large numbers remained in the Anza–Borrego Desert into late April after the wet winter of 1997–98: 150 on Mescal Bajada (J25) 26 April 1998 (M. and B. McIntosh), 30 at Vallecito (M25) 27 April 1998 (M. C. Jorgensen). By mid May the White-crowned Sparrow is rare, and the only records after 20 May during the atlas period were of single birds at Lower Willows (D23) 21 May 2001 (M. L. Gabel), in La Jolla (P7) 22 May 1999 (L. and M. Polinsky), along the Pepperwood Trail (P25) 22 May 2000 (L. J. Hargrove), and one at the De Luz Campground (B6) 29 May 2000 (K. L. Weaver). Ill health accounts for some of these stragglers; for example, the bird on the Pepperwood Trail had a tumor over one eye. The only later record published is of one in East San Diego (S10) 2–11 June 1975 (AB 29:912, 1036, 1975).
Breeding distribution: There is only one record of the White-crowned Sparrow breeding in San Diego County, of a pair with three juveniles near the Palomar Observatory (D15) 18 July 1983 (R. Higson, AB 37:1028, 1983). This is far outside the species’ normal breeding range, which extends south only to Mt. San Gorgonio, and the small colony even there is an outlier from the main range of subspecies oriantha in the high Sierra Nevada. The record at Palomar, though, came after the wet El Niño winter of 1982–83, the event most likely to induce such a bizarre occurrence.
Conservation: The White-crowned Sparrow is less common in heavily urbanized areas than where much open ground remains, whether the latter is natural or disturbed. But no trend in its winter numbers is obvious. The breeding range of our principal subspecies, gambelii, is far to the north in little-disturbed subarctic regions, so the White-crowned Sparrow seems secure as a dominant bird of San Diego County’s winter landscape.
Taxonomy: Of the White-crowned Sparrow’s five subspecies, three are known from San Diego County. Z. l. gambelii (Nuttall, 1840), with its pink bill, gray and rufous back stripes, and white eyebrow extending through the lores to the base of the bill, is the abundant winter visitor, representing 83 of 85 SDNHM specimens.
Zonotrichia l. pugetensis Grinnell, 1928, with its yellowish bill, brown-and-black back stripes, and white lores, breeds in the Pacific Northwest. It reaches the southern tip of its winter range in San Diego County. Specimens have been reported from San Luis Rey (G6), San Marcos (I9), La Jolla (P7), and Nestor (V10/11), on dates ranging from 19 October to 10 April (Grinnell 1928b, Grinnell and Miller 1944, Rea 1967, Unitt 1984). Rea (1967) also reported that “during the period 1958–63 several other White-crowns of this race were banded by us at the Old Mission [San Luis Rey], leading me to believe that the race has largely been overlooked.” But the scarcity of pugetensis in the SDNHM collection (only one of 96 county specimens), the lack of further sight reports, and the lack of records farther south attest to the rarity of the subspecies here.
Zonotrichia l. oriantha Oberholser, 1932, with its pinkish bill, gray-and-rufous back stripes, and black lores, occurs in San Diego County mainly as a rare spring migrant. Most birds must overfly the county, since the subspecies is a common breeding bird in the Sierra Nevada and a common winter visitor in southern Baja California. It is more common even in the Imperial Valley than in San Diego County. Dates extend from 8 April (1904, Witch Creek, Bishop 1905) to 5 May (1885, San Diego, Belding 1890); the bird noted 2–11 June 1975 was also black-lored. Apparently there is still only one good record of a fall migrant, of one at Point Loma 20 September 1973 (J. L. Dunn). Just as San Diego County is the southern tip of the winter range of pugetensis, it is the northern tip of the winter range of oriantha. Bishop (1905) reported an immature collected at Volcan Mountain (I20) 3 December 1904, and there are a few other winter specimens from elsewhere in southern California (Grinnell and Miller 1944).
Golden-crowned Sparrow Zonotrichia atricapilla
Less conspicuous than its familiar relative the White-crowned Sparrow, the Golden-crowned is actually more numerous in montane chaparral and the shady undergrowth of oak woodland. Manzanita, snowberry, California coffeeberry, and poison oak offer the Golden-crowned Sparrow prime habitat. In drier, more open chaparral, in sage scrub, and in riparian scrub the Golden-crowned Sparrow occurs at a much lower density. The Golden-crowned Sparrow is a winter visitor to San Diego County, occurring generally from the first week of October to the first week of May.
Winter: The Golden-crowned Sparrow occurs widely over the coastal slope of San Diego County. Its abundance is not uniform over this area but concentrated in two zones. The zone of greatest concentration is the higher mountains, where counts can range as high as 113 around High Point of Palomar Mountain (D15) 21 December 1999 (K. L. Weaver) and 100 along upper La Posta Creek (P24) 19 December 2001 (E. C. Hall, J. O. Zimmer). Within 15 miles of the coast, in the shadier canyons and on north-facing slopes, the Golden-crowned Sparrow is also common. Daily counts there range up to 80 around Torrey Pines City Park (O7) 25 January 2002 (D. G. Seay) and 66 around Batiquitos Lagoon (J7) 22 December 2001 (R. and A. Campbell). Between these zones, the species is only fairly common and can be missed where favorable habitat is sparse. On the Campo Plateau it is quite uncommon, and in the canyons draining into the Anza–Borrego Desert it is usually rare, with the only report of more than two individuals being of five in Box Canyon (L23) 13 February 1998 (D. Lantz). On the desert floor, our only winter records were during an unusual influx of several species of sparrows in response to rain (or, in the case of the Golden-crowned, possibly to snowstorms at higher elevations): four near San Felipe Narrows (I26) 10 January 1998 (A. Mauro) and eight in lower Carrizo Valley (O28) 11 January 1998 (P. D. Jorgensen).
Migration: In San Diego County, the Golden-crowned Sparrow is no more numerous in migration than in winter, as one might expect with the county’s lying near the southern tip of the main winter range. Migrants occur rarely, though, at places in the Anza–Borrego Desert where the species does not winter. Our only such record during the atlas period was of one at Agua Caliente Springs (M26) 27 April 1998 (D. C. Seals), but Massey (1998) reported a few others, including two in spring far out on the desert in Hawk Canyon (H27). Fall arrival is in early October, exceptionally very late September. Spring departure takes place in late April and early May. In the first week of May, the Golden-crowned Sparrow can still be seen in small numbers, e.g., up to 12 near Adobe Springs (C18) 2 May 1999 (A. Mauro, J. R. Barth). From 1997 to 2001, however, the only record later than 6 May was of two near the Palomar Observatory (D15) 14 May 1999 (K. L. Weaver). Later stragglers occur rarely, even into the first week of June: Tijuana River valley, 3 June 1978 (AB 332:1057, 1978), and Point Loma, 7 June 1984 (R. E. Webster, AB 38:965, 1984). There remains only a single San Diego County record of a Golden-crowned Sparrow in summer, 1000 miles south of the species’ breeding range: one at Old Mission Dam (P11) 14 August 1974 (AB 29:124, 1975).
Conservation: The Golden-crowned Sparrow occurs in residential areas planted heavily with thick shrubbery but is less numerous there than in natural habitats. Thus development of the coastal lowland degrades the sparrow’s habitat in its secondary zone of concentration. But the primary zone lies in deep canyons and rugged mountains farther inland, suggesting that the Golden-crowned Sparrow should long remain common in San Diego County. Christmas bird count results vary much from year to year, but the variations are not parallel among the counts, and there is no long-term trend.
Dark-eyed Junco Junco hyemalis
The Dark-eyed Junco is one of the most common breeding birds in the woodlands of conifers and black oaks in San Diego County’s mountains. In winter, it is even more abundant, as visitors from much of western North America flock into the county. At that season they occur in oak woodland, chaparral, high-desert scrub, parks, and well-vegetated residential areas as well as coniferous woodland. Subspecies J. o. thurberi of the Oregon Junco dominates, but two more subspecies of the Oregon, two of the Slate-colored, the Pink-sided, and the Gray-headed all occur regularly, especially in the mountains. As a breeding species the junco is spreading to lower elevations in live oak groves and orchards. Its colonizing the University of California campus in La Jolla reveals its surprising potential as an urban adapter.
Breeding distribution: Montane coniferous woodland remains the heart of the junco’s range in San Diego County, and it is here where the species’ numbers are highest: up to 175 in Matagual Valley (H19) 18 June 2000 (S. E. Smith), to 100 on Volcan Mountain (I20) 28 June 2000 (A. P. and T. E. Keenan). But field work for the atlas revealed considerable spread of breeding juncos into other habitats at lower elevations. As a result, at the scale of an atlas square, the distribution appears continuous from Palomar to the Laguna Mountains, though between 1500 and 3500 feet elevation the birds are confined to oak woodlands in canyons, largely in the northern half of the county. In Boden Canyon (J14) they descend as low as 1000 feet (two, one building a nest, 2 May 1997, C. R. Mahrdt). Breeding juncos are locally common in foothill canyons, with up to 25 at 2400–2600 feet elevation along Temescal Creek (G15) 1 June 2001 (K. J. Winter) and 20 at 1100–2000 feet in upper Boden Canyon (I14) 24 April 2000 (R. L. Barber). The southernmost site known, and thus the southern tip of the breeding range of subspecies thurberi, is Hauser Canyon (T20), elevation 1700–1800 feet (four on 18 May 2000, J. M. Wells).
The small isolated population in the Santa Margarita Mountains (C4/B5/C5) is in oak woodland (up to eight singing males around the Sky Ranch, B5, 19 May 2001, J. M. and B. Hargrove), as were three around Live Oak Park, Fallbrook (D8) 17 July 1999 (M. Freda) and occasional birds near Long’s Gulch (M15) in summer 1999 (C. H. Reiser). But two in an avocado orchard 2.25 miles west-southwest of Pauma Valley (F12) 12 June 1999 (M. Sadowski, J. R. Barth) and one in northwest Escondido (I10) 5 June 1999 (E. C. Hall) suggest adaptation to nonnative habitats.
By far the most dramatic example of the junco’s adapting to a new environment is its colonization of the campus of the University of California, San Diego (O7/O8). Here the birds live in the eucalyptus trees and ornamental shrubbery scattered among the buildings. The birds first colonized in 1983; by 2000, the population reached a fairly stable level of about 130, covering an area of slightly less than 1 square mile (P. Yeh), east to the University Town Center shopping mall (O8, one singing 14 July 1998, D. G. Seay). The population barely extends into surrounding La Jolla (P7), where we recorded the species three times, including two individuals banded on the campus and seen 3.2 miles away 20 June 2000 (M. Hinton). An even more notable recovery of a junco banded on the UCSD campus was of a juvenile found 9.5 miles away in the neighborhood of Loma Portal (R8) 16 August 2000 (SDNHM 50446). A pair was feeding young in Torrey Pines State Reserve (N8) 22 July 1989 (J. R. Jehl, AB 43:1369, 1989), but the birds have not remained there, in spite of the site’s nearness to UCSD and the resemblance of the Torrey pine groves to the species’ typical habitat.
Nesting: The Dark-eyed Junco usually nests on the ground, the nest hidden by grass, herbs, ferns, low shrubs, or leaf litter. All nests that atlas observers described were in such situations. Elsewhere in the species’ range, nests in trees or other elevated situations are known but rare (J. H. Phelps, Jr., in Austin 1968).
In the mountains, the junco’s nesting season extends from late April to mid July. With observations of nest building 18 April, feeding young 13 May, and fledglings 23 May, egg laying evidently begins about 10 days earlier than the 5 May–13 July spread of nine collected egg sets. At UCSD, however, the junco enjoys a much longer breeding season. There the birds start singing in January, build nests in February, and fledge their last chicks in August and September (P. Yeh). The scattered early records visible on the chart of the species’ breeding schedule are all from UCSD.
Migration: The juncos breeding in San Diego County are presumably nonmigratory, and this has been confirmed by studies of banded birds for the population at UCSD (P. Yeh). The local population is greatly augmented in the winter by migrants from the north, which begin arriving between mid September and mid October. In spring, wintering birds remain fairly common until the third week of April, then depart quickly. The latest records of apparent migrants are of one near Melrose Ranch (I13) 9 May 2001 (O. Carter) and one near Harper Flat (K26) 10 May 2000 (D. C. Seals). A couple of individuals in extreme northwestern San Diego County later in the spring could have been pioneers of the local population: one at San Onofre (C1) 26 May 2001 (M. Lesinsky) and one in San Mateo Canyon, elevation 500 feet (B3), 28 May 2001 (P. Unitt). On rare occasions migrants are seen in sparsely vegetated desert unsuitable for wintering birds (e.g., one near the Elephant Knees, M29, 1 May 2001, J. R. Barth).
Winter: In winter, juncos are abundant throughout San Diego County’s mountains and foothills. Flocks of dozens and daily counts over 100 are frequent. Counts run as high as 700 north of Julian (J20) 27 December 1999 (E. Post) and 551 in Cañada Verde (F20) 12 December 2000 (M. Bache). The junco’s pattern of winter abundance resembles that of resident birds of oak woodland: common near the coast in northwestern San Diego County, then decreasing, with the zone of abundance retracting inland, toward the south. Nevertheless, juncos can be common at favored spots even in south-coastal San Diego County, with up to 75 at Fort Rosecrans Cemetery (S7) 18 December 1999 (M. W. Klein) and 61 on the west side of Lower Otay Lake (U13) 19 January 2001 (M. and B. McIntosh). In high-desert scrub (juniper, Mojave yucca, desert apricot, desert scrub oak, etc.) the junco is irregularly common too, with up to 55 on the east slope of Whale Peak (L26) 15 February 2001 (J. R. Barth) and 45 in the Santa Rosa Mountains (C27) 9 January 2002 (P. Unitt). Numbers high as 225 one to two miles north of Vallecito (L25) 22 January 1998 and 115 in Little Blair Valley (L24) 20 February 1998 (both R. Thériault) occurred only in the one wet winter of the atlas period. In the low desert, the junco is much scarcer, occurring mainly in the cultivated parts of the Borrego Valley (maximum 30 at Roadrunner Tree Farm, E25, 17 December 2000, L. J. Hargrove).
Conservation: The lack of reports of breeding juncos from low to moderate elevations before the 1980s suggests that the spread is recent and the species is doing well. It was first noted summering in Boden Canyon in 1994 (C. R. Mahrdt). Though parks, college campuses, and well-vegetated residential areas offer the junco foraging habitat, its nesting on the ground is a strike against it as a prospective urban adapter.
Taxonomy: The juncos breeding in San Diego County, including those at UCSD, are J. h. thurberi, with black-headed males, gray-headed females, and the back tinged pinkish in both sexes. Junco. h. thurberi, whose breeding range stretches from San Diego County north through the Sierra Nevada, is also the dominant wintering subspecies in San Diego County, accounting for 80 of 116 winter specimens in the San Diego Natural History Museum. Two other subspecies of Oregon Juncos, differing from thurberi mainly in back color and not readily identifiable in the field, reach San Diego County as winter visitors in smaller numbers. Junco. h. simillimus Phillips, 1962 [= J. h. shufeldti Coale, 1887, of Miller (1941) and AOU (1957)], has a darker chocolate-brown back than thurberi and originates in the Pacific Northwest. It is apparently uncommon but probably regular, represented by six specimens collected on dates ranging from 9 October (1993, Volcan Mt., I20, SDNHM 48585) to 23 March (1944, Point Loma, S7, SDNHM 18855). Two further specimens are apparently intergrades between simillimus and thurberi or shufeldti. Junco h. shufeldti Coale, 1887 [= J. h. montanus Ridgway, 1898, of Miller (1941) and AOU (1957)], differs from thurberi and simillimus by having the back a drab grayish-brown and the male’s head being dark slaty-gray rather than black. It breeds in the northern Rocky Mountains. In San Diego County it is uncommon or fairly common, represented by nine specimens collected between 6 November (1984, Cibbets Flat, Q23, SDNHM 43474) and 1 March (1931, 4 miles southwest of Ramona, L14, SDNHM 14143). Junco h. shufeldti may be more prevalent in the Anza–Borrego Desert, as it is the most numerous subspecies of junco in the Salton Sink (Patten et al. 2003).
The Pink-sided Junco, J. h. mearnsi Ridgway, 1897, has a back even grayer than in shufeldti but a gray head in both sexes (black lores in the male) and broader cinnamon-pink on the sides, often extending across the breast. Immature females, though, are readily distinguished from shufeldti only in the hand. Only two specimens have been collected (18 December 1930, 4 miles southwest of Ramona, SDNHM 14117; 6 November 1984, Troy Flat, Laguna Mountains, Q23, SDNHM 43452), but sight records imply the subspecies occurs annually in small numbers. It is rare along the coast but more numerous in the mountains, with maximum counts possibly as high as seven (near Julian, J20, 27 December 1999, E. Post; upper San Felipe Valley, H20, 17 December 2001, A. P. and T. E. Keenan). More specimens are desirable to support numbers this high.
The Gray-headed Junco, J. h. caniceps (Woodhouse, 1853), with its bright rufous back and gray sides, differs grossly from the Oregon and Pink-sided Juncos, though intergrades are known and have even been given a subspecies name of their own. The Gray-headed Junco breeds in the mountains of the Great Basin and in the Rockies from southern Wyoming to northeastern Arizona. In San Diego County the status of the Gray-headed is similar to that of the Pink-sided: rare along the coast, rare to uncommon in the mountains. The Gray-headed may be somewhat more frequent than the Pink-sided, or the apparent difference may be due to the Gray-headed’s being more conspicuous in the field. Maximum counts are five near the San Luis Rey Day Use Area (G16) 22 January 2001 (W. E. Haas) and eight in Thing Valley (Q24) 2 February 1999 (P. Unitt). There are now five specimens, and sight records extend from 25 September (1960, one at Palomar Mountain State Park, D14/E14, AFN 15:78, 1960) to 19 April (2001, one in the middle fork of Borrego Palm Canyon, F22, J. R. Barth). Completely unprecedented in coastal southern California was a summer sighting of the Gray-headed Junco, of an apparent pair on Volcan Mountain (I20) 16 June 2000 (A. P. and T. E. Keenan). Parallel records must be sought among other species, such as the Red-naped Sapsucker that hybridized with the Red-breasted on Palomar Mountain or the Plumbeous Vireos colonizing the San Bernardino and San Jacinto mountains.
Two subspecies of the Slate-colored Junco also reach San Diego County, J. h. cismontanus Dwight, 1918, and J. h. hyemalis (Linnaeus, 1758). With six county specimens each in SDNHM they appear to be of roughly equal abundance—both uncommon. Sight records are a poor guide because in the field males of hyemalis stand out conspicuously while females of cismontanus could be overlooked among female Oregon Juncos. Junco. h. cismontanus has the concave border of the hood that distinguishes the Slate-colored from the Oregon Junco but the flanks have a variable amount of brown and the back is distinctly browner than the head. It breeds mainly in the interior of British Columbia. In J. h. hyemalis (Linnaeus, 1758) the males are all gray and white; the females may be brownish but no more so on the back than on the head. This subspecies has a transcontinental breeding range in the taiga from Alaska to Newfoundland. In San Diego County, seldom are more than three or four Slate-colored seen in a single large flock of juncos, but an exceptional 21 were in northeast Ramona (K15) 30 December 2000 (D. and C. Batzler). Sight records of Slate-colored Juncos in San Diego County extend from 19 October to 2 April (Unitt 1984).
Rea (1967) reported J. h. oreganus (Townsend, 1837) from San Luis Rey (G6) 17 January 1962, but the specimen (SBMNH 127), which I reexamined, is actually simillimus; the back is not dark and rusty enough for oreganus, and the flanks are not as extensively dark as in most specimens of oreganus.
There appears to be no difference in winter biology among the many subspecies of the Dark-eyed Junco; the rarer subspecies are usually found among the commoner ones in mixed flocks.
McCown’s Longspur Calcarius mccownii
Though an annual rare winter visitor to the Imperial Valley, McCown’s Longspur is only casual in San Diego County, the least frequent of the three longspurs recorded here. It has not been seen in the county since 1991, probably as a result of the elimination, especially in the Tijuana River valley, of the plowed fields the species seeks.
Migration: Ten of the 11 fall records of McCown’s Longspur for San Diego County are from the Tijuana River valley, scattered from 1965 to 1991. Their dates range from 19 October (1969, AFN 24:100d, 1970) to 6 December (1975, AB 30:770, 1976). One was at Otay Mesa (V13) 6 November 1971 (AB 26:124, 1972).
Winter: The only McCown’s Longspurs found in San Diego County in winter were two near Lake Henshaw (G17) 3–11 January 1987 (D. B. King, AB 41:331, 1987).
Lapland Longspur Calcarius lapponicus
The Lapland Longspur nests in the Arctic; in the New World, it winters mostly in the northern contiguous United States. San Diego County is well to the south of its main winter range. Like the other longspurs, the Lapland seeks fields of short grass or bare dirt. With such places becoming ever fewer, longspurs are becoming less and less frequent in San Diego County.
Migration: The Lapland Longspur occurs in San Diego County mainly as a rare migrant in late fall, from mid October to mid December. Most records are of single birds with flocks of Horned Larks; the county’s maximum was 10 Lapland Longspurs in the Tijuana River valley 22–27 November 1975. The earliest record, of one collected at Mission Bay (Q8) 2 October 1909 (Stephens 1910, SDNHM 917) was the first for San Diego County and tied as first for California. The only spring record is of one at Mission Bay 21 March 1987 (J. White, AB 41:490, 1987). Most of the county’s Lapland Longspurs have been found in the Tijuana River valley; there are also a few from Otay Mesa (V13), Point Loma (S7), and Lake Henshaw (G17).
Winter: San Diego County records of the Lapland Longspur that could be considered to represent wintering birds are from the Tijuana River valley 3 January 1965 (AFN 19:334, 1965) and 13 January 1978 (AB 32:402, 1978) and from Lake Henshaw 29 December 1977 (AB 32:402, 1978), 3–22 December 1983 (R. Higson, AB 38:359, 1984), and 3–11 January 1987 (D. B. King, AB 41:332, 1987).
Conservation: In San Diego County, like all the longspurs, the Lapland has decreased in frequency since the 1970s with the decline in agriculture. Possibly the trend toward warmer winters drives fewer longspurs as far south as San Diego. The only county records since 1996 are of single birds at the Tijuana River valley sod farm (W11) 23 October 1998 (E. Copper) and 20 October 1999 (G. McCaskie) and at Point Loma 24 October–5 November 2002 (G. McCaskie).
Taxonomy: California specimens of the Lapland Longspur are C. l. alascensis Ridgway, 1898.
Chestnut-collared Longspur Calcarius ornatus
The main winter range of the Chestnut-collared Longspur lies east of the Colorado River. In southern California, the species is rare and perhaps sporadic in fall and winter, occurring in dry grassland and agricultural fields. Since the 1970s, it has become much less frequent, as a result of loss of habitat locally, in the breeding range, or both.
Migration: In San Diego County, the Chestnut-collared, like the other longspurs, has been reported most often from the Tijuana River valley. Other fall locations include Point Loma (S7) and Lake Henshaw. The species occurs primarily from mid October to late November; 9 October (1974, one at Point Loma, J. L. Dunn) is the earliest date.
Winter: There is no clear distinction between fall and winter records of the Chestnut-collared Longspur. Reports for January and February are of one at Lake Henshaw 9 January 1977 (AB 31:375, 1977), up to 20 there 7–13 January 1978 (AB 32:402, 1978), 25 at Whelan Lake (G6) 6 February 1977 (AB 31:375, 1977), and one at Lake Cuyamaca (M20) 8 February 1987 (J. O'Brien, AB 41:332, 1987). The flocks at Henshaw and Whelan were the largest ever reported in the county.
Conservation: With the development of most sites where the Chestnut-collared Longspur formerly occurred in coastal southern California, the species has gone from regular if uncommon to casual or absent. In San Diego County the only records 1997–2003 were from the sod farm in the Tijuana River valley (W11), of three 16–20 October 1999 (G. McCaskie), one 17 October 2000 (J. A. Martin), and one 19 October 2000 (E. Copper).
Little Bunting Emberiza pusilla
One of the least expected vagrants ever to reach San Diego County was the Little Bunting, an Asian species that is only a casual vagrant even in the western Aleutian Islands. The Little Bunting at Point Loma was the only one known for North America outside Alaska until another arrived on Southeast Farallon Island off San Francisco in September 2002 (Cole and McCaskie 2004).
Migration: San Diego County’s Little Bunting was photographed at Fort Rosecrans Cemetery, Point Loma (S7), 21–24 October 1991 (AB 46:169, McCaskie 1993, Patten et al. 1995b).