Olive-sided Flycatcher Contopus cooperi

Quick, THREE beers!  Delivered from the tops of tall Jeffrey pines or big-cone Douglas firs, the far-carrying song of the Olive-sided Flycatcher is unforgettable.  The bird is only an uncommon summer visitor in the coniferous woodland of San Diego County’s mountains, but it is easily located.  It occurs widely though still uncommonly at lower elevations during migration (mainly May and September).  Even in migration it has the same habit, seeking out the tops of the highest trees for its lookout perch.  The promise of the Olive-sided Flycatcher’s incipient adaptation to lowland eucalyptus groves is offset by serious population decline over parts of its range—the bird is considered a species of special concern by the California Department of Fish and Game.

Breeding distribution: The Olive-sided Flycatcher occurs in all of San Diego County’s mountains supporting extensive stands of conifers: Palomar, Hot Springs, Volcan, Cuyamaca, and Laguna.  Even isolated Bucksnort Mountain (C20) has a few (up to six, including four singing males, on 24 June 2000 (L. J. Hargrove).  In most of these ranges the species occurs primarily at elevations over 4500 feet, rarely down to 3500 feet.  On the steep southwest face of Palomar Mountain, though, where the big-cone Douglas fir descends into the deep canyons of Marion, Agua Tibia, and Pauma creeks, the Olive-sided Flycatcher follows it, down to 1500 feet in Marion Canyon (D12; one singing male on 17 July 2001, K. L. Weaver).

            The Olive-sided Flycatcher’s population density is naturally low.  The entire county population is probably only a few hundred birds.  Seldom does one encounter more than two or three singing males in a day.  The highest counts are ten along upper La Posta Creek, Cuyapaipe Indian Reservation (P24), 28 June 1999 (D. C. Seals), eight in the Agua Tibia Wilderness (C13) 18 May 2001 (K. J. Winter), and eight along upper Nate Harrison Grade (E13) 16 May 1999 (C. Sankpill).

            The Olive-sided Flycatcher is known to have bred once in San Diego County along the coast.  From 2 May through 5 July 1982, a pair nested in a cypress tree at San Elijo Lagoon and fledged one young (King et al. 1987).  Recalling this event were single singing birds at an elevation of only about 600 feet in eucalyptus trees around Alliant International University (O10) 24 June 1998 (G. L. Rogers) and 19 and 23 June 2001 (G. Grantham).  Eucalyptus groves, with bare snags frequently emerging above their crowns, mimic the open woodland of tall conifers sought by the Olive-sided Flycatcher, especially when the trees have been partially defoliated by lerp psyllids.  A single silent individual about 3200 feet elevation between Lake Morena and Hauser Canyon (T21) 5 July 1997 (R. and S. L. Breisch) was also outside the usual range, though there are a few tall pines in the area.

Nesting: The Olive-sided Flycatcher builds its shallow cup nest in the clusters of needles toward the outer ends of conifer branches, at the middle levels of tall trees.  Atlas observers estimated the heights of the two nests at 25 and 40 feet.   The dates of breeding confirmations we recorded are consistent with the 5 June–4 July spread of three collected egg sets.  Spending fewer than four months in their breeding range, even, as in San Diego County, near that range’s southern tip, Olive-sided Flycatchers have time to raise only a single brood per season (Altman and Sallabanks 2000).

Migration: The earliest six spring dates recorded 1997–2001, 15–23 April, are all at or near sites where the Olive-sided Flycatcher nests.  Thus, as in so many other species, the locally breeding population evidently arrives before migrants headed farther north.  The Olive-sided Flycatcher is not regular at low elevations until the last week of April, though some sightings there are earlier, as early as 6 April (Unitt 1984).  Migrants peak in early May, then decrease through the third week of June.  The latest spring migrant was one in Tecolote Canyon (Q9) on 15 June 2000 (T. Plunkett), unless it too was summering. 

            In fall, migrants are encountered even less frequently than in spring, although a maximum of six was noted at Point Loma 8 September 1998 (P. A. Ginsburg).  Almost all reports are from September; dates range from 29 August (2000, one at Point Loma, J. C. Worley) to 25 October (1972, one in the Tijuana River valley, G. McCaskie).

Winter: Accidental, with one good sight record, of one at Vista 8 January 1983 (R. E. Webster, AB 27:339, 1983).

 

Conservation: Several independent sources of evidence point to a significant decline in the Olive-sided Flycatcher’s population over much of its range (Altman and Sallabanks 2000).  But in San Diego County, even though there is no quantitative study, no decline is obvious.  Our atlas results show the species still present throughout its historic range in numbers no lower than reported in the past.  Local increases in logged areas, in the context of broader-scale decline, led Altman and Sallabanks (2000) to hypothesize that logged forests are an “ecological trap,” for the Olive-sided Flycatcher.  Despite the lack of obvious change in San Diego County, the Olive-sided Flycatcher’s breeding range here is so limited and the numbers are so small that forest fire, prolonged drought, or runaway infestation of bark beetles could destroy enough old trees that the flycatcher population could fall below a sustainable threshold.  Warming of the climate warming could lead to conifers—and the many organisms dependent on them—being unable to recover from such calamities.

The species’ disappearance, between 1938 and 1986, from a seemingly unchanged tract of giant sequoia forest in the Sierra Nevada led Marshall (1988) to postulate that the decline was due to habitat loss in the winter range.  The Olive-sided Flycatcher winters in mature forest at middle altitudes, the most threatened zone, in a range centering on the seriously deforested Andes of Colombia (Altman and Sallabanks 2000). 

 

Taxonomy: Todd (1963) supported the division of the Olive-sided Flycatcher into two subspecies on the basis of size: larger C. c. majorinus (Bangs and Penard, 1921), breeding in the mountains of southern California and northern Baja California, and smaller nominate C. c. cooperi (Nuttall, 1832), breeding in boreal forests elsewhere in North America.  Among specimens in the San Diego Natural History Museum, one male from Mount Pinos, Ventura County, one male from the Sierra Juárez, and two males from the Sierra San Pedro Mártir are indeed large (wings 112.5–114.5 mm).  Three breeding females from San Diego County are also large (wings 104.5–106.0 mm).  But one male from San Diego County, from Julian (K20) 15 June 1915 (SDNHM 31919) is smaller, in line with cooperi (wing 109.5 mm).  So the validity of the distinction between the two subspecies could still use further testing.  Three of four specimens of migrants from San Diego County are relatively small, matching cooperi.

Greater Pewee or Coues’ Flycatcher Contopus pertinax

In summer and migration, of course, the Western Wood-Pewee and Olive-sided Flycatcher are the only medium to large olive-gray flycatchers expected in San Diego County.  Yet in winter, though any flycatcher meeting this description is rare, the most likely such species is the Eastern Phoebe, and the second most likely is the Greater Pewee.  Breeding in mountain forests north to central Arizona, Greater Pewees show up in southern California only occasionally.  But those that do often remain the entire winter, establishing territories in groves of planted conifers or eucalyptus trees.

Winter: Though perhaps as few as ten individual Greater Pewees have been noted in San Diego County, the records form a tight pattern: birds overwintering in tall trees in urban parks.  Some individuals have evidently returned to the same spot in successive years, especially one that spent at least five consecutive winters on the grounds of the San Diego Zoo in Balboa Park.  Such returnees accounted for the Greater Pewee being recorded in San Diego County every winter from 1984 to 1995.  The only record since then, of one in Bonsall (F8) 2 December 2000 (P. A. Ginsburg), differed from those earlier in its slightly more inland location.  Previous records were from Buddy Todd Park in Oceanside, Presidio and Balboa parks and the Maple St. canyon in San Diego, and the Tijuana River valley.  The records extend from 18 October (1990, San Diego Zoo, B. and I. Mazin, AB 45:152, 1991) to 14 April (1985, Presidio Park, Dunn 1988), except for the single record of a nonwintering bird, one photographed on Point Loma 6–7 October 1984 (R. E. Webster, Dunn 1988).  Two records as early as 19 September were not considered or were rejected by the California Bird Records Committee (McCaskie and San Miguel 1999).  The Greater Pewee was first recorded in California in 1952 (Cardiff and Cardiff 1953), in San Diego County in 1974.  The planting and maturation of tall conifers and eucalyptus trees must have been a prerequisite for the bird’s establishing its pattern of winter occurrence here.

Western Wood-Pewee Contopus sordidulus

The Western Wood-Pewee’s monotonous drawled song, “rrreea-ear” or “dear me,” lulls the ear on hot summer days in San Diego County’s foothills and mountains.  The species is common in coniferous and oak woodland, especially at openings and edges.  As a breeding bird it is uncommon in riparian woodland of the inland valleys but as a migrant it occurs in trees throughout the county.  Strictly a summer visitor to California, the Western Wood-Pewee is unknown here from November through March.

Breeding distribution: The Western Wood-Pewee has a breeding distribution typical of that of several species of oak woodland.  It approaches the coast in Camp Pendleton, along San Onofre Creek (D2), then swings inland, keeping at least 8 to 10 miles from the coast through most of the county; along the Mexican border it breeds no farther west than Marron Valley (V16/17).  Along the crest of the mountains the pewee’s distribution tracks the eastern edge of the oaks almost precisely.  The one outlying site of nesting on the desert slope is along San Felipe Creek near Scissors Crossing (J22), where perhaps there is no more than one pair (fledgling on 18 June 2001, P. D. Jorgensen).

            Western Wood-Pewees are most numerous in open pine–oak woodland in the mountains: highest counts are 35 in the Edwards Ranch on the west flank of Volcan Mountain (I19) on 21 July 2001 (D. W. Au, S. E. Smith) and 30 around Johnson and Boulder creeks on the west flank of the Cuyamaca Mountains (M19) on 22 May 1999 (K. J. Winter, S. McKelvey).  Below 3000 feet elevation, as woodland becomes more confined in canyons, the pewee population becomes sparser and patchier.  At low elevations, the greatest concentration is in the De Luz area of northwestern San Diego, with up to 15, including 12 singing males, around Sandia Canyon (C7) 18 July 1998 (K. L. Weaver).

Nesting: Western Wood-Pewee nests are rather easy to find, placed on horizontal or slanting branches of large trees, usually at a fork, sometimes saddled atop a branch wide enough to support the nest completely.  The degree of openness of the surrounding vegetation appears to be more important to the suitability of a nest site than the exact type of woodland or tree.  The nests are rather shaded but readily open to long foraging flights and view of possible predators.  Atlas observers reported nests in sycamore, coast live oak, black oak (in one case burned), willow, Jeffrey pine, and incense cedar.

            The Western Wood-Pewee is one of San Diego County’s later nesting species, with nesting activity seen commonly through the end of July.  Several records, though, suggest the birds can lay as early as the first few days of May, earlier than the 19 May–7 July spread of 25 collected egg sets and the 10 May reported by Sharp (1907) at Escondido.  For example, Karen Messer and Robert Turner noted a pewee carrying insects at Palomar Mountain State Park (E14) 17 May 1997, and Lori Hargrove noted one feeding fledglings near Shingle Spring (D21) 4 June 2001.

Migration: As a migrant the Western Wood-Pewee occurs throughout San Diego County, though it attempts to overfly treeless desert and heavily developed areas.  Spring arrival of the Western Wood-Pewee is usually about 20 April, rarely as early as 10 April (1999, one along the Santa Margarita near the Riverside County line, C8, K. J. Burns).  A bird banded by A. M. Craig at Point Loma (S7) 4 April 1969 (AFN 23:624, 1969) was exceptional.  Even at the peak of spring migration in early to mid May migrants are less concentrated than the breeding population in prime habitat, with a maximum of 12 around Scissors Crossing (J22) 14 May 1998 (E. C. Hall).  Spring migration continues commonly through the first week of June, occasionally as late as 13 June (1999, one at Oceanside, H5, J. Determan) and 17 June (2002, one at Point Loma, S7, J. C. Worley).  Atlas observers noted two midsummer stragglers well outside the breeding range along the coast, one at Los Peñasquitos Lagoon (N7) 4 July 1999 (C. Sankpill), the other near Villa La Jolla Park (P8) 11 July 1998 (M. B. Mosher).  Fall migration takes place largely in August and September, adults preceding juveniles.  One at Upper Otay Lake on 27 July 2001 (T. W. Dorman) was exceptionally early.  By mid October pewees are very rare, and the latest dates are 21 October (2003, Rancho Santa Fe, L8, SDNHM 50837), 22–24 October (1988, one at Point Loma, G. McCaskie, AB 43:169, 1989) and 30 October (1971, one in the Tijuana River valley, G. McCaskie).

Winter: Unrecorded, and hardly expected even as an accidental, given that the northern limit of the species’ winter range is Costa Rica.

Conservation: Results of the Breeding Bird Survey suggest the Western Wood-Pewee is declining over a significant portion of its range, including California (Sauer et al. 2003).  But no decrease is obvious in San Diego County, and most of the species’ breeding habitat is not heavily disturbed.  Even campgrounds and moderate cattle grazing seem unlikely to affect a bird whose stratum of activity is in the middle level of trees and descends to the ground only to pick up nest material.  Loss of winter habitat—mature montane tropical forest (Bemis and Rising 1999)—may be a greater issue for the Western Wood-Pewee than changes within the breeding range.

Taxonomy: The birds nesting in San Diego County, as well as most migrants, are the comparatively pale C. s. veliei Coues, 1866.  A darker subspecies, C. s. saturatus Bishop, 1900, breeds in the Pacific Northwest and migrates through San Diego County to some extent.  A nonbreeding specimen from the San Diego River at Cedar Creek (M17) 20 April 1985 (SDNHM 43845) and a juvenile from Pine Valley Creek at Horsethief Canyon (R19) 2 October 1992 (SDNHM 48173) are at the dark extreme for the species and thus apparently saturatus.

Yellow-bellied Flycatcher Empidonax flaviventris

During its breeding season, the Yellow-bellied Flycatcher ranges widely across the boreal forest of Canada, having a distribution similar to many warblers that reach California as vagrants annually.  The flycatcher’s apparent rarity in California (only 15 well-supported records through 2003) is due in part to the difficulty of distinguishing it from the common Western Flycatcher.  In the juvenile Yellow-bellied, however, the wingbars are yellowish white; in the juvenile Western they are ocher.

Migration: San Diego County’s first Yellow-bellied Flycatcher was in Fort Rosecrans National Cemetery, Point Loma (S7) 28 September–1 October 2003 (M. Sadowski, M. Billings, G. McCaskie, E. Copper, et al.).  The bird responded in kind to playing of taped recordings of the Yellow-bellied Flycatcher’s characteristic “pyoowip” call.  The identification is supported by excellent photographs.

Willow Flycatcher Empidonax traillii

William E. Haas and Philip Unitt

The southwestern subspecies E. t. extimus of the Willow Flycatcher is one of southern California’s rarest birds, listed as endangered and restricted to a few colonies in riparian woodland.  In San Diego County the population numbers fewer than 90 pairs, out of fewer than 200 statewide.  During migration, the darker northwestern subspecies E. t. brewsteri, which breeds from the Sierra Nevada north through the Pacific Northwest, also occurs in San Diego County.  Subspecies extimus is seen only at its breeding sites. 

 

Breeding distribution: As a breeding species, the Willow Flycatcher is now restricted in San Diego County to two modest colonies and a few additional scattered pairs.  The largest colony, with between 45 and 50 territorial males from 1993 through 2001, is along 4.6 miles of the upper San Luis Rey River between East Grade Road (just below Lake Henshaw) and the La Jolla Indian Reservation (F16, G16).  The other is along the Santa Margarita River in Camp Pendleton.  From 1999 to 2001, the birds maintained 18 or 19 territories, most along 3 miles of the river from the base airfield to Ysidora Basin (F5, G5) (Kus 2000, Kus et al. 2003a).  Near O’Neill Lake (E6), where there were three territorial males, at least two paired, in 1998 (P. A. Ginsburg).

            Four small new colonies have recently formed.  After apparent absence from the lower San Luis Rey River in the late 1970s and 1980s, a few Willow Flycatchers repopulated the lower San Luis Rey River by 1999, with four pairs near Whelan Lake (G6) in 2001, four territorial males (two paired) north of Guajome Lake (G7) in 2001, two at Couser Canyon (E10) 1999–2001, and one or two at Pala (D10/D11) in 2000 and 2001 (Kus et al. 2003a).  About 3 miles from the San Luis Rey River, in a boggy glade along Agua Tibia Creek (D12), elevation 2200 feet, K. L. Weaver noted a pair, one carrying away craneflies, 17 July 2001.  Another small colony was discovered in 1992 along the San Dieguito River between Lake Hodges and Tim’s Canyon (K11/K12/J12/J14—in 1997 one pair in each); it has since varied between two and four pairs (Kus and Beck 1998, Kus et al. 2003a).  Two territories were located along the San Diego River at the upper end (at low water) of El Capitan Reservoir (N17) in 2001 (Kus et al. 2003b).  On the east slope of the mountains, a small colony has formed in San Felipe Valley near Paroli Spring (I22), from 1996 to 2001 fluctuating between two and five pairs (W. E. Haas).  In 2002, two pairs nested downstream, 1 to 2 miles west of Scissors Crossing (J22) (W. E. Haas).

Elsewhere, there are only scattered pairs or unmated summering individuals.  In Macario Canyon just southeast of Agua Hedionda Lagoon (I6) a pair maintained a territory in 1999 but apparently did not nest (W. E. Haas).  Along Agua Caliente Creek near Warner Springs (F19) two males maintained territories in 2000 but never attracted mates (W. E. Haas).  One along Cedar Creek near William Heise County Park (L20) 16 July 2000 was followed by a pair at a nest there on 10 July 2001 (J. R. Barth).  One singing at the upper end of Sweetwater Reservoir (S13) 29 May–2 July 1997 was followed by a pair that nested there unsuccessfully from 29 May to 29 July 1998; one male maintained a territory in 1999 but did not return in 2000 or 2001 (P. Famolaro).  Some of the following, though in suitable nesting habitat, could have been migrant brewsteri: one singing male along Temecula Creek northwest of Oak Grove (C16) 20 June 1998 (K. L. Weaver)—confirmed pair a short distance downstream in Riverside County in 1997 (Kus and Beck 1998); one individual along the San Luis Rey River near Puerta La Cruz (E18) 18 June 2000 (P. K. Nelson); two along Highway 76 at Kumpohui Creek (H17) 13 June 1998 (P. Unitt); on the desert slope, silent individuals in Alder Canyon (C21) 20 June 2001 (P. D. Jorgensen) and at the head of Middle Fork Borrego Palm Canyon near San Ignacio (E22) 16 June 1999 (P. Unitt).

 

Nesting: The Willow Flycatcher attaches the sides of its open-cup nest to slender stems and twigs, which may be vertical, horizontal, or slanting.  The nest may be in an upright crotch or without support from below.  Willow Flycatcher nests, remarkably similar to those of the Lesser Goldfinch, differ notably in virtually always having loosely attached nest material hanging below the cup and the adults’ not letting the nestlings’ fecal matter decorate the nest’s edge.  From one to four eggs are laid, with smaller numbers more common late in the season and in second and third nests.  Nests are often over water or in the outer branches of a tree. In historic egg collections from southern California, 86% of nests were in willows, 4% in stinging nettle, and 10% in other plants (Unitt 1987).  Along the upper San Luis Rey River, however, the Army Corps of Engineers removed willows in the 1950s, and coast live oaks press closely against the streamside ash and alder trees in the narrow canyon.  Here, of 292 nests studied between 1995 and 2001, 71% were placed in oak trees, another 8% in multi-substrate association with live oak, most commonly incorporating California blackberry (W. E. Haas). The nest height there may vary from 14 inches to 62 feet.  Along the lower Santa Margarita, heavily invaded by exotic plants, the birds nevertheless often nest in those exotics; of 25 nests in 2001, 11 were in poison hemlock and 3 were in giant reed (B. E. Kus pers. comm.).

Female Willow Flycatchers begin building their nests usually within one week of pairing, 10–14 days after spring arrival.  Construction takes three to eight days (average 4.2 days along the upper San Luis Rey River).  Eggs may be laid as early as mid May, but typically first nests are initiated between 25 May and 20 June, often in synchrony, with older, experienced birds building the earliest nests.  Earliest documented fledging date from the upper San Luis Rey River is 24 June 1995. The latest nest initiation date recorded is 16 July (1999), though later nests have been reported elsewhere (M. K. Sogge pers. comm.). Though laying of a second clutch following the fledging of a first brood is extremely rare among the more northern subspecies of the Willow Flycatcher, it is only uncommon on the upper San Luis Rey River.  On 21 June 2000 a freak storm, dumping one inch of hail in less than one hour, ruined 19 of 31 active nests.  Within 10 days all birds renested, including one female that built her new nest directly above the destroyed first nest.    

 

Migration: The local population of subspecies extimus usually arrives in early May.  From 1997 to 2001 the earliest recorded date was 1 May 2001, along the upper San Luis Rey River (W. E. Haas), and no earlier date is known.  Subspecies brewsteri arrives later, typically in mid May.  Our earliest date away from a nesting site 1997–2001 was 11 May (1999, three in Macario Canyon, I6, W. E. Haas; 2001, two at Carrizo Marsh, O29, M. C. Jorgensen); the only earlier such date published is 8 May (1988, Point Loma, R. E. Webster, AB 42:482, 1988).  The migration of brewsteri peaks in early June (e.g., 25 at Fort Rosecrans Cemetery, S7, 8 June 2002, P. Unitt), then falls off quickly, though occasional migrants are seen at least as late as 20 June (1998, 3 miles southeast of El Cajon, R14, N. Perretta).

Most territories of extimus remain occupied through early August; Haas’ latest date for an adult (female) along the upper San Luis Rey River is 3 September (1999).  Juveniles depart somewhat later; at the upper San Luis Rey the latest date for a known (banded) juvenile from the colony is 11 September (1998).  Fall migration of adults of brewsteri begins in the third week of July and presumably accounts for the two “pairs” reported from nonbreeding habitat on Middle Peak (M20) 19 July 1987 (R. E. Webster, AB 41:1488, 1987).  These adults’ migration takes place primarily in August but largely bypasses San Diego County, as the birds swing east, avoiding Baja California and a crossing of the Gulf of California.  Juveniles of brewsteri are more numerous, though still uncommon, in the county, and occur primarily in September.  By mid October they are rare; the latest dates recorded are 26 October–3 November (1981, three at Point Loma, R. E. Webster, AB 36:218, 1982).

 

Winter: Unrecorded.  There are fewer than 10 apparently valid sight records of the Willow Flycatcher elsewhere in southern California (no specimens).  Central Sinaloa, in western Mexico, is the northern extreme of the normal winter range.

 

Conservation: Early in the 20^th century, the Willow Flycatcher was locally common in San Diego County (Sharp 1907, Willett 1912, Stephens 1919a; 35 egg sets in WFVZ).  Like that of so many riparian songbirds, the population collapsed in the mid 20^th century, as the effects of cowbird parasitism and clearing of riparian woodland compounded each other.  The riparian forest along the upper San Luis Rey River was not spared, being cleared by the Army Corps of Engineers in the 1950s.  It is probable that a remnant population of Willow Flycatchers persisted below Henshaw Dam and fortuitously began to nest in an alternative substrate, the coast live oak.  In the late 20^th century, clearing of riparian woodland was regulated, and the woodland regenerated itself in some areas.  Following the formal listing of the Least Bell’s Vireo as an endangered species in 1986, cowbirds were trapped widely, reducing parasitism pressure on all hosts.  Yet, unlike the vireo, Blue-gray Gnatcatcher, and Yellow Warbler, the Willow Flycatcher has failed to respond in proportion.  With no cowbird trapping nearby at the time, though, from the mid 1980s to the mid 1990s the upper San Luis Rey River colony evidently increased, to the point where it is now the largest colony of extimus in California, eclipsing that on the South Fork Kern River.  Along the Santa Margarita River in Camp Pendleton, the number of territories increased from five in 1981 to 17 in 1986 (L. Salata in Unitt 1987), but the figures for 1998 through 2001 are virtually static.  The incipient new colonies along the lower San Luis Rey River, in San Pasqual Valley, in San Felipe Valley and above El Capitan Reservoir are promising. Notably, the last two are in woodland that has grown only since the 1980s.  But against these gains must be balanced the species’ disappearance from several sites listed by Unitt (1987): Santa Margarita River north of Fallbrook, south end of Lake Cuyamaca, east end of Lower Otay Lake, and the Tijuana River valley.  All of these were well surveyed between 1997 and 2001.  The decline seems to have been arrested, and recovery has begun, but only slowly.  In 2001, the known San Diego County population was 88 territorial males (Kus et al. 2003a).

            Clearly, low rates of cowbird parasitism are a necessary but not sufficient condition for the Willow Flycatcher’s recovery.  Displacement of woodland by the exotic giant reed has become serious in many floodplains, especially that of the lower Santa Margarita River.  In the Fallbrook area, clearing of steep chaparral-covered slopes for avocado orchards led to excessive runoff and catastrophic flooding during heavy rain in 1993, scouring the river channel.  The vegetation recovered subsequently, but several years of below-average rainfall left the river frequently dry, and so unattractive to the flycatchers.  Along the upper San Luis Rey River, the flow depends on the Vista Irrigation District’s (VID) use of the river as a conduit for sending groundwater pumped from the basin of Lake Henshaw to the city of Escondido.  Flow through the summer is maintained to support recreation in the La Jolla Indian Reservation, the result of a lawsuit among the La Jolla band of Luiseño Indians, the VID, and the federal government.  Though cattle were removed from the Forest Service and VID lands within the colony in the early 1990s, it is still common for cattle to wander out of nearby pastures and into the Willow Flycatcher habitat.

In the upper San Luis Rey colony, human recreation, including picnicking, floating downriver in tire tubes, hunting, and fishing, is on the increase (through the summer the river is stocked at the Forest Service day use area with nonnative trout).  The spring hunting season for the recently introduced “Wild” Turkey overlaps the flycatchers’ arrival, and hunters typically use the Forest Service’s land to reach private property (W. E. Haas).  Open fires, though prohibited, are common. Willow Flycatchers in this area are especially susceptible to fire because they depend on the coast live oak trees that are more prone to burn than more typically riparian trees.  The colony barely missed huge fires just to the north in 1999 and to the west in 2003.

Because of the Willow Flycatcher’s semicolonial habits—the clumping of territories near each other—restoration efforts should be focused near existing colonies. Lamberson et al. (2000) suggested that an important factor in the recovery of the Southwestern Willow Flycatcher is the need for adequate habitat within 15 km of existing population centers.  Restoration attempts should recognize that low cowbird-parasitism rates, multilayered riparian woodland, and surface water are all important to the success of any attempt to bring back one of southern California’s most endangered birds.

 

Taxonomy: The locally breeding subspecies is the pale E. t. extimus Phillips, 1948, while the birds passing through in migration are the darker E. t. brewsteri Oberholser, 1918 (Unitt 1987).  The color of the crown, back, and neck are the best characters, though a difference is often evident on the underparts, too.  In good light, the contrasting gray neck of extimus, differing clearly from the darker, more uniform olive neck and back color typical of brewsteri, is visible in the field.  In the spring, when the birds are in fresh plumage, the pale olive edges on the crown feathers of extimus contrast with the dark centers, giving the crown a dappled appearance not obvious on the uniformly dark crown of brewsteri.  The pale edges wear off over the summer, though, and even in fresh plumage reliable identification of the subspecies requires quantification of the color or comparison with museum specimens.  The song of extimus is slower than that of other subspecies of the Willow Flycatcher (Sedgwick 2001), and this slow song is well attested by Haas’ recordings from the colony along the upper San Luis Rey River.

Least Flycatcher Empidonax minimus

A rare fall vagrant and casual winter visitor from northeastern North America, the Least Flycatcher resembles other species of Empidonax closely, being most distinctive in its bill, as short as a Hammond’s but wider and entirely pale.  Its identification requires thorough familiarity with the range of variation in all the more frequent species of the genus.

Migration: The Least Flycatcher occurs in California primarily as a vagrant in fall.  In San Diego County, at least 26 have been recorded, all but four in fall between 10 September (1980, Tijuana River valley, AB 35:227, 1981; 1985, Point Loma, R. E. Webster, AB 40:159, 1986) and 21 October (1979, Point Loma, AB 34:202, 1980).  All of these were along the coast from Point Loma to the Tijuana River valley.  There is still only one specimen, from Point Loma 16 September 1967 (A. M. Craig, SDNHM 35354).

Winter: Four records: San Diego, 14–18 December 1993 (R. E. Webster, NASFN 48:248, 1994); San Dieguito River estuary (M8), 16 December 1994 (P. Unitt, AB 49:821, 1995); La Jolla, 1–3 December 1996 (K. and C. Radamaker, NASFN 51:802, 1997); Dairy Mart Pond, Tijuana River valley (V11) 28 January 1998, 26 December 1998–23 January 1999, 17 November 1999–3 February 2000, and 9 December 2001, presumably the same individual returning in successive years, despite the hiatus in 2000–2001 (G. McCaskie).  The recency of the winter records suggests a trend toward increase in this species, whose main winter range extends as far north in western Mexico as Sinaloa.

Hammond’s Flycatcher Empidonax hammondii

An uncommon migrant in spring and fall, Hammond’s Flycatcher is not a familiar bird in San Diego County.  But, in April and early May, after the Western Flycatcher, it is the next most likely Empidonax to be encountered here.  In migration it has no special habitat preferences, other than trees or shrubs—it is as likely to be seen in sparsely vegetated desert washes as in oak or riparian woodland.  The few winter records are all from parks and gardens near the coast, except for one from the Anza–Borrego Desert.

Migration: In spring, Hammond’s Flycatcher is more frequent in the eastern half of San Diego County than near the coast, as one might expect in a species that typically avoids Baja California, keeping to the east side of the Gulf of California on its way north from wintering in the mountains of mainland Mexico.  It arrives usually in early April, rarely as early as 20 March (1994, Agua Caliente County Park, Massey 1998).  Most are seen from mid April to early May, but the highest one-day count 1997–2001 was of only five, in the Inner Pasture (N25) 2 May 2001 (A. P. and T. E. Keenan).  By the last week of May Hammond’s Flycatcher is rare; the latest spring record is of one in Hauser Canyon (T21) 5 June 1997 (J. M. Wells, J. Turnbull).

            In fall, Hammond’s Flycatcher is probably most frequent in the mountains, though most records are along the coast, where birders concentrate.  It overflies the desert almost entirely at that season.  Fall records extend from 1 September (1986, 0.3 mile west of High Point, Palomar Mountain, SDNHM 44416) to 5 November (1984, Point Loma, R. E. Webster, AB 39:103, 1985), exceptionally to 16–17 November (1974, Old Mission Dam, G. McCaskie, SDNHM 40738).

Winter: The only winter record 1997–2002 was of one in the Golden Hill section of Balboa Park (S9) 16 December 2001–1 March 2002 (M. B. Mulrooney, P. Unitt), returning 2 November 2002–18 January 2003 and 15 November 2003–24 January 2004 (G. Hollenbeck).  There are only three previous winter records of Hammond’s Flycatcher in San Diego County: October 1991–24 January 1992, Point Loma (R. E. Webster, AB 46:315, 1992), 1 December 1992–24 January 1993, Point Loma (R. E. Webster, AB 47:301, 1993), and 6 December 1992–20 January 1993, Yaqui Well (A. G. Morley, AB 47:301, 1993).  Note the coincidence of the previous records with El Niño. A supposed migrant at San Diego 10 March 1983 (another El Niño!) (AB 37:911, 1983) is so early that it may more likely have been wintering, paralleled by a specimen still in molt from Thermal in the Coachella Valley of Riverside County 19 March 1921 (Patten et al. 2003).  The species undergoes its spring molt in its winter range (Johnson 1970).

Gray Flycatcher Empidonax wrightii

Though a rare migrant and winter visitor in San Diego County, the Gray Flycatcher can be found—after a wet year—by the birder willing to invest time in the mesquite bosques and palo verde-lined washes of the Anza–Borrego Desert.  In the inland valleys of the coastal lowland it was once fairly common but is now only occasional.

Winter: The Gray Flycatcher’s main winter range lies in Mexico—the bird is common in the thorny scrub covering the southern half of Baja California and decreases toward the north.  So San Diego County lies near the northwestern extremity of its winter range.  The Gray Flycatcher is most frequent in the Anza–Borrego Desert, but that frequency is governed by rainfall.  Ten of 11 desert winter records 1997–2002 were in the two years following the wet El Niño year of 1998; there were none at all in the extremely dry two final winters of the atlas period.  Most of the desert winter records are from the floors of the Clark, Borrego, and Carrizo valleys, in or near mesquite thickets or developed areas.  There are three records also from the riparian corridor of San Felipe Valley: one on 16 December 1998 (I21; J. O. Zimmer), up to two on 23 February 1999 (J22: E. C. Hall).

            On the coastal side, the seemingly random scatter of winter records of the Gray Flycatcher (14 from 1997 to 2002) conceals a preference for open riparian scrub in inland valleys.  Pockets of semidesert scrub on south-facing slopes at some locations, especially those of repeated occurrences such as the east end of Lake Hodges (K11), and Proctor Valley (T13/14), suggest wintering Gray Flycatchers seek warm, dry microclimates, in spite of being more frequent in wet years.  The burned scrub with prickly pear thickets remaining as the most prominent vegetation, habitat of two in Jardine Canyon (C3) 15 February 1999 (P. Unitt), also evoked an image of desert.  But other records from parks, cemeteries, and disturbed areas imply the Gray Flycatcher’s winter habitat needs are not overly specialized.  One bird returned to Whelan Lake (G6) for seven consecutive winters, 1980–86 (AB 41:330, 1987).

            Most winter records are from low elevations (under 1000 feet), but a few are higher, exceptionally up to 3100 feet at Warner Springs (one on 9 December 2001, C. G. Edwards).

Migration: Despite wintering commonly in Baja California, the Gray Flycatcher is rare as a migrant in San Diego County.  It is a bit more widespread in that role than in winter, especially in the Anza–Borrego Desert in spring.  Almost all spring migrants are seen in April and the first week of May.  Aside from birds known to have wintered, the earliest was one near the Borrego Air Ranch (H26) 20 March 1998 (M. L. Gabel); late were two near Yaqui Well (I24) 13 May 1998 and 23 May 1997 (P. K. Nelson).  Normally only one or two individuals can be seen in a day; eight in San Felipe Valley (I21) 24 April 1999 during a spectacular fallout of migrants made by far the highest one-day count (W. E. Haas).  Along the coast, three at Point Loma (S7) 15 April 2001 (J. C. Worley) and nine there between 6 and 30 April 1983 (AB 37:913, 1983) are maximal.

            In fall, records extend from 24 August to 18 November (1984, three at Point Loma, R. E. Webster, G. McCaskie, AB 39:103, 1985).

 

Conservation: The Gray Flycatcher was “fairly common” or “rather common” as a winter visitor in coastal southern California early in the 20^th century (Grinnell 1915, Stephens 1919a, Willett 1933).  Yet no one since at least 1950 would use such a term for it.  Why would a bird’s winter range retract south at a time when winter low temperatures are on the rise?  Most of the floodplains and semidesert scrub making up the Gray Flycatcher’s typical winter habitat have been developed, but the species’ scarcity in the remaining habitat, and its use of disturbed areas, leave the explanation of habitat loss unsatisfying.  No further change in the Gray Flycatcher’s winter status has been evident for decades.  The trend of numbers in the breeding range is, if anything, positive, and since 1970 the species has colonized new areas north, west, and, south of its historic range in the Great Basin and intermountain plateau region (Sterling 1999).  Its spread along the north slope of the Transverse Ranges, and a summer record even for the Santa Rosa Mountains of Riverside County (Garrett and Dunn 1981), suggest the possibility of the Gray Flycatcher’s breeding some day in San Diego County.

Dusky Flycatcher Empidonax oberholseri

One of America’s most obscure birds, the Dusky Flycatcher is a summer visitor to San Diego County only in coniferous woodland on the tops of the highest mountains.  It is uncommon in the Cuyamaca Mountains, rare and irregular on Hot Springs, Volcan, Laguna, and probably the Santa Rosa mountains.  Though it nests widely in the mountains of western North America to the north of San Diego, its rarity as a migrant at lower elevations implies that its migration route to its winter range in mainland Mexico lies well to the east of us.

Breeding distribution: The lower end of the elevation zone occupied by the Dusky Flycatcher barely grazes the tops of San Diego County’s highest mountains.  The species is normally found only above 5200 feet elevation, in conifer-dominated woodland.  The vegetation zone is that where the white fir grows, though the flycatcher has no special attachment to any particular species of plant.  Most records and the highest numbers are from Cuyamaca and Middle peaks (M20) in the Cuyamaca Mountains.  The maximum daily count is 12, including nine singing males, on Middle Peak 11 June 2000 (R. E. Webster).  Elsewhere the Dusky Flycatcher is rare, with records 1997–2001 also from Hot Springs Mountain (E20/E21; 19 June 1999 and 19 May 2001, K. L. Weaver, C. R. Mahrdt) and from Morris Ranch Road (P23; 30 July 1999, K. Smeltzer) and the head of La Posta Creek in the Laguna Mountains (P23; 23 June 2000, E. C. Hall, J. O. Zimmer)—single individuals only in each case.  Previous records from the Laguna Mountains were from nearby Agua Dulce Creek and the unusually low elevation (4150 feet) of Cibbets Flat (Q23) (feeding fledgling cowbird on 4 July 1978, AB 32:1209, 1978).  Before the atlas period the Dusky Flycatcher was noted on Volcan Mountain (I20), with one on 25 May 1993 (R. T. Patton) and two on 31 May 1993 (P. Unitt), as well as on Hot Springs Mountain (Unitt 1981) and Cuyamaca Peak.  Also, the species may be a rare summer resident in the sparse stands of pinyons along the ridgeline of the Santa Rosa Mts., with two at 5700 feet elevation barely inside San Diego County 0.6 mile south of Rabbit Peak (C27) 2 May 2000 (P. Unitt) and one probable Dusky Flycatcher at 5400 feet near the summit of Villager Peak (C27) 5 June 2001 (R. Thériault).  The Dusky Flycatcher breeds commonly in the Riverside County portion of the Santa Rosa Mountains (Weathers 1983).  The single San Diego County record of breeding Dusky Flycatchers away from these principal mountains is of a pair, the female building a nest, in a north-facing canyon at 3800–4000 feet elevation about 0.75 mile southeast of Barrel Spring at the north end of the San Felipe Hills (H20; A. P. and T. E. Keenan).

            San Diego County lies near the southern tip of the Dusky Flycatcher’s breeding range; the small population discovered by Erickson and Wurster (1998) in the Sierra San Pedro Mártir is the only one known farther south.

 

Nesting: The Dusky Flycatcher’s cup nest is typically attached by its sides to vertical twigs, either upright or hanging.  Knowledge of the species’ nesting in San Diego County, though, is minimal.  Besides the record from near Barrel Spring, the only breeding confirmations 1997–2001 were of one nest building in tall Ceanothus or Cercocarpus at the south side of Cherry Flat near the summit of Cuyamaca Peak on 23 May 1998 (G. L. Rogers) and of one feeding young one quarter mile from the summit of Cuyamaca Peak 6 August 1999 (A. P. and T. E. Keenan).  Earlier records are of an occupied nest in a sugar pine on the north slope of Middle Peak 25 June 1988 (P. Unitt) and a nest with young near Agua Dulce Creek 13 July 1974 (AB 28:950, 1974).

Migration: Because of the difficulty in identifying silent Dusky Flycatchers in the field, information on the species’ migration is scanty and uncertain.  Nevertheless, the species is very rare in both spring and fall.  It is very rare also in the Salton Sink (Patten et al. 2003) and essentially absent as a migrant in Baja California (Erickson et al. 2001), so its migration route evidently swings far to the east before it reaches the latitude of San Diego County.  Eight published spring records from Point Loma extend from 21 April to 9 May (AB).  Fall dates extend from 11 September to 12 October (Unitt 1984).

Winter: Brennan Mulrooney studied one along the San Diego River in Santee (P12) 17 December 1999 (NAB 54:221, 2000).  He noted a medium-long narrow bill with a largely dark mandible, thin even eye-ring, tail flicked up repeatedly, and a “whit” call, features that in combination appear to eliminate all similar species.  This is the first winter record for San Diego County and one of very few for southern California.

Conservation: Though Stephens (1919a) said “breeds in small numbers in the higher mountains” (at a time before the Dusky and Gray Flycatchers were adequately distinguished), he collected none.  No details of Dusky Flycatcher nesting were reported in San Diego County’s mountains until 1974.  The species has remained rare except in the Cuyamaca Mountains, where it has increased and can be found regularly in small numbers.  The species as a whole is maintaining itself or increasing (Sedgwick 1993).  Johnson (1974) attributed an increase from the 1930s to the 1970s in the mountains of southern Nevada to a shift toward a cooler, wetter climate.  The birds’ habitat in San Diego County is little disturbed, but climatic warming and drying could dislodge the Dusky Flycatcher from its toehold on the mountain tops.  Annual rainfall and summer temperature data from Cuyamaca 1948 to 2002 reveal no long-term trend.

Western or Pacific-slope Flycatcher Empidonax difficilis

Few birds’ invasions of San Diego County have been as aggressive yet as little noticed as that of the Western Flycatcher.  Hardly known as a breeding species here in the early 20^th century, the Western Flycatcher is now a fairly common summer resident in native oak and riparian woodland from the coast to the mountains, as well as in groves of eucalyptus trees.  Range expansion and ability to adapt to urbanization give it a double boost.  In addition, the Western Flycatcher is common in migration throughout the county and rare in winter in the coastal lowland.

Breeding distribution: Breeding Western Flycatchers occur almost throughout the coastal slope of San Diego County in riparian and oak woodlands.  Only a few areas (Warner Valley, Otay Mesa, Otay Mountain) are so lacking in these habitats that they yield holes in the distribution as seen at the scale of our atlas grid.  The breeding distribution extends south practically to the Mexican border in the Tijuana River valley (W10, nest building on 23 May 2000, W. E. Haas; feeding fledglings on 2 July 2001, M. B. Mulrooney; W11, occupied nest on 19 June 1999, P. Unitt).  It extends down the desert slope along San Felipe Creek as far as Sentenac Ciénaga (J23; one on 8 July 2000, R. Thériault; juvenile on 6 July 2002, J. R. Barth) but does not quite reach the Tecate Divide east of Campo along the border.  In addition, Western Flycatchers breed, still uncommonly and patchily, in parks, eucalyptus groves, and residential areas.

            The greatest concentrations, as one might expect in a species expanding its range south, are still in northwestern San Diego County, especially along the Santa Margarita River near Fallbrook (C7, 25 males on 13 June 1998; C8, 27 males on 24 May 2001, K. L. Weaver).  Other notable counts were of 25 along the west fork of the San Luis Rey River below Barker Valley (E16) 23 June 2000 (J. M. Wells, J. Turnbull, P. Unitt), 20 in the Agua Tibia Wilderness (C13) 18 May 2001 (K. J. Winter), and 18–20 in Blue Sky Canyon Ecological Reserve 6 June 1997 and 16 March 1998 (M. and B. McIntosh).

Nesting: However closely the Western resembles other small flycatchers, its choice of nest site is distinctive.  The nest is a cup, but it is placed atop a solid support, with a solid surface behind it, and preferably above it, too.  Broken-off snags and knotholes in trees are the Western Flycatcher’s typical nest sites in San Diego County.  The widespread planting of eucalyptus trees, though, gave the birds a new opportunity.  Slabs of bark hanging half attached to the eucalyptus offer ideal supports and shelters for Western Flycatcher nests and allow the birds to occupy eucalyptus groves lacking any other vegetation.  Man-made sites our observers described were atop a pipe bracketed to the underside of a bridge, a ledge over a patio, and on the support structures below wooden decks.  Another interesting site was in an old Cliff Swallow nest under a bridge.

            Because past data on the Western Flycatcher’s nesting in San Diego County are minimal, our atlas results establish the first baseline for understanding the species’ nesting schedule here.  Two reports of fledglings on 7 May imply that at low elevations the birds lay as early as the first week of April, earlier than farther north (cf. Lowther 2000).   An occupied nest in Stelzer County Park (O14) on 24 March 1998 (M. Farley, M. B. Mulrooney) may still have been under construction.  A nest with nestlings in Palomar Mountain State Park (D14) on 4 August (2000, P. D. Jorgensen) implies that in the mountains they lay at least as late as the first week of July.  Early spring arrival gives the Western Flycatcher, unlike its close relatives, ample time to raise two broods in San Diego County.

Migration: Western Flycatchers typically begin arriving in San Diego County in the third week of March and quickly reach full abundance.  One along the Sweetwater River at Highway 94 (R13) 3 March 1999 (J. R. Barth) was exceptionally early, beating the previous early record of 9 March 1983 (AB 37:911, 1983) by six days.  The highest counts of migrants are from along the east base of the mountains: Agua Caliente County Park (M26), 70 on 11 May 1998; Scissors Crossing (J22), 60 on 14 May 1998 (both E. C. Hall).  The species’ spring migration period is notably long, regularly extending through the first week of June. The latest atlas record from a nonbreeding locality (6 June 2001, one in Carrizo Valley, O28, P. D. Jorgensen) is typical; stragglers can be expected later, even to 23 June (Unitt 1984).

            Fall migrants begin returning in mid August, peak in September, and trail off through October and November.  The latest specimen of an adult is dated 16 September; all seen later in the fall are juveniles.

Winter: At this season the Western Flycatcher is rare but occurs annually.  Eight, nearly half of the 19 reported 1997–2002, were in a single winter, the wet El Niño year of 1997–1998.  Almost all winter records are from low elevations on the coastal slope, from riparian woodland or ornamental vegetation in parks.  As many of the winter records are from inland valleys as from the coastal strip, east (during El Niño) to near Dulzura (U17), with one on 24 January 1998 (W. Pray, O. Carter, C. R. Mahrdt).  One at Butterfield Ranch (M23) 22 January 1999 (P. K. Nelson) made the first winter record for the Anza–Borrego Desert.  The following year saw the first two winter records of the Western Flycatcher for the Imperial Valley (Patten et al. 2003).

Conservation: At the turn of the 20^th century, the Western Flycatcher probably bred in San Diego County, as in northern Baja California still, at the highest elevations only.  Though Willett (1912) called the species common in southern California generally, the only report in the early literature of breeding Western Flycatchers likely identified correctly in San Diego County is that by Anthony (1895), who called them “rather common” between 4000 and 6000 feet elevation on Cuyamaca Peak in late June 1895.  Frank Stephens collected four specimens (MVZ) at Julian and Volcan Mt. from 31 July to 6 August 1908.  F. E. Blaisdell (in Belding 1890) called the Western Flycatcher “a summer resident” at Poway but misidentified enough other birds to cast doubt on this one.  In the early 1900s the southern limit of the species’ lowland breeding distribution was apparently north of San Diego County.

            Egg collections, dating primarily from 1890 to 1940, contain only a single set from San Diego County, collected by Griffing Bancroft at an unspecified location in 1926 (WFVZ 75013).  Thus it appears that the invasion of breeding Western Flycatchers gained momentum only after 1940 and was largely overlooked because the species has always been common in migration.  By the late 1970s the breeding population was still uncommon and scattered (Unitt 1984).  Our atlas data confirm that the spread has continued and suggest that low-elevation nesting in northwestern Baja California is now likely.

            What factors prompted the Western Flycatcher’s invasion?  The planting of eucalyptus trees, the erecting of structures that offer nest sites, and the maturation of riparian woodland in floodplains where scouring by floods is now rare must all have contributed.  Yet much of the spread has happened in canyons little touched by these forces.  The species is only lightly parasitized by cowbirds, perhaps because its nests are usually hidden from above.  No clear increase of the breeding population has been reported in California north of San Diego County, but at its northern end the Western Flycatcher’s range has also expanded, in this case to the east (Lowther 2000).

Taxonomy: The comparatively bright yellow subspecies E. d. difficilis (Baird, 1858) ranges along the Pacific coast from southeastern Alaska south at least to San Diego County.  The slightly larger and drabber E. d. insulicola Oberholser, 1897, is a summer visitor only to the Channel Islands but has not been identified conclusively in migration on the California mainland.  The drab yellow-deficient subspecies E. d. cineritius Brewster, 1888, breeds in Baja California ranged at least formerly north to the Sierra Juárez (Laguna Hanson, 24 July 1924, SDNHM 31899).  Anthony (1895) reported his late June specimens from Cuyamaca Peak (M20) as cineritius.  But six more recent (1984–1993) San Diego County breeding specimens are all typical of nominate difficilis. The southward expansion of difficilis has probably already swamped any former population of cineritius. 

The split of the Western Flycatcher into two species seems premature in the lack of adequate study in most of the area of possible sympatry in southeastern British Columbia, northeastern Washington, eastern Oregon, and northwestern Montana.

Black Phoebe Sayornis nigricans

Few birds were as preadapted to urbanization as the Black Phoebe.  A lawn, pond, or horse corral serves for foraging habitat, a building or bridge for a nest site, and a mud puddle for nest material.  The Black Phoebe is a common year-round resident where these elements are common.  Rural ranchettes, urban parks, and reservoirs offer ideal habitat, but some birds use the expanses of single-family houses.  The Black Phoebe is uncommon in wild areas where it has to content itself with its original habitat, canyons with intermittent pools and overhanging rocks.

Breeding distribution: At the scale of our atlas grid, the Black Phoebe is almost uniformly distributed over San Diego County’s coastal slope.  The high rate of nesting confirmation reflects the ease with which its nests can be found.  Despite the birds’ requiring mud for their nests, even ephemeral puddles suffice, allowing at least sporadic breeding in such largely waterless areas as the Jamul Mountains (T14) and Otay Mountain (V15).  Buildings, bridges, and culverts now offer abundant nest sites anywhere on the coastal plain that once lacked them, and in the foothills Black Phoebes still use the rocky canyons that must have been their primitive habitat.  Twenty-five to 35 in a day may be seen in the coastal regions where the population is densest, but the numbers are much lower at the higher elevations; for example, none of our observers reported more than a single family of Black Phoebes per day in the Palomar and Laguna mountains.  The Black Phoebe is scarce along the east face of the mountains but nests locally along the few perennial creeks, as in Borrego Palm Canyon (F23; fledging on 4 May 1997, P. Famolaro) and Bow Willow Canyon (P26; used nest and adults feeding fledglings on 19 May 2001, L. J. Hargrove).  On the floor of the Anza–Borrego Desert, breeding Black Phoebes are confined to developed oases and uncommon even there, with no reports of more than four individuals in a day.

Nesting: An open half-bowl built of pellets of mud, plastered to a solid surface, sheltered from above, the Black Phoebe’s nest is distinctive; only the Barn Swallow’s resembles it.  The phoebe’s habit of building under bridges and the eaves of buildings is so well known that frequently our observers did not describe the situation of the nests they located; they simply confirmed breeding by checking out the nearest such structure when they found the birds.  Nevertheless, 32 nests were described as on buildings (ranging from occupied apartment and office buildings to abandoned shacks), 10 under bridges, six on drainage structures (including two below ground level in storm drains), one in a railroad tunnel, one on an old farm wagon, and nine on natural rock overhangs along creeks.  The durability of the nests, in their protected locations, means they persist from year to year and allows the birds to refurbish them, reinforcing the rims with new mud or stacking a new nest atop an old one.  The nests’ durability also led to our observers’ reporting many old nests, up to 16 in a day southeast of Mesa Grande (I17) 15 June 2000 (D. C. Seals).  Still, nests poorly supported from below can collapse, destroying a clutch, as F. L. Unmack noted near Bankhead Springs (U27) 20 April 1997.

            Unlike our more migratory flycatchers, the Black Phoebe regularly raises two broods per year (Wolf 1997).  Thus it has a long breeding season, beginning in early March (nest building as early as 1 March, nest occupied as early as 4 March, and young being fed as early as 19 March) and running through July (nest with eggs as late as 2 July, young being fed as late as 1 August).  The season is therefore somewhat more extended at both ends than attested by the egg-date span of 17 March–16 June from collections and Sharp (1907).

Migration: There is no clear evidence of Black Phoebe migration in San Diego County.

Winter: In spite of a diet consisting almost exclusively of insects, the Black Phoebe appears practically sedentary in San Diego County, remaining in winter even at the higher elevations—up to 5400 feet at Big Laguna Lake (O23; up to two on 18 January 1998, P. Unitt).  There may be some influx from farther north in winter, as there is around the Salton Sea (Patten et al. 2003), or the local population may disperse only short distances, concentrating around water and insects.  The only area of San Diego County where numbers are clearly higher in winter is the Borrego Valley, where daily counts range up to 36 in north Borrego Springs (F24) on 19 December 1999 (P. K. Nelson).  On the coastal side, the highest count per day in winter is 64 around Lake Hodges (K10) 27 December 1998 (R. L. Barber).

Conservation: Importation of vast quantities of water, and the building of vast numbers of structures ideal for nest sites, have turned much of San Diego County into Black Phoebe paradise.  Though the species has long been common, its numbers along the coast continue to increase, as suggested by results of the Oceanside, Rancho Santa Fe, and San Diego Christmas bird counts.  San Diego count results imply that Black Phoebe numbers in that circle roughly tripled from the 1950s and 1960s to 1997–2001.  Little or no change is evident farther inland, from the Escondido, Lake Henshaw, and Anza–Borrego circles, though the terms of these counts are shorter.  Thus we may infer that the increase is a response to development creating more habitat, rather than a response to climate warming or other factors.  The Black Phoebe’s wintering in the Anza–Borrego Desert is undoubtedly a by-product of irrigation and development, and its continuing increase as a breeding species in the Salton Sea region (Patten et al. 2003) suggests that an increase in the Borrego Valley can be expected.

Taxonomy: Only the subspecies S. n. semiatra (Vigors, 1839), distinguished by its extensively white belly and undertail coverts, occurs in or near California.

Eastern Phoebe Sayornis phoebe

None of the olive-drab flycatchers is common in winter, and the most frequent at that season is actually a vagrant from eastern North America, the Eastern Phoebe.  It occurs at a rate of about one bird per year, and it usually visits ponds or irrigated areas, the same habitats as the Black Phoebe’s.

Migration and winter: The difference between these two roles is blurred with the Eastern Phoebe, as the records (at least 46 total) are concentrated in November and December.  Close to half are clearly of birds wintering.  The records extend from 27 September (1983, Lake Henshaw, G17, R. Higson, AB 38:247, 1984) and 8–12 Oct 1992 (near Imperial Beach, V10, J. O. Zimmer, AB 47:150, 1993) to 12 March (1994, near San Diego, C. G. Edwards, NASFN 48:248, 1994).  Two later records (1–2 April 1997, Point Loma, S7, R. E. Webster, FN 51:928, 1997; 18 April 1989, Agua Caliente Springs, M26, D. and M. Hastings, AB 43:537, 1989) appear to be of spring migrants.

            Most Eastern Phoebes in San Diego County have been found in the coastal lowland, but five are from elevations up to 3200 feet at Lake Henshaw, Mesa Grande (H17; Unitt 1984), and Lake Morena (T21; 24 February 1994, R. Gardner, NASFN 48:248, 1994).  There are also four records from the Borrego Valley: 10 November 1992–22 February 1993 (A. G. Morley, AB 47:150, 301, 1993), 13 December 1994 (K. Burton, NASFN 49:199, 1995), 20 December 1998 (E24, P. R. Pryde, NAB 53:209, 1999), and 17 December 2000 (E25, L. J. Hargrove, P. Unitt).

Say’s Phoebe Sayornis saya

Expanses of bare earth, often disturbed, or areas of sparse grass or weeds, with only scattered shrubs, Say’s Phoebe’s habitat hardly meets most people’s expectations for “habitat.”  Yet this bird specializes in such places, scanning the ground for insects that can be hover-gleaned, as well as foraging for aerial insects in typical flycatcher fashion.  Say’s Phoebe is primarily a winter visitor to San Diego County, uncommon to fairly common.  But it is also widespread as an uncommon breeding species in the Anza–Borrego Desert, on the Campo Plateau, and, increasingly, in the inland valleys of the coastal slope.

Breeding distribution: The Say’s Phoebe’s distribution is complex and dynamic.  The species is widespread in the Anza–Borrego Desert, where most atlas squares contain some of the canyons, bluffs, or buildings offering the shaded niches it needs for nesting. Over most of the desert, breeding Say’s Phoebes are uncommon and scattered, but, as around Canebrake (N27) 30 April 2000 (R. and S. L. Breisch), counts per day range up to 14, where scattered houses or eroded gorges winding through badlands offer more nest sites.  The desert distribution extends up to Scissors Crossing (J22) and over the divide to the Ranchita and Warner Springs areas.  A pair nesting in a drain pipe at 4900 feet elevation on the east side of Hot Springs Mountain (E21) 19 June 1999 (K. L. Weaver) was the highest known in San Diego County.  Yet Say’s Phoebe appears absent from the higher elevations of the Santa Rosa and Vallecito mountains, enclosed within the Anza–Borrego Desert.  A few Say’s Phoebes also extend up onto the plateau region of southeastern San Diego County, between Campo and Jacumba.  Though we did not confirm breeding in this area, we recorded the species through the spring and early summer and noted a few pairs.

            In the coastal half of the county, Say’s Phoebe has become widespread in the inland valleys.  The numbers are still small, with rarely more than a single family encountered in a day.  The maximum count per day in this region during the breeding season is six, as at Lake Hodges (K10) 23 June 1998 (R. L. Barber).  A few pairs are nesting practically along the coast, illustrated most notably by a fledgling 0.5 mile from the beach near San Onofre (C1) 2 June 2000 (C. Reynolds), another at La Costa (J7) 24 June 1998 (M. Baumgartel), two in Gonzalez Canyon (M8) 17 June 2001 (S. E. Smith), and one picked up injured at Mar Vista High School in Imperial Beach 26 June 1998 (SDNHM 50127).  A nest on a building at the naval radio station at the south end of the Silver Strand (U10/V10) in 2003 and 3 March 2004 was only 1000 feet from the beach (D. M. Parker).  Some interchange between the coastal and desert populations is likely, with pairs nesting as far inland as Santa Ysabel (J18; under the porch of Don’s Market, both 1998 and 1999, J. R. Barth, S. E. Smith) and Tecate (V19; pair feeding young 10 June 2000, M. and B. McIntosh).

            Complicating the distribution are scattered individuals, including independent juveniles, seen in the foothills and mountains at times when Say’s Phoebes could be nesting.  Nevertheless, only one of these falls between 8 April and 6 June, one at Cuyamaca Lake (M20) 28 May 1999 (A. P. and T. E. Keenan).  Only this record is mapped as in suitable habitat; the birds seen from June onward may be postbreeding dispersers from the desert.

Nesting: Say’s Phoebes rely heavily on man-made structures for nest sites, and all nests reported from the coastal slope were in such situations.  We noted four nests on sheltered ledges inside crevasses eroded into desert badlands, but the 14 other nests whose placement our observers described were on such things as houses, outbuildings, carports, restrooms, a metal stairway, a bridge over Poway Creek, and the Anza–Borrego Desert State Park headquarters office.

            Our observations of Say’s Phoebe nesting imply that the species usually begins laying in the third week of March, with little difference between the coastal slope and the desert.  A nest begun in Mira Mesa (N9) 3 March 2000 took two weeks to complete (S. L. Breisch).  An exceptionally early nest with two eggs at the Anza–Borrego Desert State Park headquarters 7 February 2000 was abandoned shortly thereafter; the pair renested at a more usual time (P. D. Jorgensen).  In the wet spring of 1998, though, the birds nested early, with adults carrying insects to young apparently still in the nest as early as 6 March in north Borrego Springs (F24; P. D. Jorgensen), implying laying no later than 18–20 February.  Our five earliest records of Say’s Phoebe feeding young, in fact, are from 1998.  Second or replacement clutches may be laid as late as mid June, as demonstrated by an ill-fated pair at Mira Mesa, which still had young in an replacement nest 16 July 1999, fledging by 21 July (S. L. Breisch).

Migration: Say’s Phoebes wintering in San Diego County depart primarily in March and  arrive in September.  But exact dates of migrants can no longer be picked out because of the local breeding population is increasing, apparently shifts over short distances, and the locally breeding subspecies, at least along the coast, is the same as that farther north.  Some desert breeders vacate their range from June through August (Rea 1983, Patten et al. 2003) and may disperse west into the foothills and mountains of San Diego County, as implied by scattered summer observations.

Winter: Say’s Phoebe is widespread in San Diego County as a winter visitor, but it is scarce above 4000 feet elevation and lacking from unbroken forest, chaparral, or urban development, though it uses small areas of open ground within these habitats.  Thus the distribution is patchier than evident on the scale of our atlas grid.  The species is most numerous in the inland valleys of the coastal lowland, with up to 35 in a day around Sweetwater Reservoir (S12) 20 December 1997 (P. Famolaro), and on the floor of the Borrego Valley, with up to 35 in north Borrego Springs (F24) 20 December 1998 (R. Thériault).  Over most of the county, though, the species has to be rated as uncommon, with five or fewer individuals detected per day.

Conservation: No change in the Say’s Phoebe’s status in the Anza–Borrego Desert is known, but on the coastal slope the species decreased, then increased, for reasons still obscure.  Until 1939, nesting of Say’s Phoebes was noted occasionally, with records for Escondido, 3 to 6 miles east of Encinitas, Sorrento, San Diego, and Chula Vista.  Then 40 years followed in which the species was known in the coastal lowland as a winter visitor only.  Following a report from the Tijuana River valley 9 June 1979 (AB 33:898, 1979), scattered observations cropped up in the inland valleys in the 1980s, and their rate accelerated in the 1990s.  Nesting Say’s Phoebes in this area were a novelty to our atlas observers, many of whom commented on them with surprise.  Why should Say’s Phoebe have disappeared, and why should it have returned?  The disappearance coincided with a period in which much former Say’s Phoebe habitat was converted, with irrigation and landscaping, into Black Phoebe habitat.  Though much suitable habitat remained, from Pauma Valley to Ramona to Jamul, perhaps the small population dropped below a sustainable threshold.  The accelerating return suggests that Say’s Phoebe is adapting anew, perhaps aided by a long-term trend toward a warmer, drier climate.  Clearing of scrub and erection of buildings create new Say’s Phoebe habitat, but landscaping and paving remove it.  The bird’s need for open ground for foraging suggests its potential as an urban adapter is limited.  But further increase is likely with further adaptation to low-density suburban development.  Urban nesting of Say’s Phoebes may expose the birds to unaccustomed threats: one pair that nested repeatedly atop a bell at a Mira Mesa school (N9) suffered losses to both clean-up by maintenance workers and predation by European Starlings (S. L. Breisch).

Taxonomy: Winter visitors are the dark S. s. saya (Bonaparte, 1825), widespread in western North America north of San Diego.  The coastal population, judged from the quite dark juvenile specimen from Imperial Beach, is this subspecies too.  This identification also implies that the recent increase in breeding Say’s Phoebes on the coastal slope is the result of colonization from the north.  Breeding Say’s Phoebes in eastern San Diego County are more likely S. s. quiescens Grinnell, 1926, paler than nominate saya, especially on the crown, which is practically concolorous with the back.  The only specimen so far from the Anza–Borrego Desert is quiescens, though it was collected in winter, in Mason Valley 15 January 1925 (SDNHM 2915).  Two juveniles from Laguna Hanson in the Sierra Juárez are quiescens, as are several specimens from the Colorado Desert (Rea 1983, Patten et al. 2003).

Vermilion Flycatcher Pyrocephalus rubinus

Spectacular, tame, and easy to see, habitually perching on the lowest branches of isolated trees, the Vermilion Flycatcher is a birder’s favorite.  One would think such a species a perfect poster child for promoting conservation of its desert riparian habitat.  Yet its decline in its historic California range continues unabated.  The Vermilion Flycatcher was always rare in San Diego County, but since the mid 1980s it has become even more so.  It survives precariously in five areas and seldom pioneers far from these.

Breeding distribution: Here at the northwestern corner of its usual breeding distribution along the Pacific coast, the Vermilion Flycatcher is rare and scattered in San Diego County.  Its characteristic habitat of open riparian woodland and mesquite bosques on desert floodplains is barely represented in San Diego County, though the birds and their habitat occur in the drainage basin of the Tijuana River at Valle de las Palmas in northwestern Baja California.  The most regular site for the species in San Diego County is the private Butterfield Ranch campground in Mason Valley (M23), with up to four individuals, as on 16 April 1999 (M. B. Stowe) and 21 March 2001 (P. K. Nelson).  The Vermilion Flycatcher was first reported from this site in summer 1984 (C. G. Edwards; AB 38:1062, 1984) and has remained more or less continuously ever since.  The “population” in this region extends also to adjacent Vallecito Valley (M24), with one pair, the female building a nest, at a private ranch house 21 March 2001 (P. K. Nelson).  The Vermilion Flycatcher is irregular in the Borrego Valley.  At De Anza Country Club (F24), one pair nested in March 1993 (Massey 1998); one was at a nest with eggs 2 May 1997, and a single individual was noted 5 April and 27 May 2001 (M. L. Gabel).  A pair was at Whitaker Horse Camp (D24) 13–14 May 2001 (R. and. S. L. Breisch), the male in courtship display, but the birds did not remain to nest.

One surprise of our atlas effort was the occurrence of the Vermilion Flycatcher in Warner Valley.  One pair nested north of Lake Henshaw (F17) 27 May–11 July 1997 (P. Beck), another near the old Warner Ranch house (G19) 17–25 June 2000 (J. D. Barr, E. C. Hall, M. U. Evans).  Another pair was at Lake Henshaw (G17) 12 May 2001 (R. and S. L. Breisch); single males were west of Warner Springs (F18) 28 May 1997 (P. Beck).  Elsewhere in eastern San Diego County, single males were at an old corral near Sentenac Ciénaga (J23) 14 June 1998 (R. Thériault), in McCain Valley (S26) 19 April 1999 (G. L. Rogers), and at Cameron Corners (U23) 1 April 2001 (L. and A. Johnson, fide D. S. and A. W. Hester).

Nearer the coast, the Vermilion Flycatcher appears regular at only two sites.  At Bonsall (F8), there was one 9 July 1997 (L. Gammie) and an adult with two fledglings 25 May 2000 (J. Evans).  Along the Sweetwater River, a singing male was at the Singing Hills golf course (Q14) 30 April 2000 (J., E., and K. Berndes) and a pair was a short distance downstream at the Rancho San Diego golf course in Jamacha Valley (R14) 11 April 1999 (N. Perretta, P. Nance), with a single male noted there 19 July 1999 (D. Stokes).  The Vermilion Flycatcher has been reported from this area sporadically for years.  Not far away was one at the end of Eula Lane 3.6 miles east-northeast of downtown El Cajon (Q14) 1 May 1999 (J., E., and K. Berndes).  The only other report of a possibly breeding Vermilion Flycatcher 1997–2001 was at the Eagle Crest golf course, east Escondido (J12), 31 May 1998 (C. Rideout).

Nesting: The Vermilion Flycatcher typically places its shallow nest in a horizontal fork in the middle level of trees (Wolf and Jones 2000).  Because the fork selected is free of leaves and the habitat itself is semiopen, the nests are not difficult to find—possibly making the Vermilion Flycatcher especially vulnerable to predators and cowbirds.  Because of the species’ rarity in San Diego County, our records, encompassing only eight pairs, do not define its breeding season well.  But the spread of dates, ranging from nest building on 20 March to fledglings on 11 July, implies the Vermilion Flycatcher may raise two broods, as elsewhere in the southwestern United States (Wolf and Jones 2000).

Migration: The Vermilion Flycatcher no longer has a clear-cut migration in California; the former pattern of largely summer residency has now changed to irregular dispersal.  The only record of a spring migrant 1997–2001, of a female at Point Loma (S7) 22 May 1999 (P. A. Ginsburg), was exceptionally late.  Previous records from nonbreeding localities run no later than 28 April (1990, San Diego River mouth, R. E. Webster, AB 44:497, 1990).  The Vermilion Flycatcher is most widespread during fall dispersal, beginning by 16 September (1983, Tijuana River valley, E. Copper, AB 38:247, 1984) and extending through October.

 

Winter: At this season, the Vermilion Flycatcher is little more widespread than during spring and summer.  Most records 1997–2002 were at or near locations where it was noted also during the breeding season: Bonsall, Lake Henshaw, Borrego Valley, San Pasqual Valley, Butterfield Ranch, Lakeside, Singing Hills.  Only a few records were more than 7 miles from breeding-season locations: one at La Costa (J7) 13 December 1997 (M. Baumgartel), one on the east edge of Poway (L12) 1 February 2001 (K. J. Winter), and one in Ballena Valley (K17) 25 February 2000 (D. C. Seals) and 16 February 2001 (O. Carter).  Winter numbers were also similar to those during the breeding season, with a maximum of five in the San Luis Rey River valley 1–2 miles northeast of Bonsall (E8) 14 December 1999 (P. A. Ginsburg).

 

Conservation: Though the Vermilion Flycatcher has colonized several new locations in the Mojave Desert, its career through the history of California as a whole has been one of calamitous decline.  This decline is reflected in San Diego County as well, however marginal the region is to the flycatcher’s main range.  Results of Christmas bird counts reflect the decline most clearly.  From 1960 through 1974 the Vermilion Flycatcher was annual on the San Diego count, with a maximum of eight in 1968.  From 1975 through 1986, it occurred in only five of 12 years, with no more than one individual.  Since 1986 the species has gone unrecorded.  Likewise, on the Oceanside count, the Vermilion Flycatcher was noted in 10 of the 18 years from 1970 to 1987, with a maximum of three on 22 December 1979, but not since 1987.  The areas around Bonsall where the species occurs are largely outside the count circle and within private ranches.  Nesting of Vermilion Flycatchers at Santee in 1958, Balboa Park from 1958 to 1960 (Crouch 1959), Bonita in 1968 (G. McCaskie), and Jacumba in 1986 (AB 40:1256, 1986) proved ephemeral.

            Degradation of riparian woodland is probably the factor affecting the Vermilion Flycatcher most strongly.  Because San Diego County is marginal to the flycatcher’s range, it may be even more susceptible to environmental change here than closer to the core.  Population collapse in the Coachella, Imperial, and Colorado River valleys decimated a source of immigrants.  The Vermilion Flycatcher occurs most often now in parks, campgrounds, and golf courses, which have proliferated with development.  Yet the flycatcher’s continuing decline suggests that these habitats are poor substitutes for natural riparian woodland.  Recent riparian restoration, along with flood control, favors dense woodland in narrow strips, rather than broad open woodland more suitable to the Vermilion Flycatcher.  Meanwhile, pumping of groundwater desiccates the remaining habitat.

 

Taxonomy: However brilliant the male Vermilion Flycatcher appears to those of us who are familiar only with P. r. flammeus van Rossem 1934, this subspecies, the only one in California, is actually paler, less intensely colored than others farther south.

Dusky-capped or Olivaceous Flycatcher Myiarchus tuberculifer

The Dusky-capped Flycatcher reaches California as a rare winter visitor from the southeast.  San Diego County accounts for so small a fraction of the state’s 64 records (through 2002) that we may infer that the trajectory of most vagrants passes to the north of us.  In the United States, the “Dusky-capped” Flycatcher has no dusky cap; it must be distinguished from the similar Ash-throated by its smaller size, flatter and proportionately longer bill, less rufous in the wings and tail, and, most characteristically, by its soft mournful whistle, “peeeur.”

Winter: Four records, of one photographed at La Jolla 8 March 1985 (L. Bevier et al., AB 39:211, 1985, Dunn 1988), one on the grounds of the San Diego Zoo 16 February–7 April 1988 (B. and I. Mazin, AB 42:322, 1988, Pyle and McCaskie 1992), one at Point Loma (S7) 12 April–1 May 1997 (P. A. Ginsburg, FN 51:928, 1997, Rottenborn and Morlan 2000), and one at Greenwood Cemetery (S10) 15 December 2001–22 February 2002 (J. O. Zimmer et al.).  Though the date of at least the Point Loma record suggests a spring migrant, the species’ pattern of winter occurrence in California is so well established that it seems certain that all San Diego County Dusky-capped Flycatchers arrived at that season but may not have been discovered until late in their stay.

 

Taxonomy: The one specimen from California, from Death Valley, has been identified as M. t. olivascens Ridgway, 1884, the subspecies ranging north to the northern limit of the species’ breeding range, in the mountains of southern Arizona (Suffel 1970).  Myiarchus t. olivascens has less rufous edging on its remiges and rectrices than other Middle American subspecies.  Like some other west Mexican subspecies of M. tuberculifer, it has a crown no darker than the back.

Ash-throated Flycatcher Myiarchus cinerascens

 

Common in summer, rare in winter, the Ash-throated Flycatcher breeds from the inland valleys to the mountains to the Anza–Borrego Desert in any habitat where it can find a suitable nest cavity.  The members of the genus Myiarchus are the only North American flycatchers that nest in enclosed spaces like old woodpecker holes, other tree hollows, pipes, or bird houses.  Despite the scarcity of suitable cavities, and the birds' willingness to use man-made nest sites, nesting Ash-throated Flycatchers remain largely outside the urban fringe. In the coastal strip the species is seen in primarily in migration.

 

Breeding distribution: The Ash-throated Flycatcher is one of San Diego County’s most widespread breeding birds.  It is most common in the mountains or foothill canyons where there is extensive woodland.  Exceptionally high counts during the breeding season are of 40 around Case Spring, Camp Pendleton (B4), on 25 July 1998 (P. A. Ginsburg), 50 in Matagual Valley (H19) 18 June 2000 (S. E. Smith), and 35 in the Edwards Ranch northeast of Santa Ysabel (I19) on 9 June 2001 (D. W. Au, S. E. Smith).  It is only along the coast and in the Anza–Borrego Desert where we see significant gaps in the Ash-throated Flycatcher’s range.  The Ash-throated resembles the Western Kingbird in avoiding the coastal strip as a breeding species, though it can be common just a short distance inland (e.g., 13 in Los Peñasquitos Canyon, N8, 7 June 1998, P. A. Ginsburg).  In the Anza–Borrego Desert, because it depends largely for nest cavities on the Ladder-backed Woodpecker, it is rare or lacking where the woodpecker is rare or lacking, especially in the Borrego Badlands and Ocotillo Wells regions.

 

Nesting: Like most other cavity-nesting birds the Ash-throated Flycatcher is flexible and resourceful.  Old woodpecker holes in trees are the most frequent site, but the cavity may be natural.  Atlas observers described four nests in oaks (coast live, black, and Engelmann), three in sycamores, two in yuccas, one in cottonwood, and one in the split trunk of a desert “willow” (Chilopsis linearis).  Nests in artificial sites included nine in nest boxes, five in metal or plastic pipes, one in a woodpecker hole in a fence post, one in a mailbox, and one in the tailpipe of wrecked vehicle used for target practice.  Possible but unconfirmed sites in the Anza–Borrego Desert include cavities in rocks or bluffs and rodent burrows in sandy hummocks.

            Bent (1942) reported 79 California egg sets ranging in date from 12 April to 5 July.  In San Diego County, however, we found the Ash-throated Flycatcher nesting somewhat earlier, in several cases beginning around 1 April.  Nest building was reported as early as 4 April (1997, in Earthquake Valley, K23, G. Sanders), occupied nest cavities as early as 6 April (2000, at Wilderness Gardens County Park, D11, V. Dineen).  Reports of adults feeding young as early as 19 April (1998, near Sunset Mountain, J26, F. L. Unmack, R. Orr) and fledglings as early as 2 May (2001, Inner Pasture, N25, A. P. and T. E. Keenan) also point to egg laying around 1 April.  Many of these records, though, are from the Anza–Borrego Desert, poorly sampled by early egg collections.  From Baja California, over much of which the Ash-throated Flycatcher is a year-round resident, Bent (1942) reported egg dates as early as 13 March.  Most Ash-throated Flycatcher nesting in San Diego County, though, takes place later in the summer.  An occupied nest in the Agua Tibia Wilderness (C13) as late as 22 July (2000, J. M. Wells) suggests the birds could be laying even later than Bent’s spread implies.

 

Migration: Ash-throated Flycatchers begin arriving in the latter half of March; 17 March (1998, one near Angelina Spring, I22, P. K. Nelson) is the earliest date.  As in many other species, these early arrivals (concentrated in the Anza–Borrego Desert) are likely of the local breeding population, with migrants headed farther north coming later, not in numbers until the second week of April.  Peak migration is in late April, as implied by the 75 grounded in strong wind at Vallecito (M25) 29 April 1997 (M. C. Jorgensen).  By the third week of May almost all migrants have continued north; 21 May (1999, one near the Santa Margarita River mouth, G4, P. A. Ginsburg) was the latest we recorded from 1997 to 2001.  Even later stragglers have been recorded to 6 June (1974, two at Point Loma, J. L. Dunn).  Fall migration begins by 26 July (2001, one in Chula Vista, U11, T. W. Dorman) and trails off through October.

 

Winter: The Ash-throated Flycatcher is rare in winter but occurs annually, with 20 records 1997–2002.  Of these, nine were at low elevations along the coast or in the inland valleys, one was around 1350 feet elevation in Barona Valley (M15; one on 28 December 2000, J. Smith), four were around 2800 to 3500 feet elevation in the Jacumba area (F. L. Unmack), one was around 2350 feet elevation in Earthquake Valley (K23; two on 12 February 2000, P. Flanagan, the only winter record of more than one individual), and five were on the floor of the Anza–Borrego Desert.  Previous winter records, at least 30, are all from the coastal lowland or desert floor.  San Diego County lies just to the northwest of the Ash-throated Flycatcher’s main winter range; wintering birds are quite a bit more numerous in eastern Imperial County and at the east base of the Sierra San Pedro Mártir in northern Baja California.

 

Conservation: Although the Ash-throated Flycatcher readily uses man-made structures for nesting, it is not an urban adapter.  It is absent from the developed areas of the city of San Diego and very rare in the urban canyons, with scant evidence of breeding (“distraction display” in Tecolote Canyon, Q8, 10 June 1999, J. C. Worley).  Other heavily developed areas likewise have few or no breeding Ash-throated Flycatchers.  But because of the species’ “anticoastal” distribution urbanization has likely had only a minor effect on the Ash-throated Flycatcher population.  The species is most concentrated in areas where development pressure so far is light or none.  Smooth-sided vertical plastic pipes, into which the birds can descend but not escape, are a hazard to this species (P. D. Jorgensen).

 

Taxonomy: The resident Baja California population of the Ash-throated Flycatcher, though averaging smaller than the migratory birds farther north, overlaps with the latter too much for two subspecies to be recognized.  Myiarchus cinerascens is thus best considered monotypic (Patten et al. 2003).

Great Crested Flycatcher Myiarchus crinitus

The only representative of the genus Myiarchus in eastern North America and a rare fall vagrant to California, the Great Crested closely resembles the Brown-crested and Ash-throated Flycatchers.  Fortunately, the birds reaching California are fresh-plumaged immatures that show the species’ characters well, a darker throat and breast and broad, crisp white edge on the innermost tertial that expands in width from tip to base.

Migration: All five San Diego County records of the Great Crested Flycatcher are from Point Loma in fall.  By date, these are 19 September 1975 (G. McCaskie, AB 30:128, 1976), 20 September 1983 (R. E. Webster et al., Roberson 1986), 25 September 1987 (G. McCaskie, Pyle and McCaskie 1992), 6 October 1978 (E. Copper, P. Unitt, AB 33:216, 1979; Binford 1983), and 10–13 October 2001 (R. E. Webster, NAB 56:107, 2002). The record for 20 October 1974 was rejected by the California Bird Records Committee.

Brown-crested or Wied’s Crested Flycatcher Myiarchus tyrannulus

The Brown-crested Flycatcher presents the same paradox as the Summer Tanager: a species expanding its range while its habitat has been decimated.  First found on the Colorado River in 1921, occurring in numbers there by 1930, and first found west of the Colorado, at Morongo Valley, in 1963, the flycatcher is clearly spreading northwest, out of its stronghold in the riparian woodland and saguaros of southern Arizona.  Yet in California it depends for nest sites on large riparian trees, largely eliminated with the taming of the Colorado River.  The Brown-crested Flycatcher arrived in San Diego County as a new breeding species in 2000.

Breeding distribution: Mary Beth Stowe’s discovery of a family of Brown-crested Flycatchers at the Roadrunner Club in Borrego Springs (F24) 26 August–18 September 2000 was among the more sensational events of the atlas project’s five years.  The two adults fed three fledglings high in eucalyptus trees at a pond in this community of mobile homes within a golf course.  Photographed, seen, and heard by many, these birds represented the first well-supported identification of the Brown-crested Flycatcher in San Diego County as well as the first breeding.  The pair returned the following year, first found 16 May 2001 (P. D. Jorgensen, NAB 55:356, 2001).  Nesting was not confirmed that year, but the last report, on 17 August 2001, may have been of a juvenile (fide P. D. Jorgensen).

            At least one, probably two, Brown-crested Flycatchers were calling in riparian woodland near the confluence of San Felipe and Banner creeks (J22) 13 July 2001 (M. B. Mulrooney, P. Unitt).  Two pairs summered there in 2002, and at least one of these nested in a cavity in a cottonwood (nestlings 7 July).  A pair summered there again in 2003 (J. R. Barth, P. D. Jorgensen).  Another pair colonized Lower Willows along Coyote Creek (D23) in 2002, attending a nest hole 9 July (J. R. Barth).

Nesting: Like the other species of Myiarchus, the Brown-crested Flycatcher is a cavity nester, in Arizona relying mainly on old holes of the Gila Woodpecker and flicker for nest sites.  As no large woodpeckers nest at Borrego Springs, the flycatchers at the Roadrunner Club probably used an artificial site, possibly the space behind a loose slab of eucalyptus bark. 

            The incubation and nestling periods of the Brown-crested Flycatcher are still unknown, so it is difficult to estimate when the pair at Borrego Springs may have nested.  But the family was discovered so late in the year that the birds must have laid at the very end of the species’ breeding season; Bent (1942) reported a latest egg date from Arizona of 17 July.  Perhaps these pioneers wandered southeastern California for much of the summer before finding each other, and a suitable nest site, at Borrego Springs.

Migration: The Brown-crested Flycatcher is a summer visitor to the southwestern United States, rarely arriving before the first week of May, and with an earliest California date of 24 April (Garrett and Dunn 1981).  Fall departure is usually in August, rarely as late as early September, making the late date of the birds at Borrego Springs in 2000 noteworthy, and reinforcing the idea that as pioneers they were delayed beyond the species’ usual schedule.  During regular monitoring of San Felipe Creek 2002–03, the earliest date on which J. R. Barth noted the species was 19 May 2002.

Two sightings have been reported from Point Loma (S7), 9 June 1991 (R. E. Webster, AB 45:497, 1991) and 13 October 2001 (R. E. Webster, D. M. Parker, NAB 56:107, 2002).

Winter: Unrecorded.  But two winter records for Orange County suggest that the Brown-crested Flycatcher could start a pattern of winter occurrence resembling that of other species from southern Arizona and western Mexico—the Dusky-capped Flycatcher, Tropical Kingbird, and Greater Pewee.

Conservation: The Brown-crested Flycatcher’s push west was likely inhibited by the decimation of riparian forest along the Colorado shortly after its arrival, then the lack of woodpeckers large enough to excavate cavities large enough for this biggest species of Myiarchus. Thus west of the Colorado the Brown-crested Flycatcher may depend largely on man-made cavities.  Its spread into natural habitats is contingent on the maintenance of mature desert riparian woodland, easily degraded by the proliferation of saltcedar.

Taxonomy: Specimens from the Colorado River south through western Mexico are the large M. t. magister Ridgway, 1884; presumably Brown-crested Flycatchers farther west are the same.

Sulphur-bellied Flycatcher Myiodynastes luteiventris

Though more strongly migratory than some other subtropical flycatchers that reach California as vagrants, the Sulphur-bellied is one of the rarest.  With its heavy dark streaks and bright rufous tail, it is also one of the more distinctive.

Migration: Of California’s 14 records of the Sulphur-bellied Flycatcher, two are from San Diego County.  Both are from Point Loma in fall, 7 October 1979 (C. Carpenter, G. McCaskie et al., AB 34:202, 1980; Binford 1983) and 16–20 September 1983 (R. E. Webster et al., photographed, AB 38:247, 1984, Roberson 1986).

Tropical Kingbird Tyrannus melancholicus

Among the vagrant flycatchers that originate from southern Arizona and western Mexico, the Tropical Kingbird is the most frequent.  In San Diego County it is rare but annual in fall, very rare in winter.  The yellow-suffused breast and longer, heavier bill are better features for distinguishing the Tropical from the Western and Cassin’s Kingbirds than the notched tail.  With the extremely similar Couch’s Kingbird (T. couchii) now demonstrated, on the basis of tape recordings of the diagnostic call, to have reached Orange County (Rottenborn and Morlan 2000), noting the high-pitched twittering call of the Tropical becomes all the more important to its identification in California.

Migration: The Tropical Kingbird reaches California primarily in the fall.  A few individuals are found every year, along or near the coast.  The earliest known date in San Diego County is 12 September (1962, one at Coronado, McCaskie and Banks 1964).  The species is most numerous from late September through mid October.  The maximum for a single day is seven in the Tijuana River Valley 8 October 1966 (AFN 21:78, 1967).  The species’ frequency declines gradually through November, so there is no division between fall and winter records.  One photographed at Border Field State Park (W10), 26–28 April 2001 (M. B. Mulrooney, NAB 55:357, 2001) provided a unique spring record.

Winter: There are at least 11 winter records, all within 11 miles of the coast.  Four were between 1997 and 2002: one at Bonsall (F8) 9 February 2001 (P. A. Ginsburg), one at Rohr Park (T12) 1 December 2001–14 January 2002 (C. G. Edwards et al.), two in Imperial Beach (V10) 20 December 1997–24 January 1998 (C. G. Edwards et al.), and one at the Dairy Mart pond in the Tijuana River valley (V11) 13 December 1998–5 February 1999 (G. McCaskie, NAB 53:209, 1999).  The latest winter record is of one at Coronado Cays on the Silver Strand (T9) on 2 March 1974 (AB 28:693, 1974).

Cassin’s Kingbird Tyrannus vociferans

 

“ChiBEER!”  The loud call of Cassin’s Kingbird is becoming ever more familiar as this noisy bird’s population increases.  Once localized to sycamore groves in the coastal lowland, Cassin’s Kingbird has capitalized on the proliferation of eucalyptus and other exotic tall trees, which offer it nest sites and perches as it sits on the lookout for flying insects—and flying predators.  The clearing of chaparral and sage scrub and their replacement with suburbs and rural ranches has allowed Cassin’s Kingbird to expand its range and become a common year-round resident.

Breeding distribution: Cassin’s Kingbird is widespread over the coastal slope of San Diego County wherever large trees are scattered on open ground.  It occurs up to about 3000 feet elevation, rarely as high as about 3800 feet, as along Los Coyotes Road (F20; pair on 17 April 1999, K. L. Weaver, C. R. Mahrdt).  On the east slope of the mountains, the species nests at only one site, Jacumba (U28; six on 9 April 1998, C. G. Edwards; pair nest building on 1 May 2001, F. L. Unmack).

            Cassin’s Kingbird is most numerous in the inland valleys, where it lives in the same habitat as the Western Kingbird.  But Cassin’s is fairly common along the coastal strip, as a breeding species far more common there than the Western.  Thus in San Diego County the two breeding kingbirds reverse the pattern over most of their ranges, where Cassin’s is the species breeding at higher elevations (Tweit and Tweit 2000).  Some areas where Cassin’s Kingbirds were reported in exceptionally high numbers were Lake Hodges (K10; 40, including several fledglings, 9 July 1998, R. L. Barber), Los Peñasquitos Canyon (N8; 28 on 5 July 1998, D. K. Adams), and Valley Center (G12; 21 on 6 June 1998, A. G. and D. Stanton).  Along the coast, daily counts range up to 12, as at Batiquitos Lagoon (J7) 8 July 1998 (C. C. Gorman).  At the upper limit of their elevational range, the birds are rare.  For example, in Dameron Valley (C15) K. L. Weaver had only one record, of three on 14 June 1997; around Lake Morena (T21) R. and S. L. Breisch had no more than one pair, on 5 July 1997.

Nesting:  Cassin’s Kingbirds place their nests in the forks of large branches in the upper levels of tall trees.  Of the 13 nests whose locations our observers described, eight were in eucalyptus trees, three in sycamores, one in a pine, and one in an unidentified conifer, at heights estimated up to 70 feet.  The nests may be in rather open situations, allowing them to be seen from the ground, even when in the canopy.  Cassin’s Kingbird relies on aggressive nest defense rather than nest concealment, as reflected in the 61 times our observers specified “distraction display” for such defense, against crows, ravens, Western Scrub-Jays, and Red-tailed and Cooper’s Hawks.  Nevertheless, they noted also success against the kingbirds by all these predators except the Red-tailed.

            Because Cassin’s Kingbirds nest high in trees, determining their nesting schedule is not easy.  An earliest occupied nest on 2 April, earliest nest with nestlings on 23 April, and earliest fledglings on 2 May suggest the birds begin laying in the first few days of April, agreeing with Cooper’s (1870) finding them “breeding at San Diego as early as March 28^th.”  Nest building at Oak Hill Cemetery (I12) as early as 1 March 1999 (C. Rideout) and a male with greatly enlarged testes from Santee (P12) 14 March 2001 (SDNHM 50529) suggest that some Cassin’s Kingbirds begin even earlier.  With adults feeding fledglings as late as 2 August 2001 in Gold Gulch, Balboa Park (S9) and 18 August 1978 near the Santa Margarita River mouth (G4; P. Unitt), it seems likely that some Cassin’s Kingbirds are double-brooded in San Diego County, in contrast to other parts of the range where the species begins nesting much later (cf. Tweit and Tweit 2000).

Migration: With Cassin’s Kingbirds increasing in San Diego County in both the breeding season and winter, the passage of migrants becomes less and less noticeable.  Nevertheless, our highest counts from 1997 through 2001, of 60 southwest of Fallbrook (E7) 28 March 2001 (P. A. Ginsburg) and 41 at Lower Otay Lake (U13) 23 March 2001 (T. Stands), suggest concentrations of migrants at a season suggested by past records.  Eight reports from the Anza–Borrego Desert, outside the breeding distribution, extend from 15 April (2001, one in south Borrego Springs, G24, L. Polinsky) to 7 May (2001, two in Box Canyon north of Coyote Creek, C25, D. C. Seals); four other sightings reported by Massey (1998) range as early as 22 March (1993, Yaqui Well/Tamarisk Grove, I24) and so include more of the March migration evident on the coastal side.  Some of these desert records are from wilderness areas remote from trees but others are from developed areas that the species could colonize.

Winter: Neither the distribution nor abundance of Cassin’s Kingbirds in winter differs appreciably from that during the breeding season.  The species is most concentrated in winter in the inland valleys of northwestern San Diego County.  Daily counts there range up to 44 in Fallbrook (D8) 24 February 2001 (M. Freda), 36 in Rancho Santa Fe (L8) 28 December 1997 (A. Mauro), and 36 east of Lake Hodges (K11) 15 January 1998 (E. C. Hall).  Winter records range in elevation as high as 3500 feet feet in Miller Valley (S24, one on 21 Feb 1998, M. and B. McIntosh).  There are now 12 winter reports from the Anza–Borrego Desert, where the species was first noted at this season only on 17 December 1995 (Christmas bird count).  Most of these records are from the Borrego Valley, but there are single reports each from Butterfield Ranch (M23, one on 26 February 2000, E. C. Hall), Vallecito Valley (M24, two on 21 January 2001, B. Siegel), and Carrizo Palms (R28, one on 6 January 2000, J. O. Zimmer).

Conservation: Cassin’s Kingbird is on the increase in San Diego County, both in winter and as a breeding species.  Stephens (1919a) called it “rather rare.”  Most other early writers called it “uncommon,” and that term still applied in the 1970s (Unitt 1984).  Christmas bird count results suggest that a gradual increase began accelerating in the mid 1980s.  Our atlas results revealed the species in both greater numbers and ranging to higher elevations than reported previously.  The next step may be colonization of the Anza–Borrego Desert.  The species was unknown there even as a vagrant before 1985, but one or two individuals were noted in the Borrego Valley on Christmas bird counts each year 1998–2001.  Cassin’s Kingbird is also becoming more of an urban bird, infiltrating residential areas as trees mature.

            Why should Cassin’s Kingbirds be increasing?  A trend toward warmer temperatures, especially of winter lows, may help them.  The planting of ornamental and shade trees, especially eucalyptus, gives them nest sites in many areas that once had none.  Development, especially low-density suburban development that leaves large cleared areas around scattered houses, shaded by a tree or two, has created much new Cassin’s Kingbird habitat. Urban parks, schoolyards, and ranchettes have become more important to Cassin’s Kingbird than the sycamore groves that constituted its primitive habitat.

Taxonomy: Binford (1989) synonymized the only subspecies of Tyrannus vociferans, leaving Cassin’s Kingbird monotypic.

Thick-billed Kingbird Tyrannus crassirostris

The fall-and-winter pattern of the extremely rare Thick-billed Kingbird, another species from southern Arizona and western Mexico, is a faint echo of that of the Tropical.  A dark crown and the heavy bill most obviously distinguish the Thick-billed from the other kingbirds.

Migration and winter: The Thick-billed Kingbird is known in San Diego County from five records, of 15 total for California.  One was seen in the Tijuana River valley 19 October 1965 (McCaskie et al. 1967a), two were seen at Point Loma 3 December 1966 (AFN 21:78, 1967) and 18–23 October 1967 (AFN 22:90, 1968), one was photographed at Bonita 26–27 December 1966 (AFN 21:459, 1967), and one was seen at Rickey Lake (T13) 3 November 1993 (E. R. Lichtwardt, Erickson and Terrill 1996).

Western Kingbird Tyrannus verticalis

The Western Kingbird is a common migrant throughout San Diego County and a common summer visitor in the inland valleys.  Like Cassin’s it nests in tall trees next to grassland and clearings.  The Western also takes advantage of man-made structures, especially utility poles.  Despite its abundance in spring and summer, it is extremely rare in winter, less frequent even than the Tropical Kingbird at that season.

Breeding distribution: The Western Kingbird breeds widely on the coastal slope of San Diego County where tall trees or telephone poles for nest sites are near open grassland, pastures, or clearings for foraging.  Thus its habitat is the same as the Cassin’s Kingbird’s, but the Western’s distribution is centered at higher elevations.  The Western is most common between 1500 and 4000 feet elevation, in broad valleys.  Areas of concentration are in Warner Valley (up to 55 at Lake Henshaw, G17, 17 July 1998, C. G. Edwards), Santa Ysabel Valley (up to 25 north of Santa Ysabel, I18, 20 May 2000, S. E. Smith), Santa Maria Valley (up to 36 northeast of Ramona, K15, 18 June 1999, M. and B. McIntosh), and Campo Valley (U23, up to 30 on 20 April 1997, D. S. and A. W. Hester).  The Western Kingbird shares the inland valleys at lower elevations with Cassin’s but drops out along the coast.  Within 5 miles of the coast we confirmed nesting only a few times, e.g, in the Wire Mountain area of Camp Pendleton (G5; pair nest building 20 June 1999, R. E. Fischer) and on the campus of the Educational Cultural Complex in southeast San Diego (S10; active nest 11 May 1997, P. Unitt).  At the higher elevations the Western Kingbird is fairly common around Lake Cuyamaca (M20) but absent from Palomar Mountain and scarce on Hot Springs (E21; pair on 18 June 1999, K. L. Weaver) and Laguna (O23; one from 6 to 14 June 1999, C. G. Edwards).  On the east slope of the mountains, the Western Kingbird breeds down to Earthquake Valley (K23), but on the floor of the Anza–Borrego Desert it is uncommon as a breeding species (maximum eight in the northern Borrego Valley, E24, 8 June 2001, P. D. Jorgensen) and apparently confined to developed oases: the Borrego Valley, Ocotillo Wells (I28, I29, J29), Butterfield Ranch in Mason Valley (M23), and Vallecito Stage Station (M25). 

Nesting: The Western Kingbird usually builds its nest in the upper levels of open-foliaged trees.  Atlas observers reported six nests in sycamores, five in eucalyptus, four in oaks (both coast live and Engelmann), and one each in a palm, poplar, pine, avocado, and desert ironwood.  The nests are typically on the larger branches, so they have a solid support from below.  The nest at Ocotillo Wells in an ironwood was atop an old House Sparrow nest.  Another very common site is the bracket holding an electrical transformer to a utility pole; the five nests specifically described in such stations are certainly an underestimate.

            Though the Western Kingbird begins arriving in early March, it does not begin nest building until the second week of April or laying until the third week of April.  The schedule we observed is consistent with the 17 April–9 July spread of 106 California egg dates given by Bent (1942), though the fledglings at Vallecito (M25) 16 May 2001 (M. C. Jorgensen) may have hatched from eggs laid a day or two before 17 April.

Migration: After the hummingbirds and the swallows, the Western Kingbird is one of our earliest spring migrants, and one of the most punctual.  From 1997 to 2001, the earliest spring report varied only from 11 to 14 March.  The earliest date ever reported is 6 March (1982, Anza–Borrego Desert State Park, AB 36:893, 1982).  The Western Kingbird migrates by day, often in flocks, and most of the population breeds north of San Diego County, so migrants are often conspicuous.   A concentration of 150 atop Spooner Mesa (W10) 15 May 1999 (P. Unitt) was extraordinary.  Numbers drop rapidly in mid May; late dates of birds away from breeding habitat are 27 May (1999, one in La Jolla, P7, L. Polinsky) and 3 June (2001, one in extensive treeless chaparral 3.1 miles east-northeast of Sunshine Summit, D18, P. Unitt).  In fall, migrants are seen from 12 July (2000, one on Palomar Mountain, D15, K. L. Weaver) through late September or early October, exceptionally to 3 November (1963, one in the Tijuana River valley, G. McCaskie).

 

Winter: Only four well-supported records ever, of single individuals at Oceanside 28 January 1962 (G. McCaskie), Lake Hodges 5 December 1995 (photographed; M. B. Stowe, G. L. Rogers, NASFN 49:199, 1995), near San Elijo Lagoon (L7) 26 December 1999 (R. T. Patton), and in Greenwood Cemetery (S10) 16 December 2001–7 February 2002 (G. McCaskie et al.).  Other winter reports, some in Christmas bird counts, more likely represent misidentified Cassin’s or Tropical Kingbirds.

 

Conservation: The advent of eucalyptus trees and utility poles gave the Western Kingbird many new nest sites, but in San Diego County these factors did not lead clearly to population increase and range expansion, as tree planting has in the Great Plains (Gamble and Bergin 1996) or utility poles have in the Imperial Valley.  The Western has always been considered common here.  Its habitat was converted entirely to cattle grazing, but this evidently does not affect a bird that comes to the ground only to gather nest material.

Eastern Kingbird Tyrannus tyrannus

With its simple but bold pattern of blackish upperparts, whitish underparts, and white-tipped tail, the Eastern differs conspicuously from the other kingbirds.  It is a casual fall vagrant to San Diego County, with one record in late spring.  Its frequency here appears to be on the decline.

Migration: The Eastern Kingbird is known in San Diego County from 19 records, all but one in fall from 15 July (1972, one in the Tijuana River valley, AB 26:907, 1972) to 17 October (1978, one at Vallecito, M25, AB 33:216, 1979).  All fall records are along the coast except for the one from Vallecito and another from Kit Carson Park (K11) 22 September 1979 (AB 34:202, 1980).  Only three records are since 1981, from San Elijo Lagoon (L7) 28 September–1 October 1986 (C. G. Edwards, AB 41:145, 1987) and 12 September 1988 (R. T. Patton, AB 43:169, 1989), and the single late spring record, from the Sweetwater River 0.7 mile below Highway 94 (S13) 15 June 1991 (P. Unitt, AB 45:1162, 1991).  There is still only one specimen, from San Elijo Lagoon 28 September 1963 (SDNHM 30767, McCaskie et al. 1967a).

Scissor-tailed Flycatcher Tyrannus forficatus

Most vagrant Scissor-tailed Flycatchers reaching California are immatures, lacking the adults’ long tail streamers.  Nevertheless, with its delicate pink wing linings, the Scissor-tailed is one of the most distinctive and attractive of its family.  Though as few as 20 individuals have been seen in San Diego County, the records encompass every month of the year except July.

Migration: The Scissor-tailed Flycatcher is most frequent in fall, with 13 records extending from 17 August (1986, Tijuana River valley, adult, G. McCaskie, Bevier 1990) to 24 November (1933, one at La Jolla, Grinnell and Miller 1944).  The single specimen was collected at San Elijo Lagoon 22 November 1963 (SDNHM 30769, McCaskie et al. 1967a).

            There are three records for late spring and summer, of one photographed at San Diego 13–17 June 1986 (M. and J. Fader, Bevier 1990), one at Lake Cuyamaca (M20) 25–29 June 1991 (D. D. Gemmill, Heindel and Garrett 1995), and one at Point Loma (S7) 27–31 May 1995 (J. C. Worley, P. Unitt, Garrett and Singer 1998).

 

Winter: Records at this season number four.  One was in the Tijuana River valley 22 February–3 April 1965 (McCaskie et al. 1967a).  One at San Dieguito County Park (L8) 4 December 1992 was presumed to be the same as one at San Elijo Lagoon (L7) 27–28 March 1993 (P. A. Ginsburg, B. C. Moore, Heindel and Patten 1996, Erickson and Terrill 1996).  One was at Lake Hodges (K10) 4–17 January 1994 (S. B. Grain, Howell and Pyle 1997).  Another at Lake Hodges 23 December 1998 (R. T. Patton) was likely the same as one at the east end of the same valley (K12) 2 January 1999 (C. G. Edwards).