Crows and Jays — Family Corvidae
Steller’s Jay Cyanocitta stelleri
The bird most linked in San Diegans’ minds with coniferous woodland in the county’s mountains is Steller’s Jay. Around campgrounds and picnic areas the jays are common and unavoidable; for generations the birds have learned to demand handouts from people. But in more remote areas the jays are less common and less obtrusive. One of the surprises generated by the atlas field work was how widespread Steller’s Jay proved to be in oak woodland with no conifers, especially in southeastern San Diego County.
Breeding distribution: The higher mountains—Palomar, Hot Springs, Volcan, Cuyamaca, and Laguna—are the core of Steller’s Jay’s range in San Diego County. The species is most abundant on Palomar (up to 60 around Jeff Valley, E15, 28 May 1999, E. C. Hall, C. R. Mahrdt) but common in all the other ranges too. On Palomar’s southwest slope, Steller’s Jay is resident down to about 2300 feet elevation, even to about 1800 feet in deep canyons with big-cone Douglas firs (e.g., two in Agua Tibia Canyon, D12, 17 July 2001, K. L. Weaver). A local resident reported a Steller’s Jay trapped in a greenhouse at 1600 feet elevation along Magee Road (C11) in late May 1998 (fide J. M. and B. Hargrove). The population on Palomar is linked broadly with that in central San Diego County through oak woodland in the Mesa Grande area (up to 15 in the Edwards Ranch northwest of Santa Ysabel, I18, D. W. Au). Steller’s Jay appears absent from the stand of conifers on Bucksnort Mountain (C20), but we did find an isolated population at Adobe Springs in Chihuahua Valley (C18; six on 2 May 1999, A. Mauro).
In the southern half of San Diego County, Steller’s Jay inhabits oak woodland up to 8 miles away from coniferous woodland. Points defining the southern limits of the species’ breeding range are Wilson Creek just west of Barrett Lake (S18; up to 10 on 25 May 2001; R. and S. L. Breisch); Morena Village (T22; pair nest building on 1 April 2000; R. and S. L. Breisch), and McCain Valley (S26; up to 18, plus an occupied nest, on 20 May 2000, J. K. Wilson). Steller’s Jays are apparently irregular in Hauser Canyon (T20), with a single observation of two on 15 May 1997 (J. M. Wells). The birds’ extensive use of oak woodland habitat in southeastern San Diego County is a paradox because the area is the southern tip of the range of subspecies C. s. frontalis. Steller’s Jays are absent from Baja California, their range terminating just 7 miles short of the international border.
Nesting: Steller’s Jay nests are typically well concealed in trees with dense foliage. The birds take advantage, however, of man-made structures that offer sheltered sites. Observers noted two nests under eaves of houses, one atop a sheltered bulletin board at the Doane Valley campground (E14), and one on a cow skull nailed to the side of a building.
Our observations in San Diego County imply that Steller’s Jays lay eggs at least from mid April to mid June, probably to late June, with three records of birds carrying nest material as late as 13 June. The species’ nesting season is thus the same as that reported by Bent (1946), who gave a range of 12 April–24 June for California egg dates.
Migration: In parts of its range, Steller’s Jay engages in altitudinal movements or irregular irruptions, but these events rarely touch San Diego County. On the coastal slope more than 5 miles west of its breeding range, the species has been recorded only 10 times from 4 October (1978, one at Point Loma, S7, AB 33:216, 1979) to 27 April (1998, one along the Sweetwater River above Sweetwater Reservoir, S13, P. Famolaro), 24 May (2001, one at Sky Ranch, Santa Margarita Mountains, B5, E. C. Hall, J. O. Zimmer), and 13 June (1984, one at 800 feet elevation along the San Diego River, M17, P. Unitt, AB 38:1062, 1984). The Santa Margarita Mountains offer much oak woodland, but the species is absent from the contiguous Santa Ana Mountains in Orange County, so evidently the bird at Sky Ranch was a vagrant. On the desert slope, Steller’s Jays have been noted east of their breeding range six times between 17 August (1986, two in Borrego Palm Canyon, F23, and two at Tamarisk Grove, I24, R. Thériault) and 26 April (1996, one in Borrego Palm Canyon campground, F23, M. C. Jorgensen).
Winter: Steller’s Jay is largely sedentary, so the winter and breeding distributions follow the same pattern. Most of the few additional localities where we found the species in winter could be sites where it is resident in very small numbers. The most notable of these were about 2200 feet elevation on the south side of Hidden Glen (R17; one on 22 January 2001, J. R. Barth) and about 2300 feet elevation in Lyons Valley (S17; one on 24 January 1998, S. M. Wolf). Some but not all of the low-elevation occurrences of Steller’s Jay are during invasion years for other montane birds. The two during the atlas period, of one in the Mission Hills neighborhood of San Diego (R9) 16 December 2000 (J. K. Wilson) and one in Torrey Pines State Reserve (N7) 22 December 2000 (S. Walens) coincided with irruptions of Mountain Bluebirds, Cassin’s Finches, and a flock of Pinyon Jays. The one winter record on the desert slope, however, of one at Angelina Spring (I22) 2 December 1998 (P. K. Nelson), was in a year with no such invasions.
Conservation: Steller’s Jays capitalize on the supplemental food and nesting sites that accompany the campgrounds and rural homes in their breeding range. But there seem to have been no changes in the species’ numbers over time; Lake Henshaw Christmas bird count results since 1981 show no real trend.
Taxonomy: The Steller’s Jays resident in southern California are C. s. frontalis, which lacks any white marks around the eye and is paler than other subspecies found farther north along the Pacific coast.
Western Scrub-Jay Aphelocoma californica
A year-round resident, the Western Scrub-Jay is well known to San Diegans, conspicuous in most urban areas and dominating bird feeders. Nevertheless, it remains most abundant in native chaparral and oak woodland, where it feeds heavily on acorns. Scrub oaks as well as tree oaks support the jay. In fall and early winter, when the oaks are bearing, the jays can be seen shuttling between oak groves and chaparral, carrying acorns to be cached and eaten later.
Breeding distribution: The Western Scrub-Jay is common over most of San Diego County’s coastal slope, with regions of greatest abundance in the northwest from the north side of the Santa Margarita Mountains east to Rainbow, in the north-central area from the north slope of Palomar Mountain east to Chihuahua Valley and Warner Springs, and in the southeast on the Campo Plateau. Surveys near Pine Valley revealed it as one of the most common birds of mature chaparral, exceeded significantly only by the Spotted Towhee and Wrentit and on a par with the Mountain Quail and Bewick’s Wren (Cleveland National Forest data). Daily counts in the breeding season run as high as 50, as around Sunshine Summit (D17) 1 May 1999 (A. Mauro) and in Tecolote Canyon 10 May 2001 (T. Plunkett). Field work for the atlas disclosed two areas on the coastal slope where scrub-jays are rare to absent: the lowest 5 or 6 miles of the Santa Margarita and San Luis Rey River valleys and from the Tijuana River valley east to Otay Mesa and Lower Otay Lake, a region of riparian woodland, sage scrub, and grassland but little chaparral.
In the Anza–Borrego Desert, the eastern margin of the scrub-jay’s range largely follows the edge of scrub that retains components of chaparral; very likely the availability of acorns of the desert scrub oak is the species’ limiting factor here. The jay occurs in small numbers in the higher elevations of the Santa Rosa and Vallecito mountains, where the desert scrub oak is an important component of the vegetation. But it also ranges in small numbers down Coyote Creek to the riparian oasis of Lower Willows (D23; up to two on 10 May 1997 and 25 April 1998, B. Peterson), where oaks are absent.
Nesting: Western Scrub-Jays build a bowl of coarse twigs, usually concealing it in dense-foliaged trees or shrubs. We found one nest, however, on the support for a satellite dish in a rural yard. Our observations from 1997 through 2001 imply egg laying from mid March to about 1 June—the same interval attested by 51 egg sets collected from 1894 to 1956.
Winter: In California the Western Scrub-Jay is essentially sedentary, mated pairs maintaining their territories year round unless the supply of acorns fails. In San Diego County the jay’s pattern of abundance in winter is very similar to that in the breeding season, with hardly any dispersal into the areas on the coastal slope where it is absent in the breeding season. Nevertheless, it is sometimes seen in winter in numbers considerably greater than in the breeding season, possibly because of nonterritorial birds concentrating where the feeding is good. Such concentrations were noted especially on the Campo Plateau, with up to 150 north of Lake Morena (S21) 16 February 1998 (S. E. Smith), 125 west of Campo (U22) 31 January 2000 (E. C. Hall, C. R. Mahrdt), and 235 around Campo (U23) 14 January 2001 (D. S. and A. W. Hester, M. and B. McIntosh).
Only rarely do scrub-jays venture even a short distance outside their breeding range along the edge of the Anza–Borrego Desert. There are three records for the floor of the Borrego Valley: one in Borrego Springs (F24) 20 December 1998 (R. Thériault), one in the mesquite bosque of the Borrego Sink (G25) 17 December 2000 (B. Siegel), and one at Casa del Zorro (H25) 19 December 1999 (L. D. and R. Johnson). Also on the desert floor were two on the north side of Clark Dry Lake (D26) 11 March 2000 (P. K. Nelson).
Conservation: The Western Scrub-Jay is a familiar component of San Diego County’s urban avifauna. In residential areas, bird feeders probably help compensate for the lack of oak trees as a food source. Urbanization has enabled the jays to spread into former sage scrub that was once unsuitable. In the San Diego Christmas bird count circle, most of which was marginal scrub-jay habitat before urbanization, count results show a definite upward trend in the species’ numbers. The number of scrub-jays per party-hour on the count 1997–2002 was larger by a factor of 1.93 than the 20-year average 1962–81. An increase and spread of the scrub-jay is relevant to conservation of other birds because the jay is a major predator of eggs and nestlings; Peterson (2002, Peterson et al. 2003) found the scrub-jay to be the principal predator on Bell's Vireo nests along the San Luis Rey River. Nevertheless, the scrub-jay remains considerably more abundant in its native habitats. Bolger et al. (1997) found it to be among the birds insensitive to habitat fragmentation, neither attracted nor repelled by the urban edge.
Taxonomy: The local subspecies of the Western Scrub-Jay, A. c. obscura, is a classic exemplar of a bird whose range and characters define the San Diegan District of the California Floristic Province. Aphelocoma c. obscura is the dark extreme of the species—as long as the Santa Cruz Island Scrub-Jay (A. insularis) is excluded.
Pinyon Jay Gymnorhinus cyanocephalus
Although Pinyon Jays are common in the Garner Valley of the San Jacinto Mountains only 10 miles north of the county line, and are common in the Sierra Juárez an equally short distance south of the border, they occur in San Diego County only as rare vagrants at long intervals. The stands of pinyons in the Santa Rosa and Vallecito mountains are evidently too small to support a resident population.
Winter: Of the montane birds prone to sporadic irruptions, the Pinyon Jay is one of the least frequent in San Diego County, recorded in only 10 seasons since 1877. In 1973 only a single individual was noted, but on other occasions the birds have been in flocks. Sometimes multiple flocks occur in a single year, as in 1987, when 25 were in Cuyamaca Rancho State Park (M20) 19 September (S. Mlodinow, AB 42:137, 1988) and 10 were on Volcan Mountain (J20) 28 October (P. Unitt). Some of the early records that lack good detail may also represent large flocks, but the largest with estimates of their size are of about 75 near San Onofre (C1) in March 1915 (year implied; W. M. Pierce in Willett 1933), up to 200 in the Laguna Mountains (O23) 6–12 January 1990 (D. and M. Hastings et al., AB 44:330, 1990), and the single record during the atlas period, of up to 55 at Stonewall Mine, Cuyamaca Mountains (M20), 28 December 2000–2 May 2001 (K. Satterfield, NAB 55:357, 2001). Most Pinyon Jays in San Diego County have been in the mountains or foothills; only those at San Onofre reached the coast. On the desert side, F. Stephens collected two at Vallecito (M25) 27 November 1891 (SDNHM 757–8), and L. M. Huey collected two 3 miles east of Jacumba (U29) 11 March 1945 (SDNHM 19150–1).
Migration: As expected with such an irregular species, records of the Pinyon Jay are scattered seasonally. The extreme dates are 19 September and 2 May, both records cited above. In general, Pinyon Jay irruptions start in late August or early September and continue through early January (Balda 2002).
Conservation: Pinyon Jays appear no more frequent than they did a century ago, despite the far greater number of observers, suggesting they may actually be on the decrease. The long-term trend toward a drier climate, since the end of the Pleistocene, disfavors trees like pinyons that grow in arid regions and could be a bad sign for birds like the jay that depend on them.
Clark’s Nutcracker Nucifraga columbiana
A bird of subalpine forests, Clark’s Nutcracker lives in an elevation zone too high for San Diego County’s mountains. Yet it is a permanent resident in the San Jacinto Mountains (it is seen easily at the top of the Palm Springs Aerial Tramway) and sporadic in the Sierra San Pedro Mártir. It reaches San Diego County only as a vagrant, principally to the mountains, and principally during broader-scale irruptions that often coincide with those of the Pinyon Jay. Both species rely for food primarily on pine seeds, and both are forced out of their normal habitats if the trees fail to bear.
Winter: Clark’s Nutcracker invasions of San Diego County’s mountains are rare: just eight winters (1877, 1920, 1935, 1955, 1972, 1973, 1996–97, and 2000–01) account for almost all of the records. Sometimes the irruptions bring scattered individuals, sometimes flocks, most notably on 21 February 1877 (“a fair-sized flock” at Mount Laguna, O23, F. Stephens in Willett 1912, SDNHM 755), in spring 1920 (see under Migration), and in fall 1935 (flocks of 50 to 60 in the Volcan and Cuyamaca mountains; anonymous 1935; two specimens from Volcan Mountain, I20, 28 September 1935, SDNHM 17095–6). The winter preceding the five-year atlas period brought six to Cuyamaca Rancho State Park 7 November 1996 (J. Katetzky) and three to Buddy Todd Park, Oceanside (H7) 29 December 1996–1 January 1997 (D. and C. Wysong, NASFN 51:800, 1997). In 2000–01, 15 were on Cuyamaca Peak (M20) 16 October (P. D. Jorgensen), with two seen as late as 15 April (R. Wheeler), two were in Pine Valley (P21) 17 October (M. Heilbron), and five were on Volcan Mountain (I20) 18 December 2000 (R. T. Patton).
Though occurring mainly in the mountains, Clark’s Nutcrackers have been noted seven times in the coastal lowland (at Oceanside in 1996–97; earlier records listed by Unitt 1984). The only nutcrackers recorded in the Anza–Borrego Desert are still the five during the irruptions of 1955 and 1972 (Unitt 1984).
Migration: Records of Clark’s Nutcracker in San Diego County form an interesting seasonal pattern. Most are for fall and winter, on dates ranging from 11 August (1972, one at Palomar Mountain, AB 26:907, 1972) to 21 February (1877, the flock at Mount Laguna), except for the two at Cuyamaca Peak 15 April 2001. Eight, though, are from late May and June: “flocks ranging from a few birds to 15 or 20 in the flock” in the Laguna Mountains 31 May–1 June 1920 (Fortiner 1920), one on Palomar Mountain 24 June 1967 (A. G. Morley, AFN 21:605, 1967), one along Agua Dulce Creek, Laguna Mountains (O23) 25 May 1974 (P. Unitt, AB 28:853, 1974), one along High Point Truck Trail, north slope of Palomar Mountain (C15), 31 May 1997 (K. L. Weaver), one near Filaree Flat, Laguna Mountains (N22), the same day (G. L. Rogers, FN 51:926, 1997), one near Laguna Campground (O23) 8 June 1997 (C. G. Edwards, FN 51:1054, 1997), four flying north in Lark Canyon (S26) 9 June 2001 (P. Unitt), and one at the southwest base of Volcan Mountain (J20) 15 June 2001 (E. C. Hall, J. O. Zimmer). Evidently some nutcrackers leaving their breeding range in fall have still not made it back by the middle of the following breeding season.
American Crow Corvus brachyrhynchos
No change among San Diego birds has been more striking than the proliferation of the American Crow. Until the mid 1980s the species ranged no farther south along the coast than Carlsbad, no nearer the coast in metropolitan San Diego than El Cajon. Then it surged south and west, spreading over the coastal lowland. By the new millennium it was abundant it many areas where it was absent only 15 years earlier. Primitively the crow occurred in oak and riparian woodland near grassland; now orchards, eucalyptus groves, and cities support large numbers.
Breeding distribution: The American Crow now occurs almost throughout the coastal slope of San Diego County, most abundantly in the inland valleys of the county’s northern half. Concentrations during the breeding season are as large as 200 at Lake Hodges (K10) 9 March 1999 (R. L. Barber), and 220 northeast of Ramona (K15) 26 April 1999 (M. and. B. McIntosh). The crow is abundant locally south to the Mexican border (up to 138 at Potrero, U20, 26 June 1999, R. and S. L. Breisch). The eastern margin of the range follows that of oak woodland closely, except that the species occurs uncommonly in San Felipe Valley down to Scissors Crossing (J22; up to nine on 3 June 2002, J. R. Barth; fledgling on 13 July 2001, P. Unitt). The crow is uncommon and local in montane coniferous forest and absent from sage scrub and chaparral. Its breeding range has now extended south along the coast to Point Loma (S7; birds seen carrying nest material repeatedly in 1997, J. C. Worley) and Otay Valley (V11; fledgling on 26 June 1999, P. Unitt), probably to the Tijuana River valley (V10/W10; up to 30 on 18 June 1997, C. G. Edwards).
Nesting: American Crows nest in the crowns of trees with dense foliage. In San Diego County, coast live oaks are the traditional nest site; now the birds also make much use of palms, pines, and Italian cypress, and especially eucalyptus. In groves of such trees, crows nest colonially, as they do elsewhere in California (Verbeek and Caffrey 2002).
Thirty-five egg sets collected in San Diego County from 1888 to 1962 range in date from 24 March to 18 May, and 112 from throughout California range from 21 March to 12 June. But, on the basis of an incubation period of 18 days, our observations from 1997 to 2001 suggest egg laying from the second week of March to mid May, with records of nest building as early as 12 February, nestlings being fed as early as 30 March, and fledglings as early as 25 April. In Los Angeles, Verbeek and Caffrey (2002) reported egg laying beginning 17 March.
Winter: In San Diego County the American Crow is nonmigratory, and its distribution in winter is similar to that in spring and summer. But in winter the birds gather into even larger flocks and roosts. Probably the largest of these in San Diego County is at the east end of Lake Hodges (K11), where counts range up to 1800 on 1 December 1998 (E. C. Hall). Wintering crows are already abundant in areas the species has only recently colonized, especially Bonita and eastern National City (T11), with up to 800 on 16 December 2000 (G. C. Hazard) and possibly 4000 on 15 December 2001 (D. W. Aguillard).
The American Crow is a rare winter visitor to the Anza–Borrego Desert east of its breeding range with at least 15 records, eight during the atlas period. Some of these are of small flocks, of up to six in Earthquake Valley (K23) 17 February 2001 (A. P. and T. E. Keenan) and five in Borrego Springs (F24) 17 December 2000 (J. York).
Conservation: The crow’s primitive distribution paralleled that of other oak woodland birds whose range retracts inland from north to south, though it was always common in riparian woodland without oaks in northwestern San Diego County. In many of the areas where it occurred historically the population increased: from 1975 to 1979 the Oceanside Christmas bird count averaged 253 crows; from 1997 to 2001 it averaged 1031. From 1985 to 1989 the Escondido count averaged 571; from 1997 to 2001 it averaged 2161. On the San Diego count before 1984 the crow was irregular, occurring only at the eastern margin of the circle; it was regular in small to moderate numbers from 1985 through 1995 and then increased rapidly. Yet there has been no significant change in the Lake Henshaw circle where, in contrast to the other circles, there has been little development.
The crow adapted quickly to urbanization in its original range. The mysteries in San Diego County are why the crow took so long to take advantage of new suitable habitat, why the expansion took place at the moment in history when it did, and why the increase was so explosive when it arrived.
Many San Diegans express concern for the survival of other birds in the face of proliferation of a predator on eggs and nestlings. But the effects of the crow’s population explosion remain unknown. On the other hand, the American Crow is particularly susceptible to West Nile virus, which appeared in New York City in 1999 and is spreading rapidly across North America; crows have already been decimated in parts of the eastern United States.
Taxonomy: The crow inhabiting southern California is C. b. hesperis Ridgway, 1887, the smallest subspecies of the American Crow—if the Northwestern Crow (C. caurinus) is in fact a distinct species.
Common Raven Corvus corax
The world’s largest passerine, the Common Raven is a common permanent resident of San Diego County. It occurs in all habitats, from beaches to mountaintops to desert floor. The change in the raven is less dramatic than that of the American Crow, but the raven too is on the increase, aided by increases in man-made food sources like refuse and road kills and man-made nest sites like buildings, bridges, and power-line towers.
Breeding distribution: After the House Finch, the Common Raven is the most widespread breeding bird in San Diego County. Field work for this atlas identified it as possibly breeding in 475 of 478 covered squares, and as confirmed breeding in 359. Ravens breed as dispersed pairs, but flocks may be seen through the breeding season. Such flocks presumably consist of immature birds; ravens do not breed until they are at least two years old (A. M. Rea). Sites of frequent large concentrations are Warner Valley (up to 175 east of Lake Henshaw, G18, 12 May 2001, T. Stands), Torrey Pines State Reserve (N7; up to 62 on 3 April 1998, K. Estey), and from Potrero to Canyon City (U20/U21; up to 180 near Canyon City 21 June 1999, D. C. Seals). In some cases, including the last, the reason for the concentration was a communal roost. The Common Raven tends to be less numerous in the Anza–Borrego Desert than on the coastal slope, but flocks can be seen through the breeding season there too, with up to 25 east of Peg Leg Road (F26) 1 May 2001 (B. Siegel) and 39 at a communal roost in palo verde trees near the northeast corner of the county (C29) 8 July 1999 (R. Thériault).
Nesting: Ledges and crevices in cliffs are the raven’s most common traditional nest site. Atlas observers described several on cliffs of both rock and eroded earth. Large trees are also frequent nest sites; atlas observers reported raven nests in coast live oaks, palms, eucalyptus, athel tamarisks, and one in a mesquite. Many ravens now nest on man-made structures, especially bridge abutments and the towers supporting electrical lines. Following major electricity-supply lines, such as the one crossing much of southern San Diego County, often leads to an alternating succession of raven and Red-tailed Hawk nests. Ravens nest in San Diego’s most distinctive landmark, the California Tower in Balboa Park (R9; J. K. Wilson).
Our observations reveal that in San Diego County Common Ravens lay mainly from early March to at least early May, with some in the Anza–Borrego Desert and along the Mexican border beginning in mid February (as implied by young already fledged at Tecate, V19, on 6 April 2000, M. and B. McIntosh). Bent (1946) listed California egg dates from only 2 March to 19 May, but Boarman and Heinrich (1999) reported laying as early as mid February. The wide spread of dates of ravens carrying nest material suggests that some birds start their nests weeks before egg laying and maintain them as long as they are occupied.
Winter: The Common Raven’s pattern of distribution in San Diego County in winter is much the same as that in the breeding season, with concentrations in the same areas. The highest numbers reported in winter were, with one exception, little greater than the maxima in the breeding season: 228 in Borrego Springs 20 December 1998 (R. Thériault et al.), 229 at Oak Grove (C16) 12 December 1998 (K. L. Weaver), and 395 east of Lake Hodges (K11) 2 January 2000 (C. G. Edwards). We found the Common Raven even more widely in the winter than in the breeding season, picking it up regularly in the three squares where we missed it then (up to 10 along the Silver Strand, T9, 28 February 1998, J. L. Coatsworth).
Conservation: The Common Raven is on the increase over much of its range, including California (Sauer et al. 2003). The increase includes San Diego County, though perhaps not uniformly. Christmas bird count results suggest roughly a doubling of the population from the early 1980s to the new millennium in the Anza–Borrego, Escondido, Rancho Santa Fe, and San Diego circles but no significant change in the Oceanside or Lake Henshaw circles. Factors favoring ravens include road building and increased traffic, which lead to more carrion that ravens scavenge. Man-made structures offer many new nest sites. In Idaho, Common Ravens prefer electrical-line towers over natural nest sites (Steenhof et al. 1993). The distribution of these towers may account in part for the pattern of raven abundance in San Diego County.
The increase of ravens can have a negative effect on other birds. The Common Raven is a major predator of Least Tern colonies in San Diego County, leading to efforts at control and experiments in aversive conditioning.
Taxonomy: The Common Ravens of San Diego County, like those elsewhere in both Alta and Baja California, are of the small subspecies C. c. clarionensis Rothschild and Hartert, 1902 (Rea 1983, Rea in Phillips 1986). A genetic study revealed a high degree of differentiation between it and others in both mitochondrial DNA and nuclear microsatellites (Omland et al. 2000).