Western Birds Journal

Volume 31, No. 3

Published July 1, 2000

Issue description

Volume 31, number 3 of Western Birds, published 2000

Articles

  1. Cover image V31 (3)

    W. DAVID SHUFORD, THOMAS P. RYAN (Author)

    NESTING POPULATIONS OF CALIFORNIA AND RING-BILLED GULLS IN CALIFORNIA: RECENT SURVEYS AND HISTORICAL STATUS

    Statewide surveys from 1994 to 1997 revealed 33,125 to 39,678 breeding pairs of California Gulls and at least 9,611 to 12,660 pairs of Ring-billed Gulls in California. Gulls nested at 12 inland sites and in San Francisco Bay. The Mono Lake colony was by far the largest for the California Gull, holding 70% to 80% of the state population, followed by San Francisco Bay with 11% to 14%. Butte Valley Wildlife Area, Clear Lake National Wildlife Refuge, and Honey Lake Wildlife Area were the only other sites that held over 1,000 pairs of California Gulls. In most years, Butte Valley, Clear Lake, Big Sage Reservoir, and Honey Lake together held over 98% of the state's breeding Ring-billed Gulls; Goose Lake held 9% in 1997. Much of the historical record of gull colonies consists of estimates too rough for assessment of population trends. Nevertheless, California Gulls, at least, have increased substantially in recent decades, driven largely by trends at Mono Lake and San Francisco Bay (first colonized in 1980). Irregular occupancy of some locations reflects the changing suitability of nesting sites with fluctuating water levels. In 1994, low water at six sites allowed coyotes access to nesting colonies, and resulting predation appeared to reduce nesting success greatly at three sites. Nesting islands secure from predators and human disturbance are nesting gulls' greatest need.

  2. Cover image V31 (3)

    BRIAN J. McCAFFERY, CHRISTOPHER M. HARWOOD (Author)

    STATUS OF HUDSONIAN GODWITS ON THE YUKON-KUSKOKWIM DELTA, ALASKA

    Over 100 observations of the Hudsonian Godwit (Limosa haemastica) on the Yukon-Kuskokwim Delta in western Alaska since 1983 show that the species is a fairly common migrant, uncommon summer visitant, and rare—perhaps locally uncommon—breeder there. Spring arrival and fall departure dates are among the earliest and latest, respectively, in Alaska. Observations of breeding behavior and/or recently fledged young provide compelling evidence for breeding at five sites. Although some probable breeders are found along the taiga-tundra ecotone—described as breeding habitat for the species elsewhere—others use dwarf-shrub meadows well beyond the treeline. Post-breeding birds are usually found in low numbers, but occasional aggregations of ~100 Hudsonian Godwits are among the largest concentrations of this species reported in Alaska. The Yukon-Kuskokwim Delta may support a significant fraction of the Hudsonian Godwit population in Alaska.

  3. Cover image V31 (3)

    GERARD J. McCHESNEY, HARRY R. CARTER, MICHAEL W. PARKER (Author)

    NESTING OF ASHY STORM-PETRELS AND CASSIN'S AUKLETS IN MONTEREY COUNTY, CALIFORNIA

    We report the first known nesting of the Ashy Storm-Petrel and Cassin's Auklet in Monterey County, California, on offshore rocks around Castle Rock and Hurricane Point. Four nests and 13 mist-netted storm-petrels, together with the extent of suitable habitat, suggest a population of 10 to 30 pairs. A single abandoned Cassin's Auklet egg, pink guano, and a small number of other potential nest sites imply no more than five pairs of that species. Similar small colonies of these species may be scattered on offshore rocks along the central California coast, potentially linking the major colonies on the Farallon Islands and Channel Islands.

  4. Cover image V31 (3)

    EDUARDO PALACIOS, ERIC MELLINK (Author)

    NESTING WATERBIRDS ON ISLAS SAN MARTIN AND TODOS SANTOS, BAJA CALIFORNIA

    A survey of Isla San Martin on 2 June 1999 revealed about 30 Brown Pelican, 600 Double-crested Cormorant, and over 300 occupied Western Gull nests, plus a mixed pair of oystercatchers. Thus the Double-crested Cormorant has reoccupied what was once its largest colony in North America. Surveys of Islas Todos Santos on 3 June 1999 and 27 March 2000 revealed 115 Double-crested Cormorant and at least 184 occupied Brandt's Cormorant nests, plus about 1400 nesting pairs of Western Gulls. On Todos Santos, at least two nests of the Pelagic Cormorant represent a southward extension of that species' breeding range, whereas two nesting pairs of the Reddish Egret represent a northward extension.

  5. Cover image V31 (3)

    SPENCER G. SEALY, ALISON J. BANKS, JAMESON F. CHACE (Author)

    TWO SUBSPECIES OF WARBLING VIREO DIFFER IN THEIR RESPONSES TO COWBIRD EGGS

    Using real cowbird eggs, we experimentally parasitized 41 nests of the Warbling Vireo (Vireo gilvus), three each in British Columbia and Colorado, five in Montana, and 30 in Manitoba, and recorded whether the cowbird eggs were accepted or rejected. Cowbird eggs were accepted at all nests tested in British Columbia and Colorado, but both acceptance and rejection were recorded in Montana. In Manitoba, all cowbird eggs were rejected (29 by puncture-ejection, one by desertion). The results suggest acceptance by a western subspecies of the Warbling Vireo, V. g. swainsonii, and rejection by the eastern subspecies, V. g. gilvus. The geographic variability in acceptance/rejection agrees with suggested taxonomic differences for the Warbling Vireo, i.e., that there are two species and that neither appears to vary in response to the presence of cowbird eggs in its nests.

  6. Cover image V31 (3)

    GUSTAVO D. DANEMANN, ROBERTO CARMONA (Author)

    NOTES : BREEDING BIRDS OF THE GUERRERO NEGRO SALTWORKS, BAJA CALIFORNIA SUR, MEXICO

    Ojo de Liebre (Scammon's) Lagoon, on the west coast of the Baja California peninsula, is surrounded by salt marshes and salt flats exposed to periodic tidal inundation. Part of these areas was modified in 1956 by the building of saltworks, a system of managed ponds covering 27,773 ha. These ponds contain several islands, sandbars, and sand flats suitable for nesting birds (Figure 1). In 1996 we surveyed the saltworks’ nesting birds, as part of a year-round study (Carmona and Danemann 1998).

  7. Cover image V31 (3)

    CHARLES T. COLLINS, PETER H. BLOOM (Author)

    NOTES : THE STATUS OF HARLAN'S HAWK IN SOUTHERN CALIFORNIA

    Harlan's Hawk, Buteo jamaicensis harlani, has had a checkered taxonomic history since its description by Audubon (1830) from two specimens collected in Louisiana. It has at times been considered a separate species, a subspecies of the Red-tailed Hawk (Buteo jamaicensis), or perhaps even a local color morph or unique immature plumage of the latter rather than a distinct taxon. Ridgway (1890) suggested it be treated as a distinct subspecies of the Red-tailed Hawk, but it was still considered by some to be a separate species as late as 1959 (AOU 1957, Gabrielson and Lincoln 1959). Studies by Swarth (1926), Mindell (1983), and Snyder and Snyder (1991) have now established that harlani is best treated as the local subspecies of the Red-tailed Hawk in western, central, and south-coastal Alaska, southwestern Yukon, and northwestern British Columbia (AOU 1998). This view, however, is still not unanimous (Dunne et al. 1988).

  8. Cover image V31 (3)

    TERENCE R. WAHL, BILL TWEIT (Author)

    WHERE DO PIGEON GUILLEMOTS FROM CALIFORNIA GO FOR THE WINTER?

    The Pigeon Guillemot (Cepphus columba) nests at numerous small colonies and scattered individual sites from the Channel Islands, California, north to Alaska (Ewins et al. 1993). During the nonbreeding season, birds are virtually absent from California, Oregon, and the outer coast of Washington (e.g., Briggs et al. 1987), and the winter distribution of Pigeon Guillemots breeding along the west coast of North America is at best incompletely known.

  9. Cover image V31 (3)

    Nils Warnock (Author)

    BOOK REVIEWS

    Dunlins and Western Sandpipers do, as described by Stan Senner. The immense, remote Copper River Delta, just southeast of Prince William Sound in Alaska, is arguably one of the most important stopover sites for migratory waterbirds in the world, and the author does a captivating job in describing its importance to the successful migrations of Dunlins and Western Sandpipers. Almost the entire world's population of Western Sandpipers appears to stop at the Copper River Delta during spring, and most of the west coast population of the Dunlin (Calidris alpina pacifica) does the same.

  10. Cover image V31 (3)

    Steve N. G. Howell (Author)

    BOOK REVIEWS

    The first edition of Swifts was published in 1995 and received mixed reviews (e.g., see Cotinga 6:42–43, 1996). Hence, perhaps, the fairly quick appearance of a second edition. The jacket cover notes that particular attention has been paid to Neotropical swifts and that several plates have been revised

  11. Cover image V31 (3)

    PAUL LEHMAN (Author)

    FEATURED PHOTO : TWO LITTLE-KNOWN JUVENILE SHOREBIRDS

    Our knowledge of shorebird identification, age determination, and status along the Pacific coast and elsewhere in North America was only in the fledgling stage in 1977 when Prater, Marchant, and Vuorinen published their groundbreaking Guide to the Identification and Ageing of Holarctic Waders. Additional major reference works (e.g., Hayman, Marchant, and Prater 1986; Chandler 1989; Paulson 1993; and Rosair and Cottridge 1995) and a myriad of shorter articles about shorebird status and identification have been published over the ensuing 23 years.