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Figures
Figure 28. Seasonal occurrence of the Yellow-billed Loon in California. The species has been recorded throughout the year, but most records fall between mid December and mid March.
Figure 29. In California, most Yellow-billed Loons have been found along the coast from Monterey Bay northward. Farther south was this first-winter bird (note the evenly scalloped mantle feathers) photographed on 11 December 1992 in Santa Barbara, Santa Barbara County (1993-012; Shawneen E. Finnegan).
Figure 30. Distribution of 71 Yellow-billed Loons accepted through 2003. As with the King Eider (see Figure 23), records are concentrated along the central coast from Sonoma County to Monterey Bay. Unlike that species’ pattern, however, most of the state’s remaining Yellow-billed Loon records have come from more northerly locales. Only four Yellow-billed Loons have been found inland, but numerous occurrences of this species across the continent suggest that these birds may stray to California’s lakes and reservoirs somewhat more frequently than is suggested by the records to date.
Yellow-billed Loon
YELLOW-BILLED LOON Gavia adamsii (Gray, 1859)
Accepted: 71 (69%) |
Treated in Appendix H: yes |
Not accepted: 32 |
CBRC review: all records |
Not submitted/reviewed: 21 (plus one from Nevada) |
Color image: none |
This loon has a nearly holarctic breeding range, with a North American population estimated to include fewer than 16,000 pairs, most of them in Canada (Earnst 2004). The northern Alaskan lakes of greatest importance to birds breeding in the United States may be threatened by ongoing and planned oil extraction (Earnst et al. 2005). Most North American birds winter along the coasts of Alaska and northern British Columbia, but the range of regular and semiregular winter occurrence has been expanding eastward and southward since around 1970 (Remsen and Binford 1975, Patten 2000). Records in Washington and Oregon averaged about 8.5 per year from 1979 to 1989, but only about 4.5 per year during the next nine years (Wahl et al. 2005), a decline possibly related to the 1989 Exxon Valdez oil spill in the Gulf of Alaska (e.g., Piatt et al. 1990). More recently, records in Washington and Oregon have averaged about ten per winter and nearly one per summer (fide S. G. Mlodinow). Extralimital records extend south along the Pacific coast to northern Baja California (both coasts). The species is recorded almost annually in both eastern Washington and Colorado, and vagrant records are scattered eastward across much of North America, exceptionally to southern Quebec, coastal New York, eastern Texas, and, especially in recent years, the Southeast (e.g., NAB 60:242).
California’s first Yellow-billed Loon was a first-winter male collected on 24 December 1896 at “Monterey” (probably Monterey Bay) in Monterey County. The existence of this specimen, previously unreported in the literature, finally came to light in 2005 during a search of the Museum of Comparative Zoology’s recently digitized catalog. Seven decades passed before the state’s second record, but this loon then proved to be a rare, regular vagrant to California; it has been documented somewhere in the state every year since 1971. Most occurrences involve immature birds between early November and mid April (Figure 28), and 85% (60 of 71) are from Monterey Bay northward, with only four away from the coast (Figure 30); see also Appendix H. Remsen and Binford (1975) carefully reviewed all known California records through 1974, and the CBRC largely followed their recommendations, as reported by Roberson (1993) and later refined by Cole et al. (2006). Phillips (1990) provided a more recent, and more conservative, summary of the Yellow-billed Loon’s status south of Alaska.
Remsen and Binford (1975) postulated that females “winter, or at least wander, farther south than males,” since all 12 of the then-known specimens from southerly latitudes (eight from Britain, three from California, one from Baja California) are of females. These authors also remarked on the relatively high prevalence of illness among Yellow-billed Loons in warmer southern waters, postulating that disease may play an important role in setting the southern limit of the species’ range. Binford and Remsen (1974) and Burn and Mather (1974) contributed important early identification papers.