Figure 13. All of the state’s accepted records of the Whooper Swan come from northeastern California and the Central Valley. This adult—clearly outsizing the Tundra Swan in the background—was photographed in December 1991 at the Lower Klamath NWR, Siskiyou County (1991-197; David Menke).

WHOOPER SWAN Cygnus cygnus (Linnaeus, 1758)

This large swan breeds across the middle and high latitudes of Eurasia, from Iceland and Scotland (and formerly southern Greenland) to eastern Siberia. A pair bred on Attu in the western Aleutian Islands in 1996 and 1997 (Sykes and Sonneborn 1998). The wintering grounds extend south to central Europe and central China and east to the central Aleutian Islands, where small numbers occur. The species is otherwise casual in western Alaska and casual to accidental farther east in Alaska and southward along the Pacific slope to northern California. Vagrants may occur annually in Greenland (Boertmann 1994). Most individuals found elsewhere on the continent—including those in northwestern Montana in March 2001 and November 2003 (NAB 55:326; 58:107)—are of uncertain or dubious origin (e.g., AOU 1998, McEneaney 2004, Montana Bird Records Committee data). However, a second-year individual present 26 November 2003–3 January 2004 at Yellowstone National Park in Wyoming was probably a legitimate vagrant (McEneaney 2004).

An adult Whooper Swan present from 17 to 19 January 1984 near Grimes in Colusa County (Roberson 1986) furnished the second record of an apparently wild bird in the coterminous United States, following a 1903 specimen record from Maine (Knight 1908). As summarized by McEneaney (2004), the species is frequently held in captivity (including in California, fide J. Morlan), with breeding records involving feral birds in parts of the Northeast and Midwest. For these reasons, judging natural occurrence can be difficult and contentious. The CBRC wavered for years in its assessments of origin, but eventually accepted California’s records because (a) at the time, birds known or presumed to be escapees seemed to have been confined to the Great Plains, Great Lakes, and eastward and (b) the species had been accepted as a naturally occurring vagrant to mainland Alaska (Kessel and Gibson 1978). Subsequent records of apparently wild birds have come from coastal British Columbia (Campbell et al. 2001) and Oregon. These are tempered somewhat by the known release of a Whooper Swan at Mountain Lake Park in San Francisco, San Francisco County, during the late 1980s (fide D. Roberson; see AB 43:362).

Since fall 1991, as many as five adult Whooper Swans have wintered between Summer Lake in Oregon and Lower Klamath NWR in Siskiyou County (Marshall et al. 2003). The Committee has accepted only certain records from this location as involving returning birds, and opinion is mixed regarding the most likely number of individuals involved (e.g., NAB 55:94). A possible family group consisting of adult Tundra and Whooper Swans with three cygnets was at Summer Lake from 1 to 6 November 2000 (NAB 55:94), and presumably the same group was later recorded at Unit 4 of the Lower Klamath NWR—mostly on the California side of the reserve—between 10 January and 10 March 2001 (Cole and McCaskie 2004, Oregon Birds 27:56; Figure 191). The CBRC accepted the three young birds as Whooper Swans although the possibility that they were hybrids could not be ruled out.

The possibility of hybridism kept the Committee from accepting the record of a small, Whooper-like adult present from 1 January to 10 March 2001 at nearby White Lake, Lower Klamath NWR. Observers should also bear in mind the potential for a Bewick’s Swan to resemble, superficially, a Whooper Swan or hybrid.

[RUDDY SHELDUCK Tadorna ferruginea (Pallas, 1764) – see hypothetical section]