North American Birds

VOLUME 68 NO4 2015

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

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454 n o r t h a m e r i c a n b i r d s c o m m o n s c ot e r i n n o r t h a m e r i c a both observations involving a pair of birds seen from aircraft during waterfowl surveys: at Kilen, in Northeast Greenland (81° 09' N, 12° 59' W) 28 July 2009, thought to be nigra (Boertmann and Nielsen 2010); and at Disko Island, West Greenland (70° 11' N, 54° 50' W) 29 July 2015, thought to be americana (D. Boertmann, pers. comm.). Given the scarcity of records of Common Scoter from Greenland, where waterfowl hunting is widespread, it is perhaps not sur- prising that northeastern North America has not yet recorded Common Scoter. Certainly, with the split of these scoters in 2010, there has been renewed interest in fnding the spe- cies among focks of Black Scoters in eastern North America—and now, too, in western North America, after the California record. The route by which the Common Scoter ar- rived in Crescent City is a matter for specu - lation, but it is perhaps not unlikely that the bird reached California by initially traveling westward from its Palearctic range rather than eastward: the recent reduction of sea ice in the Arctic Ocean in summer and fall is thought to be responsible for recent re- cords of species in the "wrong" ocean basin, such as Northern Gannets (Morus bassanus) in Alaska and California and Alaska (Tobish 2011, Rottenborn et al. 2012) and Tufted Puffns (Fratercula cirrhata) in the United Kingdom, Greenland, and New Brunswick (Wright 2011, Seeler 2015). This record has been accepted by the Cali- fornia Bird Records Committee as the frst state record. on a few records from Greenland, Common Scoter has long been anticipated as a vagrant to Atlantic Canada or New England. Boert- mann (1994) lists fve records of Common Scoter (eight individuals in total) for Green- land, though not all records are clearly of Common Scoter. Two specimens from West Greenland—an adult male from February 1902 and another adult male shot from a pair 9 May 1950—are specifcally noted to be Common Scoter rather than Black Scoter (Boertmann 1994). In Southeast Greenland, a pair of scoters that remained at Tugtilik through the month of July 1933 was report- ed as "Common Scoter" by Chapman (1934); these birds were almost certainly nigra, as the English name for Black Scoter (still wide- ly considered a separate species from Com- mon Scoter in 1934) was "American Scoter." Palmer (1976) treats these three records as re- ferring to Common Scoter rather than Black Scoter. Meltofte (1977) observed a single pair of Common Scoters at Danmarkshavn in Northeast Greenland 8 July through 3 August 1975 and again 13-18 June 1976; he confrms from his feld notes that these were defnitely nigra (H. Meltofte, pers. comm.). An article summarizing rare bird reports for Denmark and Greenland ("Sjældne fugle i Danmark og Grønland") published annually 1994 through 2005 in Dansk Ornitologisk Forenings Tidsskrift includes no mention of either Black or Common Scoter for Green- land, and in correspondence with ornitholo- gists active in Greenland, only two further records from Greenland have come to light, but not quite overlapping along the lower Lena River valley, and recent reports online (e.g., Sofronov 2012) corroborate these re- cords. Hybrids between Common and Black Scoters are unknown (Cramp and Simmons 1977, Bordage and Savard 2011; E. Koblik, pers. comm.), but one adult male noted in Sweden seemed aberrant enough for a hy- brid to be considered (Bradbury 2011). Black Scoter is apparently responsible for all records of Black/Common Scoters in the western North Pacifc region, including of southerly vagrants, with the caveat that females and young males are diffcult or impossible to assign to species in the feld. Common Scoter winters in saltwater habitats from Norway to the British Isles, with small- er numbers found south to Portugal and rare individuals detected west to the Azores and south to northwestern Africa, at least to Mauretania (Carboneras and Kirwan 2014, Kear 2005); it is not clear how many of the extralimital records from Macaronesia (about 20 records) or Africa are of adult males read- ily identifed as Common Scoter rather than Black Scoter, although at least a few are preserved as specimens, and one involves a banding return from Iceland (Clarke 2006). As a vagrant to eastern Asia, Common Scoter is apparently unknown, even from Japan, where serious birding, and waterfowl research, have been ongoing for decades (Ornithological Society of Japan 2012; M. A. Brazil, N. Moores, Y. Watabe, pers. comm.). Alaska likewise has no report of Common Scoter (Thede Tobish, pers. comm.). Based Figure 7. Common Scoter, Crescent City, California, 8 February 2015. This digiscoped image shows the feshy-orange coloration of the interior of the bill and tongue. Few observers that saw the bird were able to see these features. Photograph by Ollie Oliver. Figure 8. Common Scoter, Crescent City, California, 11 February 2015. In the upperwing, as in the underwing, Common Scoters show contrast between the silvery-gray and blackish feathers, but in the upperwing, only the primaries show the silvery tones, not the secondaries. In fight, Common Scoters typically show a thinner neck and head than Black Scoter (Figure 9), but this structural distinction is probably most apparent when both species are together. Photograph by Len Jellicoe.

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