ML647479884

観察結果の詳細

Continuing potential second Tufted Duck in northwest inner pond, but hybridzation with scaup possible. First photographed by Terri Gueck on Dec 13 when no tuft was apparent. Distant scope views but here are my notes after watching it for about an hour: * Flanks white - more so than the other TUDU at the outer pond which is still retaining mostly grey alternate feathers. Thus this individual looks more "advanced" but the flanks can exhibit some variation even among East Asian TUDU between November and December. * Bill bright blue with a fairly wide black nail tip, slight pale subterminal spot less extensive than the other TUDU * Short tuft thin at the base very poorly visible, not thick and bushy as on typical hybrids (although this may change in coming months). Head shape round with a slight kink where the tuft begins. * Back is a dark slaty grey with slightly brown tone, paler than most Ring-necked Ducks and the other TUDU. No apparent vermiculations visible typical of most hybrids. The chest, tertials and uppertail coverts were approximately the same shade of grey. * Spread wing - shows a fair amount of white in inner primaries, a bit more extensive than the other TUDU. * Age: No apparent juvenile feathers, and tertials have some sheen suggests this is an adult male, not a hatch-year male undergoing preformative molt. To conclude, I am personally not convinced this is a hybrid, although I am open to the possibility it could be a backcross and will leave it as Aythya sp herein. To me, the main concern is not the short tuft but the the back colouration, considering the time of the year. Although some TUDU (including native range) can show dark greyish backs, this primarily occurs in spring and one expects a fresh prebasic molt in fall to show darker tones (assuming adult not formative). Even so I believe there may be exceptions and have posted some examples from below. Regardless I think it is important to consider the variation of TUDU in fall to winter with regard to both tuft and back colouration. For comparison, the TUDU male reported in California recently had similar dusky back and short tuft: https://media.ebird.org/catalog?birdOnly=true&taxonCode=tufduc&beginMonth=11&endMonth=12&beginYear=2025&endYear=2025®ionCode=L1028642 Other recent examples from Japan and Taiwan: https://macaulaylibrary.org/asset/647214548 https://macaulaylibrary.org/asset/647401634

追加される種

• Green-winged Teal (American) Anas crecca carolinensis
• Northern Pintail Anas acuta