Answer to Mystery Bird -- 3B

We are looking at two views of a medium-sized duck. Mostly gray-brown with rufous-brown flanks (lower photograph). The tertials (again lower picture) are black and edged with white. The breast is gray-brown with a diffuse mottling and the head is rather rounded (domed?). These features tell us we are looking at a female-type wigeon. Uh, oh!! Now things are getting hard! Female American Wigeon (Anas americana) and Eurasian Wigeons (A. penelope) are very similar and to make things worse, exhibit a high degree of variability. As with any tricky identification, caution and a number of positive features are required!

Probably the best feature for separating landed female wigeons is the degree of contrast between the head and the breast. In the upper photograph, we can see a weak line of demarkation between the gray-brown head and the grayer breast. This looks good for Eurasian Wigeon. In American Wigeon, the contrast is usually much stronger.

Below are some Eurasian Wigeons photographed in Japan in early January. The female shows no more than a moderate degree of contrast between head and breast. The flanks are only slightly more rufous than the head.

The image shown below is the only picture of American Wigeon I could find in my slide collection. It shows a male and female (unfortunately the female is partially blocked) paddling on a frozen pond near Centerport, Long Island, New York (December, 1995). The head, neck and nape of the female are very gray while the flanks are a bright rust color. According to the excellent new text by Beaman and Madge (1998), the forecrown and sides of the head tend to be paler than Eurasian Wigeon and the eye patch darker. This is the case here although the head is partly in shadow.

So the mystery bird is a female Eurasian Wigeon (Anas penelope). It was photographed on the 'Whooper Pond' at East Park, Caerlaverock - a Wildfowl and Wetlands Trust reserve in Dumfries and Galloway, Scotland in January 1997.

Confirmation of the identification would come from seeing the underwings (more specifically the axillaries and central underwing). In Eurasian Wigeon, the underwing is pale grayish with darker flight feathers while in American Wigeon these feathers are clear white. Obviously, this can be difficult to see (when birds flap or take flight) and some caution is necessary in bright sunlight which can make the underwings of Eurasian Wigeon look very pale.

Useful Literature: Beaman, M. and Madge, S. (1998) The Handbook of Bird Identification for Europe and the Western Palearctic. Princeton University Press.

Copyright © 1998 All rights reserved.Angus Wilson

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