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Hybrid male wigeon in Deep Bay, spring 2009

This topic has been highlight by Record_Com at 23/12/2020 21:14.

Hybrid male wigeon in Deep Bay, spring 2009

A wigeon Anas showing characters of American Wigeon A. americana was reported from Tsim Bei Tsui and Mai Po boardwalk on 25th February and 14-15th March 2009. Three reports were submitted to the Records Committee, two of which included photos. Other photos were also posted on the Forum. These can all be seen at the following links:

http://www.hkbws.org.hk/BBS/view ... t=American%2BWigeon
http://www.hkbws.org.hk/BBS/view ... t=American%2BWigeon

Hybrids of American Wigeon and Eurasian Wigeon A. penelope have occurred previously in HK, the first in 1992, as reported by Carey (1993), who also documented their occurrence in Japan. Subsequently, there have been a series of records of hybrid male wigeon in HK, though most have been obvious as such as they had easily recognisable features of Eurasian Wigeon such as a reddish tinge to the head, greyish-fringed scapulars, greyish tones to the flanks, and a contrast in intensity between the chest and flanks.

Certainly the photographs posted from spring 2009 indicate a bird very like American Wigeon. The head lacks any reddish tinge, there is a narrow black band around the base of the bill, the white forecrown is obvious, the contrast of the cheeks is very marked and size is slightly greater than that of Eurasian. The Records Committee agreed that this was by far the strongest case for a pure American Wigeon in HK.

However, there were a few features to indicate the presence of Eurasian Wigeon genes. These are:

White on crown barely reaches peak and certainly does not extend onto nape;
Underparts do not look ‘uniform vinous-pink’, and, though hard to see well, the flanks look greyish;
The lack of uniform flank coloration;
The scapulars are greyish-toned, rather than buff.

The RC concluded that, while an American Wigeon may show one of these features, the combination is more indicative of hybrid origin. Consequently, this bird has been accepted as a hybrid male wigeon A. penelope x A. americana.

References
Carey, G.J. 1993.Hybrid Male Wigeon in East Asia. Hong Kong Bird Report 1992: 160-166.

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