ajohn

American Wigeon would be a first for Hong Kong, although is a likely visitor here.
There is a slight complication that hybrid wigeon (American x Eurasian) have been reported on several occasions.
For example, see:
http://www.hkbws.org.hk/BBS/view ... &extra=page%3D7
Did you note any features that confirm this as pure American Wigeon? Are there any photos of the bird?

I am not saying your bird isn't American Wigeon - I hope it is! Certainly it will be worth keeping a look out among the wigeon flocks in the coming days.

ajohn

The picture certainly looks promising for American Wigeon - congratulations!

I recommend everyone should keep a look out for this bird - hopefully more birders/photographers will be able to find the bird and confirm the ID.

This link shows some examples of hybrid wigeons, to show the variation
http://www.flickr.com/groups/hyb ... /72157601805249895/

Key features to check if you see the bird are the exact head pattern, extent of pink on flanks and, if possible, wing pattern (underwing and upperwing)