|> From: Michael_Price at mindlink.bc.ca (Michael Price)
|>
|> Also, to piggyback a query, does anyone have a relatively foolproof way of
|> separating female Garganey from female Green-winged Teal with sometimes
|> equally-strong facial markings? And what's with these female Mallards with
|> whitish heads and grey stripes identical to female Garganey? Is this
|> pattern of head striping generic to female 'Anas' ducks?

See articles in Birding, June 1991 and August 1992, about ID of female Teal.
The difference in face pattern is a matter of degree. The wing pattern is
apparently diagnostic. Also, the bill is larger in Garganey and the forehead
more sloping, giving a different profile.
Though many Anas spp. have a similar face pattern, it is neither a necessary
condition (cf. Wigeon, Pintail, Shoveler) nor a sufficient one (cf. Ruddy
Duck) to classify a duck as a female Anas sp.

Daan Sandee sandee at cmns.think.com
Mountain View, CA 94041