Greetings Wayne and other Tweeters

As I recall, the bird David Mandell and I found near Maryhill (which was with
GRSC and LESC) was relatively small in size, implicating a cross with LESC.
However, we felt it best left as TUDU x scaup and did not claim it as a TUDU x
LESC.

Actually, a hybrid TUDU in NA seems just as likely to be with a LESC.
Remember, ducks pair up on their wintering grounds, not breeding grounds. A hybrid
that appears in NA during winter seems just as likely to have originated from
this continent.

Why? Because in Eurasia, there are plenty of other conspecifics to hook up
with, but a poor TUDU finding itself in NA during winter will have little chance
of finding its own kind to pair up with. If it does find a mate, it will
likely be a scaup. The results of such a pairing will then, most likely, find
themselves wintering in North America. I don't see a clear factor that would lead
towards a lonely male (or female) TUDU going for a LESC vs a GRSC. Indeed,
they seem to be found with LESC moreso than GRSC, so a TUDU x LESC hybrid seems
more likely.

Proving parentage, however, might require DNA. It would be tough.

Cheers
Steven Mlodinow