Subject: Eurasian green-winged teal at Black River, Tukwila
Date: Jan 19 11:42:55 2000
From: StahlfeldE at aol.com - StahlfeldE at aol.com


Tweeters:

This is now at least the third consecutive year "Eurasian" green-winged teal
have wintered at the Black River Slough. Interestingly, in December I saw a
male with both the white vertical and white horizontal stripes, which I
guessed was a cross. I wondered how much this flock may stick together
throughout the year.

For those interested in more information, Eurasian green-winged teal were
discussed on Tweeters last March. To give credit where credit is due, Ian
Paulson wrote:

"I have been reading with interest the reports of "Eurasian"
Green-winged Teal from the region. I thought I let Tweeters people know
that there are 3 subspecies of Green-winged Teal listed below:

Subspecies English name Range
Anas crecca crecca "Common" Teal Eurasia
A.c.nimia "Aleutian" G.w. Teal Aleutian Is. AK
A.c.carolinensis "American" G.w. Teal North America

Both A.c.crecca and nimia were formerly considered a separate species the
"Common" Teal. The differences between crecca and nimia are related to
size. Nimia is slightly larger(especially in wing measurements) than
crecca, but otherwise resembles crecca in plumage. Although highly
unlikely to occur in our area (but Bellrose 1980 states: "The Aleutian
Teal(with the exception of a few stragglers to Britsh Columbia (source?))
is confined to the Aleutian Islands throughout the year.")it cannot be
100% ruled out. So I prefer the English name "Common Teal" when referring
to the birds of this subspecies group. Do any B.C. Birders/Ornithologists
know of any records of A.c.nimia from B.C.? Probably specimens only."

Michael Price responded:

"I remember chewing on the subspecific/intergrade ID problem of nimia versus
nominate crecca, as it seemed more likely, given its relative proximity to
our mid-Pacific Coast region, that it and not crecca would be the source
population for our annual influx of 'Common Teal' sightings. Nimia didn't
cooperate with that speculation, though, being not only perceptibly larger
according (informally) to some observers who have seen both crecca and nimia
together on the Aleutians--one person said, "A real horse--you'd tell it in
an instant."--but it is apparently *quite* sedentary (before people begin to
saddle up their horses about making assumptions, I'll stress I'm only
reporting what other people have said about it), very rarely appearing on
the Alaskan mainland even directly opposite its breeding grounds.

There *are* crecca-type teal showing up here which are slightly larger than
wintering 'carolinensis'--one such male used to winter in the ponds and
cattail marshes at Jericho Park even before it became a park in Vancouver BC
in the halcyon days before offleash dog-owners appropriated the place--and
the size difference was apparent if not large anytime it swam beside a male
carolinensis.

There's two possibilities: that the eastern Siberian populations of crecca
may average slightly larger than crecca from the western Palearctic, and/or
that these slightly larger males are not nimia but crecca X nimia
intergrades. It would be interesting to see if the biometrics given for
crecca in Madge & Burns' Waterfowl book refer to western Palearctic crecca
only or were averaged from measurement data representing populations right
across the entire Palearctic range of crecca from western Europe to eastern
Siberia/mainland Alaska.

Birds of BC, Volume 1 (Campbell et al, published 1990) neither takes a
stance or mentions nimia, contenting itself with saying, verbatim, "The Old
World race, known as the Common Teal or Teal (Anas crecca crecca) was
previously considered a separate species. It occurs as a regular winter
visitant to the south coast..."

Birds of Canada, Rev. Ed. (Godfrey, 1986) likewise ignores nimia, saying,
"A.c. crecca Linnaeus of the Old World... is a casual visitant to Nova
Scotia, New Brunswick, Newfoundland, Labrador, Quebec (sight record). Rare
but more or less regular visitor to southwestern British Columbia."

Incidentally, I'll bet the farm that the Eastern Seaboard birds are vagrants
from western Europe, but that the West Coast birds (and how far south do
they actually and regularly winter?) are Siberian/Alaskan 'crecca'. It would
be further interesting to see if there's consistent difference(s) in the
biometrics of the birds showing up on either coast, as that might show the
biometric range from one end of the Palearctic crecca population to the other.

So, although not an ornithologist, Ian, my best guess is that when we see
crecca-type teal on this coast in winter, we don't see nimia, just crecca,
or crecca X nimia intergrades at best, from Siberia or mainland Alaska if
they're breeding there. How you'd be able to tell, other than blood-testing,
I haven't a clue."

I didn't chase the other Eurasians, but wouldn't a "four-eurasian" day
(Dotterel, Kestral, Wigeon and Teal) have been something?

Eric Stahlfeld
Burien, WA