Subject: EURASIAN WIGEON VS. EURASIAN GREEN-WINGED TEAL
Date: Jan 21 13:12:15 2000
From: WAYNE WEBER - WAYNE_WEBER at bc.sympatico.ca


Tweeters and Vancouver Birders,

In a message about 3 days ago, Lydia Gaebe asked which is more
frequent in Tweeterdom-- Eurasian Wigeon, or (Eurasian) Green-winged
Teal? This is a slightly belated response. As some of you are
starting to realize, I like to give a statistical response to such
questions whenever possible.

In a nutshell-- Eurasian Wigeon is much more numerous than
Eurasian Green-winged Teal, by at least 10 to 1. It has also increased
steadily in frequency as a wintering bird in the Pacific NW over the
past 30 years, whereas I can detect no change in the status of
Eurasian Green-wings.

On the Ladner CBC, Eurasian Wigeon has been seen in 29 of the last
38 years, but has never been missed in the last 20. The average count
of this species is 16 birds over the 38-year period, but in the last
decade, it has averaged 45 birds. The high count is 74. Keep in mind
that only the males are normally tallied, because the females are
tough to identify, except for the rare rufous phase (which I have seen
3 or 4 times). So the actual numbers of Eurasian Wigeon are at least
twice the numbers that have been reported. The status of this bird on
the Vancouver bird checklist has increased from rare, to uncommon, to
fairly common. I would say that currently, about 1% to 2% of wigeon
wintering around Vancouver are Eurasians.
On the other hand, Eurasian Green-wings have been seen only 4
times in 38 years on the Ladner CBC. Eurasian X American intergrades
have also been seen twice.

On the Vancouver CBC, which has smaller counts of dabbling ducks
than Ladner, Eurasian Wigeon numbers have averaged 7 over the last 31
years, increasing to 15 in the last decade. However, the Eurasian
Green-wing has been seen more often than at Ladner-- 6 times in 31
years, plus 3 more times in count week. These are almost always single
birds.

Eurasian Green-wings are probably not as rare, relative to
Eurasian Wigeon, as these numbers suggest. They don't "stick out" as
much as Eurasian Wigeon because the distinguishing marks are on the
flanks, not on the head. Also, Green-wings tend to hunker down in
dense vegetation more than wigeon, and do not feed openly on golf
courses, etc., like wigeon, so oddball teal are not as easily picked
out. At places like Blackie Spit on Boundary Bay, where large numbers
of Green-wings can be seen at close range, one or more Eurasians (as
well as the occasional intergrade) can usually be found every winter.
Nevertheless, this form remains much scarcer than the Eurasian Wigeon.

I believe that Michael Price, in the attached discussion quoted by
Eric Stahlfeld, is correct in concluding that virtually all "Eurasian"
Green-wings seen in B.C. and Washington are the widespread Old World
subspecies, crecca, rather than the Aleutian form, nimia, which is
supposed to be largely non-migratory.

That's all for now!

Wayne Weber
Kamloops and Delta, B.C.
wayne_weber at bc.sympatico.ca



-----Original Message-----
From: StahlfeldE at aol.com <StahlfeldE at aol.com>
To: tweeters at u.washington.edu <tweeters at u.washington.edu>
Date: Wednesday, January 19, 2000 12:05 PM
Subject: Eurasian green-winged teal at Black River, Tukwila


>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
>