HI:
I thought someone might be interested in this?

Ian Paulsen
Bainbridge Is., WA, USA
ipaulsen at linknet.kitsap.lib.wa.us
A.K.A.: "Birdbooker"
"Rallidae all the way"

---------- Forwarded message ----------
Date: Fri, 19 Oct 2001 11:11:37 +0100
From: Killian Mullarney <kmullarney at EIRCOM.NET>
To: BIRDWG01 at LISTSERV.ARIZONA.EDU
Subject: Re: [BIRDWG01] Help with basic-pl wigeon

Just in case some of you may refer to the Collins "Bird Guide"/ Princeton
"Birds of Europe" for information on ageing/sexing Eurasian Wigeon at this
time of year, I feel I should draw attention to an unfortunate caption error
on the Wigeon plate, page 51. The left-most main figure (in both the
Eurasian Wigeon and American Wigeon arrangements) are incorrectly captioned
"juv"; they are in fact both adult females (this has been corrected in the
Collins large format edition). In autumn/fall when all wigeon are either
juvenile or eclipse adults the most reliably judged and consistent ageing
feature, when visible, is the pattern of the wing coverts. Of course, most
of the time these remain more or less completely hidden behind flank
feathers or scapulars but prolonged observation of an individual will
usually pay off, eventually, when the bird preens, or wing-stretches.The
differences in wing-covert patterns, and other associated age/sex indicators
that I have noticed are as follows:

Adult male: large white wing patch, all year round, so even full-eclipse
birds have extensively white wing coverts and a "sliver" of this is often
visible on swimming birds (as in photo 7 on Angus Wilson's site). Most are
still very much in eclipse in early-mid-October, but more advanced birds
have by now acquired quite a lot of basic plumage. Note that even in
July/August eclipse males seem always to show a large patch of grey (at
close range finely vermiculated feathers) on the mantle. Their plumage is
otherwise very dark and richly coloured, deep rust-brown. Note that the
bill, at least at this time of year is clean, pale grey blue, paler and
brighter than on juvs and with a neat, clear-cut black tip.

Adult females: variable, but median+lesser wing coverts always more crisply
and cleanly fringed white producing a "fish-scales" pattern (as in
incorrectly-captioned Collins guide illustration) than juvs.

Juvenile/first-winter (or first- basic) male: Again, variable, but wing
covert patch usually rather plain, washed-out (light) greyish-brown, never
the bold, clean white of adult males. Some juv males have a
"ghost-impression" of the adult's wing-patch (though much reduced in
extent), or a few of pale greyish-white feathers among an otherwise pale
brownish patch. Note that young males tend to have a more blackish speculum
(often with a small patch of iridescent-green) than young females. Young
birds of both sexes often have a trace of dark along the culmen (forking
toward the bill-base, just above the nostrils);this is certainly absent in
adult males, and usually also absent in adult females, but there may be
exceptions in the case of the latter. Young males which have commenced the
post-juvenile moult can often be easily sexed when they acquire a few
adult-type pale grey ( finely vermiculated at close range) scapulars or
flank feathers. By late-November many are so advanced in their body moult
that they look superficially like adult males and you may need to wait until
the wing coverts are revealed to be sure they are not adult.

Juvenile/first-winter (or first-basic) female: Often the drabbest, most
washed out members of the flock are young females. They usually have very
plain wing coverts with little more than very thin buffish fringes to the
wing coverts, though on some one row of medians may have a slightly
stronger, whiter fringe. Usually, the secondaries are dull greyish (rather
than backish) and they completely lack gloss. Note that on fresh juveniles
(of both sexes) the feathers of the breast, flanks and scapulars are
comparatively small with a beautiful, subtle regular pattern/texture, as is
visible in photos 4 & 5 of Angus Wilson's compilation.

A few years ago I devoted a lot of time to looking through Eurasian Wigeon
flocks in an attempt to work out the best means of ageing and sexing birds
at this time of year and a little earlier. At first, the variation was
bewildering but gradually I began to recognise that in spite of a high
degree of individual variation there are certain consistent traits of each
age/sex category. Many of them are really too subtle or too "personal" to
waste time describing here without having some accompanying visual. Over
and over again though, it was the pattern of the wing coverts which, in
combination with other aspects of the plumage (especially the first
post-juvenile feathers in young males) confirmed the age and sex.

I believe the "Mystery wigeon" featured in the first five photos on Angus
Wilson's site is a "dark" juvenile male Eurasian, but I would love to know
what its wing covert pattern was like! Note the bill pattern in shot 3,
which certainly eliminates adult male eclipse (as does, I believe, the
absence of clearly grey feathers in the mantle area), and the beautiful
texture of the breast/flank in shots 4 and 5, which is typical of fresh
juvenile plumage.

I'd be more circumspect about offering an opinion on the age/sex of Don
Roberson's birds except to say that neither is an eclipse male. There is
no question, however, that the axillaries are visible in the lower photo and
that they are grey, like a Eurasian.

The bottom line in all this is, try to get a look at the wing covert pattern
of any difficult-to-age/sex wigeon, and you're almost there!

Regards,

Killian Mullarney
kmullarney at eircom.net


----- Original Message -----
From: Andrew Guthrie <andrew.guthrie at EY.COM>
To: <BIRDWG01 at LISTSERV.ARIZONA.EDU>
Sent: Thursday, October 18, 2001 10:05 PM
Subject: Re: [BIRDWG01] Help with basic-pl wigeon


> Don Roberson's message comes just as Angus Wilson and I have been
> pondering the same issue on the east coast. Angus has put together a
> quick web page with pictures of a rusty-headed basic-type Eurasian Wigeon
> that I first noted at Jamaica Bay refuge in New York City on October 13,
> 2001, along with 3 "typical" male Eurasian Wigeons in various stages of
> molt. Angus was able to relocate these birds the following day and
> managed to get closer pictures of the intriguing individual.
>
> Our thoughts were similar to Don's - that the bird was likely an eclipse
> or first-year male. One question we still have is whether an adult
> eclipse male is likely to be in this plumage at mid-October. We would
> also appreciate any thoughts or comments on aging and molt timing. Wigeon
> often remain at Jamaica Bay well into late fall, so we'll try to keep an
> eye out for this individual to see if it shows any molt progression.
>
> Angus's web page is accessible at:
> http://www.oceanwanderers.com/EurWig.html
>
> Cheers,
> Andy Guthrie
> Port Chester, NY
> andyguthrie at earthlink.net
>
>
>
>
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