Hi Steve:
A great question ...
First, you reference Sibley's illustration on p 61, so I'm guessing
you are using a Sibley Guide to Eastern Birds, which I don't have
handy. My response, below, refers to the Sibley Guide to Birds that
treats all eastern and western North America species, together.
Graylags are the basic stock from which many forms of
domestic/barnyard geese have been bred and descended, just like
Mallards are the stock for many forms of domestic ("mongrel") ducks.
However, fairly pure looking domesticated Graylags do differ in
appearance somewhat from the wild Graylags of their native Europe.
The domestic forms tend to have the pot bellies and show extra
amounts of white around the face, and other places, as Sibley indicates.
However, note that in Sibley (2000), his treatment of Graylag Goose
(p 89) is on a page labelled "Domestic Waterfowl" and his
illustration of this species indicates "Graylag (Domestic) Goose." So
what Sibley is portraying is the domestic stock of Graylag, not the
wild stock of Graylag that occurs in Europe. When Sibley was
published in 2000, no records of Graylag had been accepted in North
America, so Sibley was not trying to show how to identify wild
Graylags, but rather how to separate domestic Graylags from wild
Greater White-fronteds.
If you check the National Geographic 6th edition (Dunn and Alderfer
2011), it shows Graylag in the Exotic Waterfowl section on p 48-49,
but it also refers to p 530 where Graylag is now also treated in the
"Accidental" section. This account on p 530 was added after the first
record in 2005 was accepted in North America and discusses separation
of (wild) Graylags from Greater White-fronteds. (The frequent
National Geographic edition updates are intended to keep up with new
species accepted to North America, as well as splits and lumps.)
So, most North American field guides were not really concerned with
"wild" Graylags prior to 2005 when the first North American record
was accepted. To find some good comparisons and contrasts between
wild Graylags and other similar "brown goose" species (Pink-footed,
Tiaga Bean, and Greater White-fronted) you really have to go to
European field guides.
The Mullarney and Zetterstrom Birds of Europe 2nd edition (2009) that
I showed is a good one. Other good ones that treats these brown geese
in detail are The Handbook of Bird Identification (Beaman and Madge
1998), The Complete Guide to the Birdlife of Britain and Europe
(Hayman and Hume 2002), and Birds of Europe with North Africa and the
Middle East (Jonsson 1992).
No North American guide published before 2005 is going to treat wild
Graylags and even after that, most of them will treat Graylags either
just cursorily or not at all, due to page space. I think there have
been only a handful, or fewer, reports or records of Graylag in North
American since 2005, mostly in eastern Canada. However, like the
other European goose species, they could always show up further
south. I think the identification process of a wild Graylag would be
to first eliminate domestic birds based on the dumpy shape and any
extraneous amounts of white; then look for indications of it being
wild, such as moving with migratory Canadas, wariness, no clipped
hind toes, etc.
FYI, here are reference links to what I think are the three best
European guides ...
http://www.amazon.com/Birds-Europe-Second-Princeton-Guides/dp/0691143927/ref=dp_ob_title_bk
http://www.amazon.com/Handbook-Identification-Europe-Western-Palearctic/dp/0691027269/ref=sr_1_1?ie=UTF8&qid=1330066629&sr=8-1
http://www.amazon.com/Complete-Guide-Birdlife-Britain-Europe/dp/1857327950''
Hope this helps!
Phil
At 20:53 02/23/2012, Steve Long wrote:
>Phil,
>
>Thank you for posting the pictures and notes on field marks.
>
>But, one thing is confusing me. All of the geese in your pictures
>seem to have about the same body shape and posture. In contrast,
>the picture of a Graylag Goose on page 61 of Sibley's showes it to
>be shaped more like a domestc white goose, with an obviously deeper
>body compared to its length. Sibley's even makes note of the "deep
>belly" as a field mark. Sibley's also showes a thin white strip
>between the bill and head, much like the White-fronted, but
>substantially thinner. Since Sibley's also says that Graylag
>individuals may have a lot of additional white on them in various
>places, I have been mainly depending on the body shape, rather than
>looking at the more subtle marks such as the white body line or the
>thickness of the white "front." I am pretty sure that I have seen
>both, before, and was confident of my ability to tell the difference
>until I looked at your illustrations.
>
>Can you tell us any more about the body shapes?
===================================================
Phil Davis, Secretary
MD/DC Records Committee
2549 Vale Court
Davidsonville, Maryland 21035 USA
301-261-0184
mailto:[log in to unmask]
MD/DCRC Web site: http://www.MDBirds.org/mddcrc/rcindex.html
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