Tweets,

While it is not always necessary to have a 'bird-in-hand' to determine
origins it is often the only way to determine certain features.

One thing that aviculturists often do to mark their birds (it may even be a
requirement in certain states) is to clip the hallux (hind toe) of their
birds. I believe this is most often performed on the right leg. This is a
feature that is often difficult to determine in the field, but quite easy
when the bird is 'in-the-hand' whether dead or alive.

Bands in themselves do not always tell the story as many biologists across
the world band birds (ringing is what this is called in Old World
terminology) and it is not always easy to determine if a band is from an
aviculturist or a biologist. The presence of a band, or bands, would raise
questions from any records committee though.

Another feature that is often associated with captive birds is unnatural
feather wear. Birds in captivity often show unusual feather wear in unusual
places. Sometime this is visible in the field, but sometimes it is not. It
is always visible when the bird is immobile and carefully examined at close
range. It is equally visible in field observations at very close range.
Something that wild birds, and feral birds, are often wont to sit still for.

Other features that can be shown by captive birds that are very difficult in
the field are: worn or abraded bills, worn or abraded feet and legs, missing
feathers in unusual places, etc.

The Falcated Duck that spent several winters near Coburg, OR the last few
years was viewed by hundreds (perhaps thousands) of birders. Even with the
cooperative nature of this bird it was difficult to determine certain
features that might be considered suspect of a bird with captive origins,
but my understanding is that eventually the bird showed no such features and
was considered a bird of wild origins.

I am not a proponent of killing birds just to determine such origins, but
legal hunting seasons and killed birds pretty much go hand in hand. For
records committees, or scientists, to ignore an opportunity to determine
whether an exotic species is of wild stock or captive origin is
fundamentally important not just from a records point of view, but from a
migratory pattern and population point of view as well.

Cheers

Doug Schonewald
Moses Lake, WA

-----Original Message-----
From: Devorah Bennu [mailto:birdologist at yahoo.com]
Sent: Friday, May 30, 2008 8:31 PM
To: tweeters at u.washington.edu; dschone8 at donobi.net
Subject: Re: [Tweeters] Baikal Teal Origins Question


How does one determine if a bird shows "signs of captivity"? I mean, there's
the obvious presence of bands on their legs, but you don't need to shoot a
bird to see those, so what are these "signs of captivity" to which you
refer?

GrrlScientist
Devorah
http://scienceblogs.com/grrlscientist/
Roosting high up a tree somewhere in Central Park, NYC





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