Subject: Black-tailed Gull
Date: Aug 8 07:59:25 2004
From: Mike Patterson - celata at pacifier.com


First, I said that the description did not match Charlie's
photo. This is different than saying that it wasn't a Black-
tailed Gull. Let's change the circumstances, suppose Charlie
had not already found the bird and taken unequivocal and
(in my opinion) diagnostic video.

Would the description posted yesterday have passed muster? No
black tail was seen. That's a pretty important field mark and
Marcus did ask for feedback. In the world of gulls, a California
Gull with a Ring-billed or Herring grandparent is arguably more
likely than a Black-tailed Gull without a black tail....

Bruce's follow-up description today describes the bill in
detail, the eye in detail and so forth. A much better description
and I fully concede (with appropriate apologies for any hurt
feelings associated with doubting) that the bird they saw was
almost certainly a Black-tailed Gull.

I would, however, like to point out the value of having
more than one field guide, particularly if one is going to
take on gulls. General field guides (Sibley's included if
chasing BTGU) are woefully inadequate. The length measurements
in most field guides are especially problematic, since they
represent a dead bird lying on its back and include the bill.

The range of measurements for the gulls in question:
California Gull 45-51cm (17.7-20in)
Heermann's Gull 45-50cm (17.7-19.7in)
Black-tailed Gull 46-48cm (18-19in)

Males average larger than females. In the case of California
Gull the _californicus_ subspecies is larger and darker than
the _albertaensis_ subspecies. Looking for a smaller gull may
work this time, but you may miss the next one.....

Anyway, way to hang in there Marcus and Bruce. Well spotted.
Here's hoping more find it today. I took my one shot and now
that the weather's improved, I'm oblidged to do work I can get
a paycheck for.

--
Mike Patterson
Astoria, OR
celata at pacifier.com