Andy Stepniewski forwarded the website address of the purported Texas
Thayer's Gull photo, so I could look at it. After having done so, I came
to some conclusions and only then found Andy's second message in my
mailbox. I agree with his assessment of the photo 100%. He didn't mention
the paler inner primaries, also characteristic of large gulls with darker
outer primaries (and thus not so obvious in Thayer's, with their paler
outer primaries).

HOWEVER, I learned long ago that naming a gull, especially an immature,
from a single photo is a great way to put oneself out on a limb. The
reason for my hesitation is that we have an immature Thayer's in our
collection--at least I'm calling it an immature Thayer's from bill
size--that is darker than is typical of the species and thus matches the
Texas bird's wing pattern very closely. Nevertheless, as Thayer's is very
rare in Texas, and Herring is common, the burden of proof is on the Thayer
sayer, not the nayer.

My conclusion, solid as a rock, is that the bird might be a Herring Gull.
I have to say this to be consistent, as the last "Thayer's Gull" photo sent
to me from Texas a few years ago also looked like a Herring. Maybe they're
just trying too hard.

Andy:

>I'm looking closely at Grant's Guide to Gulls, p. 253...the more I look at
>the alleged Thayer's Gull on the web,,,the more it looks like a 1st winter
>Herring Gull cause:
>
>1- head structure shows perfectly the flattened profile of a Herring Gull
>2)-contrasty primaries which Thayer's does not have
>3)-dark trailing edge of swcondaries
>4)-typical Thayers show a mottled pattern on uppertail
>5)-photo shows an individual much to contrasty when viewed from above
> for Thayer's in my opinion. Overall, Thayer's appears pretty much concolor
>above, except for the tail.
>6)-Bill structure is somewahat difficult to discern because of lack of
>resolution, but overall, it appears more like a Herring than the slight
>structure typically associated with a Thayer's

Dennis Paulson, Director phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416