Subject: [Tweeters] TB Murres
Date: Dec 31 15:06:56 2006
From: SGMlod at aol.com - SGMlod at aol.com


Hello Ned and the Rest of the Gang

TB Murre ID is a tricky business. First of all, alternate (ie, breeding birds
with all dark heads) Common Murres are going to look distinctly blacker than
basic (ie, winter) birds. So, if one is comparing back colors of a breeding
Common to a basic Common Murre, the breeding plumaged bird is going to look
distinctly blacker.

Any comparison of back color needs to be done between birds in the same
plumage. I've also seen a couple Common Murres in transitional plumage that have
appeared darker than those in full winter garb.

And on a recent seawatch with the honorable Brad Wagonner and Brad Watkins,
we saw 1200 murres stream past Marrowstone Pt and Pt Wilson. A goodly 20
percent of the birds were in breeding plumage. And though Brad and I have both had
the pleasure of studying thousands of both species in mixed flocks in Alaska,
there were birds we really, really struggled with.

The white sides bit works great if the bird is close, is nearly useless if
the bird isn't.

Bill size and shape can be very useful, but again, this is a difficult call
at any distance.

In flight, the birds are almost easier, especially in a mixed flock. The
neck, head, and bill proportions are more obvious. There are also some rump and
underwing differences (see Sibley).

Finally, if you are lucky enough to be in sunlight, it is not uncommon to
have light glint of a Common Murre's bill simulating the white "tomial" stripe on
the bill of a Common Murre.

Really, you need a great look or a fair bit of previous experience studying
murres for these details to ID a TB Murre. This is really one of those
instances where knowing the common species well is instrumental to correctly
identifying the rarer.

Best Wishes
Steven Mlodinow
Everett WA