Friday, September 24, 2010

Gray-cheeked Thrush, Sept 11th

Although I identified it at the time as a Gray-cheeked Thrush it subsequently caused me a few problems when I started to look at it more carefully on the computer screen.  Mainly that its bill was pink on the lower mandible - until just recently I had assumed that Gray-cheeked had a yellow lower mandible, where the yellow was restricted to less than 50% of the extent.  It seems like I was wrong there, and looking back through my old images of Gray-cheeked I see that some of them have pink on the bill.

The bird above is a relatively cold coloration bird, predominantly olive, with a minimal eye ring and no buffy in the face or lores.  There's quite a lot of gray-olive wash on the flanks, no contrast between tail and primaries.  The lack of eye ring and buffy lores eliminates Swainson's - and it's usually fairly prominent even on the drabbest Swainson's.  Wrong coloration for Veery (and too much spotting).

So what we have is a relatively small Gray-cheeked - it was slightly smaller than nearby Swainson's Thrushes - on the olive end of gray.  It could well be the minimus subspecies rather than the aliciae subspecies, not least of all because the latter should be a littler larger than Swainson's.  Either way it's not C. bicknelli (Bicknell's Thrush) because of bill color, lower mandible color extent and the lack of rufous on wings on tail.  However it looks rather like Bicknell's in basic structure.  It's also a first fall immature bird, based on both the buffy terminal spots on the coverts and the pointed tail feathers.