[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: article in Birding



	
While admittedly I just skimmed the article in Birding and plan to go back
to it for a thorough study, the pictures looked confusing and, as sometimes
happens in Birding, the photos do not illustrate what the text discusses.
I think primary extension was supposed to be one of the identifying
characteristics separating the two species and all of the photos were sort
of three-quarters profiles, the one angle at which it is real hard to see
primaries or primary extension.

It might be easier to remember this:  The Gray-cheeked breeds well north of
the Bicknell's.  According to Bergmann's Rule, this means the Gray-cheeked
must be bigger than the Bicknell's.  The Gray-cheeks I have seen always
struck me as large and friends who have seen what we assumed was Bicknell's
described a small bird with large eyes (I've heard Bicknell's but never
seen one).  In one case, there was a Swainson's Thrush nearby with which to
compare a suspected Bicknell's.  The Bicknell's was visibly smaller than
the Swainson's Thrush, according to what I was told.  Going by the
measurements in National Geo, Bicknell's is smaller than a Bluebird.

Granted, size can be a subjective decision, but it seems a bit easier than
trying to finnagle a look at primary extensions or deciding if the lower
mandible is almost entirely yellow/orange.  


Donna S. Bailey		
Winnsboro, SC

e-mail: dsbailey@conterra.com

URL:  http://www.conterra.com/dsbailey
	Where are the Birds?  Migration across South Carolina

URL: http://www.conterra.com/dsbailey/audubon
	Coulmbia Audubon Society