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Re: article in Birding
- To: carolinabirds@duke.edu
- Subject: Re: article in Birding
- From: "Donna S. Bailey" <dsbailey@conterra.com>
- Date: Wed, 30 Aug 2000 09:05:04 -0400
- Sender: carolinabirds-owner@acpub.duke.edu
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