Thanks Shirley for seeking informed comment from Stephen Debus - very
helpful (as one would expect). It does however raise the question (alluded
to by Stephen in his response) of whether there really are "pale-plumaged"
individuals, implying that there are also darker-plumaged individuals of
similar age (rather than them being just fully mature individuals which are
intrinsically pale by virtue of their age). Can anyone comment on this?
Does anyone know how I/we might access the article by Paul McDonald referred
to by Stephen? (I have been aware of this research and its findings for some
years but have not ever read the article.)
Thanks. Richard
From: Stephen Debus
To: Shirley Cook
Cc: Christopher Watson
Sent: Wednesday, October 05, 2011 2:19 PM
Subject: Re: Fw: [Birding-Aus] Brown Falcons with yellow cere and bare
facial parts
Hi Shirley & Chris,
Yellow cere is a character of fully adult males, and seems to be
particularly prevalent in pale-plumaged individuals (e.g. remote areas like
the Centre), perhaps where the falcons live long enough to develop the 'old
male' characters of yellow cere and eye-ring, and white breast. See:
McDonald PG (2003) Variable plumage and bare part colouration in the Brown
Falcon, Falco berigora: The influence of age and sex. Emu 103, 21-28.
Cheers,
Steve
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