Hello Tweeters,

Just wanted to chime in I post I saw that incorrectly corrects someones use of the term "brown phase" gyrfalcon. Though unusual, there are in fact adult gyrfalcons with brown plumage that superficially resemble juveniles. See photo of an incubating bird linked below. It is also incorrect to say that there are "three "color morphs or "phases" of Gyrfalcons: white, gray, and dark." Gyrfalcons show a great diversity of color and pattern and range from almost pure white to uniform brownish-black. Intermediate plumages form a continuous gradation between the two extremes with no distinct breaks or divisions. The terms morph and phase are used correctly when they apply to birds with distinct, identifiable color patterns - this does not apply to Gyrfalcon.

Take a look at the brown Gyrfalcon incubating here:

http://gerritvyn.photoshelter.com/search?I_DSC=gyrfalcon&I_DSC_AND=t&_ACT=search


Best Regards,

Gerrit




The . Although not uniformly agreed upon (see Potapov and Sale 2005), use of terms that describe distinct, identifiable color patterns such as ?morph? or ?polymorphism? for Gyrfalcons is incorrect (Cade et al. 1998, Flann 2003, Cade 2006) and misleading.

Message: 9
Date: Sat, 13 Nov 2010 22:40:34 -0800
From: "Wayne Weber" <contopus at telus.net>
Subject: [Tweeters] Brown phase Gyrfalcon?
To: "TWEETERS" <tweeters at u.washington.edu>
Message-ID: <01ce01cb83c6$d787b6f0$869724d0$ at net>
Content-Type: text/plain; charset="us-ascii"

Tweeters,



A recent message made reference to a "brown phase" GYRFALCON. For the
record, there is no such animal. The birds sometimes referred to as "brown
phase" are actually immatures of the gray morph or gray phase. Their plumage
is much browner than that of adults, and they are usually heavily streaked
on the underparts-- both of these features making them pretty easy to tell
from adults.



There are three color morphs or "phases" of Gyrfalcons: white, gray, and
dark (blackish), as well as, undoubtedly, a few individuals that are
intermediate. In Washington and elsewhere along the Pacific coast, virtually
100% of the birds we see are gray-phase. There is no brown phase-they are
just the immatures of the gray phase.



Wayne C. Weber

Delta, BC

contopus at telus.net

------------------------------
Gerrit Vyn
Multimedia Producer
Cornell Lab of Ornithology
(607)342-8631

Interpreting and conserving the earth's biological diversity through research, education, and citizen science focused on birds.