Accipiter Field Marks

Ronald J. Fleming ronaldj..fleming at sympatico.ca
Fri Feb 15 11:09:24 EST 2002


For the information of ONTbirds subscribers who are interested:

I received no less than a dozen replies to my query regarding extensive
white flanks or undertail coverts on Northern Goshawk and other
accipiters earlier this week.  Replies came from as far away as
Minnesota and Alberta, so this is indeed a website that is checked out
by many birders!

The general consensus was that this field mark is most often seen in
Cooper's Hawk, but that all three accipiters can display extensive
"fluffy" white flanks.  The most interesting reply I received stated
that this a field mark specific to male birds in courtship display,
which would be consistent with my observation of the male Goshawk this
week which showed this very conspicuous white feathering while in the
company of a much larger female that did not display show the "big white
flanks".

Although I have observed accipiters often during migration (i.e. at
Beamer Point in Grimsby), it is only during observations of birds on
their home territory (and, of course, at much lower heights than those
typical of migratory fly-bys) that this field mark has become
noticeable.  As James Holdsworth mentioned in his message to me,
accipiters are probably observed least often when they are on territory
in the forest displaying this field mark for courtship display,
therefore it may well be a specifically seasonal characteristic.

Many thanks to those of you who contacted me about this interesting
point of observation.
I made it a point to reply to all "contributors", but please note, John
Stirrat and Fred Urie, that my attempts to contact you bounced back.

Ron Fleming, Newmarket


"Ronald J. Fleming" <ronaldj..fleming at sympatico.ca>



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