[obol] Re: Pale Red-tail in CO
- From: "Richard W. Musser" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "mussermcevoy@xxxxxxxxx" for DMARC)
- To: "gismiller@xxxxxxxxx" <gismiller@xxxxxxxxx>
- Date: Sun, 1 Mar 2015 22:29:56 +0000 (UTC)
Hi Craig, Your question as to why this bird should be called a Krider's RT
or a Harlans RT, pretty much makes my point.
As far as I can tell, Kirder's RTs never wander so far west, but both
occur together during migration on our southern plains. It is my guess that
when these two subspecies migrate during Spring migration, the harlans take a
more westerly route, while the Kriders move north-----so their nesting grounds
would be separate. I stress that this is a guess. Those guys that have studied
these birds a lot more than I have, readily admit that attributing an
individual to a certain RT subspecies----is sometimes not possible. I question
the value of doing this on migration (which RT subspecies is it?), but other
measurements (other than visual look-a-likes) are invasive, expensive, and time
consuming.
I think it's okay for us to struggle with all bird science, and
particularly subspecies questions, because it's birders with their cameras, out
in the field, that are documenting the individuals that ultimately moves are
science forward. All of you that take photos and post them, will, in the end,
help clarify birds in general---we just don't know which of our contributions
will be important. We really are, when taken as a whole, "citizen scientists."
I know I haven't answered your question very well, but have rather provided
a partial explanation. Anyway, Best regards, Dick Musser (4 mi. NW of Vale)
On Sunday, March 1, 2015 11:59 AM, Craig Miller <gismiller@xxxxxxxxx>
wrote:
Hi Richard,
All your points are well-taken, and I pretty much agree with everything you
say. However, the what I was wondering (and seems to be missed, or am I missing
something?) is if we do take the edgy step of conjecturing, why doesn't this
bird fit Krider's better than Harlan's?
Craig
On Sun, Mar 1, 2015 at 9:39 AM, Richard W. Musser <mussermcevoy@xxxxxxxxx>
wrote:
Hi Craig, I think we can call this a red-tailed hawk, but assigning a
subspecies designation to migratory RTs, is simply a guess (we have no way to
prove this one way or another). I know birders that are looking for photos of
various odd appearing RTs with assigned subspecies---and then comparing the
pictures. But my point is: There isn't a way (at present) to clearly define
what a Harlans Rt really is. When we define a bird species (or subspecies), it
seems to me that we are looking for aspects that are the same; but harlan's
tails are all different, as is much of their other feathering. So exactly where
do these harlans originate? When I think back to the article with all of the
oddly appearing, "Harlans tails"----I realized that with all of my, "raptor
looking" experience in Alaska for over 25 years, I was never able to locate a
nesting pair of harlan's red-tails. Some of these raptor research scientists
have documented these "odd tailed harlans" moving into Alaska on spring
migration (and I too have seen this at the same location)----but as far as I
know, the exact region of their nesting isn't completely known.
Many of our raptor species are much more narrowly defined---our Harris's
hawk, prairie falcon, NA goshawk, and Ferruginous Hawk (for example) show
little variation----but our red-tailed hawks, Swainson's hawks, and roughlegged
hawks are buteos that are still very confused. It may be that Rts are composed
of two or three different species that can interbreed----but have only been
doing this for a relatively short time period. Humans have altered the
landscape of North America from the time that seeds were brought here by
Columbus, and later when we cut down much of the forest east of the
Mississippi---and doing this may have opened pockets of isolated buteo species,
or altered food supplies. Red-tailed hawks also show great variation in size
and weight, and I clearly recall trapping a "butterball fat" adult male Rt that
weighed only 28 oz., and later that week, at the same location, capturing a
large female at 66 oz. Both of these individuals looked like "classic" adult
red-tailed hawks----but with such a large disparity in size, it is very
unlikely that they would pursue the same sort of quarry. So how alike are they?
Do these little males breed with these huge females? An avenue that is open
to explore the Harlans Rt----is to obtain photos of adults with young---and
then to moult a few of those youngsters---to see how they appear. It may be
possible that these photos already exist from falconers taking this raptor
within Alaska and Canada---but I have no firsthand knowledge of this, and only
suggest it as a method.
I commend all of those that are trying to figure out this confusion, but
it may take DNA analysis for scientists to untangle Bueto Jamaicensis. Best
regards, Dick Musser (4 mi. NW of Vale)
On Saturday, February 28, 2015 10:59 PM, Craig Miller
<gismiller@xxxxxxxxx> wrote:
Why isn't this a Krider's?
Craig Miller
On Sat, Feb 28, 2015 at 3:31 PM, Tom Crabtree <tc@xxxxxxxxxx> wrote:
Chuck,
It would be nice to have better shots of the tail, but it is either a light
phase Harlan's Hawk or a leucistic Red-tail. It looks an awful lot like a
white-headed, light-phase Harlan's in an article by Brian Sullivan (who I hope
will comment on this) and Jerry Liguori in the March 2010 Birding.
http://www.aba.org/birding/v42n2p30.pdf This is whiter than the Harlan's I
have seen but I think it still in in the range of that race.
Tom Crabtree, Bend
-----Original Message-----
From: obol-bounce@xxxxxxxxxxxxx [mailto:obol-bounce@xxxxxxxxxxxxx] On Behalf Of
Charles Gates
Sent: Saturday, February 28, 2015 12:19 PM
To: obol
Subject: [obol] Pale Red-tail in CO
I'm going to post some links to some Red-tail photos I received. Please feel
free to comment. The photographer was Debbie Goodman and the location is just
NW of Redmond, Oregon. The date was 2/23/15.
https://www.flickr.com/photos/124095129@N06/16673978732
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