[obol] Re: Pale Red-tail in CO
- From: "Tom Crabtree" <tc@xxxxxxxxxx>
- To: <gismiller@xxxxxxxxx>, "'Richard W. Musser'" <mussermcevoy@xxxxxxxxx>
- Date: Sun, 1 Mar 2015 15:48:03 -0800
Craig & Richard,
Hopefully Brian will reply to this as he is one of the experts in the field. I
would say it isn’t Krider’s because of these factors:
1. Range, as mentioned by Richard, Krider’s don’t occur this far west
(weakest of the arguments, to be sure); Liguori & Sullivan’s article in the
March 2010 Birding says there are no documented records west of the Rockies.
2. The underparts are too white; Krider’s should show a lot of buffy
coloration
3. The tail appears to be too red. Krider’s are mostly white.
4. Adult male Krider’s (as this appears to be in age) show a dark malar
region. This bird’s is white with a few dusky streaks
5. Krider’s should show a well-defined sub-terminal band on the tail.
One other point is that Krider’s taxonomic status is unclear. Some consider it
a subspecies while others believe it is a pale extreme of the borealis
subspecies.
Tom Crabtree
From: obol-bounce@xxxxxxxxxxxxx [mailto:obol-bounce@xxxxxxxxxxxxx] On Behalf Of
Craig Miller
Sent: Sunday, March 01, 2015 10:59 AM
To: Richard W. Musser
Cc: tom crabtree; Charles Gates; obol; Brian Sullivan
Subject: [obol] Re: Pale Red-tail in CO
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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