[Mark B Bartosik]

Harlan's and Krider's Red-tailed Hawk light juveniles - photos and field marks descriptions

Seems like I had some luck several weeks ago. Same day found two light morphs of two different Red-tailed Hawks races (different species to some people): Harlan's and Krider's.

I posted links to photos (somewhere else) I took assuming that they were both Krider's. I am very grateful to William (Bill) S. Clark who took his time and not only corrected one ID but also sent me detailed information about differences between these light juveniles.

Here is a link to detailed descriptions that he is using personally to compare field marks (not published yet - posted with his permission):
http://www.pbase.com/mbb/utc_february_25_2007

I think some birders can benefit from reading about those differences. Red-tailed Hawk ID can be often quite confusing.

Best,

Mark

[ceasar]

Hi Mark,
Interesting post and pictures! Perhaps the best identifying marks on a RTH are the Patagial bars on the leading edge of the underside of the wing. Of course you have to get a good look at the underside of the birds wings to make the determination; and they alone aren't enough to make the fine distinction among light morph Eastern's, Krider's and light morph Harlan's (which, according to Sibley), are only 1 percent of the Harlan population, most of which are blackish and white, lacking brown tones and the red tail. The underside of their wings are also very dark making the patagial bars hard to see. This would probably make the dark morphs harder to ID than the light morph, which also would lack a red tail; whereas the Krider's, as shown in the Sibley illustration has a slighty reddish tail. The light morph Harlan in the Sibley illustration and in the photos you posted also appear to have longer and thicker patagials than the Kriders. These juveniles are tougher to ID because of their similar tails.

Cordially,
Bob

[Mark B Bartosik]

Hi Bob,

You can also read this blog here:

http://www.dyesscreek.com/miscellane...s/kriders.html

Interesting discussion including info about juveniles. Note that, dependent on who you talk to, percentage of light Harlan's morph is estimated from below 1% to 10-15% of their entire population. Quite large difference. Maybe most of light Harlan's morphs are ID incorrectly.

Best,

Mark

[ceasar]

Mark,
That's a very educational Blog! After reading it, I'm kind of glad I live in the East instead of the Plains states! Over the years I've had enough trouble distinguishing between Sharpshins and Coopers to keep me busy!
Bob

[JANJ]

Also have a look at this:

http://www.birdforum.net/showthread....t=kriders+hawk

Also check latest discussion here:

http://www.virtualbirder.com/bmail/index.html

This one I caught eye on again and I would like to suggest a Swainson´s Hawk and also wonder about why it didn´t was suggested then!

JanJ

[ceasar]

Here are some more pictures of variant Red-tailed hawks.http://www.trmichels.com/HarlansRedtailPhotos.htm
Bob

[lbuscher]

Those are some nice examples of the red tail in the Juve stage Mark. Many thanks to Bill Clark for allowing them to be shown. I find red tails are like sparrows (a million of them)
The book by Brian K. Wheeler on the Raptors of eastern North America has some very nice plates of this species in it also.
Lou