Text and Images as submitted by Bill Clark

I believe that the correct answer to ABA on-line quiz 22 found at: www.americanbirding.org/photoquiz/quizans22.html

is: A hybrid adult between Harlan's Hawk and Rough-legged Hawk, and not:
"This dark (brown) morph Rough-legged Hawk was photographed in Weld County Colorado, in February 2003 by the author." [Chris Wood.]

Go to [http://www.jimzipp.com/Hawk-ID.html] to see photos of the quiz hawk that have been lightened up in Photoshop, and my photos of both dark adult RLHA and banded tails of adult Harlan’s Hawks.
The following field marks of the quiz hawk support a hybrid:
1. The black feathering on the tarsi doesn’t extend onto the base of the toes, as it would on a dark RLHA. See photos aba_q22 & aba_22b.
2. Its feet are too large for RLHA. See aba_22b.
3. Its wingtips don't appear to be beyond the tail tip on the perched hawk, as they would on an adult RLHA. See aba_q22.
4. Its underwing coverts appear to be too mottled and barred, especially white on the greater primary coverts; these are usually uniformly dark on adult RLHA’s. See aba_q22c.

5. And the number and width of the dark tail bands are incorrect for RLHA. There are five or fewer as well as wider bands on adult dark RLHA’s. See aba-q22b.

One can clearly see on the quiz hawk that the tarsi are sparsely feathered and the black doesn't extend down to the bases of the toes, as it does on several of the RLHA photos.

My photos of adult RLHA’s show that the wingtips extend beyond the tail tip of a perched adult (see RLAdDarkPerch1), underwing coverts lack mottling (RLDarkInhand1, RLAdDarkFly1, RLadDark1), undertails show fewer and wider dark bands (RLDarkSpec1, RLDarkTail1, AdultDarkFM3), and tarsi are feathered to toes (RLAdDarkLeg1).
See also Figures 3 and 4 in Clark et al. (2005) and the discussion of a similar adult hybrid RLHA x Harlan’s. Also look at the undertails of dark Rough-legs and dark banded tail Harlan’s in Wheeler & Clark (1995), RL06 and RT12, and in Wheeler (2003) plate 426 and plates 339 & 343.
Large feet, shorter wingtips, mottled underwing coverts, and multiple tail bands (See composite jpeg of four adult Harlan’s Hawk banded tails) are traits of dark-morph adult Harlan's Hawk. The partially feathered tarsi argue for a hybrid between these two taxa. Often hybrids can appear more like one parent species and less like the other but show traits of both.

Photos of two other possible hybrids are posted on this web site site. One jpeg labeled (RLAdFDarkAKFly2) appears to be a hybrid between a light Harlan’s Hawk and dark Rough-legged Hawk. Note that this hawk has barred undertail coverts, a trait of Harlan’s but not Rough-leg, and the breast and underwing coverts are much paler and mottled, unlike those of dark-morph adult Rough-legs. The specimen of a hawk in the other jpeg (HybridSpecCNM) looks like a typical juvenile dark-morph Harlan’s, but it has feathered tarsi. Chris Witt is doing a DNA analyses for identity of this hawk, and we will publish our results.

I welcome any and all comments on the above.

Bill Clark: raptours@earthlink.net

Literature cited.

Clark, W. S., M. Reid, and B. K. Wheeler. 2005. Four cases of hybridization in North American Buteos.  Birding 37:256-263.

Wheeler, B.K. 2003. Raptors of Eastern North America. Princeton University Press, Princeton.

Wheeler, B. K., and W. S. Clark. 1995. A Photographic Guide to North American Raptors. Academic Press, London.

©Chris Wood 2008______aba_q22_jan2005

©Chris Wood 2008______aba_q22b_jan2005

©Chris Wood 2008______aba_q22c_jan2005

HarAd69Lt

HarAdBandedTails

HybridSpecCNM

RLadDark1

RLAdDarkFly1

RLAdDarkFM3

RLAdDarkLeg1

RLAdDarkPerch1

RLAdDarkSpec1

RLAdDkTail1

RLAdFDarkInhand1

RLAdFDkAKFly2