Posted by Chris Benesh (209.210.168.12) on May 16, 2000 at 02:36:02:
In Reply to: Re: Horrible hawks posted by Joe Morlan on May 04, 2000 at 15:27:51:
: : But to add to the levity and increase the species count for the bird on the left (now up to four choices), my first reaction was a juv. Broad-winged Hawk, and I still think that's a reasonable guess
: Broad-winged Hawk is a reasonable candidate for this bird, but what about juvenile Gray Hawk? This bird appears to show barred leg feathers and conspicuous white tips to the uppertail coverts. Would a Broad-winged Hawk show those marks?
While throwing out the usual caveats that hawks are always difficult and that single photos can most definitely be misleading, I think that the general consensus that the bird on the left is a juvenile Broad-winged Hawk is correct. There are several features that seem consistent with Broad-winged and atypical of Gray Hawk. As Rich Hoyer has suggested, the proportions seem wrong for Gray Hawk, the mystery hawk appears too short tailed. The mystery hawk appears small-billed to me as well, whereas I tend to think of juvenile Gray Hawks as having a larger bill (and in addition having a very bright yellowish cere, seemingly lacking on the mystery bird). I also think that Gray Hawks have a more attenuated shape, perhaps enhanced by a slightly longer-necked appearance than the mystery hawk.
The plumage features seem to me to suggest Broad-winged over Gray. The dark uppertail coverts with narrow white fringes seem typical of juvenile Broad-wingeds, where these feathers appear more extensively (or entirely) white in Gray Hawk. The face pattern matches closely with that of Broad-winged Hawk (with brown cheeks and a more blackish-brown malar stripe), and certainly a great majority of juv. Gray Hawks show rather extensive white cheeks (lacking on the mystery hawk) and white supercillia (but see Hoyer's comments regarding an individual Gray Hawk seen recently in Arizona). My own experience in southeast Arizona and the northern neotropics is that there seems to be rather little variation in face patterning on juvenile Gray Hawks, almost invariably seeming rather striking.
The prominent dark rear border to the remiges is correct for Broad-winged Hawk and atypical of juvenile Gray Hawks which have virtually no dark trailing edge to the underwing. Further, the apparent lack of barring on the basal portions of P6-10 is suggestive of juv. Broad-winged (these feathers are finely barred in Juvenile Gray Hawk).
Regarding the barring on the thigh feathers, I think that the pattern shown is more typical of many juv. Broad-winged (the barring on juv. Gray typically finer with thinner bars bunched more closely together).
All in all, this bird is a bit of a head-scratcher, but the details do seem to favor Broad-winged over Gray.
Most of the stuff mentioned above is covered quite well by Wheeler and Clark, 1995, Clark and Wheeler, 1987, and Howell and Webb, 1995.
Good birding,
Chris Benesh
Tucson, AZ
cbenesh@rtd.com