Thursday, June 09, 2005

Why is Pale Male so pale?

Marie,

Diane D'Arcy wondered in a forwarded note to me if Pale Male's light-colored head plumage might be evidence of some Krider's hawk parentage, however distant that might be.

This is another good question, as those familiar with the several races or subspecies of the red-tailed hawk know that several recognized subspecies have plumage colorations rather different from typical eastern red-tails, Buteo jamaicensis borealis.

The Krider's red-tailed hawk, B. j. kriderii, is a red-tail form of the Plains States that is typically very light-colored, so much so that until recently it was regarded by many avian taxonomists as a separate species, not a red-tail. Krider's' tail feathers are typically almost white, and their heads are very light-colored, usually even more so than Pale Male. But for anyone who has seen a Krider's hawk's head, Pale Male is instantly suggested.
But I don't think that Pale Male is related or the progeny of any Krider's hawks, for several reasons. The most important one is that Krider's hawks tend to stay in the Plains States. I'm sure that an occasional Krider's has been blown somewhere into the East from time to time, but I'm not familiar with any Krider's breeding anywhere east of the Missouri or Mississippi Rivers. They may occasionally drift east, but they don't breed here. Their genes don't get inserted into eastern populations.

Secondly, if Pale Male had a Krider's as a close ancestor, his tail should be pale. It's not. It's as red as all eastern red-tails. Krider's are more known for their white tails than for blond head feathers. I just don't think Krider's hawk genes could have penetrated so far east through multiple generations. I think Pale Male's pale head plumage, also Pale Male, Jr's, is at-the-edge but normal.

Contrasting with both Pale Male's and Pale Male Jr.'s head is the gorgeous dark head and back of Charlotte, Jr's mate and mother of the two eyasses at the Trump Parc ledge nest.

Charlotte's coloration, at least on the head and back, approaches the typically dark forms of the Harlan's hawk, another red-tail subspecies thought to have been a separate species like the Krider's. The Harlan's hawk, B. j. harlani, resides in the eastern Rockies and High Plains, all the way to Alaska, wintering sometimes in Texas.

But for the same reasons, I don't think that Charlotte's dark colors descend from any Harlan's ancestors. Harlan's hawks are even generally further west than Krider's. Charlotte's plumage is just like Pale Male's, but at the other end of the genetic range of eastern red-tails.

Diane's intelligent ponderings on the subject are not out of place. Red-tails of all subspecies vary greatly in their plumage, and that has field identification significance. I've personally marveled at this at national and regional falconry meets where I've seen red-tails from other areas. After trapping and banding a hundred or so Eastern red-tails, and having trained a number, I have extended experiences with these birds. I've also had the opportunity to open the drawers of stuffed specimens at university ornithology labs, and I can always spot the Ohio birds before looking at the labels. The red-tails to the east into Pennsylvania and New York are very similar to Ohio birds, and often can't be separated.

But the red-tails of Indiana, just a hundred miles to the west, have a very different look -- still real red-tails, but the feathers of the head are darker and patterned differently. This Midwest form (generally unrecognized by the taxonomists) extends over into Illinois and Iowa. In Nebraska and rest of the Plains States the birds are very different. In the Far West, red-tails of the subspecies B. j. calurus are decidedly smaller than the giant birds we have out here in the East.

Pale Male, and Pale Male, Jr., are not typically-colored Eastern's. But I still think they are both pure Eastern birds, with no genetic incursions from the West. As it happens, my current Ohio falconry red-tail, Savanna II, is large like all Eastern red-tails. But she has a non-typical buff or brown chest that's almost exactly like the Western B. j. calurus birds. A taxonomist seeing my stuffed bird in a museum drawer would surely think it to be from the West, without first looking at the label (or noting it's typical large eastern size). Red-tails frequently vary greatly in color, in all races and populations. Fortunately, these variations allow us to identify some of the individuals, Pale Male for one.

Sincerely,

John A. Blakeman