Wednesday, May 02, 2007

John Blakeman answers correspondents

Pale Male with just-captured American Kestrel
Photo by Scott Zevon 5/1/07

I wrote John Blakeman yesterday to tell him that Pale Male had been seen [and photographed] with an interesting new prey: an American Kestrel. John answered back::

About the kestrel. Come on. Red-tails can't catch kestrels, period. They are adroit little falcons that can easily avoid the hawk's pursuit.

That's what we used to believe about red-tails and the locally common red-winged blackbird. Against all understanding of the hunting abilities of red-tails, an intensive local study of red-tail nests discovered that virtually all of them had the red epaulet feathers of male red-winged black birds in the nests. Just how the hawks were capturing these fast blackbirds was a mystery.

Then, the secret was discovered, another revelation of the high intellectual abilities of the red-tail. At the time (early 1970s), there were still many fields of alfalfa being grown in northwest Ohio. The researcher, Mr. David Cornman, conducted an intensive multiyear study of 99 red-tail nests and territories in Ohio's Wood County (county seat, Bowling Green).

David noted the following. As a red-tail flew across an alfalfa field each day (red-tails are remarkably reliable and punctual in rotating through their hunting territories in the spring), he noted that male redwings would universally ascend from the hay field, where each male blackbird was the mate of 5 to 10 nesting female redwings. The male blackbirds would rise against the passing hawk in an attempt to lure it away from the nesting females so vulnerable in the alfalfa.

David watched this numerous times. On the hawk's first passage over the field, the defending male redwing would aggressively confront the hawk, but remain beyond it's reach. The hawk was mobbed all the way across the field.

The next day, on the hawk's hunting rounds, the same thing happened. The black bird mobbed the hawk, and the hawk flew un-hassled across the field.
But each day, the hawk's lack of response to the blackbird's mobbing behaviors further emboldened the pestering blackbird. Each day, the blackbird got ever closer to the hawk, which paid no apparent attention to the much smaller bird.

But finally, when the trap had been set, the blackbird mistakenly got too close to the hawk, even sometimes dropping down upon its back. As quick as a cat, the hawk flipped over and snatched the blackbird. An easy lunch for the hawk's eyasses.

There is no doubt that the hawk cleverly set this all up by so nonchalantly flying across the hay field each day, thereby eventually luring the male redwings into easy grasping range.

This, almost surely is how Pale Male got the kestrel. Smart hunter, our man.

John Blakeman

Karen Anne Kolling sent the above photo [without attribution] and asked:

Is the photo above showing moulting on the chest?

John Blakeman answers:

No, the feather gap on the chest is not a result of molting (or, moulting---I prefer the less-English Americanism).

It's merely a photographic artifact of the bird's preening. He was diligently stroking the feathers through his beak, he had merely fluffed out the ones on the flanks.

He may have molted some of the interior down feathers, along with some initial coverts (body-covering feathers), but it never leaves such a gap. The molt begins in earnest when the first primary and secondary wing feathers, along with tail feathers, are dropped. My red-tail just started her molt last week when I found a dropped red tail feather beneath her perch.

One more question, a very important one, from Bill Trankle of Indianapolis, Indiana:

Marie, I was wondering if Pale Male and Lola will remain bonded with three failures in a row. The drive to pass on genetic material is all-encompassing to these creatures, so is there a chance they'll go their separate ways in order to find a more successful mate (since I'm sure they aren't trying to reason out what happened like we are!)? I'd be interested to hear Herr Blakeman's take on this.

They may not have successfully raised any chicks this year, but our royal CP hawks are still an amazing inspiration to us all . . . .

Blakeman answers:

No one should have any concern that three consecutive years of nesting failure might cause a "divorce," that either Pale Male or Lola might direct attentions to any new mates.
Not a chance.
As long as both pair members are in good health and the prey and nest site continue to be available, the pair will remain. Many raptor textbooks note that like many waterfowl, raptors "mate for life." Actually, from banding and other field studies, we know that their fidelity is not as profound as formerly depicted, especially with the peregrines. The falcons do shift allegiances from time to time. But red-tails are much more reliable.
For old, established red-tails in ideal habitats, baring disease or injury, neither member of the pair is going to stray, either geographically nor matrimonially. The combination of several important factors will continue the pair's fidelity. First, is the settled nature of their occupation (and defense) of their prime territory. Central Park and 927 Fifth Ave is home, and a good one, indeed.
Secondly, prey abounds, probably more so than in any rural, wild territory (at least in the East or Midwest, where we don't have the ample summer populations of easily-captured ground squirrels found in the West in the first half of the summer).
Additionally, the nest site is preferred by the pair.
Lastly, they've produced and incubated eggs. That, alone, can keep the pair together in March through April.
No, the pair isn't presently feeding eysasses. But the little ones are not crucial to the maintenance of the pair bond. It's all of the above. No concern.
--John Blakeman