Monday, October 15, 2007

Lola catches a kestrel

photo courtesy of 10/13/07
[click on photo to enlarge]

Yesterday, frequent correspondent Sally Seyal wrote in with a question for John Blakeman:

On Lincoln's site today [10/14/07] he has a photo of Lola with a kestrel in her talons. I would be interested to know what Blakeman thinks about this. I know they catch birds with regularity but a Kestrel seems a much more difficult prey to snag than a pigeon, perhaps I am not giving pigeons enough credit! Perhaps she used the around the corner stalking technique!
Today John Blakeman replied:


The photo of the kestrel in the clutches of the big red-tailed hawk on was, at the least, unexpected. Red-tails don't frequently capture other raptors, especially ones as aerially adroit as the kestrel.

How might this have occurred? Red-tails are intellectual hunters, pre-calculating the probabilities and possibilities of their hunts. If it were spring, I would imagine something along the lines of the following, a scenario we've observed here in Ohio.

We've noted that many Ohio red-tail nests in May have the red epaulet feathers of consumed male redwing blackbirds, which are very similar in size to kestrels. It seemed impossible for a big, lumbering red-tail to repeatedly catch fast-flying little blackbirds. But how this was done is remarkable, and revelatory of the intellect of the red-tail.

Each day a red-tail would fly over a hay field that had a number of redwing blackbird nests, prompting a resident male redwing to ascend into the air and attempt to drive off the hawk who was spying the blackbird's females on the nests below. On the hawk's first pass over the field, the redwing stayed some distance away from the hawk, but nonetheless boldly escorted it out of the field's airspace.

The next day, the hawk resumed its flyover, and the defending male redwing became once again incensed at the hawk's passage. It flew another, albeit closer, harassing flight.
By the third or fourth day, the redwing become hazardously emboldened, and it got very close to the unresponsive hawk, thinking that it was pushing the hawk away. But hawk had this all figured out. It had lured the blackbird ever closer on each daily flyover, and finally just snatched the blackbird out of the sky when it got too close.

The hawk deliberately lured the blackbird into its talon's range by the daily flyovers. Pretty clever, these red-tails. With thousands of acres of hay fields, with thousands of spring-nesting redwing blackbirds, this was an easy and productive method to pluck defending male blackbirds out of the air.

Perhaps Lola's kestrel made the same mistake. Perhaps once each day the hawk would fly close to the falcon's perch, and it flew closer to the hawk each day. By failing to attack on early flights, the red-tail can lead the falcon or blackbird to think that it simply won't attack, that it will simply fly on past. Then, as the smaller bird got too close, the big hawk flips over and instantly plucks the smaller bird from the air.

Of course, that scenario works pretty well in spring time, when territories and young are being defended. In early autumn, however, this is not likely to be the case. Frankly, I can't explain how the kestrel let itself be captured by the red-tail. Most likely, it was incapacitated or injured in some way and became a vulnerable and visible target for the hawk.

Regrettably, I killed a kestrel one time. I was driving down a rural road at less than 50 mph, and noticed a kestrel perched on a low utility wire up ahead. It was flipping its tail back and forth, in typical kestrel fashion. But just as I began to pass by the perched falcon, it inexplicably dropped off into the air and flew right into the path of my windshield. The bird bounced over the car, and in the rear view mirror I saw the hapless falcon roll to a thoroughly dead stop in the middle of the road.

I stopped and went back to see if the falcon could be resuscitated. It had broken its neck and was dead. I tossed its carcass off into some roadside vegetation and quietly pondered the briefest lamentation.

The prey list of Central Park red-tails continues to expand. This is one I would never have expected. In this particular case, I think it was more a defect of the kestrel than the hunting prowess of the hawk that explains the sobering observation.

--John Blakeman