Tuesday, February 21, 2006

Cooper's Hawk at the owl fly-out: Blakeman comments

Second-year Cooper's hawk - 2/18/05
Photo by Lincoln Karim

As I'm sure you know, the Cooper's hawk photo you posted on Thursday, February 19 (a fine image by Cal Vornberger) is an immature, a bird in its first year. The associated article refers to an adult Cooper's. Adult Cooper's have brilliant red eyes and a slate gray back. This specimen is in typical first-year plumage, with a yellow eye and brown vertical chest markings.
The Cooper's hawk in Lincoln's photo yesterday [see above] is a second-year bird. It has adult breast plumage, but the eyes are only yellow-orange. In the third and following years, the eyes will be fiery red.

Observers might also notice the thin legs and feet, used to snatch fleeing birds from the air. The Cooper's hawk, along with the smaller, closely related sharp-shinned hawk, feed almost exclusively on captured birds. You described such an attack perfectly.

Twenty-five years ago, Cooper's hawks were rather uncommon everywhere, and were virtually absent in urban and suburban areas. Because they fed on birds, they were reduced in number by the effects of DDT, which they accumulated from their avian prey. My favored red-tails, because they eat primarily mammals that didn't accumulate DDT, were never reduced in population.

Today, because DDT is no longer used in North America, Cooper's hawk populations have exploded, and this formerly uncommon and wary hawk is now quite frequently encountered, now even in cities. It has learned that cities and suburbs now have dense concentrations of easy-to-catch small birds so vulnerably feeding at bird feeders. There is now some indication that urban Cooper's hawk populations may even be reducing urban song bird numbers in the winter around bird feeders, which artificially concentrate they choice morsels for the hawks.
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It's nice to have Cooper's hawks back in profusion. But I get a lot of phone calls of consternation from people alarmed by watching these birds kill and consume songbirds at backyard feeders. As delicately as I can, I commend the feeder owners for feeding all of the birds, predator and prey alike.
Like the bald eagle and peregrine falcon, two other raptors formerly on the way out, Cooper's hawks are back -- in profusion. It's nice to have some conservation efforts work out.

John A. Blakeman