Earth Notes
4:44 pm
Wed April 6, 2011

Earth Notes - Arizona's Black Hawks

Flagstaff, AZ – Each spring, common black hawks soar into Arizona skies from their wintering grounds in Mexico. These large, coal-black raptors, with distinctive white-banded tails, will spend six months here breeding, nesting, and raising young.

In courtship, black hawks put on spectacular aerial displays. They soar, twirl, and exchange sticks as they dive and issue their shrill call. Once mated, they construct their nests, almost always in the tallest cottonwood or sycamore alongside flowing water.

One of the best places to look for these hawks is along Fossil, Beaver, Oak, and Sycamore creeks, tree-lined tributaries of the Verde River. That's where Northern Arizona University ecologist Matt Johnson and students have been putting their spotting scopes for the last couple of years. Johnson and colleagues want to get baseline population numbers for black hawks.

On Fossil Creek, they've seen these birds of prey feeding primarily on native fish that have come back since a dam was removed. On other drainages, the birds are selecting crayfish.

Though plentiful, this introduced crustacean takes more energy to eat. The parent birds remove the crayfish shell before feeding the shreds of meat to their young. Fish, lizards, frogs, or snakes, on the other hand, are all consumed whole.

Black hawks appear to be adaptable when it comes to food. But there's one thing they must have: riparian areas for nesting. That's rare habitat these days. For black hawks, says Johnson, "It's all about the trees, the water, and what they have to feed their young."

-Rose Houk