Excerpted from Living on the Wind: Across the Hemisphere with Migratory Birds

Shortly after daybreak, the first black silhouettes of circling hawks rise above the trees, gliding off toward the flat, bare earth of the newly plowed fields. For reasons that remain unclear, Swainson's hawks spend the first hours of daylight simply sitting on the ground, sometimes feeding on grasshoppers, but mostly just standing around. Perhaps they are waiting for the sun to warm the air and produce powerful thermals, so they can depart together to look for concentrations of grasshoppers. Maybe they just aren't morning people.

Its feet harmlessly ensnared in fishing line
nooses, a Swainson's hawk is captured
for toxicology testing at Chanilao.

Goldstein refills his mug of coffee, flicks on a walkie-talkie-sized radio receiver, and begins to punch in a series of frequency numbers while waving the large, H-shaped antenna over his head. Immediately, the air is filled with electronic chirps."Okay, we've got birds in 6425, 6450, and 6475 in the south field, and  " he hits another sequence of frequencies  "6325 and 6375 in the east pasture." He grabs a couple of old T-shirts from a heap in the workroom and jumps in his pickup truck; Candi and I pile in excitedly as he skids around in the dirt driveway toward the field, sloshing coffee over everything. We vault the fence, flushing hundreds of hawks from the ground as we pound a quarter-mile across the deep, loose soil, my breath coming in ragged rasps by the time I reach one of the hawks.

An aguilucho is snagged by two toes, sitting on its rump with its wings thrown wide and its free foot ready to lash out  trying to make itself look bigger and more threatening as I trot toward it. The flight feathers are silvery gray, marked with darker bars, while the wing linings and breast are creamy white. The head and chest are brown, with a white throat like a spotlight, and eyes the color of strong tea. I gently lower a fold of the T-shirt over its head, and swiftly grab its legs while it can't see. Once untangled, I wrap the bird securely in the cloth, then one-handedly replace the trap, fixing the matted and tangled nooses as best I can. I hurry, because still more hawks are gliding out of the trees, passing just over my head for the far end of the field.