Cooper's Hawks are captured when they have young chicks by placing a captive Great Horned Owl surrounded by mist nets near the nest. When the adult Cooper's Hawks see the owl, they perceive it as a threat to their chicks and swoop down at it to chase it away. The hawks are caught by the mist nets before they do any harm to the owl.
Captured Cooper's Hawks are carefully removed from the mist net and hooded to keep them calm. Study personnel then band and measure each hawk. Once banded and measured, radio transmitters are attached.
The radio transmitters are attached using a backpack made of Teflon ribbon. The transmitters weigh about 6 grams for males and about 12 grams for females. The hawks preen the transmitter under their feathers until only the antenna is visible. Cooper's Hawks are generally hunting for food again shortly after the transmitter is attached.
The hawks are tracked using hand-held yagi antennas. Location information is recorded and used to plot home ranges and daily and seasonal movements. Tracking data are used to determine the kinds of habitat Cooper's Hawks are foraging in and where they capture their prey.