The wooden nesting box was attached to a girder about six feet below the road bed.

WSJ: 4 falcon chicks living on NY-NJ bridge are banded

Their mother's squawks competed with the din of morning-rush bridge traffic as Chris Nadareski, a wildlife biologist with the New York City Department of Environmental Protection, gently lifted the fluffy chicks out of their nesting box and used pliers to fasten metal bands around their legs.

WSJ: 4 falcon chicks living on NY-NJ bridge are banded

In the third phase of the experiment a male was placed in the cage over the box where the female had once been, and the amount of aggression towards this male from the nesting male was measured.

ECONOMIST: Animal personalities