Establishing and Defending Birds' Territories - Page 2

A band of raucous crows flies silhouetted against a cold winter sky above a cornfield in eastern Pennsylvania; Red-tailed Hawks battle over a territorial boundary in Ohio; hundreds of Barn Swallows perch upon a wire, each delicately positioned just far enough away from its neighbor to be out of reach; a Gray Catbird in the midst of a New York forest stakes out a private breeding territory with its constant melodious song.

Spacing behaviors govern the distances between individual birds. All birds indulge in some forms of spacing behavior. While some birds flock and others defend territories, many birds switch between different styles, in different circumstances. A male Red-winged Blackbird does not tolerate another male on its nesting territory during the breeding season. But Sanderlings may suddenly abandon their territories and form a flock if a Peregrine Falcon flies overhead searching for prey. Often in the very same site you can observe individuals of the same species behaving in different ways, some being territorial, others not. These individual variations are especially prevalent on territories away from the breeding ground, as in Sanderlings on winter beaches.