Introduction

The Black-capped Chickadee is one of the most familiar and widespread birds in North America. It ranges from coast to coast, including much of Canada and about the northern two thirds of the United States. Despite its vast range, this species is remarkably homogeneous in its genetic make-up. Its closest relative is probably not the superficially similar Carolina Chickadee (Poecile carolinensis) but rather the Mountain Chickadee (P. gambeli).

As Black-capped Chickadees are resident throughout their range, northern populations must withstand winters of short days and very cold temperatures. Under such conditions, they can lower their body temperature at night and enter regulated hypothermia, saving significant amounts of energy. In addition, they store food and have exceptional spatial memory to relocate it, even a month later.

Chickadees are seen most readily during winter when nonbreeding flocks visit feeders. Winter populations may contain both regular flock members, which typically spend the whole winter in a single flock, and also winter floaters—birds whose home range includes that of 3 to 5 flocks, with an established position in the dominance hierarchy of each one. Under suitable conditions, a high-ranked bird that disappears from a flock may be replaced by a floater, which assumes the rank, and pairs with the mate of the vanished bird. Such replacements evidently occur only where floater density is high.

Readers wishing details on all aspects of the biology and ecology of Black-capped Chickadees should consult Smith (1991), a monograph on the species.