Flock Switching in Chickadees: Why Be a Winter Floater?

Publisher Website
Google Scholar
Abstract
Winter chickadee flocks contain 2 sorts of birds: those that always stay in a single flock (flock regulars), and those that do not. Most of the birds that move from flock to flock are young low-ranked birds that lack pair bonds. These flock switchers are the true winter floaters in the population. When a high-ranked regular disappears during the winter, it is rapidly replaced not by the flock''s next highest regular, but by the dominant local switcher of the appropriate sex. A young bird entering the flock system as it forms in early fall must choose between 2 strategies: to be a regulr in 1 flock or to be a flock switcher. When flocks form, high-ranked regular slots will probably be filled first, followed by top-ranked switcher positions; only later will the lowest regular slots be filled. Calculations suggest that the present mixed strategy of the study population, with .apprx. 20% switchers and 80% regulars, is evolutionarily stable. The many similarities between chickadee flock switchers and underworld rufous-collared sparrows [Zonotrichia capensis] suggest that complex organization among floaters may be widespread.

This publication has 3 references indexed in Scilit: