The Effect of Countershading with Respect to Solar Orientation on Perching Behavior in Birds: An Interspecies Comparison

The Effect of Countershading with Respect to Solar Orientation on Perching Behavior in Birds: An Interspecies Comparison

Alvin Sherman Library 1054

Many species of birds display a countershaded (dark dorsum and light ventrum) pattern of coloration, while other species display a more uniform pattern of coloration. A countershaded pattern of coloration would make a bird more conspicuous when facing toward the sun and less conspicuous when facing away from the sun. Therefore, in birds, countershading may serve an adaptive function, making them less conspicuous to predators by orienting away from the sun and more conspicuous to mates at the appropriate times. It was hypothesized that countershaded birds would have a tendency to face either toward or away from the sun and that the orientation of non-countershaded species would be independent of the sun. The solar orientation tendencies of 20 common North American species of birds have been reported previously; here we present data from four additional species. Solar orientation is significantly non-random in eight species (primarily countershaded birds facing the sun). However, aside from orientation behavior, there is no clear common thread associating these species with each other.