Habitat utilization by cardinals in central and peripheral breeding populations

Abstract

Color-banded male cardinals, Richmondena cardinalis, were observed in a dense population in Tennessee and in a sparse one in Ontario. Continuous observations were made, using a tape recorder, of a bird's behavior relative to the cover-forms comprising its habitat. Frequencies of cover-forms occurring in home ranges were obtained by sampling, and a measure of a cardinal's discrimination among them was obtained using an extension of Shannon's formula. Peripheral birds showed higher discrimination in foraging sites than central birds. Cardinals in both regions showed strong discrimination among habitat features for singing and foraging. In the peripheral region, cardinals showed strong preference for non-coniferous song perches, and either actively avoided coniferous foliage or preferred other types for foraging. All nests were in coniferous foliage. Discrimination between foliage types was not so marked in the central region, where conifers occurred less frequently. Throughout its range, the cardinal requires suitable woody cover for nesting. There is evidence that males prefer high song perches, but height seems less important than conspicuousness.