Habitat selection and fidelity by White-throated Sparrows (Zonotrichia albicollis): generalist species, specialist individuals?

Abstract

Individuals from habitat generalist species are often thought to be habitat generalist themselves, but this assumption should be examined in light of mounting evidence for native and phenotypic habitat preference. We experimentally tested whether the White-throated Sparrow ( Zonotrichia albicollis (Gmelin, 1789)) exhibits habitat preferences at the individual level. The White-throated Sparrow was a habitat generalist species in our study area, with high occupancy of clearcuts as well as mature forests. However, males in mature forests whose territories were clear-cut in the winter following their breeding season (n = 14), dispersed twice as far as males from uncut mature forests (n = 21). New territories selected by males after clearcuts contained significantly more mature forest than what remained in the territory that they abandoned, but not as much mature forest as was found in their former territory. Gain in uncut habitat after dispersal was positively correlated with dispersal distance. Clear-cut locations left vacant by dispersing males were colonized by new conspecifics. Our results suggest that individual sparrows use only a subset of their species’ wide range of habitats. We question the assumption that individuals from a generalist species are versatile and unlikely to be affected by habitat disturbance.