Bird/Habitat Relationships Along a Successional Gradient in the Maryland Coastal Plain

Abstract

Bird occurrences were studied over four breeding seasons in a series of habitats representing a transition from recently abandoned pasture to mature hard- wood forest. Principal component analysis (PCA) of vegetation data gathered at 59 mist-net sites yielded a habitat ordination reflecting the successional gradient. The capture rates of most breeding bird species in mist nets were monotonic functions of the vegetation scores of mist-net sites on the dominant PCA axis. Species with the highest maximum abundance activity in early successional habitats (e.g., yellow- breasted chat, white-eyed vireo) tended to make less use of the entire successional gradient than did species primarily associated with mature forest. Total mist-net cap- ture rates increased from early successional habitat to mature forest. After adjust- ment by rarefaction to compensate for differences in sample size, bird species richness was highest in forest of intermediate age. Several measures of dominance increased with succession due to the very high abundance of a few species, combined with the occurrences of many rare species in more mature habitats. Areas of high capture rates for particular species did not correspond with the locations of singing males of those species, suggesting that habitat suitable for singing perches may differ substan- tially from habitat used for feeding and other activities.