Bird diversity in relation to vegetation composition and structure at Black Rock Forest, Cornwall, New York
Black Rock Forest (BRF) in southeastern New York has a rich assemblage of bird taxa likely due to the variety in its landscape which features toposequences (e.g., hemlock ravines and pitch pine-scrub oak ridge tops) and chronosequences (different aged successional patches) within the deciduous forest matrix. We set out to answer the following questions:
What are the most abundant birds at BRF? Which birds are restricted in distribution? Which locations have the highest bird species richness? Is forest structural complexity more important than plant species richness in determining bird species richness? Can the information we gather be used to make bird conservation recommendations?
We surveyed bird populations at BRF using point-counts throughout May, June, and July of 2011 and 2012 in six habitats (100 minutes at each). The habitats were either structurally homogeneous or structurally heterogeneous. We conducted a vegetation survey with vertical and horizontal components at each habitat in order to calculate plant vertical density indices (as a measure of forest structural complexity) and plant species richness values.
The fifteen most abundant bird taxa during the breeding season are American robin, red-eyed vireo, American crow, veery, cedar waxwing, common yellowthroat, gray catbird, chipping sparrow, scarlet tanager, American goldfinch, great-crested flycatcher, American redstart, Baltimore oriole, yellow warbler, and eastern towhee.
Our data suggest that structurally complex habitats at BRF support a higher diversity of birds than simpler ones. And, that unique habitats within the forest matrix support species that are not found in other parts of the forest, for example, chestnut-sided and blue-winged warblers in early successional patches, Acadian flycatcher in hemlock ravines , and cerulean warbler in deciduous forest near streams.
Our bird conservation recommendation for BRF is to maintain the mosaic of different aged forest patches within the forest matrix, continue creating structural complexity during timber management and attempt hemlock ravine restoration in order to preserve Black Rock Forest’s rich bird diversity. Loss of hemlock habitat due to HWA and ecological succession in general could cause some losses of bird taxa.