Relationships Between Bird Communities and Forest Age, Structure, Species Composition and Fragmentation in the West Gulf Coastal Plain
Bird communities of the West Gulf Coastal Plain are strongly influenced by the stage of forest succession, species composition of understory and overstory vegetation, and forest structure. Alteration of plant communities through forest management and natural disturbances typically does not eliminate birds as a fauna1 group from the area affected, but will replace some species with others and cause changes in the abundance and species composition of bird communities. Upland, tire disclimax pine Savannah communities composed of primarily longleaf pine (Pinus palustris) provide mature pines for Red-cockaded Woodpeckers (Picoides borealis) and Brown-headed Nuthatches (Sitta pusilla) while simultaneously providing grassland ground cover for Bachman's Sparrows (Airnophila aestivalis) and Henslow's Sparrows (Ammodramus henslowii). On the mesic mid-slopes where there is an increasing presence of loblolly (Pinus taeda) and shortleaf (Pinus echinata) pine and hardwood species, Northern Cardinals (Cardinalis cardinalis) and White-eyed Vireos (Vireo griseus) find habitat in the understory and mid-story vegetation, whereas canopy hardwoods and pines provide habitat for Red-eyed Vireos (Vireo olivaceus) and Summer Tanagers (Piranga rubra).Transition into the wet bottomland hardwood forests increases the abundance of bird species associated with deciduous wetlands such as Prothonotary Warblers (Protonotaria citrea)and Swainson's Warblers (Limnothlypis swainsonii), whereas species associated with conifers and grassland savannahs are lost. Anthropogenic or natural disturbances that set back mature stages of forest succession can dramatically alter the species composition of bird communities. Depending on patch size, forest removal can initiate forest succession and provide habitat for early succession bird species such as Blue Grosbeaks (Guiraca caerulea), Field Sparrows (Spizella pusilla), Prairie Warblers (Dendroica discolor), Painted Buntings (Passerina ciris),Indigo Buntings (Passerina cyanea),and Yellow-breasted Chats (Icteria virens). Although current data are inconclusive, patch size, forest fragmentation, edge effect, and landscape use patterns appear to influence bird communities by affecting area-sensitive species. Of greatest concern are forest-interior bird species that appear to be area sensitive such as the Cerulean Warbler (Dendroica cerulea), Northern Panda (Parula americana),Louisiana Waterthrush (Seiurus motacilla), American Redstart (Setophaga ruticilla), and Worm-eating Warbler (Helmitheros vermivorus).