A STUDY OF ECOLOGICAL RELATIONSHIPS WITHIN AN AVIAN GROUND FORAGING GUILD

Ecological relationships among Wood Thrush, Veery and Ovenbird were studied in 1979, 1981 and 1982. Vegetation structure, vegetation taxonomic composition and leaf litter characteristics differed little among the territories of the three study species. Previous researchers using more diverse study sites found distinct differences in these characteristics between Veery and Wood Thrush territories. I conclude that studies encompassing large geographic regions containing heterogeneous habitats probably do not accurately indicate more local ecological relationships. The wide range of habitat characteristics contained in "large scale" studies are not usually available to the inhabitants of smaller and more homogeneous habitats. Habitat partitioning on the basis of vegetation structure may not be as common in syntopic, localized populations as is often assumed.;The three study species appeared to select territory sites by directly assessing prey density. Wood Thrush, the largest of the three, has been considered dominant over Veery. I therefore predicted that Wood Thrush territories should contain a greater density of prey items than either Veery or Ovenbird territories. This prediction held true in 1982. I also predicted that Wood Thrushes should create territories around artificially stocked feeding trays, and thereby exclude Ovenbird and Veery territories from these areas. This experiment failed because Wood Thrushes seldom fed from the feeding trays. However, based on the measurements of natural food resources, I conclude that food assessment plays a role in territory site selection by the Wood Thrush and probably plays a role in territory site selection by Ovenbirds and Veeries as well.;I found little overlap among territories of the study species, and I observed interspecific agonistic behaviors between vocalizing Wood Thrushes and Veeries in both natural and experimental situations. Researchers using study sites containing more habitat types found extensive overlap between Wood Thrush and Veery territories and did not observe interspecific agonism between vocalizing Wood Thrushes and Veeries. I conclude that Wood Thrush and Veery tend toward interspecific antagonism and interspecific territoriality in habitats where means of minimizing competition through differences in preferred habitat are scarce.