Ecology of Small Insectivorous Birds in a Bottomland Hardwood Forest.

Changes in species composition and abundance, habitat use patterns and foraging behavior of 19 bird species in a bottomland hardwood forest in Louisiana were studied during the 1984-1989 breeding seasons. Species that used only one macrohabitat included the Yellow-throated Warbler along oxbow lake margins and the American Redstart, Swainson\u27s Warbler, and Hooded Warbler in non-flooded oak-gum-elm forest. The Northern Parula and Kentucky Warbler used 2 macrohabitats--non-flooded forest and oxbow lake margins. Thirteen species used 3 macrohabitats (non-flooded forest, seasonally flooded forest, and oxbow lake margins). I distinguished 6 groups of species that used similar microhabitat and foraging behavior. Ecological partitioning occurred primarily by (1) foraging height and height-related characters, (2) foraging locations within the forest canopy, and (3) differential use of foraging substrates and foraging maneuvers. Vegetation structure and height may be important in determining the abundance and combination of insectivorous birds existing at Tensas. Implications for management and conservation are discussed. To conserve migrant insectivorous birds, we must know the ranges, habitats, and patterns of habitat use. I selected a representative species, the Hooded Warbler, and compared habitat use and foraging ecology at a breeding and wintering site. Hooded Warbler winter distribution is concentrated along the Gulf of Mexico coast and Caribbean slope from southcentral Veracruz to Honduras. Winter habitat is typically undergrowth of humid forest; second-growth habitats are also important. At Tensas, hoodeds preferred dense foliage in the shrub and subcanopy layers, and captured prey primarily from the lower surfaces of leaves. At Los Tuxtlas, they were more generalized and captured prey from air and leaves, used a variety of other substrates, and foraged in open portions of the lower levels of the forest. Macro- and microhabitat use by Hooded Warblers were different at my study sites in the breeding and non-breeding ranges. I believe, the use of habitats varies between locations such as the wintering and breeding grounds for many species; to evaluate the relative importance of any proposed habitat changes, we must know how the changes will affect macro- and microhabitat and how the species use macro- and microhabitat