A TEMPORAL ANALYSIS OF A SINGLE LIVE OAK TREE'S BIRD COMMUNITY IN CENTRAL FLORIDA DURING AUTUMN WARBLER MIGRATION

摘要

The composition and structure of terrestrial avian communities of inland Florida, particularly in relation to the time of day, have been relatively little studied. This study employed a novel technique for investigating a bird community that uses a single live oak tree in central Florida. By recording field observations during four different time blocks over the course of ten weeks, we quantified the composition of the community that uses this tree during the fall. Thirty species were recorded, comprised primarily of year-round residents. Migratory species made up 22% of the total abundance. Blue-Gray Gnatcatchers (Polioptila caerulea) spent a highly disproportional amount of time in the tree per visit as compared to Blue Jays (Cyanocitta cristata) and Mockingbirds (Mimus polyglottos) (these were the three most common species observed). Gnatcatchers were found to stay longer because they use the live oak as a foraging site, whereas the latter two species did not often feed at the tree. Overall species richness and total bird density increased as winter approached; these variables correlated with migration induced by the changing of the seasons rather than to individual weather conditions. Birds were most abundant and diverse during the early afternoon (1200-1500) time block. Average vertical zonation in the tree changed dramatically from time block to time block, showing the effects of daily temperature variations on the behavioral patterns of this avian community.