Date of Award

1996

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Forestry, Wildlife, and Fisheries

First Advisor

Robert B. Hamilton

Abstract

Abundance of some species of Nearctic-Neotropical migrants has been declining dramatically since 1970. Most literature about Neotropical migrants is from the breeding grounds, and some is from the wintering grounds; very little is from stopover sites. I studied foraging behavior and habitat selection of insectivorous migratory songbirds at three stopover sites along northern coast of the Gulf of Mexico during spring migrations of 1993-1995. Each migrant species had its unique combination of foraging behavior and habitat use during stopover. Migrants selected certain habitat strata and plant species and avoided others. The decrease of understory vegetation in the reduced plots had greater impact on foraging behavior of understory, subcanopy, and ground foragers, and less for canopy species. Searching behavior has been studied less than attack behavior or foraging site because searching behavior is ephemeral and difficult to record. From the analysis of correspondence and cluster analyses, closely related species have similar searching behavior. Searching movements of migrants are greatly affected by various conditions such as site, plot, and flocking. Warblers (Parulinae) were found to be more flexible and more responsive to environmental conditions than were vireos. It is important to study the properties of foraging sequences before one can select a reliable method to calculate foraging rates. The overall rate is more realistic than the sequential rate; the original sequences are more biased than the closed sequences. However, the adjusted overall rate from the original sequences appears to be a compromise.

ISBN

9780591288971

Pages

151

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