Title

Foraging Behavior of the Black-Capped Vireo in Central Texas

Document Type

Thesis

Comments


Presented to the Graduate Council of Texas State University-San Marcos in Partial Fulfillment of the Requirements for the Degree of Master of Science, April 2008.
Committee Members Approved:
Dr. John T. Baccus
Dr. Thomas R. Simpson
Dr. Floyd W. Weckerly
Approved:
J. Michael Willoughby, Dean of the Graduate College

Abstract

Habitat loss, through urbanization and habitat degradation, is a major component threatening endangered Black-capped Vireo populations. Acquisition and management of breeding habitat are identified as the main objectives for recovering populations to a viable level. In order to identify attributes of suitable habitat for Black-capped Vireos, it is essential to understand the way they use their habitat. I examined Black-capped Vireo foraging behavior for adults and fledglings and identified differences that existed between the sexes at four study sites in Central Texas. G-test of Independence and Fisher’s Exact test were used to compare frequency distributions of males and females for foraging height, height of tree used, tree species, substrate and foraging maneuvers.

I found males and females foraged at different proportions relative to various height classes with males foraging at all levels but primarily greater than 3 m and females foraging almost exclusively below 3 m. Males used taller vegetation proportionally more than females, which consequently, influenced the use of different tree species. No intersexual difference was found for substrate and maneuvers during foraging attempts. All Black-capped Vireos primarily gleaned from foliage. Fledglings foraged generally below 2 m but were observed using vegetation >3 m 50% of the time. Due to the use of tree canopies for foraging by males and taller vegetation by fledglings, greater vertical strata may be an important component commonly overlooked when identifying a heterogeneous landscape for Black-capped Vireos. Additional fledgling dispersal studies are recommended to identify detailed fledgling habitat use prior to migration.