Semester

Spring

Date of Graduation

2009

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Biology

Committee Chair

Petra Bohall Wood.

Abstract

Understanding foraging ecology provides insight into species resource requirements and overall conservation needs. We examined foraging behavior and tree species selection of male Cerulean Warblers (Dendroica cerulea ) (n = 673) in response to varying degrees of habitat disturbance from silvicultural treatments at four study sites in West Virginia, Kentucky and Ohio, during the 2006 and 2007 breeding seasons. Cerulean Warblers foraged primarily in the forest canopy, along branch tips by gleaning insects off leaf surfaces, often adjacent to canopy gaps, both pre- and post-harvest. Tree species availability, based on importance values (IV) calculated from density, frequency and basal areas, differed from tree species used for foraging both pre- and post-harvest (p < 0.01). Preferred species included hickory (Carya spp.), sugar maple (Acer saccharum ), and chestnut oak (Quercus prinus), although red oak (Quercus rubra) was strongly avoided. Tree species selection changed little post-harvest in all silvicultural treatments. Aerial foraging increased after harvests. Cerulean Warblers exhibited selection preferences, suggesting, maintaining availability of preferred tree species is important for management of Cerulean Warbler populations.;Species resource requirements are an important component of habitat selection. We investigated foraging ecology and tree species selection of five Neotropical migrant species (n = 679); American Redstart (Setophaga ruticilla ), Black-and-white Warbler (Mniotilta varia), Hooded Warbler (Wilsonia citrine), Red-eyed Vireo (Vireo olivaceus), and Scarlet Tanager (Piranga olivacea) at three study sites in West Virginia during breeding seasons of 2006 and 2007. We analyzed influences of habitat disturbance from silvicultural treatments implemented during the non-breeding season between years. Tree species availability, based on importance values (IV) calculated from relative density, frequency, and basal area, differed from tree species used for foraging pre and post-treatment. Species varied in their preferred maneuver types and degree of tree species selectivity. Aerial maneuvers increased post-treatment for all species except Black-and-white Warblers. At the guild level, sugar maples were preferred and red oaks were avoided. Tree species selection changed little post-harvest. Red-eyed Vireos and post-harvest American Redstarts exhibited significant tree species selection preferences (P < 0.05) although Scarlet Tanagers were near-significant in tree species selection (P = 0.06).;Foraging ecology studies could be biased due to disparity in initial detection probabilities of foraging birds among tree species or foraging behaviors because it might be easier to detect a foraging bird when it is in certain tree species, lower in the canopy, or using aerial foraging maneuvers. Our study investigated whether the initial foraging observation is biased based on 1521 paired, single-point foraging observations for six species of arboreal foraging Neotropical migrants in two study sites in West Virginia and one in Kentucky in 2006 and 2007. We did not detect a significant difference in tree species used for foraging between the initial and second foraging observation (P ≥ 0.62). Foraging maneuvers and foraging height generally were not significantly different (P ≥ 0.09) between the two foraging observations for the six avian species tested. We conclude that the initial detection of foraging birds would not have a major influence on interpretation of foraging substrate or behavioral preferences.

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