Golden-winged warblers (Vermivora chrysoptera) of the Southern Appalachians : behavior, ecology, and conservation of a declining neotropical migrant songbird

Research on the Golden-winged Warbler (Vermivora chrysoptera), a Neotropical migrantsongbird that has experienced steady population declines over the past forty years, has generallyfocused on determining habitat requirements for the species, as well as best managementpractices for creating and maintaining habitat on the birds’ breeding grounds. Few studies haveinvestigated behavioral aspects of Golden-winged Warbler (GWWA) biology and few have beenconducted in western North Carolina (WNC). For this research project, I sought to map GWWAterritories in WNC and measure vegetation characteristics within those territories, as well asconduct a study of male aggression using conspecific playback. The primary goal of the researchwas to determine whether correlations exist between male aggression and territory/habitatcharacteristics. I augmented in-the-field vegetation measurements with analysis of LiDAR dataon shrub and canopy layers. Sizes of mapped territories were comparable to those found by otherresearchers. Within-territory vegetation characteristics, such as percent canopy cover, tree basalarea, and shrub height, were consistent with results found by other researchers. Overall, results ofLiDAR data analysis were somewhat consistent with measurements made in the field.Aggression trial results demonstrated that males exhibited varying responses to playback. This intraspecific variation may be due to personality traits that remain consistent over a bird’slifetime and/or to the timing of aggression trials with respect to breeding stage. No correlationwas found between density of males in a given area and aggression of males defending territoriesin that area. However, few sites used in this study had more than one male GWWA present; thus,investigations involving male density are not necessarily meaningful. Significant correlationswere found between male aggression and tree dbh, shrub density, and shrub height, with tree dbhpositively predicting male aggressive response and both shrub density and shrub heightnegatively predicting aggression. Due to the fact that the sample size of this study was rathersmall, further research is needed to clarify relationships between male aggression, populationdensity, and habitat characteristics. If correlations between aggression and both body size andreproductive output found in other avian species also apply to GWWA, studies of male GWWAaggression potentially have implications for conservation of the species