Journal Article

Fine-scale assessment of home ranges and activity patterns for resident black vultures (Coragyps atratus) and turkey vultures (Cathartes aura)

Beasley, James C., Byrne, Michael E., Rhodes, Olin E., Bryan, A. Lawrence, DeVault, Travis L., Holland, Amanda E.

2017

Overview

Knowledge of black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) spatial ecology is surprisingly limited despite their vital ecological roles. Fine-scale assessments of space use patterns and resource selection are particularly lacking, although development of tracking technologies has allowed data collection at finer temporal and spatial resolution. Objectives of this study were to conduct the first assessment of monthly home range and core area sizes of resident black and turkey vultures with consideration to sex, as well as elucidate differences in monthly, seasonal, and annual activity patterns based on fine-scale movement data analyses. We collected 2.8-million locations for 9 black and 9 turkey vultures from June 2013 -August 2015 using solar-powered GSM/GPS transmitters. We quantified home ranges and core areas using the dynamic Brownian bridge movement model and evaluated differences as a function of species, sex, and month. Mean monthly home ranges for turkey vultures were ~50% larger than those of black vultures, although mean core area sizes did not differ between species. Turkey vulture home ranges varied little across months, with exception to a notable reduction in space-use in May, which corresponds with timing of chick-rearing activities. Black vulture home ranges and core areas as well as turkey vulture core areas were larger in breeding season months (January-April). Comparison of space use between male and female vultures was only possible for black vultures, and space use was only slightly larger for females during breeding months (February-May). Analysis of activity patterns revealed turkey vultures spend more time in flight and switch motion states (between flight and stationary) more frequently than black vultures across temporal scales. This study reveals substantive variability in space use and activity rates between sympatric black and turkey vultures, providing insights into potential behavioral mechanisms contributing to niche differentiation between these species.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Activity patterns / Aircraft / Animal behavior / Animal Distribution / Animals / BASIC BIOLOGICAL SCIENCES / Biology and Life Sciences / Birds / Breeding / Breeding seasons / Brownian motion / Brownian movements / Data collection / Data processing / Differentiation / Earth Sciences / Ecological monitoring / Ecology / Ecology and Environmental Sciences / Ecosystem / Ecosystem biology / Ecosystems / Environmental conditions / Falconiformes / Female / Females / Flight / Georgia / Global positioning systems / GPS / Home range / Homing Behavior / Laboratories / Male / Medicine and Health Sciences / Movement / Natural resources / People and places / River ecology / Rivers / Science / Seasons / Sex / Solar energy / Solar power / South Carolina / Spatial discrimination / Spatial resolution / Species / Stochastic processes / Studies / Sympatric populations / Tracking / Transmitters / Winter