Cooperative Fish and Wildlife Research Units Program: Pennsylvania
Education, Research and Technical Assistance for Managing Our Natural Resources

Fischer, J.W., W.D. Walter, M.A. Avery. 2013. Brownian bridge movement models to characterize home ranges of avian species. The Condor 115(2): 298-305.


A Brownian Bridge movement model (BBMM) is a relatively new concept that estimates the movement path of an animal probabilistically using data collected at frequent time intervals. A BBMM assumes that locations are not independent, whereas the ‘classical’ kernel density estimator (KDE) assumes locations are independent. We estimated BBMM home ranges for 11 Black Vultures (Coragyps atratus) and 7 Turkey Vultures (Cathartes aura) equipped with global positioning system satellite transmitters near Marine Corps Air Station Beaufort, South Carolina from October 2006 to November 2008. For Black Vultures that travelled >100 km from the capture site (n=2), overall 95% BBMM home ranges (95% BBMM) were 833 and 2111 km2. For Black Vultures that did not travel as far (n=9), 95% BBMM ranged from 33 to 778 km2 and averaged (± SE) 243 ± 76 km2. The majority of Turkey Vultures travelled >100 km from the capture site (n=6) with 95% BBMM ranging from 923 to 7058 km2 and averaged (± SE) 3173 ± 1109 km2. We also estimated KDE home ranges using newer satellite technology to compare to previous studies. Overall 95% KDE ranged from 17 to 16066 km2 for Black Vulture and 988 to 36257 km2 for Turkey Vulture. The concept of an animal’s home range has evolved over time, as have home-range estimators. With increasing use of satellite telemetry, application of BBMM can greatly enhance our understanding of home ranges, migratory routes, seasonal movements, and habitat use patterns of wild birds over large and often remote areas.