SREL Reprint #3873

Survival of a long-lived avian scavenger: implications of age, season, and landscape composition for mortality risk

Spencer B. Hudson1, Eric A. Tillman1, Marian L. Wahl2, Patrick A. Zollner2, Caryn D. Ross3, Travis L. DeVault3, James C. Beasley3, Adrián Naveda-Rodríguez4, Scott A. Rush4, Noah M. Osterhoudt5, Jeffrey F. Kelly5, Adam E. Duerr6, Lee A. Humberg7, Brett G. Dunlap7, Chad Neil8, John T. Forbes8, Harris Glass9, Travis L. Guerrant10, Robert W. Byrd11, Philip W. Kavouriaris12, Andrea K. Darracq12, Matthew T. Springer13, and Bryan M. Kluever1

1USDA APHIS Wildlife Services, National Wildlife Research Center, Gainesville, Florida, USA
2Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana, USA
3Savannah River Ecology Laboratory, Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, USA
4Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Starkville, Mississippi, USA
5School of Biological Sciences, University of Oklahoma, Norman, Oklahoma, USA
6Conservation Science Global, Inc., Cape May, New Jersey, USA
7USDA APHIS Wildlife Services, Indiana State Program, West Lafayette, Indiana, USA
8USDA APHIS Wildlife Services, West Virginia State Program, Elkins, West Virginia, USA
9USDA APHIS Wildlife Services, Pennsylvania State Program, Harrisburg, Pennsylvania, USA
10USDA APHIS Wildlife Services, Missouri State Program, Columbia, Missouri, USA
11USDA APHIS Wildlife Services, Arkansas State Program, Little Rock, Arkansas, USA
12Department of Biological Sciences, Murray State University, Murray, Kentucky, USA
13Department of Forestry and Natural Resources, University of Kentucky, Lexington, Kentucky, USA

Abstract: Despite the ecological importance of avian scavengers such as vultures, demographic information that is essential to their conservation and management remains limited. The goal of this study was to evaluate survival and mortality risk in black vultures (Coragyps atratus), a protected native species of conflict management concern in the United States. Here, we combined monitoring data from a 28-year period to estimate annual survival rates among age classes and test for seasonal and age-related patterns in mortality risk. Using dead recovery information, we also summarized the causes and timing of annual mortalities. Additionally, we tested whether mortality risk was affected by aspects of landscape composition and configuration, as well as human development. Average annual survival was high overall (0.95, 95% CI: 0.92–0.98), with estimate precision markedly improved by combining datasets (72.1%–84.2% increase). Mortality risk differed by season and age class such that vultures experienced 68.7% more hazard during the breeding season, and adults experienced 66.2% less hazard than juveniles. Among the mortality causes, 67% were anthropogenic, 4% were natural, and the remaining 29% were unknown. Additionally, greater land cover diversity (Shannon diversity index) reduced mortality risk, whereas measures of landscape configuration and human development had no effect. High survival rates help explain this species' population growth and range expansion and further inform allowable take for sustainable management practices. Moreover, the identified seasonal and age-related vulnerabilities may help guide lethal control of human–vulture conflicts in an ecologically relevant manner. Maintaining diverse landscapes may also enhance survival overall, facilitating conservation of this species and other avian scavengers.

Keywords: black vulture; demography; ecology; mark-encounter; satellite telemetry

SREL Reprint #3873

Hudson, S. B., E. A. Tillman, M. L. Wahl, P. A. Zollner, C. D. Ross, T. L. DeVault, J. C. Beasley, A. Naveda-Rodríguez, S. A. Rush, N. M. Osterhoudt, J. F. Kelly, A. E. Duerr, L. A. Humberg, B. G. Dunlap, C. Neil, J. T. Forbes, H. Glass, T. L. Guerrant, R. W. Byrd, P. W. Kavouriaris, A. K. Darracq, S. M. T., and B. M. Kluever. 2026. Survival of a long-lived avian scavenger: implications of age, season, and landscape composition for mortality risk. Ecology and Evolution 16(e73226).

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).