title: Effects of Lead Exposure, Flock Behavior, and Management Actions on the Survival of California Condors (Gymnogyps californianus).
abstract: Translocation is an increasingly important tool for managing endangered species, but factors influencing the survival of translocated individuals are not well understood. Here we examine intrinsic and extrinsic drivers of survival for critically endangered California condors (Gymnogyps californianus) whose wild population recovery is reliant upon releases of captively bred stock. We used known fate models and information-theoretic methods to compare the ability of hypothesized covariates, most of which serve as proxies for lead exposure risk, to predict survival rates of condors in California. Our best supported model included the following predictors of survival: age of the recovery program, precipitation, proportion of days observed feeding on proffered carcasses, maximum blood lead concentration over the preceding 18 months, and time since release. We found that as flocks have increased in size and age, condors are increasingly likely to range more widely and less likely to be observed feeding on proffered food, and these "wilder" behaviors were associated with lower survival. After accounting for these behaviors, we found a positive survival trend, which we attribute to ongoing improvements in management. Our findings illustrate that the survival of translocated animals, such as highly social California condors, is influenced by behaviors that change through time.
authors.affiliation: Department of Ecology, Montana State University, Bozeman, MT, 59717, USA.
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Bakker
authors.affiliation: Microbiology and Environmental Toxicology Department, University of California Santa Cruz, 1156 High St, Santa Cruz, CA, 95064, USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Smith
authors.affiliation: The Nature Conservancy, 258 Main Street, Lander, WY, 82520, USA.
authors.forename: Holly
authors.initials: H
authors.lastname: Copeland
authors.affiliation: United States Fish and Wildlife Service, 2493 Portola Rd. Suite B, Ventura, CA, 93003, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Brandt
authors.affiliation: National Park Service, Pinnacles National Park, 5000 Highway 146, Paicines, CA, 95043, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Wolstenholme
authors.affiliation: Ventana Wildlife Society, 19045 Portola Dr. Ste. F-1, Salinas, CA, 93908, USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Burnett
authors.affiliation: United States Fish and Wildlife Service, 2493 Portola Rd. Suite B, Ventura, CA, 93003, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Kirkland
authors.affiliation: Microbiology and Environmental Toxicology Department, University of California Santa Cruz, 1156 High St, Santa Cruz, CA, 95064, USA. myraf@ucsc.edu.
authors.forename: Myra E
authors.initials: ME
authors.lastname: Finkelstein
mesh_terms: D000818:Animals; D002140:California; D056727:Endangered Species; D007854:Lead / Q000097:blood / Q000633:toxicity*; D011157:Population Dynamics; D020304:Raptors
chemical_list: D007854:Lead
keywords: California condor; flock; lead exposure; management actions; precipitation; survival; translocation