title: Spatiotemporal patterns and risk factors for lead exposure in endangered California condors during 15 years of reintroduction.
abstract: Large-scale poisoning events are common to scavenging bird species that forage communally, many of which are in decline. To reduce the threat of poisoning and compensate for other persistent threats, management, including supplemental feeding, is ongoing for many reintroduced and endangered vulture populations. Through a longitudinal study of lead exposure in California condors (Gymnogyps californianus), we illustrate the conservation challenges inherent in reintroduction of an endangered species to the wild when pervasive threats have not been eliminated. We evaluated population-wide patterns in blood lead levels from 1997 to 2011 and assessed a broad range of putative demographic, behavioral, and environmental risk factors for elevated lead exposure among reintroduced California condors in California (United States). We also assessed the effectiveness of lead ammunition regulations within the condor's range in California by comparing condor blood lead levels before and after implementation of the regulations. Lead exposure was a pervasive threat to California condors despite recent regulations limiting lead ammunition use. In addition, condor lead levels significantly increased as age and independence from intensive management increased, including increasing time spent away from managed release sites, and decreasing reliance on food provisions. Greater independence among an increasing number of reintroduced condors has therefore elevated the population's risk of lead exposure and limited the effectiveness of lead reduction efforts to date. Our findings highlight the challenges of restoring endangered vulture populations as they mature and become less reliant on management actions necessary to compensate for persistent threats.
authors.affiliation: Wildlife Health Center, School of Veterinary Medicine, University of California-Davis, 1089 Veterinary Medicine Drive, Davis, CA, 95616, U.S.A.
authors.forename: Terra R
authors.initials: TR
authors.lastname: Kelly
authors.forename: Jesse
authors.initials: J
authors.lastname: Grantham
authors.forename: Daniel
authors.initials: D
authors.lastname: George
authors.forename: Alacia
authors.initials: A
authors.lastname: Welch
authors.forename: Joseph
authors.initials: J
authors.lastname: Brandt
authors.forename: L Joseph
authors.initials: LJ
authors.lastname: Burnett
authors.forename: Kelly J
authors.initials: KJ
authors.lastname: Sorenson
authors.forename: Matthew
authors.initials: M
authors.lastname: Johnson
authors.forename: Robert
authors.initials: R
authors.lastname: Poppenga
authors.forename: David
authors.initials: D
authors.lastname: Moen
authors.forename: James
authors.initials: J
authors.lastname: Rasico
authors.forename: James W
authors.initials: JW
authors.lastname: Rivers
authors.forename: Carie
authors.initials: C
authors.lastname: Battistone
authors.forename: Christine K
authors.initials: CK
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002140:California; D003247:Conservation of Natural Resources; D056727:Endangered Species; D004781:Environmental Exposure; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000633:toxicity*; D046093:Falconiformes / Q000378:metabolism*; D007854:Lead / Q000633:toxicity*; D008137:Longitudinal Studies; D012307:Risk Factors
chemical_list: D004785:Environmental Pollutants; D007854:Lead
keywords: Buitre; Gymnogyps californianus; carroñero; ecotoxicology; ecotoxicología; enfermedad de vida silvestre; epidemiology; epidemiología; scavenger; vulture; wildlife disease