Journal Article

Spatiotemporal Patterns and Risk Factors for Lead Exposure in Endangered California Condors during 15 Years of Reintroduction

JOHNSON, CHRISTINE K., POPPENGA, ROBERT, WELCH, ALACIA, GEORGE, DANIEL, GRANTHAM, JESSE, BATTISTONE, CARIE, RASICO, JAMES, SORENSON, KELLY J., RIVERS, JAMES W., BRANDT, JOSEPH, JOHNSON, MATTHEW, BURNETT, L. JOSEPH, KELLY, TERRA R., MOEN, DAVID

2014

Overview

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.

• Publisher: Blackwell Scientific Publications,Blackwell Publishing Ltd,Wiley Periodicals Inc,Wiley-Blackwell
• Subject: Ammunition / Animal, plant and microbial ecology / Animals / Applied ecology / Aves / Biological and medical sciences / Birds / blood / Blood levels / Buitre / California / carroñero / Conservation biology / Conservation of Natural Resources / Conservation, protection and management of environment and wildlife / Contributed Papers / dietary supplements / ecotoxicology / Ecotoxicology, biological effects of pollution / ecotoxicología / Effects of pollution and side effects of pesticides on vertebrates / Endangered & extinct species / Endangered Species / enfermedad de vida silvestre / Environmental Exposure / Environmental Monitoring / Environmental Pollutants - toxicity / Environmental risk / epidemiology / epidemiología / Exposure / Falconiformes - metabolism / Food / Food security / forage / Fundamental and applied biological sciences. Psychology / Gymnogyps californianus / Lead / Lead - toxicity / Lead poisoning / Longitudinal Studies / Mountain peaks / Ornithology / Parks, reserves, wildlife conservation. Endangered species: population survey and restocking / Poisoning / Reintroduction / Risk Factors / Risk taking / scavenger / Species reintroduction / vulture / Wildlife conservation / wildlife disease / Wildlife refuges