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Junk ingestion and nestling mortality in a reintroduced population of California Condors Gymnogyps californianus

Published online by Cambridge University Press:  29 May 2007

Allan Mee*
Affiliation:
CRES, Zoological Society of San Diego, 15600 San Pasqual Valley Road, Escondido, CA 92027-7000, USA
Bruce A. Rideout
Affiliation:
Department of Pathology, San Diego Zoo, P. O. Box 120551, San Diego, CA 92112-0551, USA
Janet A. Hamber
Affiliation:
Santa Barbara Museum of Natural History, 2559 Puesta del Sol, Santa Barbara, CA 93105, USA
J. Nick Todd
Affiliation:
Santa Cruz Predatory Bird Research Group, 100 Shaffer Road, U.C. Santa Cruz, Long Marine Laboratory, Santa Cruz, CA 95060, USA
Greg Austin
Affiliation:
US Fish & Wildlife Service, Hopper Mountain National Wildlife Refuge 2493 Portola Road, Suite A, Ventura CA 93005, USA
Mike Clark
Affiliation:
Los Angeles Zoo, 5333 Zoo Drive, Los Angeles, CA 90027, USA
Michael P. Wallace
Affiliation:
CRES, Zoological Society of San Diego, 15600 San Pasqual Valley Road, Escondido, CA 92027-7000, USA
*
*Author for correspondence. Killarney National Park, Muckross, Killarney, Co. Kerry, Ireland; e-mail: allan.mee@ireland.com
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Abstract

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Ingestion of foreign anthropogenic material, here called junk, has been documented in many avian taxa but has become especially problematic in some Old World Gyps vulture populations within the last 30 years. Here, we document the effects of ingested junk on a reintroduced population of the Critically Endangered California Condor Gymnogyps californianus in southern California, U.S.A. Of 13 breeding attempts to date (2001–2005), only one has resulted in successful fledging. Of nests where either the nest substrate was sifted (n = 10) or nestlings (n = 8) were examined, all but one held junk. Nine nestlings hatched in the wild between 2002 and 2005; of these six died at or near nests and two were removed from the wild for health reasons. Four dead nestlings and two removed from the wild held substantial quantities of junk. In two cases, junk ingestion was determined to be the cause of death. Five of six dead nestlings had elevated hepatic copper levels (150–531 ppm dry weight) although the significance of this, if any, remains undetermined. In comparison with historic condor nests (n = 69), junk was more prevalent and of greater size and quantity in reintroduced condor nests. To date, junk ingestion has been the primary cause of nest failure in the reintroduced condor population and threatens the reestablishment of a viable breeding population in southern California.

Type
Research Article
Copyright
Copyright © Birdlife International 2007