Status of the California Condor (<i>Gymnogyps californianus</i>) and Efforts to Achieve Its Recovery

Walters, Jeffrey R.; Derrickson, Scott R.; Fry, D. Michael; Haig, Susan M.; Marzluff, John M.; Wunderle, Joseph M.

doi:10.1525/auk.2010.127.4.969

Cited by 143 publications

(101 citation statements)

References 46 publications

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“…In 1982 it was on the brink of extinction with only 22 birds left in existence (Walters et al 2010). The species is currently designated as critically endangered by the International Union for the Conservation of Nature (birdlife International 2012) as well as endangered under the United States Endangered Species Act.…”

Section: Introductionmentioning

confidence: 99%

“…Although a large portion of the condor's diet is currently from terrestrial sources, isotopic studies of historical materials and fossils show that from the Pleistocene to the 1700s, marine mammals were also a significant food source for condors on the Pacific coast (Chamberlain et al 2005, Fox-Dobbs et al 2006. Today, along the California coast, condors feed on beach-cast marine mammals with some regularity (Walters et al 2010), but the extent to which this behavior occurs has not been established.…”

Section: Introductionmentioning

confidence: 99%

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Discrimination Factors for Stable Isotopes of Carbon and Nitrogen in Blood and Feathers from Chicks and Juveniles of the California Condor

et al. 2013

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Abstract. Stable-isotope ratios of carbon ( 13 C/ 12 C; δ 13 C) and nitrogen ( 15 N/ 14 N; δ 15 N) in animal tissues are analyzed to estimate animal foraging ecology because these ratios reflect those of an animal's diet. This reflection is generally indirect, as stable-isotope ratios change with trophic level. These differences, called discrimination factors (reported as Δ), vary considerably by species and tissue. Variations in discrimination factors used in stableisotope mixing models can lead to inaccurate estimates of diets. Therefore, determining accurate discrimination factors specific to species and tissue is important. We established the Δ 13 C and Δ 15 N values between diet and blood and feathers from chicks and juveniles of the California Condor (Gymnogyps californianus). hatchlings were fed rats for 76-119 days, whereas juveniles were fed dairy calves for 64 days. The mean Δ 13 C and Δ 15 N values (± SD) between chick feathers and rat muscle were 0.4 ± 0.4‰ and 3.1 ± 0.2‰, respectively; those between chicks' whole blood and rat muscle were -0.7 ± 0.1‰ and 1.7 ± 0.1‰, respectively. The mean Δ 13 C and Δ 15 N values between juvenile condors' plasma and calf muscle were 0.9 ± 0.2‰ and 3.3 ± 0.7‰, respectively; those between juveniles' red blood cells and calf muscle were 0.3 ± 0.3‰ and 1.8 ± 0.1‰, respectively; and those between juveniles' whole blood and calf muscle were 0.3 ± 0.3‰ and 1.9 ± 0.2‰, respectively. We report the first discrimination factors for the Cathartidae (New World vultures), and our findings will have important applications in studies of the critically endangered California Condor's foraging ecology.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Discrimination Factors for Stable Isotopes of Carbon and Nitrogen in Blood and Feathers from Chicks and Juveniles of the California Condor

et al. 2013

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“…Reintroduction efforts starting in 1992 have been largely successful. Since 2011, over 200 individuals are free-flying (Mace, 2012) in California, Arizona, Utah, and Baja California, Mexico (Walters et al, 2010). Nevertheless, free-flying condor populations are far from self-sustaining in the wild.…”

Section: Introductionmentioning

confidence: 99%

Two decades of cumulative impacts to survivorship of endangered California condors in California

Kelly¹,

Rideout

Grantham

et al. 2015

Biological Conservation

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We investigated threats to the California condor (Gymnogyps californianus), a flagship endangered species, using individual data on survival during a 20 year period of intensive recovery efforts. Over the two decades of reintroductions, condors in California had an estimated median survival time of 7.8 years suggesting that 50% of condors are expected to survive in the wild long enough to contribute to recruitment. In general, annual mortality rates exceeded levels necessary for a stable population; however, mortality declined, reaching levels needed for population stability, during the second decade of re-establishment. Intensive management practices, including utility pole aversion training and clinical interventions to prevent lead-related deaths likely contributed to the decrease in mortality rates. Utility line collision and/or electrocution was an important factor causing mortality over the two decades; though, this threat has largely been mitigated through management and targeted efforts in high-risk areas. In the past, wildfires were not considered a major threat to survival of freeflying condors. However, our analyses suggest that forest fires are significantly linked to the hazard of death, and increased wildfire activity in California highlights this population's vulnerability to catastrophic losses from forest fire. Lead poisoning, which was a major driver in the population's decline, was a leading cause of death accounting for the greatest adult mortality, and lead exposure remains the most significant threat. Recent lead ammunition reduction efforts in the condor range in California hold promise for improving the recovery potential for this population.

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“…Currently, wild California Condors face multiple threats to their recovery, including lead poisoning and trash ingestion (Mee and Snyder 2007;Finkelstein et al 2012;Rideout et al 2012). Although there is clear evidence that ingestion of spent lead ammunition from feeding on carcasses is the principal source of lead exposure to condors (Parish et al 2009;Finkelstein et al 2012) other sources, such as trash ingestion, may also be an exposure risk (Walters et al 2010).…”

mentioning

confidence: 99%

“…We use the term "trash" to describe the broad category of small nonfood items, including glass and plastic debris, bottle caps, and spent ammunition casings, which condors ingest or transport back to nest sites (Mee et al 2007b). Although injury and death from physical obstruction due to trash ingestion occurs (Rideout et al 2012), the risk of lead poisoning from trash ingestion is unknown, although it has been suggested as a potential source of lead exposure to condors (Walters et al 2010).…”

mentioning

confidence: 99%

Lead Exposure Risk from Trash Ingestion by the Endangered California Condor (Gymnogyps californianus)

Finkelstein

Brandt

Sandhaus

et al. 2015

Journal of Wildlife Diseases

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ABSTRACT:Lead poisoning from ingestion of spent lead ammunition is one of the greatest threats to the recovery of California Condors (Gymnogyps californianus) in the wild. Trash ingestion by condors is well documented, yet the extent that trash presents a lead exposure risk is unknown. We evaluated 1,413 trash items collected from condor nest areas and nestlings in the Transverse Range of Ventura County, California, US, from 2002 to 2008, for their potential as a lead exposure risk to condors. We visually identified 71 items suspected to contain sufficient lead to be of toxicologic concern. These items were leached with weak acid and analyzed for lead. Twentyseven of the 71 leached items (,2% of the 1,413 items) were "lead containing" based on criteria of a leachate lead concentration .1 mg/ mL, with the majority of these items (22; 81% of the 27 lead items) being ammunition related (e.g., spent bullet casings and jacketed bullets). Only three of the 1,413 items collected were lead containing but were clearly not ammunition related; the other two lead-containing items were unidentified. Our results suggest that trash ingestion of nonammunition items does not pose a significant lead exposure risk to the California Condor population in California.

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Status of the California Condor (Gymnogyps californianus) and Efforts to Achieve Its Recovery

Cited by 143 publications

References 46 publications

Discrimination Factors for Stable Isotopes of Carbon and Nitrogen in Blood and Feathers from Chicks and Juveniles of the California Condor

Discrimination Factors for Stable Isotopes of Carbon and Nitrogen in Blood and Feathers from Chicks and Juveniles of the California Condor

Two decades of cumulative impacts to survivorship of endangered California condors in California

Lead Exposure Risk from Trash Ingestion by the Endangered California Condor (Gymnogyps californianus)

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