Eggshell Thinning and Depressed Hatching Success of California Condors Reintroduced to Central California

Burnett, L. Joseph; Sorenson, Kelly J.; Brandt, Joseph; Sandhaus, Estelle A.; Ciani, Deborah; Clark, Michael; David, Chandra; Theule, Jenny; Kasielke, Susie; Risebrough, Robert W.

doi:10.1525/cond.2013.110150

Cited by 37 publications

(49 citation statements)

References 27 publications

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“…However, recent evidence indicates that coastaldwelling condors face different anthropogenic threats that compromise their health and survival (5,6). In the Big Sur, California condor population eggshell thinning has been documented to the extent that wild-laid eggs have been removed from nests and artificially incubated at breeding facilities to prevent egg breakage and embryo mortality (5).…”

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confidence: 99%

Identification of California Condor Estrogen Receptors 1 and 2 and Their Activation by Endocrine Disrupting Chemicals

et al. 2015

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Recently, California condors (Gymnogyps californianus) have been reintroduced to coastal regions of California where they feed on marine mammal carcasses. There is evidence that coastal-dwelling condors experience reproductive issues, such as eggshell thinning, likely resulting from exposure to endocrine-disrupting chemicals (EDCs). To address this problem, we have identified and cloned condor estrogen receptors (ESRs) 1 and 2 and characterized their activation by EDCs present in the coastal habitats where condors reside. Dichlorodiphenyltrichloroethane (DDT) and its metabolites all activated ESR1 and ESR2, although their relative potency differed between the receptors. Bisphenol A, dieldrin, trans-nonachlor, and polychlorinated biphenyl 52 (PCB52) moderately activated both ESRs, whereas PCB138 and PCB153 stimulated little to no activation. Overall, EDC activation of condor ESR2, which is the first ESR2 cloned from a raptor species, was greater than that of ESR1. Significant activation of both condor ESRs by EDCs occurred at high concentrations (≥1μM), which are within the range of plasma levels of certain EDCs (eg, dichlorodiphenyldichloroethylene [p'p-DDE]) in coastal-dwelling condors. Finally, phylogenetic analyses of ESRs of 41 avian species identified a single amino acid position in ESR2 under positive selection. Mutation of this amino acid affected receptor activation by EDCs, suggesting the identity of this amino acid may influence EDC sensitivity of avian species. Together, these findings broaden our understanding of EDC interactions with ESRs in avian species. For condors specifically, these data could be used to evaluate EDC exposure risk at future release sites to identify those least likely to compromise the continued recovery of this species.

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Identification of California Condor Estrogen Receptors 1 and 2 and Their Activation by Endocrine Disrupting Chemicals

et al. 2015

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“…Snyder and Meretsky, 2003;Burnett et al, 2013), Ospreys Pandion haliaetus (Odsj€ o and Sondell, 2014) or Peregrine Falcons (Castilla et al, 2010), are still under intensive examination, determining the presence of an embryo (along with the proper identification of the region of an egg from which a shell fragment originates; e.g., Snyder and Meretsky, 2003) may be crucial to explain the causes of eggshell thinning per se. For instance, Snyder and Meretsky (2003) found in Californian Condors a small decrease in eggshell thickness between fresh and hatched eggs (1.3%), although those authors did not determine whether all the eggs were embryonated.…”

Section: Implications For Studies Of Eggshell Thinning and Variation mentioning

confidence: 99%

Embryonic eggshell thickness erosion: A literature survey re-assessing embryo-induced eggshell thinning in birds

Orłowski

Hałupka

2015

Environmental Pollution

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“…11 However, eggshell thinning and reduced hatching success, attributed to DDE exposure from feeding on beach-cast marine mammals, particularly California sea lions (Zalophus californianus; CASLs), were recently identified in coastal breeding condors and could prove to be an additional threat to condor population health. 12 Condor lead exposure is well-documented, 9,13−15 but data on exposure to DDE and other POPs are limited, despite their potential to affect condor recovery. 8 The majority (>95%) of the U.S. population of CASLs breeds on the Channel Islands off California.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Personnel maintain set locations where terrestrial animal carcasses are placed ("proffered feeding stations") to facilitate monitoring. Coastal condors are observed feeding on dead-stranded marine mammals along Big Sur, 12 whereas southern, noncoastal condors are not considered to feed on marine mammals. Ranges of coastal condors during the study period (2009− 2013) overlap with our dead-stranded marine mammal sampling locations and are distinct from noncoastal condor ranges ( Figure S1).…”

Section: ■ Introductionmentioning

confidence: 99%

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Terrestrial Scavenging of Marine Mammals: Cross-Ecosystem Contaminant Transfer and Potential Risks to Endangered California Condors (Gymnogyps californianus)

Kurle

Bakker

Copeland

et al. 2016

Environ. Sci. Technol.

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The critically endangered California condor (Gymnogyps californianus) has relied intermittently on dead-stranded marine mammals since the Pleistocene, and this food source is considered important for their current recovery. However, contemporary marine mammals contain persistent organic pollutants that could threaten condor health. We used stable carbon and nitrogen isotope, contaminant, and behavioral data in coastal versus noncoastal condors to quantify contaminant transfer from marine mammals and created simulation models to predict the risk of reproductive impairment for condors from exposure to DDE (p,p′-DDE), a major metabolite of the chlorinated pesticide DDT. Coastal condors had higher whole blood isotope values and mean concentrations of contaminants associated with marine mammals, including mercury (whole blood), sum chlorinated pesticides (comprised of ∼95% DDE) (plasma), sum polychlorinated biphenyls (PCBs) (plasma), and sum polybrominated diphenyl ethers (PBDEs) (plasma), 12−100-fold greater than those of noncoastal condors. The mean plasma DDE concentration for coastal condors was 500 ± 670 (standard deviation) (n = 22) versus 24 ± 24 (standard deviation) (n = 8) ng/g of wet weight for noncoastal condors, and simulations predicted ∼40% of breeding-age coastal condors have DDE levels associated with eggshell thinning in other avian species. Our analyses demonstrate potentially harmful levels of marine contaminant transfer to California condors, which could hinder the recovery of this terrestrial species.

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Eggshell Thinning and Depressed Hatching Success of California Condors Reintroduced to Central California

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 37 publications

References 27 publications

Identification of California Condor Estrogen Receptors 1 and 2 and Their Activation by Endocrine Disrupting Chemicals

Identification of California Condor Estrogen Receptors 1 and 2 and Their Activation by Endocrine Disrupting Chemicals

Embryonic eggshell thickness erosion: A literature survey re-assessing embryo-induced eggshell thinning in birds

Terrestrial Scavenging of Marine Mammals: Cross-Ecosystem Contaminant Transfer and Potential Risks to Endangered California Condors (Gymnogyps californianus)

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