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Identifying Potential Contaminant Exposure to California Condors in the Pacific Northwest

Potential reintroduction of the endangered California Condor to parts of its historic range in the Pacific Northwest would benefit from information on possible threats that could challenge recovery efforts. Exposure to environmental contaminants is a key limiting factor for condor recovery in its southern range.

USGS researchers assessed potential contaminant exposure across Oregon and Washington using two surrogate scavenger species, ravens and turkey vultures. Researchers examined spatial patterns of scavenger exposure to lead and mercury, two commonly occurring contaminants in the region, and identified habitats associated with high and low exposure using stable isotopes. A suite of biomarkers were also measured to examine the physiological effects of exposure. Lead concentrations were uniformly elevated across the region, whereas mercury was elevated along the coast. Co-exposure to both toxicants influenced stress hormone expression. Development of a robust exposure monitoring program for both condors and surrogate species throughout the region will be important for guiding condor recovery.

Herring, G., Eagles-Smith, C.A., Varland, D.E., 2018, Mercury and lead exposure in avian scavengers from the Pacific Northwest suggest risks to California condors- Implications for reintroduction and recovery: Environmental Pollution, p. online, https://doi.org/10.1016/j.envpol.2018.09.005.

graphs of mercury and lead exposure superimposed over image of birds scavenging a carcass on a beach
Reprinted from Environmental Pollution, Herring, et al, Mercury and lead exposure in avian scavengers from the Pacific Northwest suggest risks to California condors- Implications for reintroduction and recovery, online, Copyright 2018, with permission from Elsevier.

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