California Condor Behavior Unresponsive to Lead Exposure

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Scavenging birds are at risk of lead poisoning from consuming carcasses of animals killed with lead ammunition. Methods to identify lead exposure typically require capturing an animal to collect a blood sample; however, USGS and U.S. Fish and Wildlife Service researchers sought to design a less costly, noninvasive behavioral test to identify lead exposure in California condors.

The condors studied were tracked with GPS telemetry and blood lead concentrations were measured. Researchers measured birds’ movement rates and the proportion of time condors spent in flight to see if their flight behavior was influenced by lead exposure, yet they found no effect of lead exposure on these behavioral metrics. Wild birds are effective at hiding illness, especially condors that have a strong social hierarchy in which showing weakness is a disadvantage. The authors suggested that focusing on behaviors other than flight or analyzing tissues such as feathers - rather than, or in addition to, blood - may be more useful for identifying lead exposure in birds.

Poessel, S.A., Brandt, J., Uyeda, L., Astell, M., Katzner, T.E., 2017, Lack of observed movement response to lead exposure of California condors: Journal of Wildlife Management, p. online, https://doi.org/10.1002/jwmg.21378.

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