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Condors Have Highest Recorded Blood Lead Levels

Release Date: 08/07/2007
Contact: Carl Brenner, Supervisor, Interpretation & Education
Phone: (831) 3894485 x265

Biologists at Pinnacles National Monument have captured all of the Pinnacles' flock of California condors, and any Big Sur birds in the area, after observing five condors feeding on a pig carcass shot outside the monument with lead ammunition. Tests revealed that nearly half of the 17 tested condors had elevated lead levels and condors 306, 318, and 242 have blood-lead values indicating lead poisoning, requiring immediate transport to the Los Angeles Zoo for emergency chelation. Chelation is a process for removing heavy metals such as lead from the bloodstream and lead poisoning is defined as levels of lead in a condor's bloodstream exceeding 40 micrograms of lead per deciliter of blood (g/dL). Of the remaining birds tested thus far, 10 had blood lead values indicating they were exposed to lead (15-30 g/dL).

306 had a blood lead level of 164 g/dL, the highest recorded for a Pinnacles bird and 242 from Big Sur had a 610 g/dL reading, the highest recorded in California. "The level of lead found in these condors is alarming not only because they are some of the highest recorded levels but because we are unsure of the extent of developmental and long term health problems resulting from the significant amount of lead they have ingested" explained Court VanTassell, Wildlife Biologist for Pinnacles National Monument.

Pinnacles is assisting the University of California, Santa Cruz (UCSC) in conducting research to identify the pathways for transmission of lead to California condors. Prior research has shown that lead ammunition is a significant source of lead exposure and poisonings in California condors. Biologists observed condors feeding on the carcass of a pig killed by lead bullets. Tissue samples from the pig carcass, the bullets that killed the pig, feather samples from the condors with elevated blood-lead levels, and blood samples from all of the birds suspected of feeding on this carcass were collected and sent to UCSC for analysis and possible identification of the pathway for lead transmission.

The Pinnacles condors may still face health problems because of the elevated levels of lead in their blood. Even in the birds where levels are not high enough to warrant emergency measures, the effects of long term exposure to non-lethal levels remains a significant question for researchers and biologists. Lead in a condor's bloodstream can be absorbed into its bones, where it can slowly leach back into the blood for an unknown length of time.

The vast majority of research on the health effects of lead exposure is based on humans, but comparisons can be made for animals. When a child's brain is developing, even low levels of lead in the body can slow the child's development and cause learning and behavioral problems. It can change the way blood-forming cells work, alter the way nerve cells signal each other, and disturb or destroy the way the brain makes connections for thinking. Lead is also known to be highly toxic to the kidneys and immune systems. Some of the Pinnacles condors are testing at four times the level that would initiate a medical response in humans as outlined by the Center for Disease Control. At this time, the effects of lead exposure on juvenile condors are only measured in mortality rates.

The local community has shown increasing support for the Condor Reintroduction Program. Local ranchers have helped biologists by notifying the park when condors are roosting on their property, voluntarily granting access to private property to allow biologists to better monitor the condors, and some have committed to using non-lead ammunition (or, if using leaded ammunition, some are burying or hiding carcasses from the condors.). Without community support, this opportunity to bring California condors back into the wild will not succeed.

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