image: Reducing the use of lead ammunition will make it feasible to reintroduce condors in Northern California. view more
Credit: C. West
In 2003, Northern California's Yurok Tribe initiated efforts to reintroduce California Condors on their lands. While wild condors have not existed in the region for more than a hundred years, a new study from The Condor: Ornithological Applications suggests that hunters transitioning from lead to non-lead ammunition may allow these apex scavengers to succeed there once again.
Lead, which condors consume when scavenging at carcasses of animals killed with lead ammunition, is the main factor limiting their recovery; lead toxicosis was responsible for 26% of juvenile condor deaths and 67% of adult condor deaths between 1992 and 2009. To assess condor's prospects in Northern California, Chris West of the Yurok Tribe Wildlife Program and his colleagues trapped two other avian scavengers, Turkey Vultures and Common Ravens, at nine sites in the region between 2009 and 2013. Collecting blood samples from 137 vultures and 27 ravens, they found that lead levels in ravens were almost six times higher during hunting season, when they were exposed to animal remains tainted with lead ammunition, than the rest of the year. Vulture's migratory movements meant they couldn't be sampled across seasons, but older vultures tended to have higher concentrations of lead, suggesting that older, more dominant individuals exclude younger birds from foraging on carcasses.
While this may sound like bad news, it means little stands in the way of condor recovery if hunters shift away from using lead ammunition in the region. A statewide ban on lead ammunition in California takes effect in 2019, and West and his colleagues are optimistic that it may lower lead exposure to scavengers if it includes outreach programs to help the state's hunting community through the transition. "Our hopes for condor reintroduction to our area and recovery overall is very high. We are currently going through the National Environmental Policy Act (NEPA) process to select release locations and assess and mitigate impacts to land owners and managers in the region," says West. "The return of condors to the Pacific Northwest, after more than a century-long absence, will be a testament to the ability of federal, tribal, state, and private entities to come together to champion the cause of wildlife, ecosystem, and cultural recovery in our region."
"Northern California still has viable habitat for free-flying California Condors, and these results suggest it is possible to succeed in this region, particularly as a broader switch from lead to non-lead ammunition use is realized," adds to Kelly Sorenson, Executive Director of the Ventana Wildlife Society and an expert on condor recovery who was not involved in the study. "If we fix the lead problem, condors should survive in the wild again without the assistance of people, whether in Northern California or other suitable locations where they are being released."
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"Feasibility of California Condor recovery in northern California, USA: Contaminants in surrogate Turkey Vultures and Common Ravens" will be available September 20, 2017, at http://www.bioone.org/doi/abs/10.1650/CONDOR-17-48.1 (issue URL http://www.bioone.org/toc/cond/119/4).
About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists' Union in 2016 to become the American Ornithological Society. The Condor had the top impact factor among ornithology journals for 2016.