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Portland Audubon releases preliminary results of lead-testing study

April 30, 2014: In January 2013, the Audubon Society of Portland launched a study of lead’s impact on Oregon raptors, Turkey Vultures and ravens, the local birds most likely to eat the remains of animals shot with lead ammunition. Audubon has released a preliminary report on findings from the study’s first year, and in keeping with the weight of evidence from lead research conducted in other locations, the results clearly indicate that a ban on the use of lead ammunition for hunting should be considered in Oregon.

Portland Audubon releases preliminary results of lead-testing study

An Audubon Society of Portland veterinarian holds a Bald Eagle that was treated at the Wildlife Care Center for lead poisoning - Tinsley Hunsdorfer

April 30, 2014: In January 2013, the Audubon Society of Portland launched a study of lead’s impact on Oregon raptors, Turkey Vultures and ravens, the local birds most likely to eat the remains of animals shot with lead ammunition. Audubon has released a preliminary report on findings from the study’s first year, and in keeping with the weight of evidence from lead research conducted in other locations, the results clearly indicate that a ban on the use of lead ammunition for hunting should be considered in Oregon.

The study tracks the level of lead in the blood of raptors, Turkey Vultures and ravens admitted to the Audubon Society of Portland’s Wildlife Care Center and to Blue Mountain Wildlife, a wildlife rehabilitation center in Pendleton, Ore. Whenever the facilities receive one of these avian scavengers, staff members draw a blood sample and run it through an on-site machine that tests for the toxic metal.

Audubon tested more than 200 birds in 2013, and seven had elevated lead levels: four Red-tailed Hawks, a Bald Eagle, a Cooper’s Hawk and a Great-horned Owl. These numbers are in keeping with Audubon researchers’ initial prediction that the study would find lower lead levels in birds from the Portland-metro region, where very little big game hunting takes place, relative to those from rural locations.

To examine this difference in urban and rural lead levels, Audubon compared results from the Wildlife Care Center to data collected at Blue Mountain Wildlife, which accepts birds from rural locations in Oregon, Washington and Idaho. While Audubon only began testing birds in 2013, Blue Mountain was able to provide lead level information for birds admitted from 2010-2013.

During this time, more than 100 avian scavengers were tested at Blue Mountain using the same equipment and methods as those used by Audubon. Significantly more birds had elevated lead levels – 29 in total – and Golden and Bald Eagles were the most frequently affected species, with 48.6 percent of eagles showing elevated levels (from both facilities combined, 41 percent of eagles had elevated levels). Most of the birds with elevated levels were admitted for treatment in late winter and early spring, a time period that correlates with the big game hunting season and peak coyote hunts – and the accompanying discharge of lead ammunition into the environment.

Upon impact, lead ammunition can shatter into many small pieces. When avian and other scavengers eat the remains of an animal that has been shot with lead, they ingest fragments of the toxin along with the carcass. It only takes a tiny amount of lead to poison animals, causing immense suffering and sometimes death.

Existing lead regulations and ammunition options suggest that a ban on the use of lead ammunition for hunting in Oregon would be effective, and that its implementation would be successful. Alternatives to lead ammunition for big game hunting are widely available, and many hunters have already made the switch. In 1991, lead ammunition was banned for waterfowl hunting across the U.S.; the transition to non-lead ammunition went smoothly, and studies indicate millions of birds have been spared death from lead poisoning as a result. The state of California also recently banned the use of lead ammunition for all hunting, effective 2019, which will aid the recovery of the critically endangered California Condor. Lead poisoning is the leading cause of death for adult condors.

It’s time to make Oregon safer for wildlife and people by removing lead from the environment.

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The study’s preliminary report was prepared by Audubon Society of Portland avian biologist Joe Liebezeit and veterinarian Deb Sheaffer. Audubon will continue its lead study for at least two more years to bolster sample size, and may include test results from additional wildlife rehabilitation centers in the region. Read the preliminary report and learn more about lead in the environment. The Audubon Society of Portland thanks the Oregon Zoo for providing support for this project.


Bald Eagle receives treatment for lead poisoning in the Wildlife Care Center - Tinsley Hunsdorfer
Portland Audubon staff and volunteers prepare to draw blood from a Bald Eagle with lead poisoning - Tinsley Hunsdorfer
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