Lead continues to be a health risk for big birds in the Portland area and especially for those in rural Oregon, preliminary results of an Audubon Society of Portland study show.
The study tracks levels of lead in the blood of raptors, turkey vultures and ravens admitted to the society's Wildlife Care Center in Portland, and of avian scavengers admitted to Blue Mountain Wildlife, a rehabilitation center in Pendleton.
Most birds with elevated lead levels were rescued and brought to the two care centers during late winter and early spring, the seasons that correlate with big-game and coyote hunting seasons and during which lead ammunition is discharged into the environment.
Conservationists are increasingly concerned about birds poisoned from ingesting lead fragments while feeding on animals killed with lead ammo, or on the gut piles left behind by hunters.
Lead ammunition was banned for waterfowl hunting nationwide in 1991. California's new ban on lead ammunition for all hunting will go into effect in 2019.
Of the more than 200 birds Audubon tested in 2013, seven had elevated lead levels. They included four red-tailed hawks, a bald eagle, a Cooper's hawk and a great-horned owl.
Blue Mountain tested more than 100 birds between 2010 and 2013 and 29 had elevated lead levels. Golden eagles and bald eagles were the species most frequently affected.
Audubon expects to continue the study for at least two more years.
The study was funded, in part, by a grant from the Oregon Zoo's Future for Wildlife program.
-- Katy Muldoon