Bald Eagles Highest Lead Risk in NY

Bald eagles highest lead risk of NY deer scavengers

Peer-Reviewed Publication

Cornell University

CORNELL UNIVERSITY MEDIA RELATIONS OFFICE

FOR RELEASE: Sept. 11, 2024

 ITHACA, N.Y. - A new study from Cornell University and the New York State Department of Environmental Conservation (DEC) shows bald eagles are the most vulnerable to illness or death from “bullet-derived lead,” and the best bioindicator for ongoing monitoring of the hazard, although they are hardly alone.

Analyzing images collected from game cameras across the state, researchers documented a parade of species – 14 birds and 17 mammals, from American crows to Virginia opossums – that fed on deer carcasses and gut piles.

“A surprising number of species are at risk, and we can use bald eagles to continue to monitor lead issues because they are quite vulnerable,” said Krysten Schuler, a wildlife disease ecologist who directs the Cornell Wildlife Health Lab and co-authored the study. “With this list, we’re expanding our lead testing to more species and will think more broadly about lead exposure in these animals over time.”

To assess the risk to each species, the researchers considered their numbers, physical traits and opportunity to scavenge. Turkey vultures, for example, are less exposed because they are absent during portions of New York’s hunting season, as are some hibernating animals. The team concluded that bald eagles are the most vulnerable to lead poisoning from bullet fragments, followed by golden eagles (not common in New York), American goshawks, American crows and common ravens.

Used by most deer hunters, lead bullets shatter on impact into hundreds of fragments and particles that can spread well beyond the wound channel. A fragment smaller than a grain of rice can kill an eagle, and no amount of the neurotoxin is considered safe for humans – particularly pregnant women and children – who might unwittingly consume it in game meat.

Prior research by Cornell and DEC collaborators found lead exposure from hunters’ bullets to be widespread among bald eagles, with nearly 40% of the study sample suffering from toxic levels. In the northeast and in New York, researchers estimated that lead poisoning had slowed bald eagles’ growth rate by about 5%, limiting their resilience to other threats.

In a 2022 report, the Lead Ammunition Working Group encouraged hunters to choose non-toxic bullets, or to remove or bury carcasses and gut piles that attract eagles and other scavengers. The DEC has incorporated information about lead alternatives into hunting education courses and shared “Your Choice of Ammunition,” a Cornell-produced, evidence-based video featuring hunters and instructors. The state also implemented a pilot rebate program for non-lead ammunition that is now available statewide.