Iowa: Lead poisoning in bald eagles is a growing concern among eagle protection agencies. Eagles are poisoned by eating deer carcasses that have fragments of lead slugs in them. These deer have been shot by hunters but not retrieved.
"They started testing [sick eagles'] blood and they are finding out that they had very high levels of lead — a neurotoxin," said Plymouth County Naturalist, Victoria De Vos. "It was basically paralyzing them in different ways. Eagles aren't very delicate eaters. They don't pick through their food and see what they're eating."
"Hunters have been harvesting more deer in Iowa, and most deer in Iowa are shot with a lead slug," said Kay Neumann from Saving Our Avian Resources. She and others are urging hunters to replace lead ammunition with copper, which doesn't poison wildlife.
When a lead slug enters a deer, parts of it shatter and spread out in the animal. Even the tiniest pieces are dangerous for eagles. Two hundred milligrams --the size of a baby aspirin-- is lethal. Lead mimics calcium, so eagles' bodies (and human bodies) reasily absorb it and send it into the bones, blood and neurological system.
Already this season, Neumann has treated four bald eagles with lead poisoning.
"When they come in, they can't stand up, their stomach lining is ulcerated and they're puking green, some come in blind and they're usually gasping for air — the lead interferes with the oxygen in their blood, so they're starting to suffocate," Neumann said. "The eagles' brains swell, some have seizures ... it's horrible."
Last year in Iowa, 27 of 40 bald eagles treated at Iowa centers had lead poisoning. Since most sick eagles aren't brought in for care, Neumann estimates up to 176 of Iowa's eagles could have been affected last year.
"That's half of our breeding population," she said.
Eagles aren't the only ones eating lead in their meat. Humans may also be eating venison with lead fragments. Children are especially susceptible to lead poisoning. High levels can lower their IQ and cause attention deficit disorder or worse. Lead also causes diseases in adults, like kidney failure.
The treatment for both eagles and humans is chelation.
Chelation is a four-week process of continually cleaning the blood. Even with treatment, the eagles may still die or never fully recover. "Most of these eagles come in with really high levels," Neumann said. "Most are not making it."
Many states are pushing harder for non-lead ammunition, but Neumann said the change isn't happening fast enough. She expects to see more lead-poisoned eagles with numbers peaking in March.
"Northwest Iowa is a travel pathway for eagles," she said. "As they cut cross country away from the reservoirs heading north, they scavenge more."
De Vos said the lead poisoning seen in eagles "is a shame.""To have bald eagles just off the endangered species list, and now this," De Vos said. "It's not good."