It's about to be deer hunting season in Minnesota, and that brings a major health risk for the state's bald eagles: lead poisoning from bullets.
About 90 percent of bald eagles received by the University of Minnesota's Raptor Center have elevated levels of lead in their blood. Of those birds, at least a fifth have lead levels high enough to cause poisoning.
However, hunters can mitigate the risk to eagles by switching to copper ammunition.
Lead poisoning can be fatal for bald eagles. Ammunition with lead is "an important, if not the primary, source of lead exposure for bald eagles," according to the Raptor Center.
Using lead ammunition on federal land is illegal following a directive from President Barack Obama's administration shortly before he left office.
Minnesota has banned lead shot for hunting waterfowl since 1987. The Department of Natural Resources has considered expanding lead ammo bans, but hunters have protested.
Firearms deer season starts Nov. 4 in Minnesota.