Wildlife Habitat_Content Page_Disease Lead toxicity

Lead toxicity in wildlife

Lead is a heavy metal that can be highly toxic. It is found in many types of ammunition and fishing tackle. Leaving spent ammunition or tackle can have unintended consequences for wildlife. Wild birds are susceptible to lead toxicity when they consume lead through their normal feeding habits. Lead toxicosis can lead to severe illness and even death. In addition to waterfowl, death from lead toxicity has been documented in Wisconsin in bald and golden eagles, common loons, trumpeter swans, turkey vultures and whooping crane.

Scavengers, such as eagles, can eat lead fragments found in gut piles and carcasses of animals harvested with lead ammunition. Loons pick up small pebbles from the bottom of lakes as a part of their normal behavior to add grit to their ventriculus (stomach or gizzard), and lead fishing weights are the same size as the small stones they often prefer. Trumpeter swans feed by stirring up the bottom of lakes and eat lead fishing weights or spent lead shot pellets that remain in the environment from historic use. The consumed lead breaks down in the stomach and is transported through the blood. The lead is then absorbed into the liver, kidney and bone tissues.

Clinical Signs

Birds exposed to sudden high levels of lead can die suddenly without signs. Birds that suffer from slow, longer-term exposure to lead  can show signs of weakness, loss of muscle mass and fat reserves, green diarrhea, incoordination, paralysis or convulsions. Long-term effects of lead exposure can alter bird behavior and survival of birds.

Management

In 1991, the US Fish and Wildlife Service launched a nationwide ban on lead shot for waterfowl hunting to reduce the number of lead shot falling into waterbodies. Since the inception of dove hunting in Wisconsin in 2003, the DNR has prohibited the use of lead shot for hunting mourning doves on state-managed lands.

There are actions that hunters and anglers can take to reduce the risk of lead toxicity in wildlife. For more information, visit the Midwest Association of Fish and Wildlife Agencies website.

Additional Information