Lead and Wildlife: What’s the Connection?

Just as lead paint poses a threat to human health, lead ammunition threatens our local wildlife.

Ducks that visit hunted areas and accidentally mistake lead shot for food, turkey vultures that feed on carcasses killed by hunters using lead bullets, and worms living in lead-contaminated soils are all examples of how local wildlife is exposed to lead.

Areas with high concentrations of lead shot, including public shooting ranges may pose significant threats to wildlife. In fact, many shooting range managers and shooters are not aware of the problems lead ammunition causes to the environment.

Lead, in soil and water, is a contaminant.

Effects of Lead Shot on Wildlife

Lead changes how an animal’s body produces blood, alters normal behavior patterns, impairs reproduction, and decreases the body’s ability to fight off infectious diseases.

Nowhere is this more apparent than in amphibians. Amphibians, which includes frogs, toads, and salamanders, are considered indicators of environmental quality. Just like a “canary in a coal mine,” frogs signal environmental problems for other plants and animals. But why frogs?

  • Frogs live in the water and on land, so they are exposed to several environments throughout their life cycle.
  • Frogs have permeable skin, which means they absorb air and nutrients through tiny pores in their skin.

Therefore, environmental contaminants that enter a frog’s environment will impact them throughout their entire lifetime. And because frogs can eat contaminants or absorb them through their skin, they are more susceptible to environmental toxins.

If amphibian eggs or tadpoles are exposed to harmful contaminants, such as lead, their growth may be affected. They may become more susceptible to predation, infection or even death.

Case Study: Prime Hook National Wildlife Refuge

Biologists with the US Fish & Wildlife Service Chesapeake Bay Field Office studied frog development on a shooting range near Prime Hook National Wildlife Refuge in Delaware. Lead shot had accumulated over time, and was seeping into nearby wetlands. To determine if the wetlands were contaminated, biologists placed tadpoles in lead-contaminated soils and watched them as they grew. Biologists found that the frogs did not develop normally: their metamorphosis to adult form was either significantly slowed or stopped and many tadpoles had kinked tails. Biologists determined that the shooting range was highly contaminated, and needed to be cleaned up. Since the study was completed, the lead-contaminated soil was removed and the wetlands were restored.

For more information:

US Fish & Wildlife Service Amphibian Declines and Deformities

Sherry Krest
US Fish & Wildlife Service Chesapeake Bay Field Office

Biologists studying frog development
USFWS biologists studying frog development on a shooting range near Prime Hook National Wildlife Refuge in Delaware - Photo, USFWS

Revitalized shooting range, cleaned up, and replanted with native vegetation
After removing lead-contaminated soils on the shooting range, biologists covered the contaminated area and planted native vegetation - Photo, USFWS

Tadpoles exposed to contaminants could have their growth affected
If tadpoles are exposed to harmful contaminants such as lead, their growth may be affected - Photo, USFWS