Recreational Shooting of Prairie Dogs: A Portal for Lead Entering Wildlife Food Chains

Abstract

Abstract: Although lead shot has been banned for waterfowl hunting in North America, some predators continue to exhibit elevated lead burdens, which has been attributed to ingesting metallic lead from other projectiles. Few studies have investigated residual lead fragments in hunted upland animals. Therefore, specific portals for lead entering wildlife food chains remain largely unknown. Prairie dogs (Cynomys spp.) are shot for recreation with minimal regulation in western North America. Because recreational shooters mostly use expanding bullets and rarely remove or bury carcasses, shot prairie dogs could make lead accessible to predators and scavengers. To determine whether and to what degree shot prairie dogs carry lead fragments, we analyzed carcasses shot by recreational shooters with 2 bullet types. Bullet type influenced the probability of bullet fragments being retained in carcasses; 87% of prairie dogs shot with expanding bullets contained bullet fragments, whereas 7% of carcasses shot with non‐expanding bullets did. The amount of bullet fragments per carcass also differed between bullet types; carcasses shot with expanding bullets contained a mean of 228.4 mg of the lead‐containing bullet core and 74.4 mg of the copper‐alloy jacket, whereas carcasses shot with non‐expanding bullets averaged only 19.8 mg of the core and 23.2 mg of the jacket. Lead fragments in carcasses shot with expanding bullets were small in size; 73% of all lead mass in each carcass was from fragments that weighed <25 mg each, small enough to be easily ingested and absorbed by secondary consumers. The amount of lead in a single prairie dog carcass shot with an expanding bullet is potentially sufficient to acutely poison scavengers or predators. Therefore, shot prairie dogs may provide an important portal for lead entering wildlife food chains and may pose risks to raptors and carnivores. Managers should consider measures, such as using non‐expanding or lead‐free ammunition, to reduce the likelihood of lead consumption and poisoning in upland wildlife.