Free Lunch, May Contain Lead: Scavenging Shot Small Mammals

Abstract

Scavengers are subsidized by hunting remains worldwide. While most studies focus on carcasses of large mammals, shot small mammals likely provide a significant food subsidy as well. Millions of small mammals are shot each year for damage control and recreation, many being left in the field. Despite this high prevalence of carrion, and the potential for scavengers to ingest residual lead from bullet fragments, the fate of these carcasses is largely unknown. We deployed remote cameras to observe which scavengers consumed shot ground squirrels (Sciuridae spp.) and black-tailed prairie dogs (Cynomys ludovicianus) in 8 locations across Montana, USA. At least 5 species of mammals and 9 species of birds scavenged, including burrowing owls (Athene cunicularia). Scavengers fully consumed 67% of carcasses and partially consumed 9%. Carcasses lasted an average of 24.5 hours before the first scavenger arrived. Of carcasses that were scavenged, mammals ate 16% compared to 84% for birds, with corvids and raptors consuming an equal number of carcasses. Common ravens (Corvus corax) and black-billed magpies (Pica hudsonia) visited the most carcasses and were often the first to arrive. Overall, our results indicate that a diverse scavenger community consumes shot ground squirrels and black-tailed prairie dogs, and consequently, may be exposed to lead from bullet fragments.