Encounter Competition between a Cougar, Puma concolor, and a Western Spotted Skunk, Spilogale gracilis

Abstract

Encounter competition occurs frequently over food resources and may include kleptoparasitism, where scavengers usurp prey killed by carnivores. Scavenging may have important adverse effects on carnivores and may result in higher than expected kill rates by predators. Using camera traps placed on a Black-Tailed Deer (Odocoileus hemionus columbianus) carcass killed by a Cougar (Puma concolor) in California, we observed a series of encounters in which a Western Spotted Skunk (Spilogale gracilis) temporally usurped the carcass from the Cougar. The Western Spotted Skunk also successfully defended the carcass when the Cougar returned and attempted to feed. The Spotted Skunk was about 1% of the mass of the Cougar. Our observation is the largest reported size differential of a mammalian species engaging in successful encounter competition.