Biotic and Abiotic Factors Affecting Abundance of the American Burying Beetle, Nicrophorus americanus

Abstract

The American burying beetle (ABB) Nicrophorus americanus Oliver (Coleoptera: Silphidae) is one of several species of carrion beetles and is listed as endangered in the United States. Previous research suggests that ABB population numbers have been reduced by 90% across its former range. These beetles require vertebrate carcasses for feeding and reproductive purposes. Although ABB will utilize any size carcass for feeding, conventional wisdom indicates that 80-100 gram carcasses are optimal for reproduction. Studies aimed at elucidating biotic and abiotic factors influencing the survival of ABB are spurious. I investigated several factors potentially affecting ABB populations, including small mammal abundance, competition from vertebrate scavengers for carrion resources, and several habitat characteristics. In addition, I attempted to determine if ABB exhibit preference regarding carcass body size for breeding. Results indicate a positive relationship between ABB and the presence of mice and rats. Variables associated with ABB presence were biomass of mice, catch-per-unit-effort of mice, percentage of ground cover that was forbs and grass, low overnight temperature, and month. Competition studies indicated that scavengers are far more successful than beetles in obtaining carcasses, with 89% and 50% of carcasses being scavenged in 2013 and 2014 respectively. Lastly, beetles chose rats sized 100-160 g in 32% trials examining carcass size preference.