The Occurrence of the American Burying Beetle (Nicrophorus americanus) and Associated Silphid Beetle Community in South Dakota: Implications for Managed Relocation

The American burying beetle, Nicrophorus americanus Olivier (Coleoptera: Siliphidae), is a federally threatened species in the United States, occurring in less than 10% of its historic range. The continued monitoring of extant populations found in South Dakota, the northernmost edge of its confirmed range, is imperative to future conservation efforts, especially with the predicted loss of the species in southern regions because of climate change. Proposed strategies to preserve the species include the reintroduction or translocation of individuals from habitats that have become unsuitable. Beyond adequate habitat and carrion resource requirements, community-level silphid interactions may challenge these efforts because of competition. From 2018 to 2020, we used 80 carrion-baited pitfall traps per year to conduct two 5-day surveys in June and August. A total of 25,923 Silphidae belonging to 15 species were collected in 1200 trap nights. Cumulatively, 1150 N. americanus were captured and marked with 263 recaptures. Like past findings, N. americanus was concentrated in western Tripp County with limited occurrence in Gregory and Todd Counties, suggesting no expansion of their known range in the past decade. Generalized linear mixed-effects models indicated N. americanus abundance was significantly predicted by the co-occurrence of the carrion beetles Oieceoptoma inaequale F. and Oiceoptoma noveboracense Forster, whereas pitfall trap catches dominated by the burying beetle Nicrophorus marginatus F. had predictively less N. americanus. Collectively, these data provide insights into the existing, northernmost N. americanus population dynamics and silphid beetle communities. Concurrent with monitoring extant populations, the characterization of silphid communities that co-occur with N. americanus may provide much-needed information for managed relocation opportunities.