Nearly frozen: Overwintering behavior of burying beetles (Silphidae: Nicrophorus marginatus)

Burying beetles, including the federally endangered American burying beetle, are important detritivores that recycle decaying carrion into the ecosystem. Burying beetles overwinter as adults; however, little information is available concerning their behavior or cold-tolerance in northern latitudes.  Sixty tubes, 1.2 meters long and 10 cm in diameter, were sunk into the ground in south-central Nebraska. Two burying beetles, Nicrophorus orbicollis, were added to each tube on October 4, 2011.  Twenty tubes were extracted in January 2012, an additional 20 were extracted in March and surviving beetles were observed in remaining tubes in early April.  Contrary to our hypothesis that burying beetles would bury below the frost-line; our results suggest that burying beetles do not bury deep enough to be below the frost-line.  During the study, on-site ambient temperatures were recorded below -20 degrees C and subsurface temperatures near mean burial depth reached -5 degrees C. The results of this research help illuminate how and where bury beetles overwinter and will clarify the impacts of restoration and conservation efforts, especially in areas of road construction and farm activities as they may impact American burying beetles.