Comparison of reproductive success of in-situ burial versus the use of abandoned burrows for carcass interment by Nicrophorus investigator (Coleoptera : Silphidae)

An alternative burial behavior observed in Nicrophorus, namely the use of a bandoned burrows (holes) for carcass interment, was studied in Colorado. In 1998 and 1999, 50 carcasses of native rodents were placed in meadow habita ts known to be preferred by Nicrophorus investigator for carcass burial and rearing young. In 1998, carcasses were placed <20, 50, 100, and >200 cm fr om holes. In 1999, carcasses were placed either <120 or >100 cm from holes. In 2000, 40 pairs of beetles were provided carcasses in screened container s. Containers were assigned to one of two treatments: smoothed soil or hole . Carcasses were checked daily and carcass movement, burial, and the use of the nearby holes were noted. Broods were collected and weighed 14 days aft er interment. In the field, adult beetles dragged carcasses to nearby (20 c m) holes in 73% of burials, this percent decreased with increased distance to the hole. Time to interment was less for those carcasses moved to nearby holes. The proportion of successful broods (larvae present in buried carca sses) was significantly higher for those carcasses dragged to holes. For su ccessful broods, no differences in larval size or number were found. The de nsity of burrow openings was approximate to3 holes/m(2). The results indica te that burrowing rodent activity may have an indirect positive effect on N icrophorus reproductive success.