ABSTRACT

Burying beetles (Coleoptera: Silphidae: Nicrophorus) exhibit elaborate biparental care. Males and females independently search for small vertebrate carcasses, which serve as the sole food source for developing young. Both parents prepare the carcass for burial, excavate a cavity in the carcass within which the young feed, provision the young during the early stages of their development, and protect them from conspecific and interspecific predators and competitors. Carrion is an extremely nutrient–rich resource, but it can vary greatly in quantity and quality, and owing to its rarity and ephemeral nature, its occurrence is highly unpredictable. We propose that many of the sexual and parental behaviors of Nicrophorus can be regarded as adaptations to the unique problems posed by these resource features. Competition for carrion is intense; consequently, traits that help reduce or eliminate competition, such as carcass burial, should increase reproductive success.

Competition among burying beetles is manifest in inter– and intraspecific aggressive interactions that can escalate into damaging fights. However, losers of contests over carcasses can adopt alternative reproductive tactics: subordinate females can leave some young to be cared for by a dominant female, and subordinate males can sire offspring by surreptitiously mating with the resident female. Males can also inseminate females without having found a carcass, but the number of offspring resulting from these matings is small relative to that of parental males on carcasses.