Abstract. 1. Burying beetles are carrion feeders that specialize on small carcasses. We investigated interactions among congeners at two sites in Michigan, U.S.A., that differ in both number and relative proportion of species. 2. Intra‐ and interspecific competition for carcasses is intense. The majority of carcasses are found within 24 h of their placement. 3. Competition between N.arbicollis and N.defodiens is temperature dependent. N.orbicollis can displace N.defodiens on single carcasses, but requires warm temperatures to find the carcasses. Cool weather therefore serves as a refuge for N.defadiens. 4. The southern edge of N.defodien's geographical range is probably determined by competition with N.orbicollis. 5. N.sayi and N.tomenrosus are spring and autumn breeders respectively, and rarely interact with each other or the other two species. Nevertheless, interspecific competition is the most likely evolutionary force leading to seasonal segregation.

1. The discovery and utilization of small carcasses by burying beetles (Silphidae, Nicrophorus) was studied by placing dead mice at random points on large grids at two Iocations in Michigan, U.S.A.2. The majority of mice are found within 24 h by more beetles than ultimately will utilize the carcass. If a carcass is likely to be usurped by a larger species of beetle or by a vertebrate, then intraspecific competition may be postponed until the carcass is concealed and buried.3 . Both males and females practice parental care. Maturing broods are tended by no adults, a single female, a singIe male, or a male-female pair. No differences in brood success were observed among these categories. 4. The female lays a larger clutch than ultimately will survive. Brood size is regulated after the egg stage, such that offspring number varies, but individual offspring size does not. 5. A large amount of unexplained variation exists in brood size, in both the laboratory and the field. This variation is probably caused by the environment, and not the reproductive physiology of the beetles. Competition with microbes is a likely candidate. 6 . Differences exist not only between Nicrophorus species, but also between localities for a single species, suggesting adaptation to local environments.

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