Abstract: A monogamous pair of burying beetles (Necrophorus spp.) prepares a vertebrate carcass as a food source for their young and then protects the carcass and young from aggressive congeners. It was estimated that N. orbicollis males received four times the reproductive benefit on large (27-33 g) as opposed to small carcasses (10-18 g) in the field. Large carcasses were more likely to be taken over by free-flying intruders than small carcasses and the presence of a male parent reduced the probability of such takeovers. A male also decreased the time that a large carcass was vulnerable to a takeover. The presence of a male did not affect the number of larvae produced in field or laboratory experiments or the size of larvae reared in the laboratory. Males provided a longer duration of care when on a large carcass, when larval development was slow, or when the female was removed experimentally. The number of larvae, the number of days spent on the carcass, the mass of the carcass remaining at the end of the trial, female size, male size, burial depth and prior reproduction were not found to have independent effects on the probability of fin-ding the male on the carcass. In addition, males that were allowed to provide care prior to being placed in the field did not show a subsequent decline in reproductive success as compared to males that did not provide prior care.