Does resource availability affect offspring begging and parental provisioning in a partially begging species?

Abstract

In species where parents repeatedly provide their offspring with food, the offspring often communicate their need to the parents. Burying beetles, which breed on a wide size range of carcasses of small vertebrates, are interesting model systems to test theories on begging, because the larvae show partial begging, that is, they obtain food through both signalling to their parents (begging) and feeding directly from the carcass. We manipulated resource availability inNicrophorus vespilloides by providing parents with mouse carcasses spanning a wide size range, and allowing them to rear the larvae that hatched, so that both the amount of resources and the number of siblings varied. Time spent begging by each larva was strongly influenced by the time parents spent near the larvae. Brood size had a nonlinear effect on larval begging, with begging increasing with brood size for relatively smaller broods and decreasing again for larger broods. Carcass size and number of parents present had no effect on begging. Time spent provisioning the larvae by the parents was strongly associated with the time spent begging by each larva. Parents spent more time provisioning under biparental care than under uniparental care, while brood size and carcass size had no significant effect. These findings suggest that the larvae adjust their begging to the behaviour of their parents and the number of siblings, but not to the amount of resources. Furthermore, parents adjust the time spent provisioning to the average amount of begging by each larva in the brood, and not to the availability of resources.