THE DECISION TO FEED BY A SCAVENGER IN RELATION TO THE RISKS OF PREDATION AND STARVATION

Recent theoretical models have considered how nutritional status and p redation risk affect the decision by an individual to forage. We consi der the feeding behaviour of a scavenger under risk of predation. The intertidal gastropod Nassarius dorsatus Roding was used to test the fo llowing hypotheses: (1) a damaged conspecific should be a less preferr ed meal than a damaged predator or another species; (2) a scavenger sh ould be able to discriminate between a damaged conspecific in the pres ence and one in the absence of its predator, preferring the latter; an d (3) the decision by a scavenger to feed should reflect a trade-off b etween nutritional status and the above preferences. Results from the laboratory and field were consistent with predictions. Two hypotheses are suggested from the work: scavengers may generally be less willing to feed on carcases of con-specifics than on those of other species, a nd intertidal scavengers may commonly face a relative or absolute shor tage of food.