Responses of seed-hoarding behaviour to conspecific audiences in scatter- and/or larder-hoarding rodents

Abstract

In rodents, the presence of conspecifics may trigger changes in food-hoarding behaviour when the risk of pilferage is perceived to be high. It is not clear how hoarding intensity and hoarding patterns (scatter- or larder-hoarding) of rodents change in the presence of conspecific audiences or if the nature of the change is different between sexes, or influenced by body size. We investigated these questions in Korean field mice (Apodemus peninsulae) (KFM, showing both scatter- and larder-hoarding behaviours) and Chinese white-bellied rats (Niviventer confucianus) (CWBR, showing larder-hoarding behaviours only) through carefully controlled experiments in outdoor enclosures. We observed the seed-hoarding behaviour of focal females and males of each species in the presence of a conspecific audience of the opposite sex, same sex, and alone (control treatment). We found both rodent species increased hoarding efforts when faced with an increased pilferage risk (presence of audiences), supporting the pilferage tolerance hypotheses or forage competition hypotheses. In contrast with previous studies, we found potential pilferage risk can result in a KFM shift from scatterhoarding to larder-hoarding, supporting the larder defence hypotheses, not the catastrophic avoidance hypotheses. However, the relationship between hoarding patterns, and body size or sex, is rather complex and requires further investigation.