Conspecific pilferage but not presence affects Merriam's kangaroo rat cache strategy

Abstract

We investigated the effects of pilferage on caching behavior in the Merriam's kangaroo rat by manipulating two factors associated with pilferage: the presence of a conspecific, and the opportunity for pilferage. In one experiment we assessed animals in either "Stealer" or "Victim" roles and measured changes in caching, space use, and behavior after caches were pilfered. Victims shifted from a majority scatter-hoarding to a majority larder-hoarding strategy after their caches were pilfered by the Stealer. In Experiment 2, we measured changes after exposure to a conspecific when there was no pilferage, with or without prior exposure to pilferage from Experiment 1. Merriam's kangaroo rats were vigilant when a conspecific was present, but did not change cache strategy. Prior exposure did not have any major effect on caching or behavior. Food storage is an economic decision that is often made by a solitary forager. Our results suggest that social competition nonetheless influences such economic decisions, even in a nonsocial forager.