The use of spatial memory for cache management by a scatter-hoarding rodent

Abstract

Some scatter-hoarding species show a cache recovery advantage over naïve animals, suggesting that they rely on spatial memory of cached seeds. However, the extent to which spatial memory is used in recovery or management of caches or the pilferage of others’ caches is not known. We used Siberian chipmunks, Tamias sibiricus, to investigate this question in large, semi-natural enclosures. We found that individual chipmunks (1) clearly distinguish caches they made from those made by naïve conspecifics (or observers); (2) that this species will consistently avoid its own caches while pilfering caches of others; and (3) that this species is likely to maintain a recovery advantage when scatter-hoarding. Our study also suggests that this process of cache management is facilitated by spatial memory of caches. In a final experiment, chipmunks remembered and distinguished between their own caches and other cached nuts for at least 3 days. Our study suggests that spatial memory for cached seeds is necessary for scatter-hoarding animals to not only retrieve the food they buried but also for long-term management of caches. We argue that the behavior of avoiding one’s own caches in favor of foraging for other food stores observed here could benefit cache survival and indirectly affect the processes of seedling establishment.

Significance statement

Our study shows that spatial memory of individual cache sites is necessary for scatter-hoarding animals to not only retrieve the food they buried but also for management of caches over time. We demonstrate that Siberian chipmunks will first bury caches and then avoid their own caches in subsequent foraging, pilfering, and caching activity, suggesting that they use spatial memory to conserve their own caches. The study provides further insight into the use of memory in the scatter-hoarding process as well as the mechanisms of animal-mediated seed dispersal by scatter-hoarding animals.