Cache placement near nests by a multiple-prey loader, the Siberian chipmunk

Abstract

The rapid sequestering hypothesis predicts that scatter-hoarding animals quickly sequester food items by storing seeds in caches near seed sources to reduce competition. However, tests of this hypothesis usually use food-hoarding animals with a single load or a small load size. How multiple-load animals place their caches between food sources and nests remains largely unknown. Here, we hypothesized that multiple-load animals, compared to single-load animals, may not necessarily sequester food items but adopt alternative hoarding strategies due to their multiple-load ability. In this study, we presented seeds at different distances from the nests of the multiple-loading Siberian chipmunk, Tamias sibiricus, and mapped the spatial distribution of their caches in multiple-compartment enclosures to test our hypothesis that a multiple-prey loader will consistently establish caches near nests rather than rapidly sequester near the seed source. By using multiple-compartment enclosures with different distances between the seed source and nests, and given potential intra- and interspecific competition, we found chipmunks consistently placed their caches near nests but away from the seed source. Cache placement near nests may serve as an alternative strategy that not only guarantees a maximum harvest rate at the seed source but also ensures effective cache defence near nests. Moreover, scatter-hoarding seeds near nests may alternatively guarantee a food supply if larder-hoarded seeds are depleted or lost. Unlike seeds sequestered near food sources, caches near nests imply long dispersal distances for seeds in our study. Therefore, scatter hoarding by multiple-prey loaders is expected to be ecologically important for the structure and function of tree communities, especially in ecosystems in which seeds depend on food-hoarding animals for dispersal and germination.