Differences in Food Hoarding among Six Species of Heteromyid Rodents

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Storing food is an important adaptation of heteromyid rodents to desert environments of southwestern North America. These rodents store seeds in burrows (larder hoarding) and in small, widely scattered caches buried at shallow depths in soil (scatter hoarding). Laboratory trials were done with five species from one site and two species from two other sites to test the hypothesis that larger species would larder hoard relatively more seeds than smaller species. Subjects were tested in arenas consisting of a sand-filled box for scatter hoarding and a nest box for larder hoarding. Chisel-toothed and Merriam's kangaroo rats ( Dipodomys microps and D. merriami ) from one site larder hoarded more than sympatric dark kangaroo mice ( Microdipodops megacephalus ) and long-tailed and little pocket mice ( Chaetodipus formosus and Perognathus longimembris ). Chisel-toothed kangaroo rats larder hoarded more than Merriam's kangaroo rats and little pocket mice larder hoarded more than dark kangaroo mice. These results were consistent with reported information on the relative aggressive behaviors of the species. For subjects from the other two sites, Ord's kangaroo rats ( D. ordii ) larder hoarded more than the smaller Merriam's kangaroo rats. Pocket mice made larger scatter hoards than kangaroo rats and placed these scatter hoards closer to edges and corners of arenas than kangaroo rats. Differences among species in food-hoarding behavior should be considered in future studies of the community ecology of desert rodents.