SEED CACHING BY HETEROMYID RODENTS FROM TWO COMMUNITIES: IMPLICATIONS FOR COEXISTENCE

Diversity of species in communities of heteromyid rodents presents a classic problem to ecologists, because species are similar ecologically and share a limiting seed resource. Mechanisms of coexistence considered to date have focused on interspecific variation in ability to exploit heterogeneity in resources caused by environmental factors. An unexplored possibility is that coexistence is promoted by heterogeneity among species in seed-caching behavior. To begin evaluating this possibility, we asked whether coexisting species differ in their propensity to cache and in types of caches made. In an indoor arena, we presented millet seeds to 8 species of kangaroo rats (Dipodomys) and pocket mice (Perognathus and Chaetodipus) from 2 communities, 1 in California and 1 in Arizona. Species within communities differed in amounts of seed consumed and cached per night. Both consumption and caching increased with body mass in a manner similar to whole-animal metabolic rate, suggesting that energetics underl...