Resource Utilization by Desert Rodents in the Lower Sonoran Desert
1978
Stamp, Nancy E. | Ohmart, Robert D.
Four species of heteromyid rodents were studied in 5 communities in the Lower Sonoran Desert to examine differences in resource utilization by heteromyids in terms of: (1) collection of seed species, seed size and seed type (shrub—tree, forb and grass) and (2) association with amount of perennial cover of habitat. These rodents were not allocating resources by seed species or seed size. These rodents were collecting seeds to some degree by seed type, however, this was related to foraging in particular microhabitats. We found no correlation between numbers of each species of seed in cheek pouch contents and energy content per seed species. These heteromyids were opportunistic in collecting seeds as shown by considerable variation in seed species collected by populations and species among habitatas and seasonal variation in seed species collected. These heteromyids appear to partition seed resources by specializing on particular microhabitats. If these heteromyids use microhabitats optimally as granivores, they cannot allocate resources by seed species, size or type without risking local extinction due to the high variable production of specific seed species and sizes in the desert. The regular distribution of body sizes among heteromyids in a community appears to be a consequence of exploiting particular microhabitats in the desert community rather than allocating resources by seed—size selection.
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