Microhabitat Partitioning between Desert and Merriam's Kangaroo Rat in the Mojave Desert

Desert rodent species may coexist by partitioning habitat or resources. Dipodomys deserti and D. merriami are both granivorous kangaroo rats and co-occur across the Mojave Desert. We hypothesized that D. deserti and D. merriami coexist by using different vegetation and substrate types (microhabitats).  We quantified microhabitat use by both species based on characteristics at trap locations and at burrows on three 0.63-ha grids at Zzyzx, California.  We counted the number of shrubs within 3 m of trap stations where each species was captured, and at 30 burrows of each species. We determined percent cover of plants and substrate at four 0.0625-m² quadrats at each trap and burrow. Captures of D. deserti were clustered along the eastern areas of the grids, where gravel substrate gave way to Aeolian sands, whereas D. merriami was captured across the grids. Capture locations of D. deserti contained significantly more dead plant than those of D. merriami, whereas capture locations of D. merriami had significantly more live plants. Capture locations of D. merriami also had significantly more hard substrates than those of D. deserti, which were very sandy. Substrate at burrows of D. deserti was also significantly sandier than those of D. merriami. Our findings are consistent with previous studies of habitat preferences of the two species and suggest that D. deserti has an affinity for specialized microhabitats than the more generalized D. merriami, which may explain why the two species co-exist in areas where habitat is suitable for D. deserti.