| The largest and most dominant kangaroo rat species in the Chihuahuan Desert is the banner-tailed kangaroo rat (Dipodomys spectabilis ). This keystone species constructs mounds containing a complex burrow system around which their ecosystem engineering activities are centered. I studied a population of banner-tailed kangaroo rats at the Sevilleta National Wildlife Refuge, New Mexico from 2005--2009. Specifically, I examined how banner-tailed kangaroo rats: (1) modify their mounds in response to seasonal conditions (2) spatially affect harvester ants (Pogonomyrmex rugosus ) through ecosystem engineering activities and (3) differ in timing of natal dispersal between sexes. I used mark-recapture, genetic, experimental, and spatially-explicit methods to address these areas of interest. I observed that kangaroo rats remodeled their mounds seasonally in relation to changes in predation risk, seed spoilage risk, and metabolic costs. My results documented an additional keystone effect of banner-tailed kangaroo rats in the Chihuahuan Desert, a facilitatory impact on the spatial structure and dynamics of harvester ant colonies. I also experimentally determined that physiological cues influence timing of natal dispersal in males and females differently. |
