Seasonal link between food hoarding and burrow use in a nonhibernating rodent

Abstract

Food-storage behaviors can be plastic for food-hoarding species. Some hibernating, granivorous rodents switch seasonally from scatter hoarding (storing food in small, separate caches) to larder hoarding (concentrating food in a central location). To date, little is known about seasonal food-hoarding behaviors of free-living rodents that forage and store food year-round (i.e., nonhibernators). Using direct observations, radiotelemetry, and tracking with fluorescent powder, we discovered a striking seasonal shift in food-hoarding behaviors for Ord's kangaroo rat (Dipodomys ordii), a nonhibernating rodent in a region with dramatic seasonal climate (i.e., the Great Plains of the United States). In winter, D. ordii almost exclusively larder hoarded seeds in burrows and used a single burrow, which is consistent with the larder-defensibility hypothesis of food storage. The lack of suitable sites to scatter hoard due to snow cover and frozen soils likely contributed to larder hoarding in winter. In summer, most individuals scatter hoarded near seed sources, which is consistent with the rapid-sequestering hypothesis of food storage. In summer, individuals also commonly used multiple burrows, and differences in food-hoarding and burrow-use behavior were observed between sexes and between reproductively active and inactive females. By scatter hoarding and using multiple burrows in summer, kangaroo rats likely reduce costs associated with defending larder hoards while increasing benefits associated with reproduction. The seasonal interplay between food hoarding and burrow use by D. ordii appears to be important for securing and maintaining resources throughout the year in a temperate environment.