Stacking of seeds changes spoilage dynamics of food caches of the banner-tailed kangaroo rat (Dipodomys spectabilis)

We report a previously undescribed seed-storing behavior of banner-tailed k angaroo rats (Dipodomys spectabilis) that reduces losses to microbes. D. sp ectabilis cuts upper stems of the grass Sporobolus cryptandrus into 3- to 5 -cm sections that we refer to as seed stems. Seeds within these seed stems remain attached to their rachis; and are protected by an enveloping leaf. M ost seed stems are bundled together tightly in packs of about 50 to several hundred individual sterns and jammed vertically into cul-de-sacs excavated in the walls of their burrows. This behavior reduces rate of infection of seeds by fungi and also may reduce number of seeds pilfered by arthropods. Furthermore. compared with seeds of S. cryptandrus housed in middle section s of seed stems, those housed in the ends had a higher rate of infection. S imulated seed stems of wheat straw containing seeds of white millet (Panicu m miliaceum) had a lower rate of infection and fewer species of fungi than seeds only protected by wire mesh. Seeds closer to the top of the simulated seed steins were more likely to be infected and had more species of fungi. Community structure and dynamics: of microfungi also appeared affected by the protective layering of seed stems. We suggest that D. spectabilis manag es the structure, and perhaps dynamics, of communities of microbes within t heir food caches by modifying position, location, or organization of food i tems.