Influence of Substrate Water on the Ability of Rodents to Find Buried Seeds

Foraging success of three species of granivorous rodents (deer mouse, Peromyscus mani-culatus;. Great Basin pocket mouse, Perognathus parvus; yellow pine chipmunk, Tamias amoenus) was determined for seeds of three palatable species (antelope bitterbrush, Purshia tridentata; Indian ricegrass, Oryzopsis hymenoides; lodgepole pine, Pinus contorta) buried in dry or moistened substrates. Rodents found nearly all caches (449 of 450) when seeds were buried in moist substrate, but found only 13.3% of 450 caches buried in dry substrate. This appears to be a consequence of rodents‘ diminished ability to smell seeds in dry substrate, rather than a preference to forage where seeds are easier to detect. Great Basin pocket mice found most (83%) of the caches located in dry substrate, indicating that they may have better olfactory capabilities than do the other species. The ability of desert rodents to find buried seeds in the field may vary as soil water fluctuates. If so, rodent-seed interactions and competitive relations among granivorous rodents may change significantly between wet and dry seasons.