INTERSPECIFIC VARIATION IN THE OLFACTORY ABILITIES OF GRANIVOROUS RODENTS

Olfaction plays an important role in the foraging behavior of rodents, but little is known about how this sense varies among taxa that evolved in different ecological settings. Field experiments were conducted in 10- by 10-m enclosures to test for interspecific differences in foraging success for ponderosa pine (Pinus ponderosa) or sunflower seeds, based on olfaction, of 4 rodent species: 2 heteromyid rodents (Panamint kangaroo rat, Dipodomys panamintinus, and Great Basin pocket mouse, Perognathus parvus) and 2 nonheteromyid rodents (yellow pine chipmunk, Tamias amoenus, and deer mouse, Peromyscus maniculatus). All species found large, shallow caches more frequently than small, deep caches. Chipmunks had the lowest foraging success for buried sunflower seeds under dry conditions. Deer mice did as well as the heteromyid rodents on large shallow caches but found relatively few small, deep caches. The heteromyids were the only species that found small, deep sunflower seed caches under dry conditions, and Panamint kangaroo rats always found more caches than did Great Basin pocket mice. These results confirm that olfaction plays an important role in foraging of rodents for buried seeds and support the notion that the olfactory sense of rodent species has evolved greater sensitivity to seeds in different ecological contexts.