Salivary Water Loss during Seed Husking in Deer Mice and Great Basin Pocket Mice

Abstract

Salivary water loss during seed husking was examined in two rodent species, deer mice (Peromyscus maniculatus) and Great Basin pocket mice (Perognathus parvus), feeding on four species of seeds (lodgepole pine [Pinus contorta], antelope bitterbrush [Purshia tridentata], Jeffrey pine [Pinus jeffreyi], and sunflower [Helianthus annuus]). Great Basin pocket mice, a desert-adapted species, lost little or no salivary water while husking seeds. Deer mice, however, lost significant quantities of salivary water to all four seed species. This apparently occurred as moist surfaces of the lips and tongue contacted the hygroscopic seed coats during seed manipulation and husking. Relatively small or hygroscopic seeds, such as those of lodgepole pine and antelope bitterbrush, impose a greater relative cost in salivary water loss to deer mice than do larger seeds. Heteromyid rodents appear to have specialized lips that isolate the moist surfaces of the mouth from seeds. Furlined cheek pouches and specialized lips may as...