An oak (Quercus agrifolia) specialist (Neotoma macrotis) and a sympatric generalist (Neotoma lepida) show similar intakes and digestibilities of oak

Dietary specialization is thought to be rare in mammalian herbivores as a result of either a limitation in their detoxification system to metabolize higher doses of plant secondary compounds or deficiencies in nutrients present in a diet composed of a single species of plant. Neotoma macrotis is an oak specialist, whereas Neotoma lepida is a dietary generalist when sympatric with N. macrotis. We hypothesized that N. macrotis would have a higher tolerance for and digestibility of oak. We determined the two species' tolerances for oak by feeding them increasing concentrations of ground oak leaves until they could no longer maintain body mass. The highest concentration on which both species maintained body mass was 75% oak. There were no differences between the species in their abilities to digest dry matter, nitrogen, or fiber in the oak diets. The species' similar tolerances for oak were probably due to their similar abilities to digest and potentially assimilate the ground oak leaves.