Stephens' Woodrat, a Dietary Specialist

The feeding biology of Stephens' woodrat ( Neotoma stephensi ) was studied in juniper woodlands in Arizona. Microscopic examinations were made of fecal samples from live-trapped animals, observations were made on foraging behavior, and data on plant communities occupied by this woodrat were gathered. Stephens' woodrat is a dietary specialist, unique in its ability to utilize juniper throughout the year. Some 90% of the diet is juniper: foliage is most important, but male and female cones are also eaten. This woodrat is a highly selective central-place forager, feeding repeatedly on certain individual junipers and avoiding others. Such finely tuned foraging probably facilitates the exploitation of junipers with unusually low levels of defensive, digestibility-reducing chemicals, and may be the key to this animal's success as a juniper specialist. Stephens' woodrat may be considered a relict species, largely restricted to areas supporting vestiges of a xeric juniper woodland that in the early Holocene was widespread in the southwestern United States.