Food habits of two sympatric species of Peromyscus (rodentia : cricetidae )

Peromyscus leucopus novaboracensis and P. maniculatus Nubiterrae are two cricetid species which coexist in the area of Mountain Lake Biological Station in Giles County, Virginia. Many recent studies have been done with these mice to distinguish between alternative mechanisms for mediating their coexistence. Individual studies have examined vertical habitat partitioning (Harney 1983), food limitation (Gerzoff 1984), nest site use (Wolff and Hurlbutt 1982), and interspecific aggression (Wolff et al. 1983). All these studies have shown that these Peromyscus species are extremely similar and exhibit broad niche overlap.

The objectives of this study were to determine the seasonal food habits of Peromyscus leucopus and P. maniculatus in the Mountain Lake area and to assess quantitatively their diet similarity. In a cafeteria-style food preference study, the two species demonstrated equally high preferences for arthropods and fruit and highly similar preferences for vegetable matter and fungi. After examining the stomach contents of 109 P. leucopus and 70 P. maniculatus snap-trapped between June 1981 and February 1982, the overall diets of the two species showed no significant difference (MANOVA F=1.160, P > 0.200). Both species demonstrated seasonal changes in their diet, but the species by season comparison showed their seasonal diets to be highly similar.

Both the cafeteria-style food preference study and the food habits study show that these two congeneric species eat the same foods, in the same proportions, and with the same preference when they coexist. While this demonstrates that the potential for competition is great, it does not answer the question of how they coexist, because it appears that the food resource, as well as other resources, is not partitioned.