The distribution and behavior of Peromyscus maniculatus gracilis and Peromyscus leucopus noveboracensis (Rodentia: Cricetidae) in a southeastern Ontario woodlot

摘要: P. m. gracilis and P. l. noveboracensis are sympatric in southeastern Ontario and some adjacent areas. Similar in appearance, food and breeding habits, and frequently cohabiting certain forests, they may occupy identical niches, contrary to the competitive exclusion principle. A 12-week summer live-trapping study in a woodlot containing upland, mixed, and cedar forest associations showed that although most of their population characteristics were similar, their local distributions, densities, and certain behaviors differed. Noveboracensis inhabited upland forest but avoided mixed and cedar forest associations apparently because suitable refuges were lacking. The less dense population of gracilis was ubiquitous; gracilis and noveboracensis cohabited the upland forest. On release from traps noveboracensis sometimes 'froze' before darting in a zigzag manner to nearby cover, and ran up trees significantly more than gracilis, which usually ran instantly, rapidly, and directly to a more distant ground refuge. Low densities of both species reduced competition for available food and refuges. This may have facilitated cohabitation in the upland forest where differential use of ground- and tree-holes also contributed to reduction of competition and thus to compatibility. Coexistence may be transitory there; with denser populations, potential competition might be minimized by emigration of the more exploratory gracilis.