Experimental Examination of Nest‐Site Segregation by Two Peromyscus Species

The role of interspecific competition for nest sites in the coexistence of the white—footed mouse (Peromyscus leucopus noveboracensis) and the cloudland deermouse (Peromyscus maniculatus nubiterrae) was experimentally investigated in the montane forests of southwestern Virginia. Radiotelemetry was used on control grids, with both species present, and reciprocal removal grids to contrast nest—site selection with and without contraspecifics present. On control grids, Peromyscus maniculatus used only arboreal nests while P. leucopus used both ground and arboreal nests. In addition, relative to P. maniculatus, those P. leucopus which did select arboreal nests, used lower cavities and trees of smaller diameter at breast height (dbh). These results provide strong evidence for vertical nest—site segregation, and confirmed observations from previous studies. Though both species demonstrated shifts in nest selection between treatments in the removal experiment, the analysis of the P. maniculatus response was statistically suspect and both responses appeared to be ecologically insignificant (that is, shifts were not towards the type of nest site used by the removed species). Additionally, home range analysis and examination of nest availability suggest that large portions of suitable habitat on each grid may not have been used and that nest sites were not a limiting resource. We suggest, therefore, that interspecific competition for nest sites was probably not important to co—existence during the course of the study.