Relationships of deer mouse movement, vegetative structure, and prevalenceof infection with Sin Nombre virus

The effects of vegetative structure on movement of deer mice (Peromyscus ma niculatus) were examined in two distinct vegetation associations, one near Hesperus and the other near Molina in western Colorado (USA) from June-Octo ber 1994 to October 1998. We monitored movement by live-trapping small mamm als within Gambel's oak/mixed-grass (Hesperus) and sage brush/juniper (Moli na) vegetation types. Vegetative structure differed between the sites with Molina having more cover provided by shrubs and Hesperus having more cover provided by forbs. Adult male deer mice moved greater distances at Hesperus than at Molina. Sub-adult males tended to move greater distances than did adult females. Relative abundances of deer mice tended to differ by season, but the average relative abundance of deer mice was greater at Molina. Lon g-term prevalence of infection with SNV was greater at Hesperus and was gre atest in adult males at Hesperus (36.1%). Adult males at Molina exhibited a prevalence of infection with SNV of 25.0%. Infection with SNV tvas highly associated with scars or wounds for adult male, adult female, and juvenile male deer mice at Hesperus, but only for adult female deer mice at Molina. The presence of scars or wounds tended to be associated with greater age, b ut male deer mice at Hesperus were more likely to have wounds than female d eer mice of the same age class. A similar pattern, excluding juveniles, was observed at Molina. Intraspecific interactions and environmentally elicite d long-distance movements of deer mice may play a role in prevalence of inf ection with SNV in these animals.