Brush Deermice occupy rocky and brushy or forested environments in which rock ledges, piles of brush, fallen trees, and boulders offer shelter and denning sites. Although they are reportedly good climbers, they only occasionally build their nests in tree cavities. Learn more about the Peromyscus boylii, more commonly known as a Brush Deermouse, in this easy-to-read species overview by the Smithsonian's National Museum of Natural History.