Mammals of Spanish Peaks State Wildlife Area, Colorado

Habitats and relative abundance of small mammals in the Spanish Peaks State Wildlife Area in western Las Animas Co., Colorado, were assessed. A total of 821 mammals of 20 species was collected in 2750 trapnights between 31 May and 19 August of 1981. Eight additional species of mammals were observed on the wildlife area but not documented. The deer mouse (Peromyscus maniculatus) and rock mouse (P. difficilis) were the most abundant small mammals, accounting for 63 and 16%, respectively, of the total catch. The deer mouse was the only species caught in every habitat sampled. Abert's squirrel (Sciurus abert,) previously has not been recorded in Colorado from as far southeast as the Spanish Peaks State Wildlife Area. The mammalian fauna of Colorado has been the subject of numerous studies since the late 1800s. Early studies were by Cockerell (1890), Warren (1906), Cary (1911), and Warren (1942, published posthumously). More recent investigations include the book by Lechleitner (1969), the exhaustive compilation by Armstrong (1972), and the latilong surveys by Bissell (1978, 1982). In spite of these studies, several regions of Colorado remain poorly represented in collections. Armstrong (1972) noted that "certain poorly surveyed parts of the western two-thirds of the state appear to me to be ... significant from the standpoint of zoogeography. Western Las Animas County--the Park Plateau and Culebra Range [of the Sangre de Cristo Mountains]--is such an area." In a later publication, Armstrong et al. (1973) noted that additional field investigations were needed in the vicinity of the Wet Mountains, a biogeographically important region where several species of grassland mammals reach altitudinal extremes and certain southern species reach northern limits. With this in mind, the Colorado Division of Wildlife initiated fieldwork in the Spanish Peaks State Wildlife Area to sample the vertebrate fauna in general and to assess habitat associations and relative abundance of small mammals in particular. This report documents the mammals collected and observed in the Spanish Peaks State Wildlife Area during summer of 1981 and summarizes biological data on mammals obtained at that time.