Eligmodontia typus is widespread in southern Peru, western Bolivia, northern Chile, and all along the extent of the Andes mountains of Argentina, from the Salta province down to the Strait of Magellan (Redford and Eisenberg 1992). Typically, it inhabits open vegetation areas with high proportion of bare soil like Larrea flatlands, sandy lowland scrub areas, and sandy flats with halophytic plants (Mares 1975a, b; Redford and Eisenberg 1992). In the central Monte Desert, this species dominates sand dune habitats (Corbalan and Ojeda 2004), as well as open shrublands and disturbed grasslands of the Andean piedmont (Gonnet and Ojeda 1998). Ojeda (1989) demonstrated that in areas disturbed by fire, where vegetational complexity decrease, the population of this species increase. However, E. typus has been also reported as very abundant in dense shrublands dominated by Larrea cuneifolia, with high grass cover (Corbalan and Ojeda 2004). Using Beta-light, Thompson (1982) was able to demonstrate that the highly specialized rodents of the genus Dipodomys spend more time foraging near or beneath bushes, bounding rapidly across open areas, in contrast to results from earlier studies using live trapping. Eligmodontia typus shows a morphological similarity with the North American