The pampas deer occurs in insular populations in western, northern, and central Argentina, eastern Bolivia, central and southern Brazil, Paraguay, and Uruguay. Prior to the 1800's, the species was abundant throughout the grasslands of South America (Wemmer 1998). The Pampas deer was a widespread species occupying a range of open habitats, including grasslands, pampas and the Brazilian savanna known as the Cerrado, in eastern South America from 5º to 41ºS (Cabrera 1943; Jackson 1987; Merino et al. 1997; González et al. 1998; 2002; González, 2004; Weber and González 2003). However, the area encompassed by these habitats has been dramatically reduced to less than 1% of that present in 1900 (González et al., 1998). Currently, Pampas deer populations are generally small and highly isolated (Jackson and Langguth 1987; González et al. 1998: 2002). The largest extant populations are found in Brazil, in the northeast cerrado ecosystem where about 2,000 individuals live, and in the Pantanal where 20,000 to 40,000 exist (Pinder 1994), and was rediscovered in the South a small population in Paraná State estimated in less of 100 individuals Braga et al.2005, . In Uruguay there are two main populations: El Tapado (Salto Department) with 800 individuals, and Los Ajos (Rocha Department) with approximately 300 deer (Weber and González, 2003 ). At the turn of the century, the Argentinean population was likely very large since over 500,000 km² of grassland habitat was available. However, today only three small populations remain: Corrientes (Ituzaingo Department) with about 170 individuals (Merino and Beccaceci, 1999), in San Luís Province) with approximately 800-1000 individuals (Merino et al. 1997) and coastal Bahía de Samborombóm (Buenos Aires Province) with about 200 individuals (Merino et al. 1997) and in Santa Fé “Bajos Submeridionales” area there is a small population estimated less 50 individuals lives in an area of 23,000 ha. (Vera Department, Pautasso et al. 2002a and b). A small population may still be extant in the southeastern part of Bolivia (Weber and González, 2003). Small populations of Pampas deer may still be extant in the National Park Noel Kempff Mercado (Santa Cruz Department), in southwestern Bolivia (Anderson 1985; 1993; Tarifa 1993). However, it is restricted to relatively small patches of suitable habitat and may have become locally extinct in some of them.