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Biological Conservation 115 (2003) 121–130 www.elsevier.com/locate/biocon Pampas deer conservation with respect to habitat loss and protected area considerations in San Luis, Argentina Manuel R. Demarı´ aa, William J. McSheab,*, Kevin Koyb, Nestor O. Maceiraa aINTA San Luis. CC 17-5730 Villa Mercedes, San Luis, Argentina bNational Zoo’s Conservation and Research Center, Smithsonian Institution, 1500 Remount Road, Front Royal, VA 22630, USA Received 18 July 2002; received in revised form 10 January 2003; accepted 12 February 2003 Abstract Ozotoceros bezoarticus celer is the most endangered subspecies of pampas deer. Although common in the Argentine Pampas 100 years ago, it persists in only two small populations. The largest population has survived due to the rarity of roads, internal farm subdivisions, and the low cattle density. However, habitat condition for this population has changed dramatically in the last 16 years. Five Landsat images (1985, 1992, 1997, 1999, 2001), covering 4608 km2, were used to quantify pampas deer habitat loss due to the replacement of natural grassland by exotic pastures and crops. Image classification showed that natural grassland cover was reduced from 84.5 to 37.8% between 1985 and 2001. The annual transformation rate increased significantly from 1.4 to 10.9%. Average paddock size was significantly reduced from 1470 to 873 ha, and the number of paddocks increased from 129 to 227. The land within this area proposed for a national park has not escaped these habitat changes. In the last 6 years the amount of replaced area within the proposed park has increased from 9.1 to 51.1% due to actions by ranchers to avoid inclusion within park boundaries. Three patches of natural grassland still remain within the pampas deer distribution, one of which is the proposed national park. The implementation of a national park is a decisive challenge for the survival of pampas deer and its habitat in Argentina. # 2003 Elsevier Ltd. All rights reserved. Keywords: Habitat lost; Fragmentation; Image analysis; Pampas deer; Grassland; Exotic grasses; Argentina; Livestock 1. Introduction absence of protected areas (Burkart et al., 1994; Diner- stein et al., 1995). The pampa in Argentina, and campos in Brazil and Ozotoceros bezoarticus celer is the southernmost and Uruguay constitute the greatest grassland ecosystem in most endangered subspecies of pampas deer (Wemmer, South America and one of the few grassland ecosystems 1998; Dellafiore and Maceira 1998). It is endemic to the present in wet temperature areas worldwide (Soriano et Argentine Pampa Region and is the only deer species al., 1991). In Argentina, the pampa ecosystem covers directly associated with open grassland in this country. 460,000 km2 in the central eastern part of the country The geographical retraction of the grassland has coin- (Cabrera, 1976; Burkart et al., 1994). In the past 150 cided with a decrease of the population of pampas deer years this ecosystem was severely transformed by agri- (Maceira et al., 1996). Originally distributed across the culture and cattle breeding, with a continuous advance pampa of Argentina (Cabrera, 1943), today its popula- of the agricultural frontier from the humid east to the tion has suffered a dramatic decline due to habitat semiarid west (Anderson, 1979; Leon et al., 1984; Vig- transformation and fragmentation, hunting, and prob- lizzo et al., 2001). Analysis of the conservation status of ably competition for forage (Jackson and Giullietti, eco-regions in Latin America designate the pampa 1988) and transmission of infectious diseases (Jungius, region as endangered and of maximum priority due to 1976) from cattle. At present, only two small popula- its great transformation, biological uniqueness, and the tions persist at the eastern and western margins of the pampa region. The western population, located in the * Corresponding author. San Luis Province, is the largest both in population size E-mail address: [email protected] (W.J. McShea). and area covered. 0006-3207/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0006-3207(03)00101-0 122 M.R. Demarı´a et al. / Biological Conservation 115 (2003) 121–130 Pampas deer are distributed across 4500 km2 in San The monte region is predominately forest and shrub Luis Province. However, most animals are concentrated composed of Prosopis flexuosa, Larrea divaricata, and within 1450 km2, where extensive natural grasslands still Geoffroea decorticans, and is not suitable habitat for can be found (Demarı´ a et al., 1995, 1996; Maceira et al., pampas deer. The San Luis pampa belongs to the semi- 1997). A survey using terrestrial and aerial censuses, and arid western extreme of the pampa grassland (Leon and personal interviews with local farmers, estimated that Anderson, 1983), and is characterized by sandy soils 500–1000 deer remained in this area (Dellafiore, 1997). and rolling hills, with fixed and live dunes (Anderson et Pampas deer have probably persisted in San Luis due to al., 1970). Annual average rainfall is 450 mm, con- the peculiar characteristics of these grasslands. The area centrated between October and April. Absolute max- is composed of large private ranches used primarily for imum summer temperatures can reach 43 C, while in cattle breeding. The absence of roads and crop agri- winter temperatures can descend to À15 C. culture, the minimal internal subdivision on the ranches, Anderson et al. (1970; Anderson, 1979) described the the historically low cattle density, and the economically western extreme of the pampa region as grassland with conservative attitude of some farmers, have all con- islets of tree species, such as Geoffroea decorticans, Pro- tributed to deer survival in this region. A previous study sopis caldenia and Prosopis alpataco. Sorghastrum pelli- examining deer density and ranch characteristics showed tum is the dominant grass species in the climax that the presence/abundance of deer was positively asso- vegetation; it has been used to indicate superior stages ciated with ranch size and presence of natural grassland, of the ecological succession (Anderson, 1979). Other and negatively associated with the amount of exotic grasses associated with S. pellitum are: Elyonurus muti- grasslands, crop cultivation, stocking rate and degree of cus, Bothriochloa springfieldii, Chloris retusa, Schiza- internal fencing of the ranch (Dellafiore et al., 2001). chyrium plumigerum, Eragrostis lugens, Sporobolus Natural grasslands in San Luis Province are the last subinclusus, Aristida spegazzini, Poa ligularis and Poa great pampas deer habitat in Argentina, and the per- lanuginosa. At present these grasslands are not uniform, ception of local biologists is that the habitat condition as composition varies according to their management of the area is rapidly changing (Demarı´ a et al., 1996). history (Anderson, 1979; Aguilera et al., 1998). The source of this change is the conversion of natural Exotic grasslands are composed of Eragrostis cur- grasslands into exotic grasslands that are dominated by vula and Digitaria eriantha. Both are species which Eragrostis curvula and Digitaria eriantha. These species originated in Africa and were introduced in the are considered beneficial by ranchers because they allow region to increase livestock carrying capacity on the increased cattle stocking rates. However, exotic grass- ranches. E. curvula was introduced in the 1940s, and lands, or their indirect effects, are not favorable to its sustainability and profitability has been largely pampas deer. Although the conversion pattern and rate tested in the region (Marchi et al., 1974; Covas and of these grasslands might be important to wildlife biol- Cairnie, 1985). D. eriantha is a new pasture in the area, ogists charged with monitoring pampas deer habitat, it and livestock carrying capacity and sustainability is still is a difficult feature to measure because of the scale of undergoing testing by researchers (Frassinelli et al., the area, lack of adequate roads, and the lack of pub- 1992). lished habitat surveys that allow comparisons with past The study area was divided into two zones based on decades. The purpose of this study is to use remote the abundance of pampas deer, as defined by Demarı´ a sensing technology to quantify the amount of natural et al. (1995) and Dellafiore (1997) (Fig. 1). These grasslands remaining for pampas deer, and to use past authors estimated the distribution and abundance of and present images to document the pattern and rate of pampas deer in the region by means of interviews with change for these grasslands over the last 15 years. ranch owners or managers, and both air and land cen- suses in three different seasons during 1995–1997. The ‘‘Abundant’’ zone included all the ranches that showed 2. Methods a deer density greater then 0.40 deer/km2 during the aerial and terrestrial census (Dellafiore, 1997). The 2.1. Study area ‘‘Scarce’’ zone included the ranches where pampas deer were not present or sporadically present according to The study was conducted in 4608 km2 in the south- rancher interviews. central portion of San Luis Province, the center of wes- The area selected for a national park is located in the tern deer population (Fig. 1). This area is composed of northwestern section of the study site. The 12,000 ha two different phytogeographic regions: the pampa and park is within the San Luis pampa grassland ecosystem monte (Cabrera, 1976). The phytogeographic region of and the abundant pampas deer zone. Natural grassland monte covered an area of 454.54 km2 (9.9%) on the covers 94.5% of the potential park and is rated as very western section of the study area, with the remaining good conservation state with regards to species richness pampa region covered an area of 4153.54 km2 (90.1%). and cover (Demarı´ a et al., 1996). M.R. Demarı´a et al. / Biological Conservation 115 (2003) 121–130 123 Fig. 1. Location of study area in the semiarid westernmost portion of the pampa grassland region, San Luis, Argentina.

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