Forest matters : use of water reservoirs by mammal communities in cattle ranch landscapes in the Paraguayan Dry Chaco

Abstract

Cattle ranching has led to a significant decrease in forest cover in the Neotropic. In this study we evaluate how medium- and large-sized mammals cope in these human-modified landscapes in the Paraguayan Dry Chaco, where by state law at least 25% of forest cover must be preserved. Using a camera-trap approach, we studied how the surrounding vegetation matrix and season (dry or rainy) influence the pattern of occurrence and detectability of species around artificial water reservoirs for cattle supply. We registered 26 mammal species, and the responses of 14 different species were modelled. Five species (Tayassu pecari, Leopardus pardalis, Pecari tajacu, Mazama gouazoubira and Myrmecophaga tridactyla) showed a positive response to forest cover, with T. pecari and L. pardalis being extremely sensitive to deforestation. Also, forest cover showed a positive effect on the detectability of Tapirus terrestris and Puma concolor. By contrast, for two generalist canids, Lycalopex gymnocercus and Cerdocyon thous, and the semiaquatic Hydrochoerus hydrochaeris forest cover negatively influenced species detectability. Cattle ranches have the potential to maintain a substantial part of the original chacoan fauna, with forest cover being a main factor in structuring the mammal assemblages found around water reservoirs. Additionally, in ten species there was a moderate to strong increase in the probability of detection around water reservoirs during the dry season. The conservation of large forest tracts combined with strict compliance with poaching bans are key management strategies for the conservation of mammal diversity in the human-altered landscapes of the Chaco.