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The ecological role of native and introduced species in the diet of the puma Puma concolor in southern Patagonia J u a n I g n a c i o Z a n ó n M a r t í n e z , A l e j a n d r o T r a v a i n i , S o n i a Z a p a t a D i e g o P r o c o p i o and M i g u e l Á n g e l S a n t i l l Á n Abstract There is evidence for the ecological extinction of the native prey of the puma Puma concolor in northwestern Argentine Patagonia. In this study we examine whether this is also the case in southern Patagonia. From 2004 to 2007 we examined the puma's diet in three protected areas and two sheep ranches in Santa Cruz province. A total of 282 puma scats were analysed. In two of the protected areas and in the ranches 60-74% of the puma's diet was native prey. Prey species were primarily guanaco Lama guanicoe, followed by Patagonian mara Dolichotis patagonum, lesser rhea Pterocnemia pennata pennata, Patagonian pichi Zaedyus pichiy and Magellanic penguin Spheniscus magellanicus. In the third protected area the main prey was the European hare Lepus europaeus. Our results show a clear difference in the diet of the puma in southern compared to north-western Patagonia. Large native herbivores (i.e. guanaco and lesser rhea) maintain their role as the main prey species for the puma in southern Patagonia. We suggest, therefore, that native prey could be restored to those areas of Argentine Patagonia, such as the north-west, where they are currently ecologically extinct. Facilitating native species recovery and/or restoration and applying more rigorous controls to prevent the introduction of potential alien prey species of the puma, both within and outside protected areas, needs to be evaluated as a regional strategy.

The Lesser Rhea (Rhea pennata pennata) has suffered a marked decline in numbers over recent decades, probably mainly as a result of livestock production and overhunting. Our aim was to investigate the factors that determine the distribution of Lesser Rheas in southern Patagonia and to generate a predictive regional distribution map. We surveyed 8000 km of roads and sighted 795 Lesser Rhea individuals or flocks. We also estimated environmental predictors from remotely sensed data and analysed the occurrence of Lesser Rheas in relation to these predictors. The predictors we examined were associated with four hypotheses explaining the distribution of Lesser Rheas: the persecution by ranchers, primary productivity, topography, and anthropogenic disturbance hypotheses. We built models for each hypothesis. Our results suggest that the distribution of Lesser Rheas is not negatively affected by persecution by ranchers, as the species is more abundant in areas with high stocking levels of sheep, but is positively influenced by primary productivity and negatively by the proximity of human habitation. The resulting distribution map can be used as a management tool for government agencies and highlights the conservation priorities for managing this declining and emblematic species.