Interspecific competition between guanacos and livestock and their relative impact on Patagonian rangelands: evidence, knowledge gaps and future directions

Abstract

The livestock crisis in Patagonia has intensified the historical conflict with the guanaco over natural pastures in recent years. Ranchers are concerned that the recovery of some guanaco populations, which is perceived as uncontrolled and over carrying capacity, leads to competition for forage resources with livestock and causes overgrazing and habitat deterioration, decreasing rangelands’ receptivity. Based on these assumptions, for which there is no scientific consensus, management actions aimed at reducing the guanaco numbers have been implemented within the ranches, and more recently, changes in public policies related to guanaco management have been promoted. In this chapter, we evaluated these assumptions through a review and synthesis of the direct and indirect evidence accumulated to date on: 1) the competitive interactions between guanacos and livestock for forage resources; and 2) the role of the guanaco in the degradation of Patagonian grasslands. Our review found no ecological evidence to support the idea that guanaco reduces forage availability for livestock nor that guanaco populations threaten the integrity of rangelands and livestock production. Hence, interventions aimed at reducing guanaco populations are unlikely to improve livestock production. Instead, this unsupported belief can generate false expectations of solutions for ranchers, in addition to threatening a native species. Our review documented that the environmental carrying capacity for guanacos is underestimated when computed under the assumptions of the current management paradigm and available methods, which were developed only for livestock.