NOVARO andres Jose
capítulos de libros
Human-induced Changes in the Effect of Top Carnivores on Biodiversity in the Patagonian Steppe
ANDRÉS J. NOVARO AND R. SUSAN WALKER
Large Carnivores and the Conservation of Biodiversity
Año: 2005; p. 267 - 287
In Patagonia, populations of native herbivores and omnivores declined dramatically during the last century, due to persecution by humans, competition from livestock and exotic species, and habitat degradation caused mostly by overgrazing of sheep. In spite of reduced levels of both hunting by humans and sheep numbers over the last 20 years, populations of native guanacos, choiques, and mountain vizcachas have not recovered concomitantly. Top native carnivores, the puma and the culpeo, on the other hand, have increased in abundance and expanded their ranges, probably due to the large prey base of exotic wildlife, mostly European hares and red deer, that have replaced the native prey. We present comparisons of puma consumption of guanacos and guanaco population trends among sites that suggest puma predation could prevent recovery of low-density guanaco populations. We argue that human activities have induced top-down control of native prey by large carnivores in parts of Patagonia, likely as a result of apparent competition from non-native herbivores. This alteration in the role of native carnivores may help prevent the recovery of the once abundant herbivores and locally reduce their diversity. Such a role change for carnivores may not be unusual, as modifications of terrestrial ecosystems induced by humans throughout the world in the past millennia may have altered repeatedly the limiting role of top carnivores on their prey.