Ecological extinction of native prey of a carnivore assemblage in Argentine Patagonia

The Patagonia region of South America has been severely modified by the introduction of livestock and wild exotic species. We studied diets of culpeo foxes (Pseudalopex culpaeus), chilla foxes (P. griseus), hog-nosed skunks (Conepatus chinga), Geoffroy's cats (Oncifelis geoffroyi), and pumas (Puma concolor) between 1989 and 1994, and evaluated prey biomass on rangelands in Neuquen, Argentina. The carnivores consumed primarily (and selected) introduced hares (Lepus europaeus), red deer (Cervus elaphus), or carrion of introduced species. Native species represented 6% of the potential-prey biomass, and similar percentages of carnivore diets. We conclude that native large-bodied species (guanacos, Lama guanicoe, and rheas, Pterocnemia pennata) are ecologically extinct as prey and sources of carrion in our study area, and likely throughout Argentine Patagonia. Other ecological implications of their currently low biomass are unknown. Measures to control introduced species, prevent new introductions, and create protected areas are urgently needed. (C) 1999 Elsevier Science Ltd. All rights reserved.