Evaluation of a 10 year guanaco reintroduction in the upper belt of central Argentina

Summary

Quebrada del Condorito National Park in central Argentina lost its guanacos (Lama guanicoe) in the early 19th century, and decades of cattle grazing and burning had eroded soils and left tussock grass dominating the landscape after livestock were finally excluded. In 2007, researchers from the Instituto de Diversidad y Ecología Animal reintroduced guanacos as a low-impact native grazer to restore landscape heterogeneity and reduce erosion. A first group of 113 wild guanacos from northern Patagonia was released in 2007 without a pre-adaptation period, ear-tagged, neck-banded by sex and about 30% radio-collared; only around 20% survived the first three months, with starvation, puma predation and fence entanglement the main causes of death. A second group of 25 captive-origin animals was released in 2011 after a 40-day pre-adaptation period in a purpose-built barnyard, and post-release survival rose to over 80%. Long-term monitoring tracked behavior, habitat selection, diet and demographic parameters, and a 2016 population viability analysis found the population could go extinct within decades without further reinforcements, since low recruitment from puma predation on offspring, not poor reproduction, was limiting growth; the analysis estimated at least 130 settled guanacos would be needed for a 99% chance of persisting a century. No new releases occurred between 2011 and the ten-year evaluation, short of the original goal of a self-sustaining core of 50-plus animals. The project rates itself a failure, citing an initial hard release without pre-adaptation, inconsistent follow-through on planned annual reinforcements, and management mistakes corrected too slowly.