Guanacos in the Desert Puna: A trade-off between drinking and the risk of being predated

Abstract

Habitats vary not only in resource availability and quality but also in predation risk, among other factors. The Desert Puna of Argentina comprises two habitats: the shrub steppe and the vegas. The former, the most abundant habitat, is a topographically simple area with unavailable free water and poor food quality; the latter is a very scarce and topographically complex habitat and with water available year round and high quality food. Guanaco relies heavily on vision to detect predators and narrow and complex habitats would be risky. Hence, we expected that guanacos would use the vegas in lowest proportion and would increase the time devoted to vigilance. Guanacos spent more time in the shrub-steppe than in the vegas, where the highest percentage of vigilant guanacos was recorded. A positive and significant relationship between time devoted to foraging and number of animals per herd was observed in both habitats. In the shrub-steppe the opposite was observed for vigilance, whereas in the vegas, no relationship was observed. Despite the low availability of vegas and the high predation risk,they represent a critical habitat for guanacos in the Desert Puna, because they representing the only areas with free water available throughout year for wildlife.