Influence of environmental variables and human activities on the seasonal habitat use by guanacos in Southern Andean Precordillera (Argentina)

摘要

Food availability, predation risk, climatic adversity, and human disturbance are usually considered relevant factors influencing the distribution of wild ungulates. Poaching and habitat degradation are threats to the guanaco, a native herbivore of South America characterized by ecological and behavioral adaptations to arid environments. Guanaco presence was seasonally surveyed in mountain environments of Andean Precordillera, corresponding to a protected area and its surroundings. Field surveys and satellite images processing estimated environmental variables ascribed to four predictions: resources availability, habitat complexity, weather conditions, and human activities. Generalized Linear Models estimated the probability of guanaco presence based on each prediction, whose variables with important effect were included in combined models. The main natural influence on the presence of guanaco was plant cover. Conservation activities improved this natural influence, whereas disturbing activities restricted it. The trade-off between high resources availability and low predation risk, as well as the effect of extreme weather conditions were not evident, at least in the study's spatial scale. The model validation with new seasonal surveys confirmed a consistency over time of those environmental variables that explain the probability of guanaco presence in the Southern Andean Precordillera.