CONICET | Buscador de Institutos y Recursos Humanos

Guanaco populations face different feeeding constraints along their altitudinal migrations in Andean mountains. The guanaco´s diet and food availability were analyzed using microshistological analysis and point-quadrat trasnsects at four sampling sites from the summer range, and four winter range of a High Andean migratory population. Significant differences were detected with Kruskal-Wallis ANOVA, feeding selection by x 2 test, and dietary preferences by Bailey´s confidence interval . Summer range was characterized by having higher plant diversity with more availability of grass-likes (Ciperaceae and Juncaeae) and forbs, compared to winter range . Sites with vegas (moist areas associated to streams and ponds, with dense hydrophytic vegetation ) showed higher plant cover and diversity , also diet diversity was higher. Diet was dominated by grass-likes and grasses at sites wetlands, only by grasses at the other sites , especially in winter . The highest diet-availability similary occurred in the vega microhabitat, but species from slopes were also eaten at sites with wetlands . Grasses were prefered and shrubs where avoided in both seasonal ranges. The narrower guanaco´s diet in winter , and the higher dietary diversity where plant cover and diversity are higher, both agrre with the hypothesis af selectivce quality. A summer opportunistic feeding behavior shits to a more selective behaviour during winter. Winter browsing barely occurred, and grasses preavailed in the diet of both seasons. Altitudinal migrations, forced by the deep snow, could favor guanacos to maintain a grazer strategy year round. Vegas and grasslands , in the summer and winter ranges , have a high feeding relevance for this guanaco population, and connectivity betweeen boht ranges is essential for ther survival..