Diet selection and habitat use by the mountain vizcacha (Lagidium viscacia) in the Southern Andean Precordillera (Argentina)

Abstract

AbstractLagidium viscacia is considered as a fragile species with patchy distribution, a strict habitat specialist and an obligatory diet specialist. The Southern Andean Precordillera constitutes an interesting environment to analyze the species’ presence across the altitudinal gradient. Diet selection and habitat use were studied in the summit plateau, characterized by rigorous conditions and vegetation representative of the Southern Puna. Pellet groups were counted in transects perpendicular to rock formations, and diet and vegetation were seasonally analyzed using microhistological analysis and point-quadrat transects. Vizcachas were strictly associated with rock formations at middle and high altitudes, with higher occurrence on the mountain summit where grasslands surrounded the rock formations. Vizcachas avoided shrubs associated with rock formations and preferred grasses on sandy soils. Phenological changes slightly affected the selective diet that involves a considerable search effort and risky feeding activity. Puna grasslands constituted attractive feeding places where L. viscacia’s activity decreased with distance from rock shelters as expected for a central-place forager. Habitat partitioning allows coexistence with Ctenomys mendocinus, despite the high dietary overlap between these central-place species. The high mobility and broad diet of Lama guanicoe reduce the competition risk. Lepus europaeus preferred shrubs and forbs, determining a discrete dietary overlap with vizcachas.