Summer diet selection of a rock specialist: the Wolffsohn´s viscacha (Lagidium wolffsohni) in protected natural area of Pinturas River, Cueva de las Manos, Patagonia, Argentina

Abstract

ABSTRACT Rock specialists are mainly herbivores with similar morphological and behavioral characteristics such as spatial activity and feeding near rocky outcrops. In mountain areas, they are vulnerable due to restrictions in food searching and many are also sensitive to warm temperatures. The Wolffsohn’s viscacha (Lagidium wolffsohni) is a high-altitude rock specialist whose conservation status IUCN is Data Deficient. This study investigates its feeding behavior in relation to food availability and evaluates the degree of trophic specialization in summer. Percent vegetation cover was estimated on three rocky outcrops inhabited by the Wolffsohn’s viscacha, and diet was estimated conducting a microhistological analysis of fecal pellets from 83 fresh fecal pellet groups. Wolffsohn’s viscacha was a selective consumer of grasses and its trophic niche was narrow (Bst = 0.31 ± 0.04). Its diet consisted of 17 food items. The grasses Festuca pallescens, Pappostipa spp., Poa spp., and shrub Berberis heterophyla composed 81% of the diet. The selective feeding behavior by grasses was similar to the southern vizcacha. Both herbivores selected a high-quality shrub and grasses in summer. This feeding behavior suggests a selection based on the availability of quality food near rocky outcrops representing a low cost of searching time and high contribution of nutrients.