Scale and selection of habitat and resources: Tibetan argali (Ovis ammon hodgsoni) in high-altitude rangelands

Abstract

Processes of habitat selection occur at multiple spatiotemporal scales, where large-scale selection is often determined by predation risk and landscape features, and finer scale selection by resource abundance and quality. To determine whether this hierarchy exists in relatively homogenous systems, we investigated patterns of habitat (landscape topography) and resource (feeding patch and plant group) selection by a medium-sized ungulate, the Tibetan argali ( Ovis ammon hodgsoni Blyth, 1840), in the high-altitude rangelands of the Indian Trans-Himalaya. We ran ecological niche factor analyses to explore habitat selection, bias-reduced logistic regression to analyze the selection of feeding patches, fuzzy correspondence analysis for vegetation categories, and microhistological analyses for the selection of plant groups. For springs and summers of 2005–2007, argali preferred an intermediate range of altitude, slope, and forage abundance. Selection of feeding patch was mainly determined by forage quality, not biomass, selecting graminoids and forbs, in particular. The avoidance of habitat with high forage abundance could indicate a trade-off between forage quality and quantity; a pattern consistent at the feeding-patch scale. Our results provide evidence that the hierarchical pattern of habitat selection probably also occurs in relatively homogeneous systems.