Scale-dependent niche segregation along dimensions of rocks, vegetation and elevation in sympatric pikas of Ladakh

Abstract

Microhabitat selection in patchy environments supports the co-existence of closely related species competing for resources. We examined niche partitioning in three sympatric species of pikas, Ochotona macrotis, Ochotona nubrica, and Ochotona ladacensis from Ladakh, India, that display contrasting lifestyles, social behavior and co-occur at small spatial scales. We used a classical paired quadrat approach to document biologically relevant vegetation and landscape features (niches) likely to support the presence of different species. We used a Bayesian framework to describe niche spaces , estimate niche widths and overlaps between species pairs. In addition, we used a GLM framework to identify factors that promote the presence of different species in the landscape. The rock-dwelling Ochotona macrotis was a specialist, exclusively associated with microhabitats offering a good cover of large-sized rocks and no shrubs. The social, Ochotona nubrica, was a specialist found across elevations but associated exclusively with mature stands of scrub vegetation (Caragana sp in the South-East and Hippophae sp in the North-West) occupying a unique niche. The social Ochotona ladacensis, although an elevational specialist, was likely to be found in microhabitats of other species characterised by moderate rock cover and low-lying Caragana scrublands, in addition to being found in alpine grasslands and meadows.