Winter habitat partitioning between asiatic ibex and Blue sheep in Ladakh, Northern India

Abstract

Asiatic ibex Capra ibex sibrica and blue sheep Pseudois nayaur are the most abundant wild ungulates in theLadakh Region of the Indian Trans-Himalaya. Both species use rugged terrain to escape predation, and the competitiveexclusion principle suggests that the distribution of one species may be affected by the presence of the other.Ievaluatedhabitat use by these mountain ungulates in the Shun Gorge, at the eastern boundary of ibex distribution intheZangskar Mountains, Ladakh, India. I hypothesised that due to their high affinity toward cliffs as a predator escapestrategy,ibex and blue sheep overlap in their habitat use, especially in winter when they are likely to be confinedbysnow cover.Resource selection indices and chi-square statistics revealed that both ibex and blue sheep preferhabitatclose (1-50 m) to cliffs. The two species were also similar in their use of habitat in terms of slope angle,exceptthat ibex avoided gentle slopes (<15°) and blue sheep avoided very steep slopes (>45°). Both used habitats intermsof elevation and snow cover non-selectively except that blue sheep avoided very low areas (<4000 m), andibexavoided snow-free areas. I suggest that there is high potential for competition between the two species, and thepresenceof one species may negatively influence the distributional pattern of the other.