Spatial niche overlap between vicunas and guanacos

Abstract

Through the analysis of habitat use in free-ranging, sympatric guanacos Lama guanicoe (Muller, 1776) and vicunas Vicugna vicugna (Molina, 1782), we tested whether spatial segregation between the two species occurred in a high-altitude (4000-5000 m) Andean ecosystem, North-Eastern Argentina. Puma presence was recorded in only one of the two summers when data were recorded. Therefore, we also tested the effects of predation risk on camelid habitat use and overlap. The two camelids adopted a very similar space use strategy, but guanaco tended to be observed more frequently than vicunas in the forage-rich patches in close proximity to water. The three different social units, characterising the organization of both wild camelids, had partially different habitat uses and the variations between them contributed to narrow the extent of spatial overlap between species. In response to increased predation risk, camelids decreased the use of the areas where most signs of hunting activity occurred. Predatory pressure had a levelling effect in habitat use variation, thus further reducing inter-specific segregation.