CONICET | Buscador de Institutos y Recursos Humanos

Local habitat selection and seasonal movements are key elements in life strategies of many animal species as means to cover their vital needs. This is specially true for populations living in areas close to species' distribution extremes as their proximity to the realizable niche limit makes survival more dependent on an efficient use of available resources. In this context, we describe seasonal variability in space and habitat use by a small population of guanaco (Lama guanicoe Müller 1776) living at the driest limit of its Argentinean distribution. During the wet and dry seasons of 2005 and 2006 we GPS-located al1 guanaco observations obtained during systematic surveys through the Ischigualasto-Talampaya World Heritage Site (Argentina), located at the phytogeographic region of the "Monte Árido", dominated by shrubby plants such as Larrea spp, Zuccagnia punctata, Atriplex spp. and Prosopis spp. in addition to several cacti species (Trichocereus, Cereus, Tephrocactus, Opuntia spp). Temperatures vary from -10º to 50ºC and annual precipitation is about 100 mm. Guanaco observations were obtained from daily surveys of the area totalling approximately 150 hours by season. Variables of the environment and the group of animals were also collected for each observation. We defined 6 different plant communities to characterize the habitat where guanacos were found: dense scrubland (dominated by shrubs such as Zuccagnia punctata, Larrea cuneifolia and Geoffroea decorticans with >20% plant cover), open scrubland (with shrubs like Larrea spp. and Plectocarpa tetracantha, always with 66%). Nevertheless, the analysis of the core areas (estimated using a density estimator kernel at 50%) showed a much lower seasonal overlap (average for two years; CCI

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