Density and habitat use of an isolated population of the guanaco (Lama guanicoe) in the Monte desert of Argentina

• ACEBES, P.; TRABA, J.; MALO, J.E.; OVEJERO, R. & BORGHI, C.E

MAMMALIA

Año: 2009

0025-1461

&amp;lt;!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&amp;gt; First density estimations of the guanaco population and a review of its habitat use are presented for an area of Monte desert. Transects were carried out throughout the Ischigualasto Provincial Park (60,369 ha; San Juan, Argentina) in the wet and dry seasons of 2005. In a parallel systematic survey throughout the area all guanaco observations were GPS located and the habitat occupied by solitary individuals and herds identified. Herd size differed significantly between the dry season and the wet season (dry 6.70 ± 3.56, wet 4.86 ± 4.08, t-test: -2.09; df = 73; p < 0.01). Population densities were estimated with DISTANCE 5.0 software, showing differences between the wet season (0.597 individuals/km²) and dry season (0.115 individuals/km²). Such densities are only slightly lower than those found in Tierra del Fuego or Península Valdés. Thus, the population estimate for the Park ranges between 75 individuals in the dry season and 388 individuals in the wet season. Guanacos showed differential habitat use between seasons (c²= 23.85; df = 9; p < 0.01), using the mixed creosote bushland and saltbush more intensively during the wet season, and open scrubs and columnar-cactus slopes in the dry season. Our results indicate strong seasonal variation in guanaco numbers and their more intensive use of the most productive patches.