Guanaco vs. donkey: what are they eating at Ischigualasto Park (San Juan)?

REUS M. L., CAMPOS C. M. , GIANNONI S. M., ORTIZ S. G., LASPINA C. A., NAVAS A. C. Y PECO, B.

Mendoza

Congreso; X International Mammalogical Congress.; 2009

SAREM

Lama guanicoe and Equus asinus are native and exotic herbivores that coexist at Ischigualasto Park. This study analyzed and compared diets during the wet and dry seasons of 2006. To quantify food supply, plant cover was estimated on 4-m2 plots along 15-m long transects. Diet was analyzed by microhistological analysis of fecal samples (N=42 for guanaco; N=13 for donkey). Kruskal-Wallis test was used for comparisons. Food supply in both seasons (% wet season vs. % dry season; significant difference) was composed of: Zuccagnia punctata (3.12 vs. 1.73), Cactaceae (1.86 vs. 2.60; p= 0.02), Prosopis torquata (1.47 vs. 1.70) and, with percentages below 1%, Capparis atamisquea, Trichomaria usillo (p=0.01), Cyclolepis genistoides and Pappophorum philippianum (p=0.02). In the wet season, the guanaco mostly consumed shrub like Z. punctata (mean frequency 22.5), C. atamisquea (15.3), P. toquata (11.3) and T. usillo (8.2), whereas in the wet season it also incorporated grasses (16.2) and Cactaceae (14.2). In both seasons the guanaco consumed Tillandsia sp. The donkey’s diet was primarily composed of grasses in both seasons (Tricloris crinita, Distichilis scoparia, Pappophorum philippianum, Asistida mendocina). The donkey also consumed Deutherocohnia longipetala, C. genistoides, P. torquata and Solanum sp. In comparing the diets of both herbivores, differences emerged in consumption of P. torquata, Z. punctata, Cactaceae, T. usillo, C. genitoides and grasses (p = 0.0001). The guanaco eats primarily shrubs and uses Cactaceae and grasses in lower proportion. On the other hand, the donkey selects primarily grasses and consumes shrubs in lower proportion.