Interactions between feral donkey and protected species in Ischigualasto Park (San Juan, Argentina).

CAMPOS, C.; REUS, L.; BORGHI, C. ; GIANNONI, S.

Mar del Plata

Conferencia; BIOLIEF 2011. 2nd World Conference on Biological Invasions and Ecosystem Functioning.; 2011

Grupo de Investigación y Educación en Temas Ambientales (GrIETA)

Naturalized herbivores can cause the extinction of native plant through their effect on plant reproduction, and can compete for the use of resources with native herbivores. In Ischigualasto Provincial Park, we assessed the effect of feral donkey´s herbivory on columnar cacti Echinpsis terscheckii and the potential overlapping in the use of food resources between the donkey and the native Lama guanicoe. We quantified the donkey´s damage on 180 cacti and measured its effect on the reproductive output, controlling the effects of plant size and habitat characteristics with GLM. Results showed a negative herbivory effect on the number of flowers and fruits, but not on fruit weight. During the wet and dry seasons, we analyzed food availability and diet composition of both herbivores. Diets were compared using MANOVA, the Kruskal Wallis test, the Shannon index (indicator of trophic niche breadth), and Pianka´s index (indicator of dietary overlap). Donkeys´ diet showed a high intake of grass, particularly during the wet season when diet became more diverse, and a constant use of shrubs along the year. L. guanicoe?s diet was adjusted to the most stable and abundant food resources (shrubs), which constituted more than 60% of the diet; it was less diverse than the donkeys´ diet. Diets showed a low overlap during the wet season (O=0.22), but it increased during the dry season (O=0.57). Both herbivores can be considered consumers of mix feeding. However, in Ischigualasto Park, L. guanicoe showed a strong tendency to be a browser, while donkeys behaved as a grazers. Presenting Author Contact Details: Claudia Campos, Grupo Interacciones Biológicas del Desierto (INTERBIODES), IADIZA (CCT, CONICET), CC 507, 5500, Mendoza, Argentina. E-mail: ccampos@lab.cricyt.edu.ar Two-sentence Summary of the Study: Feral herbivores can affect native plants and animals. We assessed the impact of donkeys´ herbivory on the columnar cacti Echinpsis terscheckii and the overlapping in diets between donkey and Lama guanicoe. Preferred Presentation Mode: Oral Preferences for Session Assignment: 1.c. (Invasive species impact- On one or a few native species), 2.c. (Invasive species establishment and spread- Interaction with native species or other invaders), 3.d. (General biology of invasive species- Natural history).