Ecological strategies of the wild boar, Sus scrofa, in the Monte Desert, Argentina

CUEVAS, MARÍA FERNANDA; OJEDA, RICARDO; JAKSIC, FABIAN

Sand Hutton, York

Simposio; 8th International Symposium on Wild Boar and Ohter Suids; 2010

The Food and Environmet Research Agency

Arid and semiarid ecoregions of Argentina are undergoing rapid habitat conversion because of grazing, logging, agriculture, and disturbance caused by invasive species. The wild boar, Sus scrofa, was introduced in Argentina in 1906 for hunting purposes. Its impact on biodiversity is well known around the world, but knowledge about its ecology is scarce, this being the first ecological study of the wild boar in the Monte desert biome of Argentina. The objectives of our study were to characterize two aspects of the wild boar ecology (habitat use and food use) and their impact on vegetation and soil properties in a seasonal and heterogeneous environment. The study was conducted during 2008 and 2009 in the Man and Biosphere Reserve of Ñacuñán. Transect surveys were conducted two times of the year (during the wet and dry seasons). Wild boar signs (tracks and rooting) were recorded within 5 m of either side of each transect. At each sign we recorded information on habitat and anthropogenic variables. The faeces found were collected for diet analysis. To measure the disturbance generated by wild boar rooting we compared the percentage of plant cover and soil hardness and moisture between rooted and non-rooted soils. During both seasons, at the habitat level, the wild boar showed preference on Larrea shrubland for feeding, avoiding Prosopis woodland and sand dunes. At the microhabitat level they were associated with high cover of herbs and distance to the nearest water source during the wet season. Instead, during the dry season we found a positive association of wild boar with shrub < 1 m and with litter cover, and a negative association with herbaceous cover. Ninety-four percent of the diet consisted of plant matter and 6% was animal tissue. Herbs composed the bulk of the diet, representing almost 45% of the total items found in the faeces. Rooted soils showed significantly less hardness and higher moisture than non-rooted soil. Disturbance by wild boar rooting altered the percentage of cover of perennials grasses, shrubs and herbs in both seasons except for Pitraea cuneato-ovata, which had high cover in rooted soil during the wet season. The Larrea shrubland is the habitat associated with herbaceous cover, which is the main food item in the wild boar diet. This suggests that wild boars select their habitat for foraging depending on the availability of food during the wet season. The success of colonization by P. cuneato-ovata in rooted soil could then be due to soil physical characteristics modified by the wild boar, for example, reduced compaction and increased moisture in those sites. This does not happen during the dry season, where the humidity does not vary between treatments. (Partially supported by ALARM EU project-; Agencia 25778 and CONICET PIP 5944; FONDECYT-FONDAP 1501-0001).