Fernando Videla

Habitat use by guanacos (Lama guanicoe, Camelidae) in northern Patagonia (Mendoza, Argentina)

Strategies of habitat use of the guanaco were analyzed in early and late summer, when parturition and lactation increase nutritional needs and predation risk. The daily distribution of guanacos was followed by scan‐sampling, relief and soil were measured in each habitat, and vegetation was analyzed by the point‐quadrat method. Guanacos showed a selective habitat use, preferring open areas with grasslands, gentle terrain and low hiding cover. The density of guanacos was positively associated with the intensively eaten grass Panicum urvilleanum, and negatively associated with rocky soils, high shrublands and avoided plants. A weakening of the selective habitat use occurred when the abundance of guanacos increased in the study area during late summer, ceasing avoidance of poor and risky habitats.

Diet Selection by the Fossorial Rodent Ctenomys mendocinus Inhabiting an Environment with Low Food Availability (Mendoza, Argentina)

The seasonal diet of Ctenomys mendocinus was determined in a habitat of the Andean Precordillera, through microhistological analyses of stomach contents and in relation to food availability. Diet included 23 genera of plants and only 6 of them were consumed with frequencies higher than 4%. The grasses Stipa and Elymus comprised about 80% of the diet. A high proportion of aerial plant material was registered throughout the year suggesting a tendency to forage on the surface. Dietary selectivity was evidenced by a preferential consumption of grasses and avoidance of shrubs. Moreover, most dietary items frequently used were eaten in proportions that differed from their availabilities. This non-opportunistic feeding behavior, specialized in a few dietary items, did not agree with the one expected for a subterranean rodent inhabiting an environment with severe climatic conditions, low food availability and patchy distribution of food resources.

Diet of brown hare (Lepus europaeus) and food availability in High Andean mountains (Mendoza, Argentina)

Abstract Diet selection by Lepus europaeus was studied in high-altitude mountain environments with severe weather, presence of wetlands, and no agricultural activities. Diet was assessed using fecal microhistological analysis, and food availability by point-quadrat transects in four habitats, two of them with wetlands. Significant differences were determined with Kruskal-Wallis ANOVA, similarities by Renkonen index, and feeding selection by χ2-test and Bailey’s confidence interval. The diet included 63% of all species present. Shrubs dominated the diet. Food use was opportunistic in habitats without wetlands, where grasses and shrubs were more available. Plant cover and availability of grass-like plants were higher in wetland habitats, where shrubs and forbs were preferred and grass-like plants were avoided. Similarity between diet and food availability was higher on dry soils, dominated by grasses and shrubs, than in wetland microhabitats with higher plant cover, diversity, and percentage of grass-like plants. Dietary generalism was confirmed, especially when excluding wetland vegetation. Hard Juncaceae cushions accounted for the pronounced selectivity in habitats with wetlands. Dry soils, where shrub patches provided good food and shelter, appear as major feeding microhabitats for L. europaeus. Spatial heterogeneity protection, at landscape and microhabitat scales, is relevant to the brown hare conservation in High Andean environments.

Dietary overlap of coexisting exotic brown hare (Lepus europaeus) and endemic mara (Dolichotis patagonum) in Northern Patagonia (Mendoza, Argentina)

Abstract Introduced brown hares are present across the distribution range of maras, which are endemic to Argentina’s open steppes. Food competition with exotic herbivores could be partially responsible for declines in mara populations. Diets of sympatric hares and maras were compared to detect dietary overlap according to food availability. Diets and availability were estimated using microhistological analysis and point-quadrat transects, over four seasons. Horn’s index estimated dietary overlap, Kruskal-Wallis ANOVA detected significant differences, and permutational multivariate analysis of variance (PerMANOVA) determined the multivariate response to factors. Grasses prevailed among available items and in both diets. Plant cover and richness increased in summer and forbs in spring. High dietary overlap decreased in autumn-winter, when hares ate more forbs and tall shrubs and less low shrubs than maras. Interspecific overlap was higher inside a protected area with higher food diversity, more forbs, and low shrubs. Both herbivores shifted to different foods as availability decreased. When forbs declined, they were less eaten by maras than hares. Broader habitat use allows hares to search for preferred forbs farther away than maras. The more adaptive hare could become a stronger competitor in impacted environments. Better food availability inside than outside the protected area is a feeding advantage for the coexistence of these herbivores.