No abstract

No abstract

The brown hare, a Leporid widespread in the world, is now dispersed across Argentina after its introduction at the end of the 19th century. Studies on hare feeding ecology are important to evaluate a potential competition with domestic and native wild herbivores. This study analyses the brown hare diet in relation to food availability, and dietary overlaps with several herbivores in northern Patagonia. Food availability was estimated by point-quadrat transects, and hare diet by microhistological analysis of faeces, carried out in five habitats in five seasonal samplings. Significant differences were detected by Kruskall-Wallis ANOVA with multiple comparisons by Tukey test. Feeding selection was detected by w 2 test, and dietary preferences by the confidence interval of Bailey. Grasses and chamaephytes were the most available plant categories, with Stipa, Panicum and Acantholippia as main species. Grasses and phanerophytes were the main dietary categories, including Poa, Panicum, Bromus, Adesmia and Prosopidastrum. The phanerophytes Prosopidastrum and Ephedra were more eaten in winter, when the main food item (Poa) presented lower availability. A higher dietary proportion of the chamaephyte Acantholippia occurred in rocky habitats, where the coarse dominant grasses were always avoided. Hares shared most food items with several wild and domestic herbivores in northern Patagonia. The lack of preference for forbs differentiates brown hares from other herbivores. However, hares exhibited important dietary similarities with plain and mountain vizcachas, goats and horses, and an interspecific competition for food is highly probable.

Architecture ofBurrow systems of the fossorial rodent Ctenomys mendocinus Philippi, 1869 were studied in the Andean Precordillera. These burrows were linear, with laterals and branches forked off the main tunnel. Their size and architecture did not differ between sexes. Burrows showed a constant heading along the main tunnel, with a mean directional angle close to 0°. Most forks of the main tunnel were originated more than expected at plants, indicating a change of search pattern where plants were encountered. This behaviour suggests a tactic consistent with area-restricted search. These systems were compared with others of the same species located in a habitat with higher cover and structural complexity of vegetation, at the Mendoza Piedmont. Female burrows were larger and male burrows more bifurcated in the Precordillera. These burrows were more complex than those from the Piedmont, owing to the presence of secondary tunnels. The mean directional angle close to 0°, orthogonal branches and angles of ascent of laterals close to 40° were attributes shared by the systems of both habitats. C. mendocinus maintains a basic search pattern as an optimal forager, and increases the systems size and complexity probably as an adaptive strategy to optimize the foraging efficiency and minimize the predation risk.

No abstract