RESUMO
The success of conservation programs for the taruka (Hippocamelus antisensis d'Orbigny), an endemic and endangered deer, depends on many factors, highlighting anthropogenic and ecological effects. Among the latter, how this herbivore interacts with forage resources is important. The objective of the study was to describe the main attributes of the diet of this deer in rangelands adjacent to agricultural areas of the foothills of the Tarapacá Region, Chile. The botanical composition of the diet (BCD) was determined by microhistology of feces and fecal nitrogen (NF, %) was measured in two contrasting seasons (rainy summer and dry winter). From the BCD and FN, their relative diversity (J) and crude protein percentage were estimated. In the BCD, Medicago sativa dominated (27.6 ± 8.2% vs. 53.9 ± 9.2%, in rainy summer and dry end winter, respectively), followed by herbaceous dicots (46.2 ± 9.4% vs. 19.4 ± 8.7%) and shrubby species (21.5 ± 7.8% vs. 23.4 ± 7.0%), from rangelands. The contribution of grasses and graminoid species was low, not exceeding 3% and 0.4% of the diet, respectively, with no differences between seasons of the year. Intake of horticultural crop species was marginal (1.3 ± 1.3%), being detected only in the wet season. Diet relative diversity was higher during the wet period (0.75 ± 0.07) compared to the dry period (0.58 ± 0.06), since in the first period it was possible to find a greater number of palatable species. There were no significant differences in the FN attributed to the time of the year (average of 1.8 ± 0.19%), which indicates that the diet of this deer would be stable in terms of its protein quality. These FN levels estimate sufficient dietary protein content to satisfy maintenance and early pregnancy, but these could be limiting during late gestation and lactation.
RESUMO
For an adequate management of natural grasslands, the knowledge and understanding of the dietary habits of herbivores and their trophic interactions are fundamental. During two summer seasons, in a mountain range of a sector of the Coquimbo Region, Chile, the botanical composition, diversity, and similarity of the diets of horses, European brown hares, and guanacos were studied, as was the selectivity of the main grassland plant species, using feces microhistology. The contribution of hydromorphic grasses was similar in the diets of guanacos (35.90 ± 7.27%) and horses (32.25 ± 4.50%), differing from that found in hares (16.32 ± 5.32%). Dryland grassland grasses contributed similarly to the diets of horses (13.21 ± 3.22%), guanacos (22.53 ± 5.21%) and hares (18.35 ± 3.81%), as well as graminoids, which averaged 47.79 ± 6.66%, 35.63 ± 10.76% and 38.94 ± 7.88%, in diets of horses, guanacos, and hares, respectively, without significant differences. The contribution of herbaceous dicotyledons was only important in hares (23.76 ± 3.76%), while that of shrubs was low (<3%) and similar among the three herbivores. Dietary diversity was similar among the three herbivore species (73-79%), with a higher degree of dietary overlap between horses and guanacos (55.7%), which was higher than that obtained between hares and guanacos (50%) and between horses and hares (48%), for which there would be a potential trophic competition between them. The most abundant species of dryland and wet grasslands generally fulfill a functional role of subsistence and a nutritional role of maintenance; however, for the three herbivores studied, a different selective behavior was evidenced, according to their physiological differences, with the selection process little affected by the relative abundance of these species in the grasslands. Due to the above, herbivores resort to the selection of certain species that, despite being not very abundant in grasslands, play an important nutritional and functional role, improving the quality of their diets.