OCTODON-DEGUS - NUTRITIONAL-VALUE AND FOO D PREFERENCE IN THE OCOA PALMAR, LA-CAMPANA-NATIONAL-PARK, CHILE

We provide strong experimental evidence, based on nutritional composit ion and assimilation efficiencies, supporting the hypothesis that Juba ea chilensis seeds represent a very important resource to Octodon degu s population of Palmas de Ocoa, from an energy point of view. Of the e ight food items considered, Colliguaya odorifera seeds are the higher quality. Even though J. chilensis seeds have a relatively lower concen tration of nitrogen an ions, their relatively higher average biomass, which provide to the animal who find and eat them with a significant h igher amount of nutrients and calories, grants it also a high quality level. Our preference results strengthen the idea that animals selecti vely forages on food that is higher quality for it. The different nutr ient and energy composition, the different assimilation efficiencies, and the seasonal dependence of the availability of the trophic resourc es studied reinforce the adaptive advantage which represents to O. deg us being a generalist herbivore. Non of the food items considered coul d by itself satisfy the energy and nutrient requirements of this anima ls during their life cycle.