Foraging strategy in an herbivorous small mammal in central Chile: Time minimizer or energy maximizer?

Traditionally, it has been difficult to apply the foraging theory in herbivores because different parts of a plant exhibit different nutritional values. The linear programming method (LPM) is a tool that allows us to solve these problems because it evaluates animal's energy and nutritional requirements as well as its constraints (e.g. time and digestion). In this work we evaluate the foraging strategy of the herbivorous rodent Octodon degus (Octodontidae), under two seasonal experimental simulations differing in food nutritional quality and ambient temperature. This allows us to detect the possible constraints and trade-offs between food selection and thermoregulatory stress, as well as to compare observed diet selection against predictions of the LPM. Our results show that during summer O. degus behaves as a time minimizer, while in winter it behaves simultaneously as energy maximizer and time minimizer. We discussed this information in terms of space use, physiological constraints and foraging behavior.