Herbivores confront a food resource base with a complex assortment of nutrients and toxins. Because of this complexity, diet selection in herbivores is poorly understood. Pikas (Ochotona princeps) are mammals (related to rabbits) that inhabit mountainous regions and unlike many other small mammals, remain active all winter. During the winter, pikas survive on stored vegetation ("haypiles"), collected during the previous summer. The winter diet stored in the haypile differs considerably from the plants that pikas consume in the summer, although both are collected simultaneously. This project focuses on identifying the factors responsible for these different diet choices. Hypotheses that 1) pikas select their summer diet to be nutrient-rich and toxin-poor, but that their winter diet choice is more intricate than simple avoidance of plant toxins; and that 2) pikas manipulate plant toxins in their winter diet, will be tested. Data on nutrients, toxins, and morphologies of available food plants will be collected and used to test these hypotheses. The significance of the research extends beyond understanding the question of diet selection in pikas. Identifying the factors governing diet selection, may lead to better diets for herbivorous animals in zoos. Moreover, this information could be used to exploit plant toxins to naturally regulate herbivorous pest populations, especially rodents.
