Sélection et utilisation des ressources fourragères par les herbivores : Théories et expérimentations à l'échelle du site et de la station alimentaires

Abstract

A better understanding of the animal x plant interaction is needed to develop management practices which will maintain a sufficiently rich and abundant vegetation in the pastures. Such practices would permit the animals to meet their nutritional requirements, and to ensure a sufficient production, while contributing to the maintenance of the environment. This review, drawn on a large number of experimental studies, takes stock of the factors influencing the selection and use of feeding sites and stations by herbivores. First, we present the theorical framework in which the experimental observations are discussed. The general context of Optimal Foraging Theory (OFT) and its predictions are described and discussed. Second, we analyse how forage (quantity and quality, plant species, distribution), environment (topography, distance to water, predator risk) and some animal factors (cognitive abilities, social organization) affect the choice and use of feeding sites and stations. The OFT successfully explains the foraging behaviour of herbivores. However, animals' choices are rarely as absolute as predicted. Under natural conditions, animals not only respond to food resource, but they are also constrained by some non alimentary environmental factors and by the limits of their cognitive abilities (memory, discrimination). Other complementary approaches, such as « hedonism » and « nutritional wisdom », can partly influence animals' choices and are also briefly discussed.