Habitat use by large and small herbivores in a fluctuating Mediterranean ecosystem: Implications of seasonal changes

摘要

Different-sized herbivores differ in several aspects from their relationship with food to predation risk whilst foraging. Consequently, the spatial distribution of food, food quality and refuge availability can determine differences in habitat selection by large and small herbivores. In regions under Mediterranean climate, food and water availability are subjected to spatial and temporal variations and habitat selection needs to be interpreted within a seasonal context. To assess the influence of seasonality on foraging habitat use by large and small herbivores, we developed a priori models taking into account direct factors influencing habitat use (food, refuge and water), and indirect soil factors (moisture, fertility and stoniness). Models were tested for free-ranging sheep and wild rabbits in spring, summer and winter using structural equation modelling. The importance of direct factors varied with body size and season. Sheep were highly influenced by food abundance throughout the seasons. Rabbits were mainly influenced by refuge availability in spring and winter, when food was not a limiting resource. However, in summer, the relevance of refuge disappeared and food quality became an important factor. Seasonality can modify the relative importance of known predictors for habitat use by large and small herbivores inhabiting Mediterranean environments.