ASSESSMENT OF HABITAT QUALITY IN THE MEDITERRANEAN PINE VOLE (MICROTUS-DUODECIMCOSTATUS) BY THE STUDY OF SURVIVAL RATES

Habitat quality should be usefully defined in a demographic perspectiv e. Survival and fecundity rates are sufficient to allow population per sistence in a high-quality habitat but not in a low-quality habitat. T he Mediterranean pine vole (Microtus duodecimcostatus) occurs in apple orchards in southern France, but its populations in this habitat are often driven to extinction by chemical control. However, recolonizatio n occurs promptly when control ceases. We tested the hypothesis that m eadows surrounding the orchards are high-quality habitats (sources) fo r the Mediterranean pine vole. We livetrapped four populations, three in apple orchards and one in a meadow. Survival rates were estimated u sing probabilistic open-population models. Our analysis led us to conc lude that meadows are low-quality habitats, particularly since no juve niles survived in this habitat during the main part of the study. Reco lonization of chemically controlled patches is probably allowed by asy nchronous control among orchards. We further discuss the usefulness of probabilistic open-population models for the investigation of variati ons in survival rates both within and between populations.