Food habits of European badgers (Meles meles) along an altitudinal gradient of Mediterranean environments: a field test of the earthworm specialization hypothesis

Food specialization by European badgers (Meles meles) is a largely debated controversy. Data from Mediterranean areas indicate small importance of earthworms (Lumbricus spp.) in badger diet and support the idea that badgers are generalist predators. Nevertheless, only dry areas have been sampled so far. We studied badger diet in six areas along an elevation gradient with different rainfall and habitat conditions, which influenced earthworm availability. We evaluated the influence of earthworm availability on badger diet along this environmental gradient. Badgers used a wide range of prey items in the different habitats and seasons sampled. In contrast with other Mediterranean studies, earthworms made an important contribution to badger diet (27% of estimated volume). Earthworm occurrence in the diet was high in elevated and wet habitats and in spring and autumn-winter. Earthworm consumption was nonlinearly related to availability, indicating high intake compared with availability in wet areas. Moreover, in summer, availability was virtually zero in all habitats, whereas consumption averaged 15% volume of the diet. We tentatively suggest that badgers compensate for variations in earthworm availability by changing their foraging tactics. This suggests that badgers could be viewed as specialist foragers for earthworms in some Mediterranean environments.