Biogeographical patterns of the diet of Palearctic badger:Is badger an earthworm specialist predator?

Badgers were hypothesized as an earthworm specialist predator. We reviewed spatial patterns and food habits of the Eurasian badger (Meles spp.) in relation to geographical variables like latitude, elevation, aspects, and environmental variables, such as temperature, snow cover depth, precipitation, primary productivity, and human influence. The relative frequencies of occurrence of food items in the diets of badgers in 19 studies across 22 localities worldwide were included in the analysis plus the data from our study on the badger diet on the Qinghai-Tibetan Plateau. Principal component analysis (PCA) was used to extract the main components of dietary composition. Multiple regression analysis was applied to reveal the relationship between trophic diversity and the main PCA factors and biogeographical variables. We found a clear latitudinal gradient in the dietary composition of badgers, which was characterized by a greater consumption of insects and reptile in southern area and a higher intake of earthworm in northern regions. Nevertheless, badgers are not an earthworm specialist predator. Furthermore, trophic diversity of badger diets was significantly positively correlated with latitude and human activity. Abundance and availability of foods appear to determine badger foraging tactics. Badgers are adept in exploiting local resources and our results confirm that badgers are generalist predators with opportunistic foraging behavior across their entire distribution range.