Food habits and trophic niche overlap of the red fox and the stone marten in a Mediterranean rural area

The food habits of the red fox Vulpes vulpes (Linnaeus, 1758) and the stone marten Martes foina (Erxleben, 1777) were studied in a rural hilly area in Siena county, central Italy, using faecal analysis. Both frequency of occurrence and volume of the different foods were quantified. Rodents, especially Apodemus sp., were an important prey for both species. Predation on poultry and game birds was nearly absent, whereas fruits and insects were seasonally taken by both species. Rosaceae fruits were the most eaten plant item. Within this category the fox fed mainly on Malus sp. and Pyrus sp., while the marten showed a preference for Rubus sp. and Sorbus domestica. Only fruits of Prunus spinosa were eaten in comparable quantities. Beetles were well represented in the diet of both carnivores, although they tended to concentrate on different species. Grasshoppers were preyed in small quantity. The overall diet overlap of foxes and stone martens was extensive: a surprising result, if the different body size, locomotor adaptations and living habits of these carnivores are considered.