Individual red foxes prefer different foods in the city and the countryside

The diet is crucial to the survival of any animal. Using stable isotope analysis, the team led by first author Carolin Scholz (Leibniz-IZW) has now decoded the dietary spectrum of individual foxes in urban and rural areas. The results confirmed that red foxes are omnivorous and can feed on a wide variety of different animals and plants. At the same time, the results showed two different sets of specialisations: "Firstly, the diet of country foxes was much more varied than that of urban foxes," explains Scholz. "We detected a broad diet in foxes in unsealed habitats, ranging from plants, molluscs and insects to larger prey items. In contrast, urban foxes probably take advantage of the benefits of big city life and mainly fed on food items with increased ?13C values, an indication of food thrown away by people." Secondly, the isotope analyses confirmed that every fox is picky and specialises on particular food items, whether in the city or in the country. So, although the population of country foxes has a broad diet, each country fox follows quite a one-sided diet. City foxes celebrate a double monotony at the dinner table: both individuals and the population as a whole very often eat (different kinds of) discarded food.

The red fox's ability to eat almost anything is certainly a key to success in conquering urban habitats. The fact that urban foxes all eat more or less the same food probably also indicates that there is plenty for all of them, says Scholz. "Obviously there is enough for everyone. We city dwellers set their table abundantly -- with leftover food, waste, compost and pet food."