Trophic adaptations of the red fox Vulpes vulpes on Urup Island (Kuril Archipelago)

We have studied the composition of scats in the free-ranging population of the red fox Vulpes vulpes on Urup Island during the population depression of the island's key prey — the brown rat Rattus norvegicus caraco. The scat samples were collected on the northern and southern points of the island. We determined the occurrence of certain food components and biomass of the different-sized fractions of the faecal particles after sieving. Vertebrates make up a small part of the red fox`s diet, both in terms of occurrence and biomass of the remains in the scats. The occurrence of the micromammals is less than 20%. Bird remains occur in the scats twice as high especially in the northern part of the island, where there are forest communities. Insects and crustaceans have the greatest occurrence and the bulk of the biomass in the faecal fragments. This demonstrates the importance of coastal and tidal habitats for the red fox. The berries of wild shrubs are often found in the scats. The discrete mean (dMean) of faecal particle size is 2.47 ± 0.12 mm for all samples. The dMean value is determined by the proportion of the largest faecal particle fraction. The proportion of the smallest size fraction of particles reliably correlates with the fraction of insect biomass. The negative correlation is found between the proportions of the biomass of insects and crustaceans, and between the proportion of crustaceans and the proportion of plant items in the scats. In the period of reduction and absence of some foods in local island sites, the red fox switches to alternative forages easily, confirming its dietary plasticity and opportunistic omnivory. The importance of certain food items in the fox nutrition and the ecological significance of this mesopredator in the ecosystems of Urup Island have been discussed. How to cite this article: Scopin A.E., Lipatnikova S.V., Shikhova T.G. 2021. Trophic adaptations of the red fox Vulpes vulpes on Urup Island (Kuril Archipelago) // Russian J. Theriol. Vol.20. No.2. P.188–203. doi: 10.15298/rusjtheriol.20.2.08