Comparison of red fox Vulpes vulpes and pine marten Martes martes food habits in a deciduous forest in Hungary

Feeding habits and interspecific trophic niche overlap of two sympatric predators, the pine marten Martes martes and the red fox Vulpes vulpes, were studied in a deciduous forest habitat in Hungary with conditions of differing abundance and dominance in the rodent community. The main food source of the predators consisted of small mammals, mainly rodents. Consumption of small mammals was higher during bank vole Clethrionomys glareolus dominated years than in Apodemus mice dominated years. Both predators preferred bank voles as prey and consumed less Apodemus mice and shrews (Soricidae) than expected by availability. The two opportunistic predators utilised different, seasonally-dependent food resources. Martens consumed more plants, reptiles, amphibians and fish, whereas foxes consumed more small mammals and ungulate carcasses. In summer and autumn, percent biomass of bank voles in marten diet and Apodemus mice in fox diet was positively correlated with the number of rodents in the available food resources. In winter and spring, the density of rodents varied slightly; therefore, variations in the diets of these two predators were not related to prey density. The prey consumed was characteristically terrestrial and small sized (< 50 g). There was no difference in prey weight distribution between martens and foxes, but martens consumed more arboreal and foxes more terrestrial prey. The standardised food niche breadth did not differ significantly between the two species. Food niche overlap between the two predators was higher in winter and spring, but the difference between seasons was not significant (mean overlap = 72%). In comparison with higher latitudes, we found a larger food niche overlap in our study.