Dynamics of red fox population in Bialowieza Primeval Forest in the years 1981-2016

Abundance of red fox (Vulpes vulpes) populations in Poland and Europe have increased in the past decades, especially in the areas of high anthropogenic transformation. The aim of this study was to assess the current density of red fox in natural forests and to analyse changes in its abundance since 1981. The fieldwork was carried out in Polish part of the Bialowieża Primeval Forest (BPF), including Białowieża, Browsk and Hajnówka forest districts as well as Białowieża National Park. A standard method of snow tracking along transect routes (15 to 94 km long in the subsequent winters, altogether 199 km) was used. Taking a density of snow tracks per 1 km of a transect route per 24 h and the length of daily movements of red foxes (13,8 km) we calculated the population density. Results were compared with historical data derived with the same method. Mean number of tracks of red fox in the years 2011−2016 equaled 6.1/km/24h (SD=3.9). Density of fox population was 0.69 individuals/km2, which results in the abundance of the population in the whole area of BPF of 414 individuals in winter time, while of approximately 869 individuals in spring. Comparison of current data with the results from last three decades showed an increasing trend in the population of the analysed species. Nevertheless, in comparison to central or western Poland the density of the red fox in the BPF is still relatively low. Possible factors that suppress this population are parasites, infections (mange, rabies) and large carnivores