ESTIMATING BROWN BEAR POPULATION DENSITY WITH CAMERA TRAPS IN CENTRAL BALKAN MOUNTAIN, BULGARIA
ELITSA POPOVA1*, ATIDZE AHMED2, IVAN STEPANOV3, DIANA ZLATANOVA1, PETAR GENOV2
1 Sofia University “St. Kliment Ohridski”, Faculty of Biology, 8 “Dragan Tsankov” blvd., Sofia 1164 Bulgaria
2 Institute of biodiversity and ecosystem research, BAS, Blvd. “Tsar Osvoboditel” 1, Sofia 1000 Bulgaria
3 State hunting enterprise “Rositsa”, 5462 Stokite, Sevlievo, Bulgaria
*Corresponding author: elitsa.d.popova@gmail.com;
Keywords: Ursus arctos, camera traps, high population density, supplemental feeding
Abstract: Eestimating population size and density for mammals which are not individually recognizable is particularly challenging. However, these indicators are vital for species management. In this study we make the first attempt to estimate the population density of the endangered in Bulgaria brown bear (Ursus arctos L.) using camera traps. Thirty eight camera traps were set up at random locations (spaced at approximately 1 km from each other) between July and August 2017 in the State hunting enterprise “Rositsa”, located on the Northern slopes of the Central Balkan Mountains, Bulgaria. Fifty independent registrations of brown bears were collected and analyzed through the newly developed method without the need for individual recognition proposed by Rowcliffe in 2008 – the random encounter method. The results indicate local population density of 1.78 ind./km2, which is unusually high especially in comparison to the observed densities in the neighboring National Park Central Balkan (0.1-0.2 ind./ km2). This is most likely due to the rich natural food base, the protection against poaching and the supplemental feeding in the hunting area which attracts many individuals and increases the density locally. This leads to a perceived “overpopulation”, but in fact this is a local concentration of individuals and not a true high density. The proposed method is cost-effective and can be used to complement or enhance current monitoring schemes.