Syntopic populations of Orsini’s viper (Vipera ursinii) and adder (Vipera berus) in northeastern Montenegro

Abstract

During inventory of herpetofauna in National Park «Biogradska Gora» (Bjelasica mountain, north - eastern Montenegro), we located syntopic populations of Vipera ursinii and V. berus. Founding site, a mountain valley, is situated on the altitude of approximately 1683 m above sea level, above the tree line. The slopes of the valley are covered predominantly by open grass, with scattered bushes of Juniperus sp. and Vaccinium sp. Results of preliminary research suggested that both populations are abundant (on average, 3.5 and 1.5 new specimens per day were recorded for Orsinii’s viper and adder, respectively, during 6 consecutive days, on an area of approximately 4 ha). Sex ratio in samples of records differed between two species (6:1 and 4:5 for V. ursinii and V. berus, respectively).Upon our knowledge, syntopic populations of these two species are rare in the Central Balkans and thus provide opportunity to analyze degree of intraspecifi c competition in natural conditions and resource partition in regard to, at least, food and space. We tried to discuss here data about diurnal activity, microhabitat and food preferences, reconstructed from our fi eld notes and to propose detailed plan for future research.