Białowieża Forest is divided into Polish and Belarusian parts that differ in habitat structure and degree of protection. The forest supports two European bison, Bison bonasus (L., 1758), populations that are isolated from each other. We analysed bison habitat use from relocations of 34 radio-collared bison from both populations collected in 1993–2003. The two bison populations differed considerably in habitat use, but home-range sizes were similar. The habitat structure in the Polish part is more advantageous for bison (deciduous forests prevail) than in the Belarusian part; however, open areas form a rich source of forage for ungulates in the Belarusian part, which presumably helped to eliminate the difference between the two parts. In 1977–2003, the annual temperature in this area rose and the total precipitation diminished. As a result, the habitat use by bison changed in both populations when compared with those in earlier studies; use of coniferous forests decreased, while use of deciduous forests and alderwoods increased. Generalized linear models on relationships among climatic factors and habitat use showed that the amount of water accessible in the period up to 4 years ago was the main factor affecting the use of various forest types. Habitat preferences differed between adult bulls and groups that included cows, but were similar in both populations irrespective of the differences in habitat composition.
Movements of European bison (Bison bonasus) beyond the Białowieża Forest (NE Poland): range expansion or partial migrations?
