Summary:

The adverse effect of roads on the environment is observed both during their construction and use. Increasing areas of farmland and forestland are subjected to transformations disadvantageous for animals. It is connected with the loss of natural habitats, changes in water relations and fragmentation of forest complexes. The possibility of free migration of representatives of a given species is the basis for the sustainable functioning of a population. In order to provide ecological communication of an area divided by a road or railway more and more often crossings for animals are being build over or under this road or line. The aim of the investigations was to determine the acceptance level by migrating game of two overpasses built over communication routes: a road and a railway line. Investigations were conducted on a crossing for animals over trunk road no. 5 in the Wielkopolski National Park and on the two newly constructed crossings over a modernized railway line E 20 at the Rzepin – Kunowice section. The effectiveness of crossings over the railway line was assessed by tracking. The crossing over the road was monitored using a specially designed filming unit. Analyses of the operating crossings for animals over railway line E 20 and trunk road no. 5 showed that migrating game accepted investigated objects. This was facilitated by appropriate selection of crossing locations, applied construction parameters and the vicinity of backwoods. Monitored crossings were used by e.g. roe deer, wild boars and red deer. Migrating large game used overpasses both over railway lines and roads with a width of approx. 40m; however, it seems advisable to construct crossings of min. 80 m in width. Acceptance of crossings is accelerated by their appropriate location, applied construction design and the manner of management of both the object and the adjacent areas. Even the most cautious species relatively fast got used to the newly constructed bridges located at migration routes. The age structure of animals using crossings resulted from the structure of inventoried populations inhabiting the hunting district. Representatives of even the most cautious age classes used these crossings. Migration through crossings takes place mainly at night, although there were recorded numerous cases of passages during the day (both for wild boars and red deer) over the busy trunk road no. 5.