Ocena występowania i tendencji zmian liczebności dużych i średnich ssaków w polskich parkach narodowych

Paper presents the results of evaluation of the occurrence and population trends of mammals in 23 Polish national parks. Investigation was based on survey carried out among national park field workers. 29 large and medium−sized mammal species were found in Polish national parks. Growth in the populations of beaver Castor fiber, fox Vulpes vulpes, otter Lutra lutra as well as wild boar Sus scrofa were observed. A clear population regression was recognised for muskrat Ondatra zibethicus and brown hare Lepus europaeus.