Reserve's fauna is presented by taiga species. There are 29 species of mammals there. Rodents represent a major part.
Squirrels, hares, stoats, martens, foxes, moose and brown bears are typical. Muskrats are often seen in the vicinity of water. Populations of the brown bear Ursus arctos and the moose Alces alces are common for neighbor countries. Weasels, wolverenes and otters are rare animals.
The reindeer is indigenous to Pasvik Inari region; its domesticated forms are spread there. Wild deer can be found in the central part of Kola Peninsula and in the east. Reindeer breeding is widely spread in Finnish Lapland and Finnmark, Norway. It is in its primeval form there. Herds graze in different areas depending on season and forage availability. In Russia reindeer breeding is developed in the east of Kola Peninsula.
Two hundred and twenty nine species of birds are registered in Pasvik Reserve. The Paz River and adjacent wetland sites are an important habitat for such birds as black-throated divers, whooper swans, goldeneyes, smews, mallards and red-breasted mergansers. Sandpipers (snipes, wood sandpipers and spotted redshanks) and common cranes are typical on swamps. As for birds of prey, one can see an osprey, a white-tailed eagle, a goshawk, a rough-legged buzzard, a kestrel and a marsh owl. Such forest species as woodpeckers, tree pipits, robins, redstarts, bramblings, chiffchaffs, flycatchers and buntings are registered in the nesting season. Many birds spend the winter in the forests; they are black grouses, wood grouses, partridges, hazel-hens, waxwings, tomtits, sparrows and redpolls. Common chats, meadow pipits and whimbrels can be seen in mountain tundra.
There is one species of Amphibians and one species of reptiles in the region. They are the brown frog and the common lizard.
There are twelve species of fish in the Paz River basin such as the brook trout, the trout, the whitefish, the grayling, the burbot, the pike and the perch.
We have just started research into fauna of the invertebrates. Seven hundred and seventy six species of insects had been registered in the territory of the reserve by 20th century. They represent eight subclasses. Hymenoptera (181 species) and dipteran (543 species) are better investigated. The fauna of spiders runs to sixty eight species; they represent thirteen families. But these figures are not final as research is on.