The formation of flora and fauna on these comparatively small islands was determined by the following factors: geographical position, island isolation, the north-south alignment of Sakhalin and the Kurile Islands, mountainous relief, volcanic processes, and the influence of the Pacific Ocean.

In Sakhalin and the Kurile Islands nature has created unique landscapes with a combination of northern Okhotsk and southern Manchurian flora. As well as typical taiga animals, the islands also contain warmth-loving species - amphibians, reptiles, birds, and even subtropical and tropical beetles and butterflies. Some areas of Sakhalin, and whole island systems in the Kuriles, are almost or completely untouched by man's activity. These primordial and very picturesque places are biospheres that preserve rare and disappearing species of flora, fauna, and ecological systems.

The Museum display shows the wide variety of animals inhabiting Sakhalin and the Kuriles, and also some species which have disappeared from the islands because of man's activities. During this short period in the history of the Earth, (in places little more than 250 years), the fauna of some islands has been impoverished. Bones of a wild boar and a sika deer were found at neolithic sites in the south of Sakhalin, but soon disappeared from the record. About 150 years ago the elk and the Manchurian deer were exterminated, but have since been re-introduced. Intensive wood felling caused the disappearance of the sable (since restored) and several taiga birds by 1945. By the beginning of the 1950s the raccoon dog disappeared as a result of intensive hunting, and it has also since been re-introduced. Mountain sheep were exterminated in Atlasov Island by the beginning of the 18th century, the wolf vanished from Paramushir, Shumshu and Kunashir Islands by the beginning of the 20th century, the river otter was exterminated on Kunashir, and the brown bear had gone from Shumshu by 1945.

Islands are limited and isolated territories, where the disappearance of animals as a result of hunting or economic development occurs more often and more quickly than elsewhere. We must remember how vulnerable island ecosystems are.

The region is home to ninety mammals, with fifty-six land species. The display includes a wolf (Canis lupus). This predator is not typical of Sakhalin, but was killed in the northern part of the island in 1955. This reminds us that the island is not entirely isolated, and that in the winter new species can move into it from the mainland across the ice of Nevelskoy Strait (7.5 kilometres). Not long ago tiger and lynx were known to cross from the mainland. Similarly, the fox and raccoon dog from Hokkaido crossed to the southern islands of the Kurile ridge, and the white fox from Kamchatka to Paramushir Island.

There is an exhibition on the biological group 'Northern deer.' The Northern deer (Rangifer tarandus) is a typical resident only of the tundra like landscapes of northern Sakhalin.

The diorama display shows the dark coniferous taiga of Sakhalin (fir and silver fir trees) and some typical residents. One of the biggest among them is the forest cat, or lynx, (Felis lynx), the rarest animal on the island.

The diorama is supplemented with a systematic collection and grouping of native mammals, typical residents of mountain and valley forests, and the taiga rivers and their banks. The biggest animal is the brown bear (Ursus arctos), quite often met with in Sakhalin, the South Kuriles (Kunashir and lturup) and the North Kuriles (Paramushir). A rare hoofed animal, the Siberian musk-deer (Moschus moschiferus) is represented in Sakhalin by its subspecies Sakhalin musk-deer (M.m.sachalinensis), entered and registered in the Red Book, which lists Russia's endangered species. The regular fox (Vulpes vulpes) from the canine family (Canidae) is common in all the islands of the region. The collection also includes animals from the marten family (Mustelidae): a sable (Martes zibellina), typical of forests, a river otter (Lutra lutra), a rare wolverine (Gulo gulo) and the uncommon ermine (Mustela erminea) and weasel (Mustela nivalis.) There is also, from the hare family, a white hare (Lepus timidus), and from the rodent family, (Rodentia), a squirrel (Scirius vulgaris) and an Asian chipmunk (Tamias sibiricus.)

Some animals have been introduced into Sakhalin, and the collection includes a raccoon dog(Nuctereutes procyonoides) as well as the Siberian weasel (Mustela sibirica itatsi), an American mink (Mustela vision,) and musk rat (Ondatra zibethica), these animals living partly in the water and partly on land. A developed river network and the abundance of inner reservoirs in the island have allowed these animals to flourish.

The introduction of mammals to Sakhalin and the Kuriles started in 1916, to replenish the hunting and fur-bearing animals. Nine species were brought to the islands from the mainland. Besides those above, there were Manchurian deer (Cervus elephas), elk (Alces alces), blue fox (Alopex lagopus semeniovi), and a white hare (Lepus timidus) to the Northern Kuriles, and European mink (Mustela lutriola) and American mink in the Southern Kuriles.

Restocking of native mammals was also carried out. Sable were returned to the southern part of Sakhalin and to Moneron Island, after being completely exterminated by 1945. Northern deer (Rangifer tarandus) were imported to Simushir Island, but failed to acclimatise.

The varied landscapes provide favourable conditions for plenty of animal species in Sakhalin and the Kurile Islands. At the same time, the difference between southern and northern parts of Sakhalin and the difference between the South, Middle and Northern Kuriles ensure a wide range. On the whole, Northern Sakhalin fauna is of the same origin as the fauna of the nearby mainland; the fauna of the Northern Kuriles is com-parable to that of the Kamchatka Peninsula, and the fauna of South Kurile Islands is similar to that of Hokkaido, Japan's northern-most island.