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Rodents, Lagomorphs, and Insectivores
Approximately one-third of all mammals on the Kamchatka Peninsula belong to the order of rodents. The squirrel family (Sciuridae) in Kamchatka includes three species: the red squirrel, the Kamchatka (black-capped) marmot, and the Beringian ground squirrel (evrazhka).
Red Squirrel (Sciurus vulgaris)
Until the 20th century, squirrels were absent from Kamchatka. According to P. T. Novograblenov (1930), the first sightings of this animal were recorded in 1920 on the northwestern coast of the peninsula. The squirrels spread through the valleys of the Talovka, Pustaya, Lesnaya, and other rivers. By the late 1920s, they had dispersed across almost the entire peninsula, except for its southernmost tip.
However, the conditions in Kamchatka's stone birch forests proved less than ideal for the squirrel. As the sable population recovered, squirrel numbers began to decline. Only in the valley of the Kamchatka River, where spruce and larch forests grow, does this rodent find conditions close to optimal.
The squirrel is a typical forest dweller, perfectly adapted to an arboreal lifestyle. Its body length reaches 25 cm, and its bushy tail accounts for about three-quarters of that length. Weight can reach up to 350 g. The ears are large, with tufts at the tips. The hind legs are noticeably longer than the front legs. The squirrel's fur is quite high, dense, and soft, dark gray in color; in summer, it becomes coarser, sparser, and shorter, taking on a brownish hue. The belly remains white year-round.
The squirrel's favorite foods are spruce seeds and dwarf pine nuts. It readily eats mushrooms, and in years when conifer seeds are scarce, mushrooms become its staple diet. Berries, buds, shoots, bark, and even insects play a secondary role. For winter, the squirrel stores small supplies of mushrooms and nuts.
The squirrel builds spherical nests (called dreys) from twigs of various sizes, placing them in tree branches.
The mating season runs from February to April. When food is scarce, the rut is delayed and less active. Unlike on the mainland, repeated mating is quite common in Kamchatka. Pregnancy lasts 38–39 days. A litter usually contains six young, rarely more. Litters are found from April to August.
Population trends are clearly reflected in pelt harvest data. Over the past 25 years, annual harvests have ranged from 500 to 7,300 pelts. According to rough estimates, between 10,000 and 25,000 squirrels currently live in Kamchatka. The population depends directly on the yield of spruce seeds.
The squirrel is a secondary fur-bearing species on the peninsula. In monetary terms, its share of Kamchatka's commercial fur harvest ranges from 0.3% to 2.8%. However, due to extensive logging and forest fires, the squirrel population in Kamchatka may decline.
Kamchatka Marmot, or Black-Capped Marmot (Marmota camtschatica)
The Kamchatka marmot is one of the least studied members of the squirrel family on the peninsula. It is a fairly large rodent adapted to life in the harsh conditions of mountainous landscapes.
Appearance. The marmot has a dense, massive build. An adult's body length reaches 50–65 cm, and weight ranges from 3 to 6 kg. The tail is relatively short and covered with thick fur. A distinctive feature is the dark, almost black cap on its head, which gives the species its alternative name. The back coloration varies from sandy-yellow to reddish-brown, while the belly is lighter.
Habitat and Distribution. The Kamchatka marmot is endemic to the peninsula, meaning it is found nowhere else in the world. It inhabits mountain tundras and rocky slopes, preferring areas with good visibility and available shelter. Marmot colonies are located at altitudes of 300 to 1200 meters above sea level. It is found in central and northern Kamchatka, including the Koryak Highlands.
Lifestyle. Like all marmots, the Kamchatka species is diurnal. It is a typical colonial animal — families live in burrows that form complex systems of underground passages. The burrows have multiple entrances, nesting chambers, and food storage areas. Marmots hibernate deeply during winter, sleeping for 7–8 months (from September–October to May–June). Before hibernation, they accumulate significant reserves of subcutaneous fat.
Diet. The marmot's diet consists mainly of herbaceous plants: grasses, sedges, and various forbs. It also eats berries, mushrooms, and some rhizomes. Unlike squirrels, marmots do not store large amounts of food for winter — during hibernation, they rely on accumulated fat reserves.
Reproduction. Marmots reach sexual maturity at 2–3 years of age. Mating occurs in spring, immediately after emerging from hibernation. Pregnancy lasts about 30–35 days. Litters typically contain 4–6 pups, which are born blind and hairless. The female nurses them for about a month. Young marmots stay with their parents until the following spring, after which they disperse.
Conservation Status. In the past, the Kamchatka marmot was hunted for its meat and fat. Currently, its numbers are relatively low, and it has become rare in some areas. Accurately estimating the population is difficult due to the inaccessibility of its habitat. The Kamchatka marmot is listed in the regional Red Data Books of some parts of the peninsula. Hunting is restricted or completely prohibited.
Interesting fact. Marmots are very cautious animals. When danger approaches, they emit a loud whistle to warn their relatives. For this reason, they are sometimes called "mountain whistlers."
Arctic ground squirrel (Spermophilus parryi), locally known as "evrazhka"
This rodent has a body length of 26–29 cm and a tail length of 8–11 cm. Its weight ranges from 600 to 950 g. The upper part of the back is brownish-ochre with a distinct spotted pattern, while the top of the head exhibits brownish-rusty tones.
In Kamchatka, the Beringian ground squirrel is found primarily in the alpine mountain zone but also occurs at other elevations, down to sea coasts. At the upper limit of its range, the evrazhka often shares habitat with marmot and pika colonies. The main populations are concentrated in the northern part of the peninsula — in the Penzhinsky, Olyutorsky, Karaginsky, Bystrinsky, and Tigilsky districts.
Winter burrows are dug to a depth of up to half a meter, although the nesting chamber is sometimes located deeper. Temporary shelters consist of simple, unbranched tunnels and may be found at shallower depths. The complexity of permanent burrows varies depending on the age of the settlement and the soil type.
The diet consists mainly of above-ground plant parts, roots, rhizomes, seeds, mushrooms, and berries. When plant food is scarce, these rodents eat insects and small rodents. Cases of cannibalism have also been recorded. By the time they enter hibernation, ground squirrels accumulate subcutaneous fat — up to 10% of their body weight.
Winter hibernation lasts 6–7 months. The animals emerge to the surface in late April. Mating begins almost immediately after awakening and passes quickly. Females give birth in early June, with litters typically containing 5–7 pups. The young grow rapidly, reaching adult size by autumn, and participate in reproduction the following year.
The ground squirrel is considered a secondary fur-bearing species, although its commercial importance was greater in the past. For example, in 1936, ground squirrel pelt harvests in the Kamchatka region exceeded 37,000 skins. In several districts, the evrazhka serves as common prey for predators such as foxes and bears.
To enrich the region's commercial fauna, two rodent species with the most valuable fur — the Canadian beaver and the muskrat — were introduced to Kamchatka. These acclimatization efforts were carried out by the regional hunting and fur management authorities, with methodological support from researchers at the Kamchatka branch of the All-Union Research Institute of Game Management and Fur Farming (VNIIOZ).
Canadian beaver (Castor canadensis)
The Canadian beaver belongs to the beaver family (Castoridae) and is one of the largest rodents in the modern fauna. An adult can reach one meter in length and weigh up to 30 kg.
The beaver's body is perfectly adapted to a semi-aquatic lifestyle. Its hind feet have well-developed swimming membranes between the toes. The bare tail is strongly flattened horizontally and covered with horny scales. The fur is dark brown with a reddish tint.
Beavers are active during twilight and at night. They feed on bark and thin branches of trees — preferring Chosenia, willow, and poplar — as well as on aquatic and shoreline herbaceous plants.
Beavers live in families, each occupying a specific stretch of a river. They dig burrows into riverbanks, with the entrance always located underwater. On bodies of water with low banks, beavers construct lodges using branches, plants, and mud. Often, they build dams downstream from their homes. The water raised by the dam floods the banks, giving the animals access to new feeding areas.
The estrus period in females occurs in January–February. Mating takes place in the water. Pregnancy lasts 105–107 days. Litters consist of 3–5 kits. Baby beavers are born with their eyes open and covered in soft, fluffy fur.
Introduction to Kamchatka. Beavers were first brought to the peninsula in 1977. A total of 61 animals captured in the Leningrad region were released into the rivers of the Milkovsky district. Later, beavers were also released into rivers on the western coast of Kamchatka — in the Tigilsky, Sobolevsky, and Ust-Bolsheretsky districts — as well as into rivers of the Ust-Kamchatsky district.
The animals have successfully established themselves in all release sites. Currently, their population numbers about 500 individuals. Efforts to further introduce beavers across Kamchatka are still ongoing.
Muskrat (Ondatra zibethicus)
The muskrat is a rodent belonging to the family Cricetidae. Its native range is North America. In 1928, the Kamchatka Joint-Stock Company released 35 muskrats — purchased in Canada — onto Karaginsky Island. Targeted acclimatization on the peninsula itself began in 1959. Between 1959 and 1965, a total of 2,186 individuals were released across the Kamchatka region. Today, the muskrat is widespread throughout the peninsula and has colonized almost all suitable water bodies.The muskrat's body length reaches up to 36 cm. Its tail is long, laterally flattened, and accounts for about 70% of its body length, functioning as a rudder in the water. The edges of the hind toes have fringes of short hairs that increase the paddling surface. Incomplete swimming membranes between the toes serve the same purpose. When swimming, the animal presses its front feet against its chest. The upper body coloration ranges from brown to blackish-brown, while the underside is lighter. At the base of the tail are specialized glands that secrete a musky substance.
On banks with high shores, the muskrat digs complex burrows with a nesting chamber located above the water level and an entrance underwater. Sometimes it builds mixed shelters. During winter, it remains active — it creates breathing holes in the ice and tunnels under the snow.
Its diet consists of shoreline plants (sedges, horsetails, and others) and aquatic vegetation (pondweeds and others). Animal matter in its diet includes mollusks and small fish.
The breeding season begins in April–May. Females produce two litters per season. Pregnancy lasts about 25 days. Litters average 6–8 young.
Muskrat trapping has been conducted since 1966. Currently, 15,000–20,000 muskrat pelts are harvested annually. The muskrat is a carrier of tularemia, and infections among muskrat hunters are not uncommon in Kamchatka.
Lagomorphs
The order Lagomorpha includes the mountain hare and the northern pika. For a long time, they were classified as rodents, but the main difference lies in their dentition: lagomorphs have not one but two pairs of incisors, with one pair located behind the other. The front incisors are large and chisel-like; the rear ones are small and oval-shaped. Lagomorphs and rodents evolved from different groups of primitive insectivores.
Northern pika (Ochotona hyperborea)
The northern pika is a small mammal, with a body length reaching up to 19.5 cm. Its ears are short and rounded. The hind legs are about 25% longer than the front legs. The tail is not visible externally. Summer fur is ochre-brown in color, while winter fur is gray or grayish-brown.
The pika is found throughout the Kamchatka Peninsula and inhabits mainly the subalpine belt (the upper forest boundary). The limits of its vertical distribution coincide with the boundaries of herbaceous vegetation and shrubs. It is most often encountered in rocky talus slopes. Occasionally, pikas settle in so-called "logjams" — accumulations of driftwood (snags and logs) on mountain rivers.
Throughout the summer, pikas store food for the winter. They gather plants in any weather, even in the rain, and dry them: on sunny days, they dry them on rocks; on rainy days, they dry them in niches beneath the rocks. By observing where a pika dries its hay, one can predict the weather for the next day or two. The pika feeds on its stored supplies for 8–9 months, from September to June.
The mating season occurs in May–June. Pregnancy lasts about 30 days. During the breeding season, the female produces only one litter, which contains 2 to 6 young. Shelters for pikas include cavities in rocky talus, driftwood piles, and occasionally short burrows with one or two side branches.
The pika's population density is difficult to determine. In optimal habitats, several dozen individuals may live on one hectare. Many pikas are infested with the warble fly (botfly) — up to 30 larvae have been found under the skin of a single animal. The pika serves as prey for the ermine and the sable. Its role as a consumer of plant biomass (phytomass) is significant; in some areas, this leads to depletion of vegetation near pika colonies.
Mountain hare (Lepus timidus)
The mountain hare reaches a body length of up to 65 cm and weighs between 2.5 and 4.5 kg. In summer, its fur is reddish-brown, which provides excellent camouflage in the forest. In winter, the hare turns completely white, with only the tips of its ears remaining black. Its short tail is white year-round.
Hares are found almost everywhere. In the mountains, they ascend to the highest parts of the slopes, avoiding only the steepest and rockiest areas. Their movements are generally local and related to seasonal changes in habitats — for example, moving up into the mountains or concentrating in specific areas.
Mountain hares are primarily crepuscular animals. During daylight hours, they are active only in the mating season, when they lose their usual caution. During the spring (May–June) and autumn (October) molts, hares move very little because they temporarily lack their protective coloration.
The hare feeds exclusively on plant matter. In winter, its diet consists mainly of shoots and bark of shrubs and trees. In summer, it consumes many herbaceous plants.
Female hares come into heat twice a year, during the spring–summer period. Pregnancy lasts up to 52 days. Litters contain 3 to 9 leverets, which are born well-developed: with their eyes open and covered in thick gray fur. During their first few days, leverets are relatively immobile and rely on their ability to hide.
The mountain hare population undergoes significant long-term fluctuations. In 1966, 2,800 hares were harvested; by 1971, the harvest had increased to 11,300; and in 1973, it dropped again to 2,300 individuals. The reasons for such dramatic fluctuations are not fully understood. The last notable population depression was recorded in 1980. During years of high abundance, the hare plays an important role in the region's hunting industry. Hare meat is a valuable food product, especially in the north.
In addition, it is worth briefly mentioning the group of small mammals commonly referred to as "mice." This group includes voles and lemmings (order Rodentia), as well as shrews (order Insectivora).
Voles
Voles inhabit all landscape zones of Kamchatka — from mountain bald peaks (golts) to sea coasts. The most numerous species is the northern red-backed vole, which is found mainly in forests and shrub thickets. Interestingly, the red-backed vole was accidentally introduced from the peninsula to the Commander Islands (Bering Island). This happened in the 1970s–1980s.
The tundra vole (or "economka") prefers moist floodplain meadows, as well as subalpine and alpine meadows. The gray red-backed vole chooses shrubby forest edges and dry floodplains.
Vole populations undergo significant year-to-year fluctuations. According to long-term data, population outbreaks occur every three years (or sometimes every four years). Voles are the most preferred prey for the region's most important fur-bearing animals: sable, red fox, and ermine. They also serve as supplementary food for the otter, mink, lynx, wolverine, many birds of prey, and even the brown bear. Due to their abundance, voles have a noticeable impact on vegetation and are often responsible for the emergence and spread of certain natural focal diseases.
Lemmings
Three species of lemmings are known in Kamchatka: the wood lemming, the Siberian (or Ob) lemming, and the collared lemming. All three species have a patchy distribution. The wood lemming is found in foothill stone birch forests and in the "conifer island" of the Kamchatka River valley. The Siberian lemming inhabits floodplain, wet, and dry tundras. The collared lemming stays in dry tundras near the upper forest boundary (the subalpine zone). All lemmings are generally low in numbers. The only exception is the wood lemming, which in some years reaches high numbers only in the larch-spruce-birch forests of Central Kamchatka.
Shrews (Sorex species)
This group includes the following species: the large-toothed shrew, Kamchatka shrew, even-toothed shrew, tiny shrew, and masked shrew. These are the smallest mammals in Kamchatka and are found in almost all biotopes. In some years, they rival voles in abundance, but they play a secondary role in the diet of most predators. The smallest predators — the least weasel and the ermine — readily feed on shrews.
At the same time, these small animals bring significant benefits to the forest: they destroy harmful insects and perform a sanitary role by feeding on dead animals.