Richness of life and the world is based on species variety which has been formed during the long evolution therefore it is so important to know which animals and how many of them inhabit our region. How many is indeed?

Lemmings, voles and shrews of the Kola peninsula

Mammals class is represented in the Lapland reserve by 31 species, 40 % of them are rodents. It appears that mammals exceed all the other vertebral – fishes, amphibians, creepers and birds all put together by their biological mass, i.e. live weight per area unit. The biggest share of this mass – 93 % – accounts for representatives of rodents order. Rodents are widely spread across the whole world and inhabit all kinds of landscapes: from lowlands to mountain tops up to 5 500 meters above sea level. Animals live under stones, roots, fallen tree stems, less frequently they are mining holes. They can swim. It is counted that vole-like rodents accounted for area unit is in average 1 animal per each 10 m2. So it is absolutely logical that given such an abundance of rodents they shall be studied, otherwise many feeding and ecological relations and interrela- tions in nature will remain unclear. Let’s try to review variety of wild rodents of the Kola pen- insula – lemmings and field voles living in river valleys, forests and tundra. These numerous animals are divided into three groups: lemmings (Lemming) (picture 2), red-backed voles (Myodes or Clethrionomys) and common voles (Microtus) (picture 1). The first group consists of two species: Norwegian lemming Lemmus lemmus and wood lemming Myopus schis- Picture 1 peninsula of the Kola and shrews Lemmings, voles ticolor. The second group combines three species: European Field vole 1

Lapland state nature biosphere reserve Picture 5 Gray-sided vole

Picture 2 Picture 3 Norwegian lemming Field vole

field voleClethrionomys glareolus, Siberian filed voleClethri - onomys rutilus and gray-sided vole Clethrionomys rufocanus (picture 5). The third group is represented by tundra vole Mi- crotus oeconomus, short-tailed vole Microtus agrestis and wa- ter vole Arvicola terrestris.

Rodents are widely spread across the whole world and inhabit all kinds of landscapes: from lowlands to mountain tops up to 5 500 meters above sea level.

All lemmings and voles have a hamster-like appearance and almost single-color fur. Red-backed voles are dark-red, all common voles are of a dark-gray color (picture 3). Multicol- ored fell of a Norwegian lemming differs it from the others. Fore-limbs and hind-limbs of all rodents have five digits, ad- aptation for climbing is almost absent. Semiaquatic species sometimes have webbed feet on hind-limbs. Feeding ration – predominantly vegetation feed (pic- ture 4) – determines a specific dentition system: sharp incisors without roots and therefore ever-growing –two from above and two from below – are located under an upper dissected lip. Thick enamel is covering them only on the front, rear incisors Picture 4 consist of soften dentine. Thus a tooth is worn down in homo- Picture 6 of the Kola peninsula of the Kola and shrews Lemmings, voles Rodents’ feed: cowberry and lichen Nephromaarcticum (at the top); geneously and a forefront always remains sharp. Rodent’s feed Arctous (at the bottom) Wood lemming 2

ABCGheritage – Our common arctic heritage is low in calories and they have to consume it in huge quan- tities, this peculiarity influenced constitution of the animals: their intestinal tract is very long and always filled with feeding. Diet of rodents inhabiting the Kola peninsula is different. Voles’ feeding consists of “soiling food”: grasses, leaves, but- tons, berries and cortex of different plant. Lemmings’ ration is not like this, their stomach is capable to process green mosses, sedge, cereals. Peculiarity of a Norwegian lemming is its “strict diet” – an animal cannot live without green mosses. Moss reserves in the northern forests are abundant therefore lemmings have no competitors. The author had a chance to watch the way a lemming is feeding – having found a moss lawn, an animal starts biting off a top of each plant, a set. Af- ter feeding is completed with all moss subshrubs, a lemming is searching for a new place with moss and eats it. By that one rodent uses moss from an area of not less than 34 m2 to Picture 5 load up. After this kind of “trimming” moss stops growing and Gray-sided vole fades. Large areas of rust mosses resembling small burnt-over foci on soil appear during a season. After damage moss recov- ers for a long time, during 5–6 years. In such periods lemmings can suffer a shortage of feeding, especially in winter. Lemming – is a small rodent, endemic, as it inhabits only Scandinavian countries and the Kola peninsula (picture 6). Fur is long and thick, doesn’t get wet in water much, that let an- imals leave in humid areas. Lemmings maintain their fell dry by periodical greasing it with sebaceous matter from an oil Diet of rodents inhabiting the Kola peninsula gland located on a sacrum. Its marking is very remarkable: is different. Voles’ feeding consists of “soiling food”: a black-red ribbon is stretching from a head to a tail, sides are grasses, leaves, buttons, berries and cortex ocher-colored, abdomen is of yellow color. For its dress lem- of different plant. Lemmings’ ration is not like this, mings received the second name – “colorful” lemming. Fox, er- their stomach is capable to process green mosses, mine, marten are easily hunting their kill – all lemmings do to sedge, cereals. protect themselves is a threatening posture and charring. Swimming lemming, by the way they all are good swimmers, peeps even at fishes if they are close to lemmings. Many car- nivorous animals and birds have adapted find and hunt lem- mings digging out ice-hole up to 70 cm deep. Given the abun- dance of lemmings owls catch them in excess and being not able to consume such an amount of feed, throw their pecked bodies on forest paths. One lemming’s claw of a fore-hind digit is flat and bifur- cated, an animal uses it to comb hairs and can dig soft soil or snow. Small animal digs burrows near stones or stumps, and sometimes simply seeks for shelter under the roots of trees and shrubs. Sometimes a stem or branch of a fallen birch can serve as a shelter for lemmings, an animal gets rid of spunk in the middle of it. At the beginning of winter, when the snow is thin, short trenches of rodents are seen well, and in the middle of winter, lemmings protecting themselves from cold under snow build tunnels with small vents on the surface. During thaw animals come out to the surface, and typical dog- trot traces can be found on snow. If you are tired of walking in forest in the summer, do not rush with a choice of rest place. Mind your steps carefully – for certain you will see a narrow path in the grass. Sometimes Picture 4 Picture 6 such a tunnel is stretching for 40–50 m. For lemmings it is Rodents’ feed: cowberry and lichen Nephromaarcticum (at the top); peninsula of the Kola and shrews Lemmings, voles Arctous (at the bottom) Wood lemming complicated to run new ways every time, that is why they lay 3

Lapland state nature biosphere reserve Picture 7 Picture 8 Picture 10 a, b Norwegian lemming Gray-sided vole Norwegian lemming is looking out from its shelter

feeding roads from one island of dwarf birches to another one. If you sit quietly, you can see a lemming itself – it is a very agile animal. Among rodents namely lemmings have the most signifi- Lemming – is a small rodent, endemic, as it inhabits cant fluctuations in numbers. Usually lemmings reproduce only Scandinavian countries and the Kola peninsula. in snowless period, while it is noticed that in some years Fur is long and thick, doesn’t get wet in water much, in spring lemmings population becomes more when compar- that let animals leave in humid areas. ing with amount before hibernation. Year-round observations helped to explain this unique phenomenon. Temperature un- der the snow does not fall below 0–4 °C and these conditions are suitable for breeding under snow, we can observe it in the reserve: given an abundance of feed rodents can produce offspring under a snow blanket. Lemmings are extremely pro- lific, one female delivers up to 20 babies per summer. Norwegian lemmings (picture 7) are mysterious animal. Picture 11 Up to the present moment a nature of their regular migrations Northern red-backed vole and dramatic population fluctuations related to it is still not clear. There is a lot of lemmings in certain years, they are found everywhere in forests (“peak” of their population), then this period is followed by 3–4 years when no lemming is encoun- tered – population “failure”. (picture 10) Before disappearance big amount of lemmings is found at river, lake coasts, swim- ming in water. At that lemmings groups are following different directions, and they stick to it until the end. Thus, for example, one lemming swimming across a lake got over a boat, resur- faced and kept on swimming in the same direction driven by a strong biological urge. Bilberry is a main feeding for red-backed vole. As it is known in early spring two types of buds are swelling on this subshrub – with future leaves and flowers. Red-backed voles cut a small branch, bring it to their burrows and eat buds there, at that they start from the larger flower buds. To load up one red- backed vole cuts up to two thousand of these buds per day. Picture 9 of the Kola peninsula of the Kola and shrews Lemmings, voles Picture 12 On the eve of summer when young leaves appear rodents live Gray-sided voles Gray-sided vole 4

ABCGheritage – Our common arctic heritage Picture 10 a, b Norwegian lemming is looking out from its shelter

mainly on them. Later they feed only with bilberry, as a rule only with seeds. Tundra’s side hills are usually rich in blueberries crop, up to one tone per each hectare, therefore such areas attract red- backed voles, this is a place where population of these animals in spring is the biggest and main bilberry crop is consumed by rodents. In winter while staying under snow cover, animals nibble bilberry stems which stay green. The swollen bilberry buds is a good feed for voles in spring as well, when snow is melting “trimmed” bilberries are seen among ground plants – a “calling card” of rodents. Common voles differ red-backed voles by their habitat and feeding ration: they prefer to live close to water, their main Picture 11 feed is sedge. Rodents use sedge not to the full extent, they Northern red-backed vole only gnaw a lower stem part as being the sappy and the rest part of it is thrown away. As a result in spring wintering areas of these animals, more often bogs, are surrounded by well seen rollers of dried grass. At the same place a nest-shelter of a common vole can be noticed resembling a lock of hay of a spherical shape. Entry to a nest is located on side, inside it is soft lined with wool and flags. As a rule before spring nests become uninhabited as only a small amount of animals manage to survive a long winter, and surviving part of the population avoiding spring flooding of their nests migrates to forests. Sometimes tundra vole in- habits residential places, penetrates into houses, garages, cold cellars and incur displeasure of people by damaging fruit trees and shrubs gnawing stem’s cortex. Tundra vole also collects for winter big amounts of rootstocks (for example, willowherb) or potato (picture 8, 11). In winter voles and lemmings activities doesn’t fade. Under snow cover ground plants are maintained in “preserved” way –

Picture 12 peninsula of the Kola and shrews Lemmings, voles Gray-sided vole these are blueberries, red bilberries, black crowberries, cade, 5

Lapland state nature biosphere reserve spruce seeds, linches, European aspen or birch cortex decum- bent by snowfall, ramined from autumn time. Some rodents are squirreling away reserves for winter. For example, in the end of summer when birch and European aspen leaves didn’t go yel- low, a common red-backed vole “help” them to fall: an animal climbs a tree using a long tail it cuts leaves and thin branches which fall down on ground. Leaves dry out by a natural way and remaining green is eaten by voles in a hungry winter period. Voles are feeding coniferous trees cortex, for example, a pine which is being nibbled by rodents in winter. In winter, but more frequently in the beginning of spring rodents appear on snow surface. Some of them are searching for feed on trees (Siberian vole), the others collect fallen birch seeds (gray-sided vole) (pic- ture 9, 12), and few are migrating (lemmings). We have already mentioned about an ambiguous role of ro- dents in nature. First of all it shall be kept in mind that pop- Picture 13 Picture 15 ulation of larger animal’s species and some species of birds “Mice-eater” goshawk Common shrew depends on population of voles and lemmings. Many animals enjoy eating rodents, an overwhelming majority of carnivorous birds and owls are hunting voles. Even fishes, especially pikes are watching for a lemming swimming across a river. Vole’s enemies in natural conditions are 10 species of animals and 23 species of birds. The only thing that protects voles – is their significant fertility, but maintaining it constantly on a high level is impossible due to natural resources scarcity. (picture 13) Many animals enjoy eating rodents, an overwhelming The Lapland reserve has been keeping register of small ro- majority of carnivorous birds and owls are hunting voles. Even fishes, especially pikes are watching dents for 75 year. A consistent pattern was identified: in some for a lemming swimming across a river. years red-backed voles population can be extremely abundant Vole’s enemies in natural conditions are 10 species (especially south and center of the Kola peninsula), and remains of animals and 23 species of birds. The only thing low in other years. that protects voles – is their significant fertility, but Moreover, it turns out that population of small mammals maintaining it constantly on a high level is impossible inhabiting the Kola peninsula has an evident periodicity: two due to natural resources scarcity. years of rich abundance are followed by two years of depres- sion or decline. However exceptions are still encountered. Sometimes voles and lemmings population are not decreas- Picture 16 ing according to a forecast and thus there can be not two, but Long-tailed shrew three years when rodents are abundant. This periodicity is also typical for neighbouring countries – in Finland and Norway – and is called “Scandinavian type of vole-like rodents population dynamics”. Indentified consistent pattern allows making fore- casts of rodents population. This knowledge in its turn is useful for sanitary services to prevent outbreaks of zoonotic diseases and while monitoring hunting sectors. Alternation of rodents mass reproduction periods is a part of natural development. We will try to review this process. When there are a lot of voles carnivorous animals and birds are not wasting much effort to hunt their kills and reproduce successfully. Vole-like rodents themselves gradually start feeling shortage of winter feeding, competition for best life environment is growing. Rodents pop- ulation decrease accelerates because an increasing army of car- nivores keeps on hunt them and aggravate their depression. In one or two years ground plants are recovering – grasses, berry subshrubs and mosses and amount of carnivores on the con- trary gets less followed by another vole-like rodents population increase. This elementary natural process in called in ecology as of the Kola peninsula of the Kola and shrews Lemmings, voles Picture 14 Picture 17 a “population cycle of small rodents population”. “Mice-eater” fox in winter Water shrew 6

ABCGheritage – Our common arctic heritage Simultaneously surrounding forests become a good habitat for squirrel population growth – spruce and pine seeds give a rich harvest. It happens that a blue hare’s population be- comes high as well. Such an abundance of feeding resources can’t but affect population of carnivorous animals and birds. Results of winter enumeration carried out in these years con- firm that amount of “voles-eaters” significantly increased in the reserve – ermine, weasel, also foxes and martens (pic- ture 14). As for the birds, kestrel, shrike, hawk-owl, goshawk, rough-legged hawk are encountered more often. Animals switching to rodents hunting don’t take nests of birds in spring, that let partridges and capercaillies brood more successfully. In nature of north of the Polar Circle rich abundance of ro- dents is followed by a period of dramatic decrease in their population. Autumn and beginning of winter become a critical Picture 13 Picture 15 moment in life of the mammals. Life period of voles and lem- “Mice-eater” goshawk Common shrew mings is short and they disappear in winter, while numerous army of carnivores has a lack of feed during cold period.

Except rodents territory of the Kola peninsula is home to the smallest mammals – shrews, in the Murmansk region they are represented by six species.

Searching for feed a part of animals switches to another nutrition sources, some of them notwithstanding their natu- ral caution approach roads, inhabit city parks, penetrate into buildings, switch to hunting pigeons, sparrows, rats. Not all of carnivores are able to survive a long winter. In spring ani- mals bring forth their offspring, but less than during favourable years. Thus, abundance of carnivores decreases after decrease in amount of their kills so that to increase in two-three years again – this is a wild nature economics. Picture 16 Long-tailed shrew Except rodents territory of the Kola peninsula is home to the smallest mammals – shrews (Soricidae), in the Murmansk region they are represented by six species (picture 15, 16) Ani- mals resemble a mole by their appearance – the same elongat- ed face and a velvet fur. They are tiny in size with weight from 5 to 12 g, fur color is not bright, of brownish shades. Shrews live everywhere, prefer habitats with soft forest soil, water bodies coasts. They are searching for favourite feed – worms, shells, spiders and various insects – in fallen leaves, dried grass (here is where a name shrew-like order comes from, previously called insect-eaters). All shrew have special glands with smell- ing secretion, and smells are very important for mammal ani- mals, not less than color of birds’ coats. All shrews are typical in terms of their appearance and life style except Eurasian water shrew (genus Neomys) (pic- ture 18). This is the largest species represented at our region, its weight is up to 40 grams and length is up to 10–13 cm. Fur marking is remarkable, contrast – top is of a color and bottom is of a white color. This animal ranges close to water, is able to swim very well, dives. Eurasian water shrew lives on everything

Picture 17 peninsula of the Kola and shrews Lemmings, voles Water shrew it finds at stream bottoms – insect slugs, rarely – frogs and 7

Lapland state nature biosphere reserve small fish. Water shrew Neomys fodiens and pigmy shrew Sorex minutes are rare species among shrews and are listed into the Red Book of the Murmansk region. South of the Kola peninsula is a place where one can rarely meet a passing by species of bats – northern bat Epte- sicus nilssonii. Forelimbs of an animal are turned into leath- ern wings – an elastic membrane joined together long digits as well as shoulder and tail. Northern bat species is large: wing-spread 25 cm, body length – 5.5 cm, weight – 11 g. Fur is thick of a brown color. Hindlimbs have clinging claws and has a grabbing function. Animals inhabit caves, hollows, build- ings, hunt mosquitos, butterflies, beetles at twilight, by that they are using more hearing capacity and echoscopy. A north- ern bat is distinguished by fast-moving flight and rapid mo- tion trajectory changing. Sometimes an animal makes distant flights comparing to the birds; ringing method was used to de- Picture 18 fine a distance of bats migration – 150 km. Water shrew of the Kola peninsula of the Kola and shrews Lemmings, voles

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ABCGheritage – Our common arctic heritage