Lemmings, voles and shrews of the Kola peninsula

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Steven Moore
5 years ago
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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.

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.

1 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 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 m 2. So it is absolutely logical that given such an abundance of rodents they shall be studied, otherwise many feeding and ecological relations and interrelations in nature will remain unclear. Let s try to review variety of wild rodents of the Kola peninsula 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 schisticolor. The second group combines three species: European Picture 1 Field vole 1 Lapland state nature biosphere reserve

Picture 2 Norwegian lemming Picture 3 Field vole field vole Clethrionomys glareolus, Siberian filed vole Clethrionomys rutilus and gray-sided vole Clethrionomys rufocanus

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.

Multicolored fell of a Norwegian lemming differs it from the others. Fore-limbs and hind-limbs of all rodents have five digits, adaptation for climbing is almost absent.

Feeding ration predominantly vegetation feed (picture 4) determines a specific dentition system: sharp incisors without roots and therefore ever-growing two from above and two

2 Picture 2 Norwegian lemming Picture 3 Field vole field vole Clethrionomys glareolus, Siberian filed vole Clethrionomys rutilus and gray-sided vole Clethrionomys rufocanus (picture 5). The third group is represented by tundra vole Microtus oeconomus, short-tailed vole Microtus agrestis and water vole Arvicola terrestris. Rodents are widely spread across the whole world and inhabit all kinds of landscapes: from lowlands to mountain tops up to meters above sea level. 2 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). Multicolored fell of a Norwegian lemming differs it from the others. Fore-limbs and hind-limbs of all rodents have five digits, adaptation for climbing is almost absent. Semiaquatic species sometimes have webbed feet on hind-limbs. Feeding ration predominantly vegetation feed (picture 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 consist of soften dentine. Thus a tooth is worn down in homogeneously and a forefront always remains sharp. Rodent s feed Picture 4 Rodents feed: cowberry and lichen Nephromaarcticum (at the top); Arctous (at the bottom) ABCGheritage Our common arctic heritage

Picture 5 Gray-sided vole Diet of rodents inhabiting the Kola peninsula is different. Voles feeding consists of soiling food : grasses, leaves, buttons, berries and cortex of different plant.

Picture 6 Wood lemming is low in calories and they have to consume it in huge quantities, this peculiarity influenced constitution of the animals: their intestinal tract is very long and always

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.

3 Picture 5 Gray-sided vole Diet of rodents inhabiting the Kola peninsula is different. Voles feeding consists of soiling food : grasses, leaves, buttons, berries and cortex of different plant. Lemmings ration is not like this, their stomach is capable to process green mosses, sedge, cereals. Picture 6 Wood lemming is low in calories and they have to consume it in huge quantities, 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, buttons, 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. After 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 m 2 to load up. After this kind of trimming moss stops growing and fades. Large areas of rust mosses resembling small burnt-over foci on soil appear during a season. After damage moss recovers 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 animals leave in humid areas. Lemmings maintain their fell dry by periodical greasing it with sebaceous matter from an oil gland located on a sacrum. Its marking is very remarkable: a black-red ribbon is stretching from a head to a tail, sides are ocher-colored, abdomen is of yellow color. For its dress lemmings received the second name colorful lemming. Fox, ermine, marten are easily hunting their kill all lemmings do to 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 carnivorous animals and birds have adapted find and hunt lemmings digging out ice-hole up to 70 cm deep. Given the abundance 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 bifurcated, 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 dogtrot 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 such a tunnel is stretching for m. For lemmings it is complicated to run new ways every time, that is why they lay 3 Lapland state nature biosphere reserve

Picture 7 Norwegian lemming Picture 8 Gray-sided vole 4 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.

Usually lemmings reproduce in snowless period, while it is noticed that in some years in spring lemmings population becomes more when comparing with amount before hibernation.

Temperature under 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

Up to the present moment a nature of their regular migrations and dramatic population fluctuations related to it is still not clear.

4 Picture 7 Norwegian lemming Picture 8 Gray-sided vole 4 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 significant fluctuations in numbers. Usually lemmings reproduce in snowless period, while it is noticed that in some years in spring lemmings population becomes more when comparing with amount before hibernation. Year-round observations helped to explain this unique phenomenon. Temperature under 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 prolific, one female delivers up to 20 babies per summer. Norwegian lemmings (picture 7) are mysterious animal. Up to the present moment a nature of their regular migrations 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 encountered population failure. (picture 10) Before disappearance big amount of lemmings is found at river, lake coasts, swimming 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, resurfaced 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 redbacked vole cuts up to two thousand of these buds per day. On the eve of summer when young leaves appear rodents live Lemming is a small rodent, endemic, as it inhabits only Scandinavian countries and the Kola peninsula. Fur is long and thick, doesn t get wet in water much, that let animals leave in humid areas. Picture 9 Gray-sided voles ABCGheritage Our common arctic heritage

Picture 10 a, b Norwegian lemming is looking out from its shelter Picture 11 Northern red-backed vole Picture 12 Gray-sided vole mainly on them.

Tundra s side hills are usually rich in blueberries crop, up to one tone per each hectare, therefore such areas attract redbacked voles, this is a place where population of these animals in spring is

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.

Rodents use sedge not to the full extent, they only gnaw a lower stem part as being the sappy and the rest part of it is thrown away.

5 Picture 10 a, b Norwegian lemming is looking out from its shelter Picture 11 Northern red-backed vole Picture 12 Gray-sided vole 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 redbacked 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 feed is sedge. Rodents use sedge not to the full extent, they 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 inhabits 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 these are blueberries, red bilberries, black crowberries, cade, 5 Lapland state nature biosphere reserve

6 spruce seeds, linches, European aspen or birch cortex decumbent by snowfall, ramined from autumn time. Some rodents are squirreling away reserves for winter.

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.

Some of them are searching for feed on trees (Siberian vole), the others collect fallen birch seeds (gray-sided vole) (picture 9, 12), and few are migrating (lemmings).

6 6 spruce seeds, linches, European aspen or birch cortex decumbent 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 yellow, 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) (picture 9, 12), and few are migrating (lemmings). We have already mentioned about an ambiguous role of rodents in nature. First of all it shall be kept in mind that population of larger animal s species and some species of birds 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) The Lapland reserve has been keeping register of small rodents for 75 year. A consistent pattern was identified: in some years red-backed voles population can be extremely abundant (especially south and center of the Kola peninsula), and remains low in other years. Moreover, it turns out that population of small mammals inhabiting the Kola peninsula has an evident periodicity: two years of rich abundance are followed by two years of depression or decline. However exceptions are still encountered. Sometimes voles and lemmings population are not decreasing according to a forecast and thus there can be not two, but 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 forecasts 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 population decrease accelerates because an increasing army of carnivores 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 contrary gets less followed by another vole-like rodents population increase. This elementary natural process in called in ecology as a population cycle of small rodents population. Picture 13 Mice-eater goshawk 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 14 Mice-eater fox in winter ABCGheritage Our common arctic heritage

Picture 15 Common shrew Simultaneously surrounding forests become a good habitat for squirrel population growth spruce and pine seeds give a rich harvest.

Results of winter enumeration carried out in these years confirm that amount of voles-eaters significantly increased in the reserve ermine, weasel, also foxes and martens (picture 14).

Animals switching to rodents hunting don t take nests of birds in spring, that let partridges and capercaillies brood more successfully.

7 Picture 15 Common shrew 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 becomes 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 confirm that amount of voles-eaters significantly increased in the reserve ermine, weasel, also foxes and martens (picture 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 rodents is followed by a period of dramatic decrease in their population. Autumn and beginning of winter become a critical moment in life of the mammals. Life period of voles and lemmings 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. Picture 16 Long-tailed shrew Picture 17 Water shrew Searching for feed a part of animals switches to another nutrition sources, some of them notwithstanding their natural 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 animals 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. 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) Animals resemble a mole by their appearance the same elongated 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 smelling secretion, and smells are very important for mammal animals, 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) (picture 18). This is the largest species represented at our region, its weight is up to 40 grams and length is up to 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 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.

8 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 Eptesicus nilssonii. Forelimbs of an animal are turned into leathern 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, buildings, hunt mosquitos, butterflies, beetles at twilight, by that they are using more hearing capacity and echoscopy. A northern bat is distinguished by fast-moving flight and rapid motion trajectory changing. Sometimes an animal makes distant flights comparing to the birds; ringing method was used to define a distance of bats migration 150 km. Picture 18 Water shrew 8 ABCGheritage Our common arctic heritage

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