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Steppe Mouse (Sicista subtilis)

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This is what the academician P.S. Pallas called the steppe mouse in the 18th century when the species was first described, referring it to the family of mice. Now the mice belong to the jerboa, with representatives of which they are related, albeit distant. The range of the steppe mouse extends from Central Europe in the west to Lake Baikal in the east. Here it inhabits the steppes and semi-deserts, reeds thickets along the shores of various water bodies and forest belts, are found in fields and vegetable gardens. Wherever the steppe mouse lives, everywhere for its habitat it chooses dense vegetation: thickets of grass, reeds or young shrubs.

Mice are very small animals not exceeding seven centimeters in length and reach a weight of 11-13 g. Their body is covered with a short brownish-gray wool. A dark strip stretches along the back, from head to tail, the length of which reaches II cm. It was she who gave rise to the first name of this animal - “striped mouse”. In nature, animals lead a solitary lifestyle, with the exception of a short breeding period.

The steppe mice have a very imperfect thermoregulatory mechanism, which makes them incapable of resisting the vagaries of nature. Therefore, even in the summer, an unexpected cold snap greatly reduces the activity of the animals: they hide in a shelter, curl up and fall asleep. Animals sleep on their side or sitting on their hind legs and wrapping their tail around their bodies. Their temperature drops significantly, the intensity of all metabolic processes in the body decreases. In such a numbness, the animals are located until the air temperature rises to optimal values.

This feature of the biology of the mice served as the reason for the name of one of the species, namely, the forest mice - “chilly mouse”.

The steppe mice practically do not dig their own burrows, but inhabit the abandoned dwellings of voles, gray hamsters or other rodents. The nearest surroundings are their individual territory on which animals feed themselves. Mice are active only in the evening and at night.

The main food of animals is the seeds of numerous herbaceous plants and shrubs prevailing in this area. various insects and larvae occupy a large place in their diet.

Watching mice in nature is very difficult. But with their cellular content, you can easily find out a lot of interesting things about their behavior.

At first, the animals pursue each other, starting fights, trying to occupy this territory for themselves. After two or three weeks they are reconciled with the forced neighborhood and subsequently live together, resting in one nest. At dawn, the animals leave the nest and start looking for food. Having a little refreshment, they arrange a small warm-up: chasing each other on the ground, climbed branches, played. Closer to dinner, they went to the nest to rest, and by evening they resumed activity.

Mice reproduce from late April to early May. During the rutting season, animals become very active, especially males looking for females. Excited male mice, such as forest mice, emit peculiar high, often repeated trills. Animals reproduce such songs while sitting still or during their wanderings. Only during the rutting season do males leave their

plots and far away from the hole. They violate the existing boundaries of individual possessions, falling into unfamiliar places and often become victims of numerous predatory animals and birds.

When the searches, full of dangers and adventures, are completed successfully and the male finds a chosen one, the animals, after a short period of acquaintance and courtship, mate. It will take another four or even five weeks until the babies are born. A very long gestation period for such a small animal! In females, the number of cubs ranges from 2 to 8. Newborn babies are quite large - up to 3 cm, which is more than a third of the length of an adult animal. At the same time, their complete helplessness amazes them. The body of the kids is naked and completely devoid of pigment, which makes it possible to distinguish blood vessels and even the stomach through a thin skin. The ears are folded and firmly pressed to the head, and the ear canals are closed.

At a weekly age, mice begin to cast their voice. Hungry, they quietly squeak and, if the female is in the nest, they are looking for maternal nipples. By the age of two weeks, the body of the animals is covered with velvety fur, and the kids begin to crawl actively, crawling out of the nest, but the burrows never leave. For orientation, they use only the sense of smell and touch. By the end of the fourth week, the mice have cut eyes and they become sighted.

Caring females milk their descendants with milk for up to five weeks, although they try to bite the seeds already in the third week of life. In general, babies develop very slowly and by the age of one and a half months, when they become fully independent, their weight reaches five grams, and in size they make up about two-thirds of an adult animal.

At first, babies appear on the surface only in the evenings and in the warm morning hours. If the night coolness catches them away from the nest, they may fall into a stupor, which is associated with imperfect thermoregulation.

At the end of summer, the grown mice finally leave not only the mother’s nest, but also the area of ​​its habitat. They go in different directions to look for places suitable for settlement, where they arrange their own homes. Young animals become sexually mature at 2.5-3 months.

The movements of the animals are fast and impetuous, but unlike real jerboas, the steppe mice are not capable of two-legged running. The main way of their movement is lynx. This type of running is characterized by symmetrical and consistent! the work of limbs located diagonally, i.e. in the process of movement, after resting on the right front and left hind legs, support on the left front and right hind limbs follows. When running fast, the traces of the front legs are significantly overlapped by the traces of the hind legs.

Another way the mice move is by jumping. Movement in this way is observed at the start, when a frightened mouse makes several jumps up to 30 cm long each, after which the animal goes to trot.

The hind legs are most stressed when moving, and the forelimbs are indispensable when climbing plant stems. Mice are very dexterous animals: they climb freely on inclined and vertical stems and twigs. During climbing, they constantly use their tail to maintain balance, and often the stem also covers them, but such a grip is not tight.

The long tail of the mice serves not only as a balancer while running or as a support, but also as an expression of emotions. It was noticed that an excited and aggressive-minded animal keeps its tail upright. Frightened mice raise their tail above the ground, while they themselves are trembling finely and gently banging their teeth. When feeding and in a calm environment, the tail of animals is lowered to the ground and serves as a support for them.

The voice of the mice is a high melodic whistle. His excited animals publish during a fight, as well as in a hopeless situation. Of the senses, hearing and vision are best developed. The animals are very sensitive to light, so during the day they move with their eyes closed, but at night they can even discern even small details of objects.

The sensitive ears of the mice are able to capture the rustles produced by small insects. The sense of smell is poorly developed: they catch the smell of prey at a distance of 5-6 cm.

In the summer, there is also a change in the hairline, which does not occur simultaneously in all animals. First, at the beginning of summer, males molt, then, a month later, females, and in August they change their infant outfit to permanent growing up babies. In the second half of summer and early autumn, the steppe mice feed intensively, accumulating a thick layer of subcutaneous fat. With a decrease in night temperatures to several degrees of heat and the approach of frosts, the steppe mice retire in their warm nests. The latter are located at depths of several tens of centimeters up to the surface of the soil. Sometimes, nests are located in the litter or dense thickets of vegetation. Usually, it has a spherical shape and consists of dry stalks of grass and other plant debris.

Mice, like other jerboas, spend their entire cold time hibernating, using accumulated fat reserves during sleep to support their lives. The animals sleep, bending their legs, pressing their ears and bending their heads to their chests. His mouse tail tightly presses to the body.

During hibernation, despite the very low level of all life processes, animals lose a lot of weight. For six months, and this is how much their hibernation lasts, they lose up to 5 grams, which is up to a third of their original weight. Many mice die during winter sleep. Some have accumulated an insufficient amount of fat reserves, others have chosen the wrong place and froze or they were flooded with melt water.

The surviving animals leave their winter shelters when stable warm weather is established and night frosts cease. Males wake up first, a little later than females.

Awakening after hibernation is a complex physiological process that requires significant energy and takes about half an hour. The awakening animal begins to yawn, stretching its front legs and breathing fast and deep, while at the same time emitting a faint, often repeated squeak. Stretching and flexing his muscles, the mice gradually restore blood circulation, warm up. Their ears rise, their eyes open and the animal wakes up. For some time, his coordination of movements was impaired and the mouse is not very confident, staggering, gets to his feet, sometimes falls. Several minutes pass and the movements become more confident and the animal goes for water and food.

In search of food, mice spend most of the day trying to quickly restore what they lost for a forced winter hunger strike. And they really need strength, because the most crucial period ahead is reproduction.

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