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Seasonal migrations of animals are one of the most impressive phenomena in nature. Birds are the most avid travelers in the animal world. Half of all bird species fly long distances to places where there is plenty of food or where they can hatch their chicks. Huge flocks or herds, as if on command, move from their place and set off on a journey hundreds and thousands of kilometers away.
Migration may be caused by the need to search for food, the lack of which is due to natural reasons. On larger territory In Africa, for example, during drought, the grass dries out completely, and wildebeest and zebra are forced to go in search of new fresh pastures. Later they return. However, not all animal migrations are so impressive. Some animals living in the mountains simply descend from the mountains a couple of hundred meters into the valleys in the fall, and then climb up the mountains again in the spring.
In addition to seasonal migrations, there are also so-called animal migrations, common among cicadas and lemmings. This occurs when the number of animals begins to exceed the food supply available in a given habitat, and part of the population is forced to go in search of a new habitat for life.
Antelope - jumper
The jumping antelope paid quite dearly for the appearance of Europeans in Africa. In the 19th century in poor areas South Africa millions of these antelope grazed. In dry times, when there was no more grass left in the pastures, antelopes went in search of water and food, covering vast distances, but when Europeans appeared and began to develop these lands, antelopes could no longer move freely. The end of their migrations has come. Now in Africa these antelopes survive in much smaller numbers.
Arctic terns
Arctic terns hatch their chicks in the far North (sometimes beyond the Arctic Circle), where they feed on fish, diving into the sea after them. After mating season, Arctic terns travel to the other side of the world to spend the winter on the pack ice in Antarctica. Here they use the same hunting tactics as in the North, feeding on small fish swimming close to the surface of the water. To live in daylight all the time (which allows fishing around the clock), the tern travels from one pole to the other twice a year. Every year this little bird covers a distance of 32,000 km. Cruising from the Arctic to the Antarctic summer, she spends noticeably most life than any other creature. Some terns cross the Atlantic Ocean during their migrations.
Migration of butterflies
Monarch butterfly caterpillars feed in summer poisonous plants from the swallow family, growing in Canada and the USA. The poison accumulates in their body and then passes into the body of butterflies, which in the fall in huge swarms fly south. In the spring they return again, with the females laying eggs along the way.
Animal migrations in the steppes of central Asia
Saiga (saiga) - an antelope with a bizarrely shaped thick nose - has been living in the steppes for 20,000 years Central Asia. Male saigas have horns, which they use in battles for females. Each male gathers from 5 to 15 females around himself and protects them from other males. In winter, when it starts to blow cold wind and the northern regions are buried in snow, thousands of saigas go south in search of new pastures. They return in the spring. Their movements are closely watched by other animals. Eagles try to attack young calves, and wolves feed on the females' placentas.
During the last ice age saigas inhabited the territory from England to Eastern Siberia. Currently, they remain only in the steppes of Central Asia. Until recently, they were even endangered. Fortunately, efforts made to rescue them were successful. Now their number has increased and they can continue seasonal migrations. They are perfectly adapted to their environment. Saigas are artiodactyl animals and, on thin legs, can move at high speed across the snowy steppes. An adult saiga reaches 75 cm in height. In summer, the saiga's fur is short and light brown; in winter it becomes very thick and somewhat lighter.
Why do mass animal migrations occur?
Migrations are characteristic of many animals. All migrations can be divided into two main groups: regular and irregular. Regular migrations are primarily associated with feeding and reproduction of animals. For example, numerous herbivores living in steppes and savannas are forced to constantly migrate from one pasture to another in order not to undermine their own food supply. Many predators migrate after the herds of their prey. Sometimes periodic migrations serve as an escape mechanism from predators or blood-sucking insects. For example, reindeer during mass appearance midges migrate to places where there are fewer of these insects.
Very often, regular migrations are associated with the fact that animals feed and breed in different places. A good example can serve as fish that breed in rivers, spend most of their lives in the seas and oceans, where they feed, grow and reach maturity, and migrate again to rivers to reproduce. Such fish are called anadromous. These include many sturgeon and salmon. There are also fish that feed in rivers and migrate to the seas to reproduce, such as eels. They are called catadromous. Mass migrations to breeding grounds are also typical for other animals: whales, amphibians, and some crustaceans. The well-known annual migrations of birds also belong to the same type of migration. They are connected not only with the need to spend the winter in warmer countries. If the whole point of flying was determined only climatic factors, then it would be easier for the birds not to return to the north at all, but to breed in wintering areas. The point is most likely that in those places where migratory birds breed, there are fewer competitors and predators, so the offspring are more likely to survive than if breeding took place in wintering areas.
Among irregular migrations one can indicate, for example, migrations associated with an outbreak of a particular species. Such migrations can be considered as a kind of adaptation to reduce intraspecific competition in those species whose numbers are subject to significant fluctuations, such as lemmings or locusts. During a population outbreak, the physiology, behavior and even morphology of individuals change. Thus, the sedentary form of the locust turns into a migratory one. Previously, these forms were considered different species.
Quite often, irregular migrations occur in connection with some kind of natural disaster: fire, flood, drought or crop failure. For example, in years of poor spruce seed harvest, massive migrations of crossbills occur.
Animal migration is the regular and directed movements of animals “back and forth” from one habitat to another, caused by changes in living conditions in their habitats or associated with their development cycle. Distinguish between: periodic (migratory birds, seasonal migrations fur seals) or non-periodic (eviction due to lack of food of nutcrackers from the north of Siberia to the south, etc.) migrations. They can be passive (larvae, eggs, adults carried by sea currents) and active (locust flights, migratory fish, migratory birds). Migrations are also distinguished: feeding (in search of food), wintering (flounder in winter forms aggregations in deep, warmer waters; in the same “wintering pits” they spend cold season bream, pike perch, catfish, etc.).[...]
The absence of older animals (5-7 years) in the population indicates a shorter life expectancy of amphibians under the influence of toxicants Wastewater compared to their life expectancy, as established earlier, in “conditionally clean” zones (Misyura, 1989). At the same time, this leads to a decrease in the reproductive potential of the population as a whole and the possibility of its existence only if animals migrate to a given reservoir from spawning grounds.[...]
Regulation of the number of large animals is achieved through strict control of the size of the feeding area per animal. Such control is carried out different ways(sound signals from neighbors, animal migration, etc.).[...]
K. is used to study the migration routes of animals (especially birds), establish the boundaries of their habitats, the characteristics of seasonal biology, and solve other problems. COMBINED IMPACT - see art. Environmental impact. COMMENSALISM, or freeloading [from lat. sot - s and mensa - table, meal] - a type of cohabitation of organisms when one of them (commensal) constantly or temporarily exists at the expense of the other, without causing him harm. COMPENSATORY BEHAVIOR - a complex of behavioral reactions of organisms aimed at weakening (compensation) of the limiting influence environmental factor.[ ...]
The influence of artificial obstacles on animal migration. Artificial obstacles that impede the seasonal migrations of deer are created by laying above-ground, above-ground and semi-underground main pipelines, power lines, automobile and railways and other extended structures. Animals gather in huge herds in front of such obstacles.[...]
MIGRANTS [from lat. migratio - relocation] - migrating animals (see Migration of animals) or substances that easily move in various components of the biosphere (for example, aquatic microorganisms, air microorganisms). MIGRATION-WATER HARMFUL INDICATOR - see Art. Indicators of the harmfulness of soil pollution.[...]
Ground routes of oil and gas pipelines and roads can cross the migration routes of animals. Driven by the will of instinct, animals try to cross them and in doing so expose themselves to additional danger. In practice, there are cases when entire herds died due to the division of winter and summer pastures wild deer.[ ...]
Since July 1982, the Law “On the Protection and Use of Wildlife” has been in force in Russia. It establishes state responsibility for the animal world, declares the position that animals are one of the main components natural environment and important component natural resources. The law provides for the preservation of all species diversity animals, protection of their habitat, breeding conditions and migration routes of animals, scientifically based, rational use and reproduction of the animal world, regulation of the number of animals in order to protect human health and farm animals, as well as preventing the death of animals during agricultural, logging and other work, the use of plant protection products, mineral fertilizers and other drugs. A special place in the law is given to the protection and restoration of the numbers of rare and endangered species.[...]
Correct routing of roads and design of road structures in habitats of wild animals is impossible without taking into account the peculiarities of their behavior and habits. Animal migration routes are characterized by various signs: goals of movement, direction, time of year, duration. There are regular, reversible and irregular migrations, horizontal and vertical (in the mountains), daily and seasonal, active and passive. Depending on the species, large ungulates move alone, in small groups or in large herds, which must be taken into account when designing special crossings for them. Herds of reindeer or saigas number up to tens of thousands of individuals; moose and roe deer migrate alone or in small herds (up to 7 individuals), wild boars - in groups of 10-15 individuals.[...]
The Administrative Code of the Russian Federation regulates administrative liability for violations of legislation on the protection and use of wildlife in Art. 7.11 “Use of objects of the animal world without permission (license)”, as well as for offenses in relation to living resources of the continental shelf (Part 2 of Article 8.17, Article 8.20), in relation to animals during agricultural economic activity(Article 10.11), in case of violation of veterinary and other rules (Article 10.6 “Violation of animal quarantine rules or other veterinary and sanitary rules”, Article 10.7 “Concealment of information about sudden deaths or simultaneous mass diseases of animals”, Article 10.8 “ Violation of veterinary and sanitary rules for the transportation or slaughter of animals, rules for processing, storage or sale of animal products"). In Art. 8.33 provides for liability for violation of the rules of the habitat and migration routes of animals, Art. 8.34 - for non-compliance established order creation, use or transportation of biological collections, Art. 8.36 - for violation of the rules of relocation, acclimatization or hybridization of objects of the animal world, Art. 8.37 - for violation of the rules for using them, Art. 8.38 - for failure to comply with the rules for the protection of fish stocks, Art. 8.35 - for the destruction of rare and endangered animals, Art. 8.29 - for destruction of animal habitats.[...]
Bioindication - assessment of the state and changes in the environment by studying the structure, condition, numbers, behavior, in particular migrations, of animals and plants.[...]
The height of the mesh depends on the type of animal that most often appears on the road. Fences are installed on animal migration routes across roads with a traffic intensity of more than 2,000 vehicles/day (along the border of the right-of-way) with a height of 2.0...2.5 m at least 0.5 km in each direction from the established route of movement animals. The height of the fence is 2.25...2.80 m for deer, 1.6... 1.8 m for roe deer, 1.2... 1.4 m for wild boars. Fences require careful installation and careful maintenance. High coarse mesh fences (mesh) keep out roe deer, deer, etc., low fine mesh fences are suitable for keeping badgers, hedgehogs, etc., smooth-walled steel or concrete structures are used to protect amphibians. To avoid isolating habitats, fences should be combined with devices that help animals cross the roadway.[...]
Partial damage to the environment caused during oil production can be compensated through the construction of fish factories, fur farms and feeding stations for wild animals, and the organization of specially protected natural areas, financing regional environmental programs, etc. Compensatory measures should also include the organization of passages on animal migration routes through linear communications, tunnels under roads, passages under structures on stilts and pipelines for the passage of large animals. [...]
Impact low temperatures, fires, radiation, strong winds will be accompanied by disintegration ecological systems, reproduction of pests of forests, fields, gardens and vegetable gardens. Animals will die from hunger, frost and lack of water. As a result of animal migration, the spread of human and animal diseases will begin. Ultimately action radioactive substances will lead to the death of the animal world. Tropical forests will be especially sensitive, because plants in the tropics and subtropics do not have a dormant period that allows them to withstand temperatures even above zero.[...]
Avoidance of adverse effects - the body produces such life cycles and behaviors that avoid adverse effects. For example, seasonal migrations of animals.[...]
Any phenomena associated with noticeable human impacts on nature, the reverse influences of nature on humans and their economy, with life and economically significant processes, mass irregular migrations of animals are called environmental problem.[ ...]
The Code of Administrative Offenses establishes that violation of the rules for transportation, storage and use of plant protection products, growth stimulants, mineral fertilizers and other preparations that cause harm to wildlife entails a fine or warning. Violation of rules for the protection of habitats, migration routes of animals, rules for trade in zoological collections, as well as rules for the transfer and export abroad of objects of the animal world, unauthorized relocation, acclimatization and crossing of animals also entails a warning or a fine. [...]
For biota, the tertiary stage of technogenesis is expressed in the replacement of traditionally typical forms of vegetation with a restoration series or fundamentally new types of vegetation, in changes in the paths of natural migration of animals, in the disappearance of individuals and even entire species of flora and fauna.[...]
Environmental advantages of an intermodal corridor: the possibility of combining environmental protection measures on all types of transport, localizing impacts along the route (noise, gas pollution, the possibility of active engineering protection of border green areas, organizing passages for animal migration), modern processing of cargo flows.[...]
Thus, we see that living organisms adapt to very difficult living conditions, which become the norm for them. But such adaptation takes a long time; it requires not hundreds, but thousands of years. Often it is necessary to adapt quickly, for example, when animals migrate from their usual habitat due to deteriorating living conditions: natural disasters, geological disasters, floods, droughts, climate change, food shortages. And the body copes with this.[...]
Biogeocenoses are open systems; they exchange matter and energy with each other. The substance is transported in the form of gas, liquids, bulk and other materials. Interbiogeocenotic transfer of living matter and energy is observed during the movement of organisms, for example, during the dispersal of plants and animal migrations.[...]
Change of conditions in aquatic environment causes certain behavioral reactions of organisms. Changes in illumination, temperature, salinity, gas regime and other factors are associated with vertical (descending into the depths, rising to the surface) and horizontal (spawning, wintering and feeding) migrations of animals. In the seas and oceans, millions of tons of aquatic organisms take part in vertical migrations, and during horizontal migrations, aquatic animals can travel hundreds and thousands of kilometers.[...]
For example, in the 60-70s. At the cost of great efforts, the Kalmyk saiga population was restored. Its population exceeded 700 thousand heads. Currently, there are significantly fewer saiga in the Kalmyk steppes, and its reproductive potential has been lost. There are various reasons: intensive overgrazing of livestock, excessive use of wire fences, development of a network of irrigation canals that cut natural ways migration of animals, as a result of which thousands of saigas drowned in canals along the way of their movement. [...]
River sections converted into the so-called tailwaters of reservoirs, where they should be covered with a stable ice cover, in many cases lose this property. A winter polynya forms and functions in the lower pool, i.e. a river that does not freeze even in the most severe frosts, and the ice cover that replaces it downstream turns out to be fragile, uneven and not continuous. Thus, below each large dam in winter there is an insurmountable barrier to the migration of animals and to the maintenance of economic ties. For example, on the Yenisei River, the winter polynya stretches from Divnogorsk, which is 30 km above Krasnoyarsk, and almost to the mouth of the Angara. By the end of winter, its length decreases. Normal changes The length of the winter polynya of the Yenisei River ranges from 280 to 50 km.[...]
The rhythm of phenomena in geographical envelope. The geographic envelope of the Earth is constantly changing, and the relationships between its individual components are becoming more complex. These changes occur in time and space. There are rhythms in nature of different durations. Short, daily and annual rhythms are especially important for living organisms. Their periods of rest and activity are consistent with these rhythms. The circadian rhythm (change of day and night) is determined by the rotation of the Earth around its axis; annual (change of seasons) - the revolution of the Earth around the Sun. The annual rhythm is manifested in the existence of periods of rest and vegetation in plants, in the molting and migration of animals, in some cases - in hibernation and reproduction. The annual rhythm in the geographic envelope depends on the latitude of the place: in equatorial latitudes it is less pronounced than in temperate or polar regions.[...]
Nutrition is one of the oldest connections between the body and the environment. Adaptation to its deficiency can also be behavioral. them, instinctive, and determined by processes occurring at the molecular level. The first includes primarily eating more food than the body's energy expenditure requires. Excessively consumed food is converted into fat reserves, which are consumed in unfavorable conditions; for food production. This is observed, for example, in copperheads, whose females feed their cubs in winter without leaving the den. Other examples of instinctive adaptation to a lack of food are the storage of food for the winter by many rodents and various migrations of animals (whether within their habitat, to areas richer in food, or over long distances, as in migratory birds). An essential way of adapting to a lack of food and water is the previously discussed winter and summer hibernation, which is associated not only with changes in the nature of nutrition, but also with seasonal fluctuations temperature regime, length daylight hours and other environmental conditions.[...]
At all stages of justification and decision-making on the use natural resources and the location of energy facilities, an analysis and assessment of the impact of the planned economic activity on the environment, including the ecology of adjacent areas, will be carried out. Developed regional energy development programs and construction of new energy facilities must undergo mandatory environmental assessment. In this case, research must be carried out social consequences planned activities with analysis of possible emergency situations, determination of preventive measures negative consequences in the short and long term and assessing the degree of risk and reliability of objects. As a rule, new facilities of the fuel and energy complex will provide a set of means for carrying out environmental monitoring, in particular, monitoring the state of hydrological systems, monitoring seismicity and hydrodynamics of oil and gas production areas, monitoring the migration of animals and birds, and restoring their populations.
The main reason for migration is the need for food and conditions that ensure reproduction, as well as competition for convenient habitats. When, for example, a herd of buffalo or wildebeest doubles in size, its members are forced to wander over much larger areas than before in search of food. Because it serves as food for them fresh grass, the abundant growth of which is associated with a certain season, the movements of these animals also become seasonal. Before the colonization of North America, bison made such journeys twice a year, traveling from Canada to Mexico.
Much less often, migration is driven by the desire to protect ourselves from climate “extremes.” Even on the islands of the Arctic Ocean, neither musk oxen nor bull-hunting wolves try to move to more dense areas in winter. warm places. Arctic foxes even move further north at this time of year to stay close to polar bears and feed on the remains of the seals they kill. Lemmings and Scottish snowshoe hares also remain to spend the winter in the north, as well as other animals and birds. Even the baribal bear does not go south, except in the harshest winters, when he moves to places where he can calmly hibernate without being so exposed. severe trials(in case of overspending energy resources he risks not waking up after hibernation).
Migrations arose in animals during their historical development, they are an interesting biological adaptation. The emergence of migrations is, of course, associated with the evolution of the species to which they are characteristic. They were formed from the aggregate movements of animals over countless generations. Animals following in the wrong direction died. Those that chose the right path survived and returned with offspring. At first there was no need to travel long distances; it was enough to simply find unoccupied territory; but, repeating every year, the wanderings acquired the character of a stable habit, which eventually developed into an instinct characteristic of the entire population.
Migration ecology arose and is developing as a synthesis of ecology and physiology. This field of migration studies covers a wide range of different aspects of migration behavior. It is very interesting to study the issues of variability in migratory behavior, differences in the timing and routes of migration, and individual variability in migration distribution over time and territory in various species.
Migrations probably formed gradually, under the influence of slow climate change, such as the retreat of glaciers. With the melting of glaciers, a gradual expansion of areas suitable for obtaining food and reproduction began. This reason for migration seems more plausible than the assumption that throughout the millions of years of the Ice Age, animals retained the desire to return to their native lands.
A number of scientists have suggested that some modern migration routes have developed against the background geographical conditions more ancient eras, and also that as the continents shifted relative to each other, the migration routes connecting the places where reproduction took place with feeding grounds lengthened. But migrations could also occur suddenly.
All these ideas do not necessarily contradict one another. Migrations may have resulted from a combination of climate change and a series of invasions caused by for various reasons. In the case of trans-equatorial migrations, when the territories where animals live in different seasons, separated by a significant distance, their occurrence is determined a large number complex interacting factors. Be that as it may, any hypothesis remains just a guess until it is confirmed by observations or tested experimentally.
A developed form of migration is characterized by a fairly high speed and range of movement.
IV. Migrations
Migration (from Latin migrans) means relocation. Migrations are widespread among animals throughout globe and represent an interesting adaptation to the transfer of not favorable conditions, which sometimes occur in nature.
In autumn, as feeding conditions worsen, the bulk of arctic foxes and reindeer migrate from the tundra to the south, into the forest-tundra and even into the taiga, where it is easier to obtain food from under the snow. Following the deer, tundra wolves also migrate south. IN northern regions tundra white hares at the beginning of winter undertake mass migrations to the south, in the spring - in the opposite direction
Migrations of animals occur when different conditions and they pass differently.
Regular seasonal migrations of desert ungulates also depend on seasonal changes vegetation cover, and in some places - on the nature of the snow cover. In Kazakhstan, saigas often live in the northern clayey semi-desert steppes in the summer; in winter they migrate south, to the area of less snowy wormwood-fescue and wormwood-hodgepodge semi-deserts.
In general, migration is characteristic of a relatively smaller number of species among mammals than among birds and fish. They are most developed in marine animals, bats and ungulates, while among the species of the most numerous groups - rodents, insectivores and small predators - they are practically absent.
Animals have periodic migration, they are also called eviction. Periodic evictions - migrations include those that represent a mass departure of animals from breeding grounds without subsequent return to their former habitats. According to science, such evictions are caused by a sharp deterioration in living conditions, as well as lack of food, which is associated with the emerging high population density of the species, forest and steppe fires, severe droughts, floods, excessive snowfall, and other reasons. From this it is clear that numerous circumstances can cause masses of animals to move over long distances. Invasions are the movement of animals outside their homeland. Such movements differ from true migrations in their irregularity and large intervals between successive invasions. Sometimes they are considered as the initial stages of the formation of real migrations, arising from explosive settlements - “emigrations”. Infestation is like a safety valve triggered by excessive population density. This in itself favors the existence of the species only in an indirect way. In normal natural conditions population processes are in equilibrium, and population growth leading to eviction rarely occurs. Invasion is a phenomenon whose disadvantages are striking, but which at the same time provides an advantage over a long period of time that more than outweighs the disadvantages. A typical example of these migrations is the migration of lemmings and squirrels. Irreversible periodic migrations are characteristic common squirrels. They (migrations) arise quickly in response to emerging unfavourable conditions. Migrations begin in July-August, when squirrels begin to feed on seeds and nuts from the fresh harvest and discover their deficiency. Migrations last about 6 months. Squirrels sometimes travel up to 500 km or more. Squirrels do not migrate in groups, but singly. The wanderings of squirrels repeat periodically every 4-5 years and greatly influence the yield of fur and the economy of squirrel hunters. The speed of squirrels during migration reaches 3-4 km/h.
Migration (from Latin migrans) means relocation. Migrations are widespread among animals all over the globe and represent an interesting adaptation to endure unfavorable conditions that sometimes arise in nature.
In autumn, as feeding conditions worsen, the bulk of arctic foxes and reindeer migrate from the tundra to the south, into the forest-tundra and even into the taiga, where it is easier to obtain food from under the snow. Following the deer, tundra wolves also migrate south. In the northern regions of the tundra, white hares undertake mass migrations to the south at the beginning of winter, and in the opposite direction in the spring. migration seasonal relocation animal
Animal migrations occur under different conditions and occur differently.
Regular seasonal migrations of desert ungulates also depend on seasonal changes in vegetation cover, and in some places, on the nature of the snow cover. In Kazakhstan, saigas often live in the northern clayey semi-desert steppes in the summer; in winter they migrate south, to the area of less snowy wormwood-fescue and wormwood-hodgepodge semi-deserts.
In general, migration is characteristic of a relatively smaller number of species among mammals than among birds and fish. They are most developed in marine animals, bats and ungulates, while among the species of the most numerous groups - rodents, insectivores and small predators - they are practically absent.
Animals have periodic migrations, they are also called evictions. Periodic evictions - migrations include those that represent a massive departure of animals from breeding grounds without subsequent return to their former habitats. According to science, such evictions are caused by a sharp deterioration in living conditions, as well as lack of food, which is associated with the emerging high population density of the species, forest and steppe fires, severe droughts, floods, excessive snowfall, and other reasons. From this it is clear that numerous circumstances can cause masses of animals to move over long distances. Invasions are the movement of animals outside their homeland. Such movements differ from true migrations in their irregularity and large intervals between successive invasions. Sometimes they are considered as the initial stages of the formation of real migrations, arising from explosive settlements - “emigrations”. Infestation is like a safety valve triggered by excessive population density. This in itself favors the existence of the species only in an indirect way. Under normal natural conditions, population processes are in equilibrium, and population growth, leading to eviction, rarely occurs. Invasion is a phenomenon whose disadvantages are striking, but which at the same time provides an advantage over a long period of time that more than outweighs the disadvantages. A typical example of these migrations is the migration of lemmings and squirrels. Irreversible periodic migrations are characteristic of ordinary proteins. They (migrations) occur quickly in response to emerging unfavorable conditions. Migrations begin in July-August, when squirrels begin to feed on seeds and nuts from the fresh harvest and discover their deficiency. Migrations last about 6 months. Squirrels sometimes travel up to 500 km or more. Squirrels do not migrate in groups, but singly. The wanderings of squirrels repeat periodically every 4-5 years and greatly influence the yield of fur and the economy of squirrel hunters. The speed of squirrels during migration reaches 3-4 km/h.
Animals make seasonal migrations annually and at certain times of the year. These migrations are regular and reversible. Animals, leaving their breeding places, return to the same places when favorable conditions arise. Seasonal migrations are characteristic of the Arctic fox, the main reason for which is food. Arctic foxes follow migrating lemmings, completely repeating the characteristics of their migrations. The migration of predatory animals is mainly associated with the migration of small animals, which provide food for predators.
Seasonal migrations are especially clearly manifested in places with a sharp change in living conditions from winter to summer, in places with harsh winter and hot, dry summers. This phenomenon has the character of a purposeful mass movement, although it is not always clearly visible. The reasons that cause seasonal migrations are always complex. However, the most noticeable of them is hunger. Another reason is the attack on animals by midges: mosquitoes, gadflies, horseflies.
Seasonal migrations, in turn, are divided into horizontal and vertical.
Horizontal migrations mean those when animals move from one place to another, changing environmental conditions within their typical landscape. Such migrations are typical for reindeer, cats and other animals.
Vertical migrations are understood as those when animals in the same season of the year find for themselves in the spring Better conditions in high mountain areas on alpine meadows, and in the fall they descend to foothill pastures. Such movements are typical for mountain inhabitants - goats, chamois and other ungulates. Mountain ungulates rise to the heights in summer upper belts mountains with their rich grass stand, but in winter, as the depth of the snow cover increases, they go down. And in this case, some predators, such as wolves, are observed combined with ungulates.
Diurnal migrations are also known among animals - this is the transition of animals from daytime resting places to places of watering places, salt licks and feeding grounds. Diurnal migrations are typical for hares, deer and other animals.
All of the above migrations are called active because the animals carry them out with great excitement, they sometimes appear in populated areas and in other places that are not typical for their habitat and often, unfortunately, remain unaccounted for.
In contrast to active migrations, passive migrations are also observed among animals, i.e., those when animals move away from their breeding grounds and usual habitat with the help of ice or water flow. For example, the migrations of walruses, polar bears, and arctic foxes that got onto ice floes and were carried by the current into the ocean to some islands are known. During high water, hares and muskrats, falling on floating objects or ice floes, descend long distances downstream. A significant role in passive migrations is played by different types transport. Particularly characteristic is settlement through vehicles mouse-like rodents. As a result of passive migrations, house mice, rats and other animals were settled almost all over the world. Many of the introduced animal species get along well in new places. Thus, there is an increase in the range individual species harmful rodents.
Migrations of rodents are of interest in the sense that many of them can be used in hunting and fishing and in the fight against agricultural pests.
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