Which birds make the longest migrations? The bird with the longest annual flight has been named

A group of Danish, Icelandic and American ornithologists have recorded the world's longest annual flight. The miniature bird “made” the previous champion by about 7 thousand kilometers.

Let us recall that previously the longest flight was considered to be the flight of gray petrels (about 64,000 km). Arctic terns ( Sterna paradisaea), plying between Greenland and Antarctica, they cover a total of up to 71 thousand kilometers! Previously it was believed that these birds fly half the distance.

Considering that each individual lives for about 30 years, it turns out that during its life Arctic terns cover about 2.4 million kilometers (the equivalent of three flights to the Moon and back).

The study was carried out thanks to the development of specialists from the British Antarctic Survey. Previously, transmitters were too bulky and heavy for terns, which weigh only about 110 g. That is why larger species of birds became the first “storytellers”. Now scientists have been provided with devices weighing 1.4 grams, which are easily secured with straps on the legs of terns.

Top: simplified route map Sterna paradisaea. Below are several real bird paths. Green lines show the migration routes in autumn (south), red - winter, yellow - spring (north) (illustrations by Grønlands Naturinstitut, PNAS).

During his record flight Sterna paradisaea they move in a zigzag manner, in particular, in the spring they do not fly directly across the Atlantic, but move from Antarctica to Africa, then to South America and only then to the Arctic.

“There have been many theories about why birds move the way they do and what they do along the way. For the first time, we can talk about this with complete confidence,” says Egeuang.

In a paper published open access in PNAS, the authors note that the birds often stop for as long as a month in the open ocean (in the North Atlantic). Most likely, in order to “refuel” with local fish and small crustaceans. After this, the terns move towards the tropics.

Wherein Sterna paradisaea, apparently, follow large spiral wind currents, being afraid to fly during strong atmospheric disturbances.

But still the real reason such long-distance migrations still remain a mystery to ornithologists. Egeuang suggests that the migration is stimulated by the rich supplies of the polar regions.

Further details of the study can be found in the Greenland Natural Resources Institute press release (in Danish) and on the website about Arctic terns.

How many kilometers do you think a small animal can fly during migration? beautiful bird 40 cm long, with snow-white plumage, a black head and a red beak? Maybe several thousand kilometers? But the Arctic tern, which is the name of this amazing representative of birds, is ready to surprise anyone with its outstanding record: in a year it covers a distance of 80,000 kilometers!

The Arctic tern is common in the polar regions of northern Europe, Russia, and Canada. Her favorite place habitats are rocky shores and beaches, where the bird builds a nest with a partner that it chooses for life. By the way, Arctic terns live quite a long time by the standards of the animal world - up to 30 years and even more. But this species became famous throughout the world thanks to its unique ability cover a mind-boggling distance of 80,000 kilometers in 1 year, flying to wintering grounds and back. It turns out that the flight range of the average Arctic tern, which lives, for example, 25 years, is about 2,000,000 kilometers without taking into account flights in its habitat. That's five distances from the Earth to the Moon!

The arctic tern accumulates this kind of mileage when traveling from the Arctic to the Antarctic and back. It was possible to calculate the exact migration routes of this species thanks to the development of technology, namely the reduction of GPS sensors.

Previously, they were so bulky that it was not possible to place them on miniature birds, so as not to cause overwork during a long flight. Therefore, observations were made of larger birds.

This is interesting: It's not just birds that have GPS transmitters attached to them. They are also hung on domestic cats to find out their routes of movement. What came of it - .

But now ornithologists have been able to track the exact flight route of Arctic terns, and the bird has finally taken its rightful place as the record holder for the longest migration.

The term "migration" comes from Latin word"migratus", which means "to change". This word has a special meaning when it refers to. Migration is the movement of animals from one region (or) to another. It occurs during certain periods of time or seasons of the year. Animals migrate to reproduce, grow, find food, or escape cold weather. For many, migration occurs twice a year. They fly away in the fall and return again in the spring.

What makes a bird, a bird?

All types of birds have feathers. There are other characteristics that are common to the class of birds, but feathers are the only feature that is completely unique to these animals. Many may say that flight is what makes birds special, but did you know that not all birds fly? Emus, cassowaries, and rheas are birds that do not fly. Flightless birds, such as penguins, swim perfectly underwater.

Birds have many interesting adaptations that allow them to fly. Light but strong bones and beaks are an adaptation to reduce weight during flight. Birds have unique eyes, ears, legs, and can also build nests. Some species are capable of making beautiful sounds.

Why do birds migrate?

Many birds seek out places that are warm, have an abundance of food, and have the opportunity to breed and protect themselves from predators. In, especially in, the climate is warm enough that birds can find enough food throughout the year. Steady daylight gives them plenty of time to eat every day, so they don't have to fly off to find food.

How do birds navigate?

Navigation is complex because it requires birds to understand three things: their current location, their destination, and the direction they must follow to get there.

Some birds use the Sun and stars for navigation. Others navigate by objects such as rivers, mountains or coastlines. Some birds can even use their sense of smell. Although birds are also capable of moving in cloudy days and fly through where there are no clear landmarks. So how do they do it?

Scientists have concluded that birds sense the Earth's magnetic field thanks to magnetoreception. Birds' beaks contain something called magnetite, an iron-containing mineral that acts as a compass. Other scientists believe that birds can see the magnetic field with their own eyes. Science doesn't yet know everything about bird orientation, but they probably use multiple navigation methods.

Why do birds fly like a wedge?

It is not by chance that a flock of birds flies in a wedge. Large birds such as geese and ducks form a wedge to reduce air resistance. The wedge allows flocking birds to fly further and more efficiently than birds flying alone.

When flying in a wedge formation, efficiency increases by 70%. The lead bird and the trailing wedge have the hardest time, while the birds in between benefit from the wingbeats of other birds.

In addition to improving flight, this method is also useful for communication between birds. Wedge flight allows birds to fly close to each other, as well as to hear and see their relatives. They communicate information to each other (via sounds) and can stick together.

The danger of migration

Sometimes birds must fly through harsh habitats, such as deserts where there is little water or oceans where there is no place to rest and feed.

Even if they find food and water, the birds need to land on the ground, where they risk becoming prey.

There may be many predators along the migration route. Depending on their size, migrating birds become prey for foxes, wolves, humans and other animals. Some birds may be attacked more large species birds during flight. Sometimes difficult weather conditions make the flight difficult and even lead to death. It happens that birds collide with airplanes, which is dangerous both for themselves and for the airplanes.

How do ornithologists study birds and their migration?

Bird ringing is one of the methods used to study them. Scientists place a small, individually numbered metal or plastic ring on the bird's leg or wing. They also use special networks known as mystic networks as a way of capturing wild birds for research.

This way, birders can capture the same bird multiple times, measure and weigh it, and collect other important information over long periods of time. Sometimes scientists use satellite data to track bird migration routes.

Fascinating facts

• The Arctic Tern has the longest known migration route. It flies about 70,000 km per year between its breeding grounds in the Arctic and winter areas in.
• Birds can fly at speeds from 30 to 80 km/h.
• Large birds fly faster than smaller species.
• In 10 hours of flight, some birds cover about 650 km.
• Radar surveys show that most flights occur at altitudes of less than 3 km, but some birds have been recorded at altitudes greater than 8 km.
• Birds that fly long distances fly at higher altitudes than those that fly short distances.

This small white bird with a black “cap” on its head holds the record for the longest migratory route. In order to overwinter, it flies from the Arctic to Antarctica, and returns back in the spring. During the year, the Arctic tern flies an average of about 70,000 km, and some individuals manage to fly more than 80,000 km. Considering that the length of the equator is just over 40,000 km, it turns out that the tern migrates from pole to pole 2 times a year equal to that to completely fly around the entire Earth.

Arctic tern

Arctic tern forms separate species in the tern family and is a native inhabitant of the cold Arctic lands. It nests in the northern lands of Canada, Alaska, along the entire coast of Greenland, Scandinavia and the tundra zone of Russia from the Kola Peninsula to Chukotka. When cold autumn sets in in the Arctic, the bird heads south. It spends almost all its time above the surface of the sea and moves south and south until it reaches the eternal ice of Antarctica. It's summer in the southern hemisphere at this time, and the little bird is the only creature on the planet that sees summer twice a year.

Arctic tern sitting on the snow

The bird flies 19 thousand kilometers one way. In total, in a year it covers more than 80 thousand kilometers. The lifespan of this species is on average 20 years. During this period, individual birds cover 2.4 million km. No other bird can boast of such distances.

You can give an example. In the summer of 1982, the chick was ringed on the Labrador Peninsula (Canada). In October of the same year, he was discovered in Australia near Melbourne. At the same time, the young bird covered 22 thousand km. Another pilgrim, also ringed in Labrador, was found 4 months later in South Africa. From this it can be seen that the Arctic tern travels all over the world, and distances are not an obstacle for it. But in the spring the bird invariably returns to the northern tundra and begins to breed.

Appearance

This bird is very similar to a seagull, but its body is shorter and its wings are longer. The length of the body from the tip of the tail to the tip of the beak reaches 33-40 cm. The wingspan is 74-85 cm. Weight ranges from 90 to 130 grams. Visually, the bird appears large due to its long wings. Top part heads are black. The plumage on the body is white. There is a light gray coating on the chest, outer side of the wings and back.

The tail is white above, light gray below. The beak is dark red, the legs are short, and the feet are webbed. The tail is fork-shaped. Males are no different from females in appearance. IN winter period The bird's forehead turns white. Juveniles in the first year of life have a brownish-motley coating on the back, and the length of the tail is shorter than that of adult birds. In the second year, all age-related features disappear.

Reproduction and lifespan

The Arctic Tern arrives in its native Arctic tundra after long journeys in the midst of spring. This bird adheres to monogamous relationships, so the pair is formed for life. Courtship is accompanied by “dancing” in the air, while the male gives the lady of his heart a small fish. If she accepts the gift, the birds begin to fly together and make various crackling sounds.

The nest is usually made on the shore of a pond. In summer there are many lakes in the tundra, and birds settle near them. But they prefer small islands surrounded on all sides by water. Several pairs usually live on the islands. They form a small friendly colony. Conflicts among terns almost never arise. The nest is very primitive. The female rakes up grass or moss and lays eggs in this depression. There are usually 2 or 3 of them. Both the female and the male take part in incubation. The incubation period lasts 22-27 days.

These birds are very brave. In case of danger, they fearlessly attack birds of prey, arctic foxes, and humans. At the same time, they use their strong beak. His blow is very noticeable. Therefore, people should not go close to the nests of these aggressive birds without a hat, as they can be seriously injured. This fearlessness attracts shorebirds, ducks and other peaceful birds. They try to nest next to terns, as they scare away all the predators around.

Chicks hatched from eggs are covered with down. After just a couple of days, they begin to actively explore the nearby territory, but do not move away from the nest. In case of danger, they run away and hide behind hummocks or in the grass. Parents feed their babies for a month.

Behavior and nutrition

During migrations, the Arctic tern feeds on fish, krill, mollusks and crustaceans. It hovers above the sea surface at a height of 10-12 meters and looks out for prey. Dives perfectly, but to shallow depths. During the nesting period, it is content with water insects, larvae, and small fish. It usually does not exceed 5 cm in length. It pecks at berries from plant foods.

Number

In general, the number of the species is at a stable level. According to experts, there are at least 1 million Arctic terns living in the world today. But birds are dispersed over a vast territory, covering almost the entire globe. Even during the nesting period, they spread over a very large area. Therefore, this million does not catch the eye. The colonies are small and located at a decent distance from each other. In former times, bird feathers were used to make ladies' hats, so terns were caught. Nowadays, this species has no commercial value.

Every spring, billions of birds fly to their nesting sites. Day and night, in flocks and alone, they are irresistibly drawn to the north. Year after year, century after century, millennia. And even millions of years ago, when there were no people on Earth yet, and there was no one to admire the greatness of what was happening, birds were already making their migrations. Why? Behind the apparent simplicity of the question lies many mysteries, over which scientists around the world are still puzzling.

Where are we flying?

Residents of the northern latitudes of Russia do not need to explain that in winter the birds there are cold and hungry. That's right: the regular change of places among birds is indeed associated with seasonal climate changes. But still, we don’t know everything about why birds choose such and not other directions and destinations.

Firstly, the generally accepted idea that birds move from north to south is not entirely true. Most birds are from high latitudes and middle zone flies to the southern regions, but the flight direction is not always parallel to the compass needle. Moreover, birds do not fly in a straight line, or the shortest route, but along complex trajectories, different for each species. Waterfowl often stick to waterways - large rivers, cascades of lakes and swamps of a meridional direction, and their paths can follow the bends of these natural landmarks. Small songbirds make their way over forest areas, and in forest-steppe zone and in developed agricultural areas above chains of forested islands. Not long ago, it was reported that flocks of birds flying at night could follow light-filled highways. Large birds with soaring flight need areas with rising air currents to gain altitude and glide from one such area to another, describing an intricate winding trajectory. Serious deviations in the route may be due to natural obstacles. Birds usually avoid flying across wide expanses of water, and, having reached the sea, turn to where it is narrower. Places of such narrowings can serve as “bottlenecks” for the bird flow, through which all the birds from the huge nesting and wintering areas fly twice a year. For the bird population of Europe crossing the Mediterranean Sea, such bottlenecks are the Straits of Gibraltar and the Dardanelles. In autumn, an incredible number of people gather near the Bosphorus birds of prey: Here they gain altitude for the “jump” across the sea to Asia. Ornithologists who keep records of passing birds experience serious difficulties: try counting several thousand soaring eagles, whose circling resembles a swarm of mosquitoes!

The curvature of the trajectory may be due to the need to go around the mountain range. One of these barriers is the Caucasus, and migrants are forced to “hug” to the coasts of the Black and Caspian Seas, where some sort of “bottlenecks” of passage also arise.

Or another mystery: for some birds, the routes “there” and “back” do not coincide; ornithologists call such migration routes loop-shaped or circular. During circular migrations of birds living in Europe, the spring route, as a rule, lies further east than the autumn route; the deviation can reach tens and hundreds of kilometers. The barn swallow has a “loop” in the Mediterranean part of its route, as well as the oriole, roller, and shrike. Some scientists explain them by seasonal winds, others see a repetition in the autumn trajectory historical paths introductions into nesting areas, a kind of “memory of the species,” and spring migration, when birds rush to nesting sites, occurs along the shortest route. Among the champions in terms of the size of the migration loop is the brown-winged plover. This is a small sandpiper, an American relative of our golden plover, which lives in northern Russia. The migratory route of the brown-winged plover is an impressive tour along the entire axis of the New World. From the tundras of Alaska and northern Canada, these waders fly east to Labrador, from there in a giant intercontinental rush to reach Brazil and Argentina. Birds weighing only about 150 grams travel almost 3,900 kilometers over the sea without landing. On the way back they do not perform such feats. Flying north, they stick to land and fly over all of southern, central and North America, since in the spring the feeding conditions there are incomparably better than in the fall. The slender-billed petrel has an even wider loop. For nesting, these birds gather in huge colonies on the coasts of South Australia and Tasmania. When the chicks fly, the petrels begin their journey around Pacific Ocean: first along the western coast to the Bering Sea, then parallel to the American coast to southern California, from there across the ocean to New Zealand, after which they return to the nesting areas.

Migration Brownwings	Autumn and spring flight routes medium curlews	Slender-billed migration loop petrels

All of the above examples are, in one way or another, related to movements in the meridional direction. But there are also latitudinal migrations. One of the busiest flyways in Europe, where birds from arctic tundra Russia follows the wintering grounds of Western Europe, the White Sea-Baltic, oriented from west to east. It's interesting that from the north Western Siberia Some bird species fly to the west, while others skirt the Urals from the east and move south to the Caspian Sea, wintering grounds of the Middle East and Africa. What explains the choice of direction? One version is related to the history of post-glacial bird distribution. As the glacier retreated, they gradually developed new lands. Some species were introduced from the south, and others from the west. Chicks born in a new territory remember the image of their homeland and its location, so that after the winter “vacation” they can confidently find their way back, continue the family line and consolidate migration traditions.

But ornithological mysteries are not limited to the variety of flight trajectories. Most birds fly much further than necessary to reach warm feeding areas. Barn swallows, or killer whales, the usual companions of rural residents, fly from the European part of Russia to southern Africa for the winter, bypassing the gentle Mediterranean, where some other refugees from Europe safely spend the winter. Moreover, at the risk of their lives they fly across the sultry Sahara. Why are they so attracted to the African landscape? It is even more difficult to explain the adherence of birds from Siberia to African wintering grounds: after all, it is much closer for them to fly to the southern regions of their continent. And there are many such species: of the 80 species of long-distance migrants nesting in Western Siberia, 37 spend the winter in India, and 33 in Africa.

Birds of the southern hemisphere, upon the onset of phenological autumn, fly away in a northern direction, symmetrically as it happens in the northern hemisphere. There are relatively few such species, since the land area in the southern hemisphere is smaller. During the winter, those living high in the mountains descend lower and into the foothills; these migrations are called vertical. Migratory birds are also found among tropical birds, but they fly shorter distances. But where environmental conditions are relatively constant, the majority lead a sedentary lifestyle.

The choice of flight route is aimed at optimizing the bird's energy expenditure. Some species benefit from straightening the trajectory and making a long throw, others have to lay a hook, avoiding obstacles, and still others need to stop to rest. Small songbirds can fly for several hours at a time, covering up to 500 km per day, and then stop for a day or several to refresh themselves. As a rule, there are many suitable places for this, and you can meet them almost everywhere during migration. It is more difficult for semi-aquatic birds, because they need reservoirs with certain parameters: some - deep, others, on the contrary, with shallows, and most importantly - with suitable food. In such species, the route is a series of long “jumps”. Birds sometimes have to fly for several days from one stop to the next. Areas where a particularly large number of birds gather receive the status of key ornithological areas, which are taken into account when creating nature reserves, nature reserves and when developing economic plans.

Migrations different types birds differ not only in routes, but also in spatial organization. Some species fly in narrow currents, in particular soaring birds such as eagles or storks, since rising air currents are not formed everywhere. Migrants with flapping flight fly in a wide front, but for their flights some places are more convenient, while others are less so, so in some places there are condensations of flows that can merge and branch. The best natural corridors are usually used by many species at once, and knowing them is important for developing bird conservation measures.

Do we really understand why they return in the spring? Why don’t they want to settle forever in southern wintering areas? The reference to historical traditions, fixed by instinct, clarifies little. You need to understand why the northern regions are attractive to birds. Ornithologists have several answers for this. For example, there is an opinion that the driving motive of the entire migration cycle should be sought not in the autumn flight to warmth and prosperity, but in the spring movement to the north, and the main reason for migration is the desire for seasonal abundance of food. In damp, cool climates temperate latitudes and the Arctic, insects breed in huge numbers, in which the larvae develop in aquatic environment. This is an excellent protein food for feeding chicks. The dietary properties of aquatic invertebrates are no worse, and they are easy to catch in the shallow waters of the northern seas. The tidal zone, coastal marshes and deltas of large rivers - and many of them flow into the Arctic Ocean - are a haven for waterfowl, focused on eating green food and fish. But it’s not just food that attracts migrants. Northern latitudes are also remarkable because in the summer daylight hours days when parents can collect food for the chicks are longer there than in the south. And in the Arctic it doesn’t get dark at all in the summer.

Protect with the whole world

Birds know no boundaries. Their flyways run through the territories of many states on different continents. The efforts of those who protect birds will be in vain if they are protected in one country and exterminated in another. Bird protection is unthinkable without international cooperation, and the most reasonable way is to unite the efforts of those countries that are on the same flyway. Based on data on the migrations of many species, scientists have identified eight generalized flyways: the East Atlantic, Mediterranean-Black Sea, West Asian-African, Central Asian, East Asian-Australasian and three flyways across the Americas: the Pacific, Mississippi and American Atlantic. Countries along each flyway sign international conventions outlining their obligations to protect migratory birds.

The main agreement is the Bonn Convention on the Conservation of Land and Sea Migratory Animals, signed in 1979 in the city of Bonn within the framework of the UN Program for the Conservation of Migratory Animals. environment, and came into force in 1983. The Convention adopted two important lists: the list of migratory species threatened with extinction (this is the so-called Appendix I), and the list of migratory species that need the international cooperation. Our country, unfortunately, has not joined this convention, although all five Eurasian flyways pass through its expanses. 1. The East Atlantic Route stretches along the Atlantic coast from Africa to northern Europe, along the coast of the Arctic Ocean to the Taimyr Peninsula, and in the west enters North America, covering Greenland and the Canadian Arctic Archipelago. The western stream of wheatears belongs to this flyway (see below for more on this heroic bird). 2. The Mediterranean-Black Sea flyway, used by barn swallows and white storks living in Europe, connects the breeding areas of birds in northern and central Europe with the African wintering grounds. 3) The West Asian-African Flyway connects the Arctic from Yamal to the New Siberian Islands with eastern Africa and the Middle East. These three routes are covered by the African Eurasian Migratory Waterbird Agreement (AEWA). 4. Central Asian - includes the nesting areas of the Laptev sector of the Arctic and adjacent parts of the Kara and East Siberian seas and runs through the entire Asian continent to India. This migratory route ensures the existence of bar-headed geese - extreme high-altitude flight enthusiasts flying over the Himalayas, and many others rare birds, for example, black crane and lapwing. 5. The East Asian-Australasian route extends from the Russian one Far East and Alaska through East and South-East Asia to Australia and New Zealand. Among the most famous members of this flyway is the Spoon-billed Sandpiper, a small, funny-looking bird that in recent years has found itself in critical condition due to uncontrolled mining in countries South-East Asia. To protect birds migrating along this flyway, an international Partnership was created in 2006, which included the Russian Federation.

Difficulties of wandering

The life of migratory birds is very difficult. According to the Secretariat of the Migratory Birds Convention, between 1978 and 2000, almost half of migratory bird species declined in numbers, and 4% disappeared completely. Long-distance migrants suffer more than birds with short routes. the main problem 80% of all migratory species experience changes to agricultural land. This includes plowing of meadows, fragmentation of natural landscapes, and overgrazing of livestock. Industrial fishing of forage invertebrates can lead to tragic consequences, as happened with Icelandic sandpipers from Canada. Their numbers have decreased fivefold due to the extermination of horseshoe crabs, whose eggs the waders sustained during breaks, and which, unfortunately, were too attractive to fishermen as bait. A similar story happened with the European subspecies of the Icelandic sandpiper, which could not withstand the competition for food mollusks with farmers. The construction of dams, drainage works and straightening of river channels can radically change the appearance of a habitat and make it unsuitable for birds. We know firsthand how this happens - let us remember the tragedy of the Aral Sea, which disappeared from the face of the Earth along with the wintering grounds of waterfowl, when the flowing rivers were dismantled for irrigation needs. A special problem is high-rise buildings erected by humans. In the USA it was calculated that within a year from a collision with various kinds artificial barriers kill 4-5 million birds, especially those flying at night and targeting long distances. Massive construction of wind power plants, seemingly very progressive from an environmental point of view, can create a negative effect if they are installed in areas of concentrated bird flight. We recently encountered such a problem as it happens on Black Sea coast Bulgaria. There is another serious danger for diurnal birds of prey: power lines that are not equipped with special protection. Tired birds land on the wires, and when they take off, touching them with their wings, they receive a powerful electric shock.

And, of course, hunting, especially on the spring migration route, which bird defenders regard as eating away the seed fund. When thinking about species that became extinct due to hunting, the passenger pigeon is usually mentioned. But there is something else. The Eskimo Curlew, a small sandpiper that nested in the tundra of North America, was once one of the most numerous birds in the world. However, in just two decades between the 19th and 20th centuries, American farmers brought it to the brink of extinction. Unfortunately for themselves, these birds were distinguished by unprecedented courage: they did not abandon their downed brothers and tried to protect them from hunters. What made it easier for the shooters to do their dirty work (about tragic story Eskimo curlew, Canadian writer Fred Bodsworth wrote the novel “The last of the Curlews” or “The Last of the Curlews” in 1955. Later, a very beautiful and sad cartoon was made based on it. Unfortunately, neither the book nor the film have been translated into Russian. Even those species for which it is prohibited can suffer from hunting, and not necessarily through the fault of poachers. The goose called the lesser white-fronted goose, unfortunately, is very similar to an ordinary one. hunting species- a white-fronted goose, and gets shot by accident. The cost of mistakes made by hunters, aggravated by disturbance at nesting sites from tourists and fishermen, is terrifying: over the past 30 years, only about 10 thousand of the former hundreds of thousands of lesser white-fronted lesser white-fronted ducks worldwide have remained.

Migration status

No matter how dangerous the life of heavenly wanderers is, they still make their flights and cannot do otherwise. Migration is not a volitional decision of one bird or a flock, but a seasonal state of the organism fixed by evolution. When caught in captivity, even under ideal conditions, birds experience incredible anxiety during migration, forcing them to fight against the walls of their cages, sometimes to the death. Ornithologists explain it by a migratory state, including in this concept a whole complex of changes in the bird’s body: physiological, hormonal, behavioral.

The migratory state is a natural phase annual cycle birds, which consists of the breeding season, molting, migration to wintering, a second molt and return migration to the nesting grounds. Each phase is characterized by a special hormonal status. In preparation for spring migration, as a result of increased synthesis of pituitary hormones, in particular prolactin, birds' appetite increases and their metabolism is adjusted to storing fat; after the winter break, the gonads begin to work. Behavior also changes: training flights begin, contact signals are increasingly heard, which the birds exchange on the way, and for many, the circadian rhythm is also disrupted: they switch from daytime activity to nighttime activity.

In birds of the same species living in the same region, different phases of the annual cycle occur simultaneously. To synchronize physiological processes, the most important of all environmental factors is photoperiod. When daylight hours reach a certain length, a cascade of regulatory changes is launched, automatically following one after another throughout the entire annual cycle. The starting point is the beginning of preparation for spring migration - so this phase is especially important.

By the sky, by the stars and by the magnetic field

Speaking about migrations, we cannot ignore the mystery of how migratory birds orient themselves in space. To solve such a problem, a person will need a map and a compass or a GPS satellite positioning device. But birds have none of this. Experiments with birds in a migratory state, placed in a round cage with blank walls and a transparent ceiling, showed that in sunny days Some diurnal migrants have a distinct directional movement pattern that is weakened during inclement weather. This means they can navigate by the sun. But for most birds, clouds are not an obstacle, because they are gifted with the ability to distinguish polarized light. For them, the color of the sky turns out to be different in the direction of the sun and in the area above the perpendicular to its rays, even if the star is hidden behind the horizon or clouds. Similar experiments with nocturnal migrants in a planetarium, where the location of constellations can be arbitrarily changed, confirmed the ability of birds to navigate by Polaris and several neighboring stars. And at Princeton University they successfully confused blackbirds by placing the cell in an artificial magnetic field. In solving the mystery of magnetic orientation, scientists have made great progress in the last two years. It turned out that birds are able to “see” the Earth’s magnetic field: in experiments on birds with damaged nerves, scientists from Germany convincingly proved that birds perceive it through their eyes. In the biochemical mechanism responsible for field perception, the leading role belongs to the cryptochore pigment, which perceives blue color, as well as superoxide (O2-1), which enters into a chemical reaction with it. Receptor magnetic field Superoxide serves in this system, since its molecules are able to change orientation depending on the direction of the field lines.

The ability to find their way to wintering grounds and back is given to birds from birth, and is not acquired through experience. It is known that in some species, young individuals fly away for the winter separately from adult birds, and even earlier. How would they get there without an innate program? Its existence was also proven in experiments with marked stork chicks, who were raised in captivity and then taken to another country and released after the local storks flew away. Observing the movements of the new settlers, ornithologists discovered that they all flew in the direction traditional for their population, as if they had started in their homeland. But starlings seem to know not the azimuth, but the coordinates of their destination. In similar experiments, they flew straight to a wintering site, which they had never been to before, although the direction from their native nest to it differed by 60º. This means that innate programs are different: flexible in starlings, and inflexible in storks.

Spring is coming!

Duration daylight hours is not indifferent to humans either. As the hours of darkness lengthen, many experience seasonal depression, but as soon as the day gets even a little longer, and, despite the January cold, we feel a surge of optimism. And how much joy the first song of the great tit brings - they begin to sing already in January, and in warm winters even at the end of December. Tits live sedentary lives and sense the coming spring by the increase in photoperiod. The bird population of the central zone begins to be replenished with returnees from the south at the end of March: white wagtails run across the lawns, birdhouses come to life, and rooks return to the old colonies. With the arrival of April, the sky is filled with schools of gulls, ducks and geese. And every day brings me meetings with new birds.

Some statistics

Of the 9,856 bird species in the world, 1,855 are migratory. The flight speed of small bird species during migration is about 30 km/h, and for large species it is about 80 km/h. Birds can fly without a break for several days and cover up to 4000 km. The average flight altitude is about 5 km, but most birds fly much lower. Statistics of aircraft collisions with birds say that 75% of all cases occurred no higher than 300 m, 20% - from 300 to 1500 m, and only 5% - above 1500.

Gallery of Champions

Among migratory birds, the champion in flight height is the bar-headed goose. They nest in central regions Asia, and for the winter they fly to India, for which they have to fly over the Himalayas, since the roundabout route would be too long for them. They have to fly at incredible heights. There is a report of a flock of bar-headed geese meeting at an altitude of more than 10 kilometers. The air there is so thin that helicopters cannot fly: they lack the lifting power of the rotors. This is unthinkable for the human body: climbing the peaks of the Himalayas requires a long preparation to accumulate additional hemoglobin in the blood and oxygen masks during the ascent. Geese do this without any preparation. What physiological mechanisms are involved? And in general, how do they manage to stay in thin air? Maybe this type of geese has some special wing shape, or the flapping frequency is higher than that of other geese? As research by Canadian ornithologists from the University of Vancouver has shown, the wingspan is indeed slightly larger, but it does not have a noticeable effect on the aerodynamic properties of the bird. Physiological characteristics are much more important. In experiments, it was found that a decrease in heat transfer and increased ventilation of the lungs help bar-headed geese overcome high-altitude hypoxia. However, according to theoretical models, these factors are not enough for effective breathing at high altitudes. According to Chinese scientists, bar-headed geese have a slightly different hemoglobin structure than other birds, but how it affects the efficiency of oxygen binding is still unclear. So we are still very far from solving this riddle.

Speaking of leaders, we cannot ignore the absolute champion in terms of annual flight distance: the Arctic Tern. The nesting grounds of this species are located above the Arctic Circle, and for the winter the terns move to Antarctica. But recently it turned out that we still don’t know everything about the migrations of this bird, and even having elevated it to the rank of champion, we nevertheless underestimated its abilities. By attaching subminiature geolocators weighing just 1.4 grams to several Arctic terns, which record daylight hours and sunrise and sunset times on a memory card, ornithologists were able to map the movements of eleven birds from Greenland and Iceland. It turned out that, having reached the southern limits, the terns do not stop, but continue to move along the edge Antarctic ice who goes west to South America, and who go east to Australia. The additional “hook” is comparable in length to the length of the “main” flight, that is, the total length of the annual migration is twice as long as previously thought. Thus, in a year each bird flies not 40 thousand kilometers, as previously thought, but from 80 to 80 thousand! Over the course of its entire life—and these birds live for more than 30 years—the Arctic tern clocks up more than two million kilometers—like three flights to the moon and back.

But if you look for the absolute champion in terms of the total length of the path traveled in a lifetime, then it will turn out to be the small or common petrel. This bird lives for a long time, up to 50 years, and during this time it manages to fly about 8 million kilometers. Among the leaders in flight range is the common wheatear. These birds do not fly from north to south, but with a large latitudinal shift. Wheatears winter in sub-Saharan Africa and migrate in several streams to breed. One leads to Greenland and Canada, for which the birds cross the Atlantic Ocean - this is one of the longest oceanic flights made by passerine birds. And at the same time, unlike terns, they do not have the opportunity to feed. And the other - to the north of Eurasia and Alaska. Birds flying to the east of their range, to Alaska, need to fly across all of Siberia, and the total length of round-trip routes is more than 20 thousand kilometers.

And finally, the absolute champion in terms of non-stop casting range is the Godwit Sandpiper. From Chukotka and Alaska, flocks of godwits fly to Australia for the winter and even New Zealand, and, as satellite observations of birds tagged with radio transmitters have shown, right across the ocean. One female flew from Chukotka to the New Zealand shores in eight days, covering 11,680 km without rest! Not surprisingly, before migration, their body consists of 55% fat, which is necessary to ensure the flight without refueling.

Krasnova Elena Dmitrievna, Ph.D. biol. Sciences, researcher, Faculty of Biology, Moscow State University. M.V. Lomonosova