Where do birds fly in the fall? Seasonal migrations of birds. Birds at different times of the year

In the large bird world there are migratory and non-migratory migratory birds. For migratory birds, the change of seasons is preparation for great trip, and for non-migratory birds, the onset of the cold season becomes long and difficult time to survive this difficult time during the winter.

Birds in spring

With the arrival of the first warm days, migratory birds return to their native lands. There is a lot of work waiting for them at home: building nests and hatching chicks.

Wagtails are the first to return to their habitats. They are especially punctual, so they never miss the beginning of ice drift.

At a time when the earth was almost freed from heavy snow cover, the rooks have already arrived. They are the very first to hatch their chicks, which is why their nests are already built in March.

Also early migratory birds are starlings and larks. The first song of the lark is evidence that the cold will not come again. As a rule, males return first, followed by females. And the last of the starlings and larks to return are those who were delayed or lost on the way.

Birds return home from warm regions not because there is nothing to eat there. It's all about the instincts of birds. They are drawn to their homeland by the desire to reproduce.

The flight of birds to their native lands is much faster than their departure. And the whole point is that they are in a hurry to hatch their cubs, which does not tolerate delay.

It is possible to roughly determine the periods of arrival of birds to their native lands. In mid-March, rooks return to their homeland, and by the end of this month starlings arrive.

In early April, larks, swans, thrushes, finches and kites can be observed. In the middle of this month, geese, ducks, gulls, cranes and waders arrive. And at the end - warblers, redstarts, woodcocks and tree pipits.

But May is characterized by the arrival of swallows, flycatchers, nightingales, swifts and willows.

Bird life in summer

The main task of each species of birds for the summer is feeding and adapting the chicks to life. If the summer turns out to be rainy and cool, then the life of birds becomes somewhat more difficult. Chicks die from colds and hunger. And the parents themselves are in great danger while it rains.

Drought is also not a favorable state of nature for birds. For birds living in swamps, drought is a disaster. During such periods, wading birds are forced to go out in search of a new habitat. And if the hot days drag on, the vegetation begins to dry out. This situation is dangerous for all types of birds.

The main task of birds for the summer is to teach their chicks to fly, so that in the fall they can fly south with their parents.

Usually, summer days are accompanied by early dawn and late sunset, so the days of many birds become longer. So, for example, chickadees, they wake up with the first rays of the sun and fall asleep at sunset.

And the songs of the redstart can be heard at any time of the day, because they wake up before sunrise and fall asleep at dusk.

IN summer time During the year, birds are especially active and lead their usual way of life. Day and night predators hunt in forests and steppes. The familiar inhabitants of crowded places fly along the streets of cities and villages.

Which birds fly away in the fall and which ones stay?

Why do birds fly south? Because in winter they do not have enough food, and there is a possibility that their body will not tolerate severe frosts. Migratory birds are most of inhabitants of the tundra, and in the taiga some species are such. The number of migratory species depends on how suitable the habitat is in terms of food - whether there are enough food supplies. Thus, it turns out that half of the forest feathered inhabitants fly south. And fields, swamps and ponds are left to spend the winter without their winged inhabitants.

Migratory birds include finches, wagtails, song thrushes, chiffchaffs and swallows. Lapwings, tree pipits, larks, orioles, robins and redstarts also prefer migrating to warmer lands.

But there are birds that are able to withstand cold days; they are called sedentary. These birds include: woodpeckers, tits, pikas, nuthatches and jays. Cold days are not scary for wood grouse, black grouse and hazel grouse. And the crossbill bird can generally build nests in winter and breed offspring.

It is worth highlighting the nomadic bird species. They don't fly away warmer climes, but are constantly moving from place to place. For example, waxwings, titmice, walnuts, redpolls, bullfinches and many others.

How birds winter

Winter is not an unexpected period in the life of birds. Those who stay for the winter are truly prepared for harsh conditions. Birds stock up on food and seeds. And sometimes they go out in search of fallen earrings, cones and nuts.

So, for example, jays. They can often be seen searching for acorns, even potatoes and grain.

And the hazel grouse grows a special fringe on its legs, so it can hold on to icy tree branches.

Birds that feed on buds, seeds and catkins are more provided with food in winter. These are - white partridges, hazel grouse, black grouse, wood grouse.

But birds that prefer to eat seeds and leaves are always in a difficult search for food. For example, goldfinches, linnets, siskins, redpolls. These birds are saved only by the seeds of spruce and pine trees.

The famous American scientist, a major expert on bird flights, D. Griffin, once noted that the flight abilities of birds are limited only by the limits of space on the planet.

Of course, the expression is very figurative, and Griffin wanted to emphasize the enormous capabilities of birds. But he, of course, knew that the possibilities were not only not limitless, but also quite limited. A bird cannot at all fly where it wants and when it wants - we already know this; it cannot fly away arbitrarily, “assigning” deadlines to itself; its flight has a certain range, and speed, and height. Finally, although it has colossal energy resources, they still have limits.

In this chapter we will try to understand the question of how birds fly. But to figure it out, and not to answer it, there is still too much that is mysterious and unsolved in bird flights.

Let's start with the fact that birds do not fly away and arrive home at the same time.

Now, thanks to many years of observations, the average and extreme dates of arrival and departure of birds have already been relatively accurately established; it is known that they fly in waves, or “echelons”. For example, in middle lane There are seven such waves in our country.

The first wave is rooks. Perhaps no one except rooks risks flying at such an early hour. It's mid-March. The second wave occurs at the end of March - the very beginning of April. At this time, starlings arrive (the average date is March 30), larks and finches (the average arrival date is April 1–5, respectively).

The third wave is from April 10 to 20, when robins, blackbirds, birds of prey, waterfowl and many other birds arrive.

Fourth wave (until approximately April 25). Most small birds arrive at this time. In the most last days April - early May there is a fifth wave: cuckoos, whirligigs, swallows. At the beginning of May - the sixth wave: swifts, nightingales, gray flycatchers. And finally, the last, seventh wave. It occurs at the end of May, when the latest birds, such as orioles, shrikes, and lentils, arrive. Of course, the dates, as we have already said, can be shifted - sometimes the birds arrive earlier than usual, sometimes later. But one echelon never overtakes the other - the first is delayed, and accordingly the second, third and others lag behind.

There is another interesting pattern, this was noticed back in 1855 by K. F. Kessler: birds that arrive early almost always fly away late in the fall, and those that arrive late in the spring fly away early, among the first. For example, swifts arrive with the fourth echelon of birds, and are among the first to fly away - in August. By the way, this phenomenon for a long time it was inexplicable: swifts catch insects in the air, just like swallows. But swallows arrive earlier and fly away later. It turns out that it's all about vision, or more precisely, about the structure of the eyes: swallows can see insects flying around and chase them. Swifts do not chase insects - they hardly see them. They fly with their mouths open and, like a net, capture those they come across on the way. There is a large percentage of randomness here. And if there are a lot of insects, this percentage is large enough to satisfy both the adult birds and the chicks in the nest. And when there are few insects, the percentage decreases.

The example of the swift is quite convincing. And the amount of food determines the timing of the arrival and departure of birds. The German scientist A. Altum in the middle of the 19th century defined these phenological connections as follows: “Not a single bird returns before its food appears. The cuckoo appears no earlier than the overwintered silkworm caterpillars reach half their size and climb the trees. The oriole returns no earlier than the cockchafers begin to fly. Warblers arrive only when the small naked caterpillars of various leaf rollers and moths grow up. Swallows do not appear until the buzzing of at least some flies is heard, and flycatchers only when flying insects appear in large numbers.”

The connection between the timing of arrival and dietary habits is beyond doubt. But the timing is also related to the wintering places: birds wintering not very far away, as a rule, arrive earlier, and those wintering in distant regions - much later, although there is already enough food for them. The timing of departures and arrivals also depends on geographical area where birds live.

But if departure is associated with certain changes in external conditions, with certain signals, then arrival at certain time remained largely a mystery: after all, where the birds winter, they in no way feel the changes taking place in their homeland. Of course, the annual cycle of changes in physiological state is also very important and probably determines the time of departure. Then there was a lot of uncertainty until people understood: not only the departure time plays a role here, but also the flight itself. And it depends on many additional conditions, in particular meteorological ones. It's really hard to do general conclusion for all migratory birds - each species reacts differently to weather. Nevertheless, it is known, for example, that birds have a completely different idea of ​​\u200b\u200b“non-flying” weather than we do. In non-flying weather, from our point of view, birds fly beautifully; moreover, it is in calm rainy weather that they fly especially energetically. They fly, of course, on clear, warm nights.

But a sharp drop in temperature, even if the weather is clear, “flying”, is a significant obstacle for birds: sometimes they remain on the ground for a long time, waiting for warming.

Wind is also of great importance. If only because it can either make the flight very difficult, or, conversely, make it easier. Thus, many birds already stop flying when there is a headwind, the speed of which is 5 meters per second. However, other species can fly in a headwind, the speed of which reaches 20 meters per second.

In dense fog, birds have poor orientation and often lose direction or stop flying altogether.

The weather is just one example of how birds are not so spatially independent. They also depend on each other.

We have already said that before leaving, birds gather in flocks. (Only a few birds fly alone - for example, hoopoe, cuckoo, kingfisher, warblers, robins, raptors, and even then not all.)

Flocks can be large or small, and their size varies greatly within the same species. For example, ducks can fly in a flock of ten birds or several hundred, pelicans can have a flock of 20–30 to 100–200, finches can have flocks of several hundred birds, and starlings can have flocks of tens of thousands.

But whatever the size of the flock, it has a certain structure, characteristic of certain types. So, for example, cranes and geese fly in a wedge or at an angle, ducks fly either in an oblique row or at an angle, pelicans and lapwings fly in a wide, stretched chain. And cormorants can fly in a chain, or in a wedge, or in an oblique row, changing formation in flight.

Other birds do not fly in formation, but in closed flocks. Here, too, there are differences: some flocks, for example flocks of starlings, are very dense, creating the impression of a single mass, especially when the birds maneuver in the air, and do this very clearly, others are more loose, others are even more sparse, and finally, some predator birds They seem to be flying separately, at a sufficiently large distance from each other, but at the same time so that they can see each other.

Often flocks remain in wintering grounds. Apparently this has some biological significance. But the fact that flocking is important for many birds, primarily during the migrations themselves, is beyond doubt. For example, the wedge formation of geese, cranes, and curlews makes the flight easier for weaker birds: strong individuals fly at the head of the wedge and take on the aerodynamic loads. In general, this system saves birds up to 20–23 percent of energy. Some scientists believe that even the type of flock itself is important for birds - it seems to serve as an additional signal to fly.

Many people watch birds migrating. However, only specialist ornithologists can observe all birds during migration, and even then this became possible only in Lately, when locators appeared in their arsenal, when aviation began to help them. After all different types birds fly at different times of the day - for example, swallows, swifts, larks, blackbirds, flamingos, storks, cranes, birds of prey fly during the day. Starlings, waders, and lapwings can also be seen during the day, but more often they, like most birds in general, fly at night. This is connected, of course, with food and rest during the journey. If the birds have enough rest in the morning or during daytime stops and find enough food, they fly the rest of the daylight hours. But most birds spend a lot of time searching for food and resting during migration. Therefore, they spend all daylight hours on the ground, and in the evening they take off in flight. This has its advantages - in any case, they fly more at night than birds flying during the day. In addition, it is safer at night in many ways.

But it is difficult or almost impossible to see all the flying birds, not only because many fly at night and we learn about their passage only by their voices. And also because they fly quite high. True, not as high as previously thought (it was assumed that the usual flight altitude of birds during migration is 2000 meters, and for some it is almost 5 thousand). As we have now been able to establish with the help of observations from airplanes, gliders, balloons and thanks to locators, individual species they really fly very high, they even break records that people didn’t even know about. Thus, ducks and plovers, it turns out, can fly at an altitude of 2000–2500 meters, rooks at an altitude of 3300 meters. But at such a height the oxygen content in the air is very small. But rooks apparently easily tolerate low concentrations of oxygen. Even more surprising is that some birds, including small ones (pipits, redstarts), were found at an altitude of 6000 meters. But the real record was set by the geese - they rose to 8850 meters. True, they did not fly at such an altitude all the time, but only when flying over the Himalayas (although some scientists believe that they often fly very high). At this altitude, oxygen is three to four times less than usual. This phenomenon, that is, the ability of birds to feel good in such an environment, has not yet been studied or explained. However, only very few birds fly at such an altitude (according to D. Griffin - 1 percent at an altitude of more than 3 thousand meters and 10 percent at an altitude of 1.5 thousand meters). The usual altitude at which birds fly is 450–750 meters. Of course, this is not so little, especially for small birds (though many small birds fly even lower), and it is very difficult or even impossible to see birds, especially at night. This is partly why it is difficult to determine the flight speed of birds during migration. And what, exactly, should be meant by speed? The speed of flight or the speed of flight in general, that is, how long does it take for a bird to fly a particular distance? Both are, of course, very interesting, but both are very difficult to establish.

The “cruising speed” of a bird is difficult to establish because it often depends not on the efforts of the bird itself, but on where it flies - how dense the air is, how strong and what direction the wind is. Previously, it was believed that birds fly only with a slight headwind - a tailwind supposedly “ruffles” the feathers, and this interferes with flight. It is now known that birds prefer to fly when there is a tailwind: it helps in flight. For example, if a bird is flying at 15 meters per second and the headwind is 10 meters per second, then the bird will naturally move forward at 5 meters per second. With a tailwind of the same strength, it will fly at a speed of 25 meters per second. There are known cases when birds, which usually fly no more than 70 kilometers per hour, flew 150 kilometers in an hour thanks to a tailwind. Therefore, to establish the true flight speed of a bird, it is necessary to know the strength and direction of the wind exactly at that moment and exactly at the altitude at which the bird is flying. At an altitude of several meters and several hundred meters, the wind strength is very different. And still modern methods Research has already been able to establish the average flight speed of some birds. The mallard duck makes 96 kilometers per hour, swifts fly at about the same speed, small songbirds usually fly at a speed of 30–60 kilometers per hour, and crows fly at about 50–60. Starlings make 65–80 kilometers per hour, falcons also do about the same, geese from 70 to 100 kilometers per hour, and swallows 100–120.

Nowadays, no one is surprised that, say, a falcon, capable of reaching speeds of up to 200 kilometers per hour during a hunt, flies much slower: it is clear that the sprint distance is significantly different from the stayer distance. Something else is somewhat surprising: a swift, capable of flying at a speed of 100-120 kilometers per hour and seemingly having the opportunity to fly to Odessa in a ten-hour flight, if it makes this journey, it is not in a few hours, but in a few days. And not only the swift. Any bird, even a less fast-flying one, could be much more short time find themselves in wintering areas. For example, starlings flying from the Moscow region to spend the winter in Austria or France, at an average flight speed (70 kilometers per hour) could reach their destinations in 30–40 hours. And they fly for 50 days! So, during their flights average speed is it decreasing? No, the speed does not decrease, they just can’t fly at that speed for very long (with rare exceptions, which we will talk about).

Moreover, after flying for one day or one night, they then rest for several days, feed, gain strength and replenish energy reserves. In addition, there may be temporary obstacles on the way in the form of heavy rains, strong wind or a sharp drop in air temperature. And this is an additional delay.

The famous phenologist Professor D.I. Kaigorodov, with the help of a large network of his observer correspondents, established the average speed of movement of some birds to their homeland and associated this with the forward movement of spring. According to Kaygorodov, the rook, for example, moves on average 35 kilometers per day and populates its nesting area in the European part of the USSR within 35 days, the stork moves at a speed of 60 kilometers per day, and populates the nesting area within 17–20 days , cuckoos move at a speed of 80 kilometers, and their period of settlement in the European part of the USSR in the spring is 25–30 days. In other words, birds move as many kilometers per day as they could fly in one hour. Another way to put it is that many birds could populate their entire nesting area in one day. However, we must take into account that they rest and feed more than they fly. The same applies to ducks, moving at an average speed of 50–60 kilometers per hour, and to small passerine birds, which fly at approximately the same speed (although the finch flies slower - its average speed during flights is 17.5 kilometers per hour). hour). Seagulls move at a speed of 10–20 kilometers per hour (the same ones that are often said to be “fast-winged”; in principle this is true, but not during flights). It is not surprising, therefore, that they from Lake Kiyovo near Moscow, for example, to wintering places - the shores of the Black and Mediterranean seas - take 40 days to reach. The hawk is also quite rightly considered an excellent flyer. However, during flights its average speed is a little more than 12 kilometers per hour.

German ornithologist I. Steinbacher provides the following data: the stork flew 610 kilometers in two days, the warbler flew 2200 kilometers in 10 days, and the coot flew 1300 kilometers in 7 days. It would seem that a fairly decent flight speed is 200–300 kilometers per day. However, this applies only to birds flying relatively short distances. The longer a bird's path, the slower it flies. The flight speed of redstarts wintering in different areas was monitored globe. One, which wintered closer to its nesting area than the others, flew about 170 kilometers daily, the other - about 60, and the one that flew the furthest - only 42 kilometers per day.

True, all these dates and calculations are correct for autumn flights. In spring they occur faster, and for some (stork, shrike) almost twice as much. And the closer to their native places, the faster the birds fly. But they shorten the flight period not by increasing speed, but by resting and feeding time.

However, a leisurely flight is a rule with many exceptions. Birds flying over land along certain “ecological chutes” can afford to take their time, where there are places suitable for resting and replenishing supplies. But what about those who have to fly over the sea? And fly not a dozen, not a hundred, but thousands of kilometers? For example, small falcons and golden bee-eaters wintering on the coast South Africa? After all, their path over the sea is 3 thousand kilometers! And there is no place to rest or feed! One of the species of plovers that nests in Chukotka and Alaska winters on Hawaiian Islands. To reach their wintering grounds, these birds also need to fly 3 thousand kilometers over the sea. And they fly this distance without stopping, spending 22 hours on the flight. Another species of plovers flies from Scotland to South America. The distance is 3600 kilometers, and also without rest.

American Tree Warbler, which breeds in Alaska and winters in South America, during its journey it lands on the ground only once. The rest of the time she is on the road. 100 hours of non-stop flight!

The snipe nesting in Japan amazes scientists - it flies 5 thousand kilometers without rest! And this is twice a year!

However, many birds annually fly a distance equal to almost half the equator. For example, quails flying from the Voronezh region to winter in Africa fly 10 thousand kilometers annually; swifts, redstarts, swallows, pied flycatchers wintering in tropical Africa, fly 15 thousand kilometers twice a year. But Arctic terns - this example has already become a textbook example, but never ceases to amaze the imagination! - annually fly from one pole of the Earth to the other and back. And not in a straight line. First they fly from Canada and Greenland to Europe, then along the coast of France and Portugal to Africa. Here some turn sharply to the west and cross again Atlantic Ocean. Having reached Brazil, they rush to the Falkland Islands (Malvinas) and Tierra del Fuego.

Others fly to Antarctica directly across Africa. The route of terns is about 20 thousand kilometers. There and back - a trip around the world along the equator!

So what helps birds overcome such distances and even make flights in general? Even though we said that birds fly slowly, resting for a long time, this is still not an easy walk. Fog and cold often cause death huge amount birds - they go astray and find themselves in unfavorable conditions, their energy reserves run out, and the birds die from exhaustion, they are destroyed by storms and storms. And yet, migratory birds set off on their journey twice a year.

So far we have talked about the motivations that force birds to travel. And now a little about what exactly helps them make these journeys.

The answer suggests itself - of course, wings. Yes, wings. You can't fly without them. But sedentary birds that do not travel also have wings. Then the answer may be this: some birds are good flyers, while others are bad. But what does it mean to be a good and a bad flyer? Quails don't seem to be very good flyers. Nevertheless, they go on long journeys and even fly across large expanses of water without stopping. And tits are not migratory birds. Nevertheless, they are capable of flying quite well. For example, it was calculated that the blue tit, a small bird from the family of thick-billed tits, “flew” more than 1,000 kilometers in a few days of building a nest; the blue tit, feeding its chicks, flies at least 100 kilometers every day. So it's not about the ability to fly or the wings. Although bird wings are a unique phenomenon. It is no coincidence that the great Leonardo da Vinci studied the flight of birds for thirty years, and he cherished dream was to create aircraft- bird flyer.

And now, when supersonic planes and intercontinental missiles have been created, when man has already begun to conquer space, he continues to think about the wings of birds, about amazing ability these neighbors of ours on the planet.

Sometimes birds are compared to airplanes, noting that their wings are both load-bearing planes and a motor that pulls them forward. Indeed, one part of the wing is a propeller (the ends of the flight feathers seem to rotate), and the other (located closer to the body) is a supporting plane. Other birds are sometimes compared to helicopters - these birds' wings actually work like a helicopter's rotor. But birds, for all that, are also flyers. It is precisely such devices that people dream of and cannot yet create. After all, a flywheel can lift a load 10 times more than an airplane, and 30 times more than a helicopter. It can fly fast like an airplane and does not need a takeoff run like a helicopter. And this is also very significant: due to the need to build large airfields, aviation plays a smaller role in people’s lives than it could play. And man looks at the birds with hope: sooner or later they will reveal their secret to him, and then man will create an amazing flying machine.

However, it is possible to build a flywheel only by studying the laws of bird flight and translating it into engineering language. Blindly copying a bird's eye view will achieve nothing. There have already been many attempts at simple imitation, and they all ended in failure.

But wings are wings, as we have already said, almost all birds have them, almost all, or at least very many, actively use them, but in long journeys only a fifth of the entire winged population of the Earth departs. Because, in addition to the wings, you also need fuel for the “engine”.

We have already said that birds, especially small ones, spend a lot of energy. It is often said that energy metabolism birds are at the limit of the capabilities of a living organism. This is in its normal state, that is, when the bird feeds, preens itself, jumps on branches, flies from tree to tree, and sleeps. The American ornithologist Candy noted in this regard that if a person had to spend so much energy (or he had the opportunity to spend it), then he could lift a load weighing 400 kilograms to a height of one meter every second during the day. This is the energy expenditure of birds in their normal state, but the cost of flights is two to four times greater. The bird’s energy is fat reserves that are burned during the journey; this is the “gasoline” that the engine needs.

For a long time they thought that poultry did not need fat - it bothered it. It is now known that fat is not only not a hindrance - it is necessary. It is even calculated how much fuel you need to have to fly a certain distance. Of course, the golden plover, flying from the Aleutian Islands to Hawaii and making 252 thousand wing beats in 35 hours of non-stop flight (huge muscle tension!), needs one amount of fuel, other birds, although they make long and long flights, need less: they replenish supplies along the way. But, in general, fuel is one of the main conditions - it is no coincidence that often half the weight of a bird preparing for a trip is fat. (True, it can be much less - 10–20 percent, but always as much as she needs.) “Birds never store fat in excessive amounts,” writes V. R. Dolnik. “Usually, the maximum level of fat reserves of a migratory bird corresponds to the amount of necessary expenses for throwing through an obstacle on the migration route.” However, West German scientists believe that they also have a reserve, “emergency reserve.” For an hour of flight, during which they cover fifty kilometers, these scientists believe, they need 0.25 grams of fat - “fuel”. Birds have much more, and often fly less than fifty kilometers a day, and they constantly replenish their fat reserves along the way. However, this issue is still controversial. On the one hand, excess supplies are an extra burden that interferes with flying; on the other hand, there may be unseen circumstances, when more energy is required than stored or “calculated”. Over time, of course, this issue, like many others, will be resolved. Finally, the following question will be resolved: how, in what way do birds fly.