Flight speed

There is hardly any question connected with the flight of birds, so erroneous views are widespread as with the question of the speed of flight. Most people's opinions about the speed at which birds fly are based on random short-term observations, and therefore it is usually greatly exaggerated. Others compare the speed of birds flying with the speed of a car, train or plane. However, they will not find such speeds even in the fastest flyers known to us. So, for example, swifts fly at a speed of 40-50 m / s (regardless of the wind), which corresponds to approximately 150-160 km / h. (Compare: the maximum speed of the express train is 39 m/sec, or 140 km/h.) This, of course, does not mean that birds cannot fly faster at all. Swifts chasing each other reach speeds of up to 200 km / h, and the falcon rushes at the victim at a speed of 70 m / s, i.e. 250 km / h. But these limiting speeds for a very short time are exceptions: they at best characterize the flight ability of some species, but they cannot be used to estimate the speed of flight during migrations when prolonged exertion is necessary.

During long migrations, not only the ability to fly is important, but also the wind. Depending on its direction and strength, the speed of birds can significantly decrease or increase. Particularly high speeds in flight can only be explained by taking into account the support from the wind. Thus, in the example above, the speed of English lapwings flying across the Atlantic Ocean, equal to approximately 70 km / h, increased to 150 km / h due to a tailwind, the speed of which reached 90 km / h. Taking into account the delaying or accelerating influence of the wind, it is possible to accurately measure the own speed of birds over short distances and, accordingly, calculate the true speed of passage. For the first time such calculations were made by Tineman on the Kursk Spit. Subsequently, they were made by Meinertzhagen, Garrison et al.

Table 8. Flight speed of birds during the flight, km/h

View	According to Tineman	According to Meinertzhagen
Sparrowhawk	41,4	*
herring gull	49,7	*
Big sea ​​gull	50	*
Crow	50-52,2	51-59
finches	52,5	32-59
peregrine falcon	59,2	*
Jackdaw	61,5	*
Starling	74,1	63-81
Falcon	*	66-79
waders	*	66-85
geese	*	69-91
ducks	*	72-97
swallows	*	100-120

The figures given in the table give a clear idea of ​​the maximum flight speeds of birds. In general, it is obviously equal to 40-80 km / h, and the speed of small songbirds approaches the lowest figures. Birds migrating at night seem to fly faster than those migrating during the day. The low rate of migration of predatory and other large birds. The same species of birds usually fly much more slowly in the nesting area than on the migration, if at all these speeds can be compared.

No matter how small the speed of bird flight is usually, or rather how small it may seem to us, it is quite sufficient for some species to reach their wintering grounds in a few days and nights. Moreover, with such a speed, under the condition of a tailwind (as, for example, when flying ocean lapwings), many migratory birds within a few days or nights could fly to the tropics. However, the birds cannot save specified speed flight longer than a few hours; they almost never fly several days or nights in a row; as a rule, their flight is interrupted for a short rest or for longer stops; the latter give the flight as a whole the character of a leisurely "walk". This is how long-term migrations occur.

When considering the accurately established by the ringing average speeds of day or night flight certain types it should always be borne in mind that they do not characterize the ability to fly and the speed developed during the migration, but indicate only the duration of the migration and the distance between the places of ringing and finding ringed birds in terms of one day. Numerous finds of ringed birds prove that birds quickly fly most of the way, and use the rest of the time to rest in places rich in food. This type of passage is the most common. Much less often there is a uniform distribution of load and rest.

The birds flying on long distance, the average daily path is approximately 150-200 km, while those flying not so far do not cover 100 km in the same time. These data are consistent with the flight duration of 2-3 or 3-4 months. many species that winter in Tropical and South Africa. Thus, for example, the stork, which usually departs from Germany at the end of August, reaches wintering grounds in South Africa only at the end of November or in December. The same terms apply to the zhulan. Swallows migrate faster - from September to early November. However, how great the individual differences are in this case can be seen from the example of 3 ringed coot redstarts, one of which covered 167 km daily, the other 61 km and the third only 44 km, and these numbers decrease as the time interval for which they are calculated increases (6, 30 and 47 days). Based on these results, it can be concluded that daily speed is most consistent with true travel speed when it is calculated from short-term totals. This conclusion is best proved by the following examples of the speed of passage of individual birds: the stork covered 610 km in 2 days, the black-headed warbler in 10 days - 2200 km, the coot in 7 days - 1300 km, the other coot in 2 days - 525 km, the mallard in 5 days - 1600 km. These data can be contrasted with the daily speed of the song thrush - 40 km (calculated for 56 days of flight), the chaffinch - 17.4 km (calculated for 23 days of flight) and the sparrow hawk - 12.5 km (calculated for 30 days of flight). These data are comparable to the above data on redstarts, whose average speeds are strongly affected by long rest stops with increasing duration of passage.

Another important factor that should not be overlooked when evaluating the daily path and speed of passage is that any numerical data can only be calculated for the ideal flight path, i.e., for a straight line connecting the places of banding and finding the banded bird. In reality, the flight path is always longer, the deviations from the straight line are often very significant, and the work done and the speed are much higher than calculated. These errors are almost impossible to eliminate and therefore must be taken into account, especially on very long flights.

In addition, attention should be paid to when these data were obtained. The fact is that during the spring migration, the indicators are in many cases much higher than during the autumn. In isolated cases, it could be proved with certainty that the spring migration is twice as fast as the autumn migration, for example, in the stork, American godwit and shrike.

Stresemann (1944) accurately established that in spring the passage of the shrike lasts approximately 60 days, and in autumn - about 100 days. On average, these birds fly about 200 km per day. However, they only fly at night for 10 hours. at a speed of 50 km/h. After such a flight, they always rest, so that a distance of 1000 km is covered by them in 5 days: migration - 2 nights, sleep - 3 nights, feeding - 5 days.

A few more words about the maximum speeds and duration of flight, which characterize the possibilities of migratory birds: Turnstone, a small coastal bird, ringed on Heligoland, was found after 25 hours. in northern France, 820 km south. Numerous small songbirds regularly migrate in 12-15 hours. The Gulf of Mexico is 750-1000 km wide. According to Moreau (1938), some small falcons (Falco concolor and F. amurensis), as well as Asian bee-eaters (Merops persicus and M. apiaster), wintering on the coast of South Africa, also fly at least 3000 km over the sea. The Hawaiian Islands serve as a wintering ground for a number of northern waders, which, migrating from the Aleutian Islands and Alaska, where their nesting sites are located, are forced to fly 3300 km over the open. by sea. golden plover, for a particularly strong flyer, it would take approximately 35 hours to cover this distance at a speed of about 90 km / h. Higher speeds have been noted in another species of plovers flying from Nova Scotia to the northern tip. South America 3600 km above the sea. Almost unbelievable is the passage of one of the Japanese breeding snipe, which winters in Eastern Australia and must cover almost 5,000 km to reach wintering grounds. On the way, he probably does not rest at all, since he has never been celebrated in other places.

Flying over bodies of water can be equated with flying over large deserts. Such a run also, of course, takes place without interruption, for example, the passage over Western Sahara of small songbirds, wagtails and pipits, requiring 30-40 hours. continuous operation, if the speed of their passage is considered to be approximately 50 km / h.

conquered the air

Speed, range, flight altitude of birds

Regarding the flight speed of birds, researchers hold different opinions. It is very strongly influenced by atmospheric phenomena, therefore, during long-distance movements, birds either fly faster, then slower, or take long breaks to rest.

Having released a bird in some place, it is very difficult to say when it will arrive at the “destination”, because it may not fly all the time of its absence. The speed calculated by simply dividing the distance by the flight time of the bird is often an underestimate. In especially "responsible" moments - chasing prey or fleeing danger - birds can develop very high speeds, but, of course, they cannot withstand them for a long time. Large falcons during the rate - the pursuit of birds in the air - reach speeds of 280-360 km / h. The usual, "everyday" speeds of medium-sized birds are much less - 50-90 km / h.

All of the above was about flapping flight. Glide speed is also difficult to measure. It is believed that the hobby glides at a speed of 150 km/h, the bearded vulture - 140, and the vulture - even 250 km/h.

The range of non-stop flights of birds has been discussed for a long time. Just like speed, it is very difficult to measure. A falcon released near Paris was found a day later on the island of Malta 1400 km away. Whether he was delayed on the way or flew all the time is unknown. In general, birds stop on the way quite often, and their segments of non-stop flights are small. This cannot be said about flights over water barriers, where the birds have nowhere to sit. The record for the distance of a non-stop flight belongs to waders - brown-winged plovers, annually flying over the ocean from Alaska to Hawaii and back 3000 km. Birds fly without landing through the Gulf of Mexico (1300 km), the Mediterranean Sea (600-750 km), the North Sea (600 km), the Black Sea (300 km). This means that the average range of a non-stop flight of birds is about 1000 km.

As a rule, the height of the flight of birds does not reach 1000 m. But some large predators, geese, ducks, can also rise to much greater heights. In September 1973, an African vulture collided with a civilian aircraft at an altitude of 12,150 m above the Ivory Coast. Griff knocked out one of the engines, but the plane landed safely. This, apparently, is an absolute record for the height of a bird's flight. Before that, the bearded vulture was noted in the Himalayas at an altitude of 7900 m, migrating geese in the same place at an altitude of 9500 m, a mallard collided with an aircraft over Nevada at an altitude of 6900 m.

The fastest birds on the planet

Birds are the fastest living creatures on Earth, significantly ahead of the "water" and "land" representatives of the fauna in speed. The answer to the question of which of the birds is the fastest is possible only on the condition that the birds will be evaluated based on the characteristics of their flight, because. some develop maximum speed in a dive flight, while most birds fly in a normal horizontal way. Let's first get acquainted with the fastest representatives of just such a horizontal flight as the most natural.

Common kestrel (Falco tinnunculus) - 63 km/h

common kestrel- a small bird with an average flight speed of about 63 km / h. The kestrel flies by alternating slow or fast flight with gliding. Sometimes birds can soar and even hover in the air, then the tail hangs, as it were, and the wings make quick small flaps (“vibrate”). The common kestrel can also move by inertia with folded wings, or fly with incomplete opening.

Swallow - 65 km/h

swallows outwardly similar to swifts, but not so fast. The speed of swallows is usually about 40 km / h, but they can reach up to 65 km / h. The streamlined shape of the body, pointed narrow wings, forked tail - all this helps the birds to catch insects on the fly, provides the swallows with endurance and good maneuverability.

Fieldfare Thrush (Turdus pilaris) – 70 km/h

Thrush fieldfare(Turdus pilaris) is one of the large and interesting thrushes. These flocking birds are very widespread throughout Eurasia. Fieldfare thrushes have an unusual voice and interesting plumage. They have a gray head and the upper part of the tail, the rest of it is black, a white chest with streaks, the wings and part of the back between them are brown (“caftan”). The speed of these birds is about 70 km / h, while they are somewhat larger than starlings in size (25 cm) and wingspan (39-42 cm).

Common starling (Sturnus vulgaris) - 70 km/h

Heralds of Spring starlings(Sturnus vulgaris) can boast not only a pleasant voice and an enviable "family", but also the speed of their flight. They are capable of flying at speeds up to 70 km/h. Starlings live on almost all continents of the planet. It is interesting that starlings do not build nests as such, they simply lay out a suitable place with fluff and grass. Males help females in raising offspring: they feed the chicks, teach them to fly. When "family" duties are completed, starlings gather in flocks and circle around in search of food.

carrier pigeon - 100 km/h

Everyone knows carrier pigeons also excellent fliers. Pigeons have an incredible memory, they can travel great distances, completing the task of the owner or returning home. The speed of their flight is not even very small - 90-100 km / h. They are able to spend up to 16 hours in the sky. Interestingly, more monuments have been erected to carrier pigeons than to other birds. Moreover, there is a monument to the carrier pigeon in almost every European city. Most of them are associated with the merits of carrier pigeons during the Second World War.

Common eider (Somateria), male and female - 100 km/h

Birds of the genus eiders(Somateria) from the family of ducks, although they spend most of their lives on the water, they bypassed many other birds in terms of flight speed. The speed that an eider can develop is about 100 km / h. Birds make their flights in fairly large groups in the construction of a "wedge" or "line". There is no need for eiders to rise high into the sky, because their food is in the water (mollusks, crustaceans, worms, etc.), so they fly low. These birds are excellent divers, they can dive to a depth of 20 meters. Eiders rarely come out on land.

Grey-headed albatross (Thalasarche chrysostoma) - 130 km/h

Grey-headed albatross(Thalassarche chrysostoma), the bird with the largest wingspan (3.5 m), certainly does not make such rapid dives as the peregrine falcon, and does not circle in its sleep, but it is able to maintain an average flight speed of 130 km / h for more than eight hours in a row. This fact was established thanks to tracking sensors attached to the paw of one of the birds of this species. These data are even recorded in the Guinness Book of Records.

Black swift (Apus apus) - 150 km/h

And finally, the champion in horizontal flight speed - black swift. This is a small bird with a wingspan of 40-46 cm. The structure of their body allows black swifts to reach speeds of up to 150 km / h. Interestingly, these birds practically live in the sky, spending 24 hours a day there for over 3 years. Birds even sleep in flight: rising to a height of 2-3 thousand meters, they circle in a circle, waking up every 5 seconds in order to flap their wings.

And now it's time to get acquainted with the absolute speed record holder. This peregrine falcon. And, although it is inferior to the black swift in horizontal flight speed, at the peak it develops simply crazy speed.

The peregrine falcon (Falco peregrinus) manages to reach speeds of more than 360 km/h at its peak

A representative of the falcon family, the peregrine falcon, hunts a flying bird, rising above it and, folding its wings, then rushes from above. He strikes with paws folded and pressed to the body. According to exact calculations, falling on the prey at an angle of 25 °, the falcon flies at a speed of 75 meters per second; when falling at an angle close to a straight line, the speed increases to 100 meters per second or 360 km / h. There is evidence that the peregrine falcon is able to reach speeds of up to 440 km / h, which is comparable to the speed of some aircraft. Peregrine falcons start chasing prey already from a distance of one to one and a half kilometers.

Not only creatures living on land are trying to demonstrate their speed qualities, but also those who are able to rise high into the sky. After all, there, just like on earth, there is a constant struggle for life. And here, as they say, you have to try very hard to get out of this struggle as a winner.

The speed of animals living on land depends entirely on the structure of the skeleton and on the strength of the limbs. The speed of birds that soar high in the sky depends a little on other important factors. Here the speed of envy is not only from the structure of the skeleton and from the strength of the wings, but also from the special ability to use all this. Our conversation will go about the fastest birds.

1 place. peregrine falcon

Peregrine falcon (lat. Falco peregrinus) - this predatory bird the size of an ordinary gray crow, but this does not prevent it from being the fastest among all birds. The falcon hunts in the air: before attacking the prey, the falcon rises high up, gaining the required height, and only then falls down like a “stone”. In such a fall, the predator develops speed as much as 100 m / s, which equals 350 km / h.

2nd place. Black swift

Black swift (lat. Apus apus) is the main rival of the peregrine falcon in high-speed flight, as well as one of its victims. However, the falcon loses heavily to the swift in level flight, which allows the second to elude its enemy. Although the black swift is a small bird (its wingspan is 40-46 cm), it can easily reach speeds of up to 150 or even 180 km / h.

These birds live all their lives in the air, where they spend all 24 hours, and black swifts live a little over three years. These birds even manage to sleep in flight: having risen to a height of 2 to 3 thousand meters, they circle there in a spiral, waking up every 5 seconds to make another flap of their wings.

3rd place. Grey-headed albatross

Grey-headed albatross (lat. Thalassarche chrysostoma) is a sea bird with the largest wingspan of 3.5 m! Naturally, the albatross cannot make such dizzying dives as the peregrine falcon, but it can fly at speeds up to 130 km / h, which it can maintain for 8 hours.

In addition, he can sleep at an altitude of about 2-3 kilometers, circling almost in one place. Due to its unique speed qualities, the gray-headed albatross is listed in the Guinness Book of Records.

4th place. Gaga

Gaga (lat. somateria) is a species of large seabirds. Eider in horizontal flight can reach speeds of up to 100 km / h. Although it is not as fast as the albatross, however, it has excellent qualities swimmer: with the help of its wings, the eider can dive to a depth of 20 meters, where it catches fish, crustaceans, various invertebrates and mollusks. Eiders almost never come out on land.

5th place. Pigeon

Pigeons are wonderful flyers with incredible memory. Thanks to this quality, carrier pigeons have been used at all times to send correspondence. Especially during World War II. The flight speed of a carrier pigeon is 85-100 km / h. They can be in flight for about 16 hours - without rest! In many countries, monuments have been erected to the carrier pigeon.

6th place. Starling

Starlings (lat. Sturnus vulgaris) is a small bird that not only sings beautifully, but also flies beautifully, developing a flight speed of up to 70 km / h. The starling can travel hundreds of kilometers during its annual seasonal migration. It should be noted that starlings are able to fly into the hole of their “home” at high speed and at the same time it is not injured at all.

7th place. Thrush fieldfare

Thrush fieldfare (lat. Turdus pilaris) - differs from the rest of its counterparts in the way of life. He likes to settle in small copses and park areas - this bird cannot be found in dense forests. The very name of this bird speaks of its extraordinary love for mountain ash. Despite the fact that it is slightly larger than the starling, however, its speed is less - about 70 km / h.

8th place. swallows

Swallows are very often confused with swifts, however, swallows have wider wings and a more pronounced "fork" of the tail. In addition, swallows lose to swifts in speed. The speed of even a coastal, even a village swallow is about 65 km / h. But swallows are much more maneuverable than swifts, they can easily and not only at high speed, but also practically on the spot, turn around 360 degrees.

9th place. common kestrel

Common kestrel (lat. Falco tinnunculus) is a bird of prey, a distant relative of the peregrine falcon. It hunts small rodents, attacking them from above. Develops speed up to 60-65 km/h. Easily alternates slow and rapid flight, preferring a soft glide in the air.

10th place. Chizh

Chizh (lat. carduelis spinus) is a small songbird that almost never descends to the ground, preferring to sit on the branches of trees. In the air, the siskin is capable of reaching speeds of up to 60 km / h.

Lesson on the topic
"The reason and significance of warm-blooded birds"

When studying the topic “Bird Class”, the guys for the first time get acquainted with such an important concept as warm-bloodedness. It is very important that students understand that the maintenance of a constant body temperature is ensured by the interaction of a number of physiological systems of the body. A good knowledge of this material is necessary to explain complex evolutionary and ecological problems.

Teacher.

- Guys, why are there fewer birds in the forest in winter than in summer?
(Suggested answers: little or no food(for insectivorous birds), a lot of snow, cold.)
- Can a feather cover protect birds from frost in winter? ( Maybe, but only partially.)
The main questions that we must answer during today's lesson are: what warms the bird's body? How do they maintain a constant temperature? Where does the energy for flight come from?
How is heat generated in general? ( Suggested answers: in the combustion of organic matter, which occurs in the presence of oxygen.)
- What drives the car? What makes organisms move? ( Due to the energy generated during combustion(oxidation)organic matter with the participation of oxygen.)
How much energy do birds need? After all, they can fly long distances, develop high speed. (Working with tables.)

Table 1. Distances traveled during flights

Table 2. Surface area of ​​the wings and the load on them

For comparison, the glider model has a wing load of 2.5 kg / m 2.

Table 3. Wing beat frequency

Table 4. Maximum flight speed

How less bird, the more food per gram of body weight it needs. As the size of the animal decreases, its mass decreases faster than the surface area of ​​the body through which heat is lost. Therefore, small animals lose more heat than large ones. Small birds eat an amount of food per day equal to 20–30% of their own weight, large birds - 2–5%. A titmouse can eat as many insects in a day as it weighs itself, and a tiny hummingbird can drink an amount of nectar that is 4-6 times its own weight.

Repeating the stages of splitting food and the features of the respiratory system of birds, we fill in the scheme No. 1 in stages.

The progress of work when filling out the scheme

Intense motor activity of birds requires a lot of energy. In this regard, their digestive system has a number of features aimed at the efficient processing of food. The beak serves as an organ for capturing and holding food. The esophagus is long, in most birds it has a pocket-like extension - goiter, where food softens under the influence of goiter fluid. The glandular stomach has glands in its wall that secrete gastric juice.
The muscular stomach is equipped with strong muscles and is lined from the inside with a strong cuticle. In it, mechanical grinding of food takes place. Digestive glands (liver, pancreas) actively secrete digestive enzymes into the intestinal cavity. The split nutrients are absorbed into the blood and carried to all cells of the bird's body.
How long does it take for birds to digest food? Small owls (house owls) digest a mouse in 4 hours, a gray shrike - in 3 hours. Juicy berries in passerines pass through the intestines in 8–10 minutes. Insectivorous birds fill their stomach 5-6 times a day, granivorous birds - three times.
However, in itself, the absorption of food and the entry of nutrients into the blood is not the release of energy. Nutrients need to be "burned" in tissue cells. What system is involved in this? ( Lightweight, air sacs.)
Muscles must be well supplied with oxygen. However, birds cannot ensure the delivery of the required amount of oxygen due to the large amount of blood. Why? ( An increase in the amount of blood would increase the mass of the bird and make it difficult to fly.)
An intensive supply of oxygen to tissue cells in birds occurs due to “double breathing”: oxygen-rich air passes through the lungs both during inhalation and exhalation, and in the same direction. This is provided by a system of air sacs penetrating the bird's body.
In order for the blood to move faster, you need high blood pressure. Indeed, birds are hypertensive. In order to create high blood pressure, the heart of birds must contract with great force and high frequency (Table 5).

Table 5. Heart weight and heart rate

As a result of the oxidation (combustion) of nutrients, energy is generated. What is she spending on? (We are finishing filling out scheme No. 1).

Conclusion. An active oxidative process helps maintain a constant body temperature.
High body temperature provides a high metabolic rate, rapid contraction of the heart muscle and skeletal muscles, which is necessary for flight. High body temperature allows birds to shorten the period of development of the embryo in the hatching egg. After all, incubation is an important and dangerous period in the life of birds.
But constant body temperature has its drawbacks. Which? Fill out chart #2.

So, maintaining a constantly high body temperature is beneficial for the body. But for this it is necessary to consume a lot of food, which must be obtained somewhere. Birds had to develop various adaptations and behaviors to get enough food. Here are some examples.
Next, students make presentations on the topic “How different birds forage for their own food” (their preparation could have been homework for this lesson).

Fishing Pelicans

Pelicans sometimes fish together. They will find a shallow bay, cordon it off in a semicircle and begin to flap the water with their wings and beaks, gradually narrowing the arc and approaching the shore. And only after driving the fish to the shore, they start fishing.

Owl hunt

Owls are known to hunt at night. The eyes of these birds are huge, with a greatly expanding pupil. Through such a pupil and with poor lighting, enough light enters. However, it is impossible to see prey - various small rodents, mice and voles - from afar in the dark. Therefore, the owl flies low above the ground and looks not to the sides, but straight down. But if you fly low, the rustling of the wings will scare away the prey! Therefore, the owl has soft and loose plumage, which makes its flight completely silent. However, the main means of orientation in nocturnal owls is not sight, but hearing. With its help, the owl learns about the presence of rodents by squeaking and rustling and accurately determines the location of the prey.

Armed with stone

In Africa, in the Serengeti reserve, biologists have observed how vultures got their food. This time the food was ostrich eggs. To get to the delicacy, the bird took a stone with its beak and threw it with force at the egg. The strong shell, which could withstand the blows of the beak of even such large birds as vultures, cracked from the stone, and one could feast on the egg.
True, the vulture was immediately pushed back from the feast by vultures, and he was taken for a new egg. This most interesting behavior was then repeatedly noted in the experiment. Eggs were tossed to the vultures and expected to happen. Noticing the delicacy, the bird immediately picked up a suitable stone, sometimes weighing up to 300 g. The vulture dragged it in its beak for tens of meters and threw it at the egg until it cracked.
Once a vulture was given fake chicken eggs. He took one of them and started throwing it on the ground. Then he took the egg to a large rock and threw it against it! When this did not bring the desired result, the vulture began to desperately beat one egg against another.
Numerous observations have shown that the birds tried to split any egg-shaped object with stones, even if it was huge or painted in unusual colors - green or red. But they did not pay attention to the white cube at all. Scientists have found, in addition, that young vultures do not know how to break eggs and learn this from older birds.

osprey fisherman

The osprey is an excellent angler. Seeing the fish, it quickly rushes into the water and plunges its long sharp claws into the body of the victim. And no matter how the fish tries to escape from the claws of the predator, it almost never succeeds. Some observers note that the bird holds the caught fish with its head in the direction of flight. Perhaps this is an accident, but it is more likely that the osprey is trying to catch fish in such a way that later it would be easier to carry it. Indeed, in this case, air resistance is less.

Conclusion from student reports - the progressive development of the brain and the leading sense organs (vision, hearing) is associated with intensive metabolism, high mobility and complex relationships with environmental conditions.
Now explain why birds became widespread in all climatic zones. What is bird flight? ( Warm-bloodedness allows birds not to be afraid of frost, to remain active even at very low temperatures. environment. However, the lack of food in winter forces them to migrate to more nutritious places.)