Outside the window, autumn, foliage falls from trees, birds gather in flocks to fly to warm countries.
It is known that they fly away every year at the same time when the seasons change. Flight of birds astonished the imagination of man since time immemorial.
And how do birds know about the time of flight? And how do birds find their way during flights?
On October 30, the next meeting of curious children took place in the Tuchkovskaya Children's Library, in the club “Why?”
The librarian spoke about the natural phenomena associated with the flight of birds.
During the conversation, the guys shared their observations of the birds of our region, told that they make bird feeders and feed the remaining wintering with us in the winter.
Come to the club of young women, it is always interesting here.
Responsible for the event librarian Svirschevskaya EA
What makes a bird a bird?
All species of birds have feathers. There are other characteristics common to the class of birds, but feathers are the only trait that is completely unique to these animals. Many may say that flying makes birds special, but did you know that not all birds fly? Emu, kiwi, cassowary, penguins, ostriches and nandus are birds that do not fly. Flightless birds such as penguins swim perfectly underwater.
Birds have many interesting devices that allow them to fly. Light but strong bones and beaks are adaptations for weight loss during flight. Birds have unique eyes, ears, legs, and can also build nests. Some species can make beautiful sounds.
Why do birds migrate?
Many birds seek places in which it is warm, there is an abundance of food, as well as the ability to breed and protect themselves from predators. In the Southern Hemisphere, especially in the tropics, the climate is quite warm, so birds can find enough food throughout the year. Sustained daylight gives them plenty of time to eat every day, so they don’t need to fly anywhere to find food.
The conditions in the countries of the Northern Hemisphere, for example, in Belarus, Russia, Ukraine, and others are different. During the long days of the northern summer, birds have more time to feed their chicks with abundant insect populations. But as the days shrink in the fall and food supplies become scarce, some birds migrate south to the so-called “warm lands.” However, not all birds migrate. There are species that manage to survive in the winter, while remaining in the Northern Hemisphere. For example, pigeons, crows and blackbirds remain in their native habitat all year round.
When do birds migrate?
Each species migrates at certain times of the year. Some birds are highly irregular in their migration patterns. Some species begin their migration south in early July, while others do not migrate until the weather is too cold or food is no longer readily available. Various studies show that shorter daylight hours stimulate the migration of many birds.
Where do the birds fly?
Many species migrate over long distances. The most common picture is that birds migrate in the spring to the temperate or arctic zone of the Northern Hemisphere for breeding, and then fly south in the autumn to warmer regions of the world.
Migrating birds follow certain routes. They generally avoid mountains or large hydrosphere objects that can block their path.
For soaring birds, such as ospreys, eagles, vultures, and hawks, these routes depend on air currents allowing them to plan above ground. They use hot air, known as thermal (thermal flux), to take off. Thanks to planning, they save the energy needed for long flights.
How do birds eat during migration?
Some birds regularly eat during migration, while other species accumulate a special high-energy fat in the body before a long flight. This allows you not to think about food for several weeks.
Most birds that need food during migration fly at night in small flocks. They feed and rest during the day to avoid some predators.
How are birds oriented?
Navigation is difficult because it requires birds to understand three things: their current location, destination, and direction that they must follow in order to get to the goal.
Some birds use the sun and stars to navigate. Others are guided by such natural objects as rivers, mountains or coastlines. Some birds may even use their sense of smell. Although the birds are also able to move on cloudy days and fly across the ocean, where there are no clear landmarks. So how do they do it?
Scientists have concluded that birds sense the Earth’s magnetic field through magnetoreception. In the beaks of birds is the so-called magnetite - an iron-containing mineral that acts like a compass. Other scientists believe that birds can see the magnetic field with their own eyes. Science does not yet know everything about bird orientation, but they probably use several navigation methods.
Why do birds fly in a wedge?
A flock of birds flying in a wedge is not accidental. Large birds, such as geese and ducks, form a wedge to reduce air resistance. A wedge allows flocks of birds to fly farther and more efficiently than birds flying alone.
When flying with a wedge, efficiency increases by 70%. The leading bird and the closing wedge are the hardest, while the birds between them benefit from flapping the wings of other birds.
In addition to improving flight, this method is also useful for communication between birds. Flying wedge allows birds to fly close to each other, as well as hear and see their relatives. They transmit information to each other (using sounds), and can stick together.
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 for rest and feeding.
Even if they find food and water, birds need to land on the ground, where they risk becoming someone else’s prey.
There may be many predators on the migration path. Depending on size, migratory birds become prey for wild cats, foxes, wolves, humans, and other animals. Some birds may be attacked by larger bird species during flight. Sometimes difficult weather conditions make it difficult to fly and even lead to death. It happens that birds collide with airplanes, which is dangerous both for themselves and for airplanes.
How do ornithologists study birds and their migration?
Banding birds is one of the methods used to study them. Scientists put on a foot or wing of a bird a small, individually numbered metal or plastic ring. They also use special networks, known as mystical networks, as a way to capture wild birds for research.
Thus, ornithologists can capture the same bird several times, measure and weigh it, and also collect other important information for a long time. Scientists sometimes use satellite data to track bird migration routes.
Velvet season - time of flights
The bird migration season is in full swing. It started in early August, when the first swifts flew away, in the second half of August the fringes and warblers began to leave the cold edges, and by the end of the month - swallows. Now there is a migration of blackbirds and starlings. Waterfowl will soon fly: ducks, mallards. We can still see the seagulls in central Russia, but they too will soon go to warmer countries.
Migration ends by November. At the beginning of the month, almost all migratory birds leave the central part of Russia. Instead, birds from the North fly to these lands for the winter. In mid-October, residents of the Black Earth region can already observe the first bullfinches and waxwings. And by the beginning of November, almost all birds arrive, which are traditionally depicted on New Year's cards.
“Before a long flight, the birds eat a lot for several weeks, accumulating subcutaneous fat. Thanks to such reserves, they are able to withstand loads and do without food for a long time during the flight. If the flock feels that the forces are running out, then it is time to stop for a few days in the place where there is food. Eat up again, accumulate fat and fly on, ”says ornithologist Pyotr Vengerov.
Birds hibernate in the south of Russia, Ukraine, Southern Europe. For example, blackbirds and starlings are waiting for the winter in France, Spain or Italy, cranes in Egypt, ducks prefer the Balkans, hardy swans fly to the UK, and white storks and swallows go for winter to South Africa.
The only thing scientists can not figure out is how the birds understand what course they need to keep. Peter Dmitrievich suggests that such information is “recorded” in their hereditary program. However, there are versions that birds are able to choose the right route in three ways: by responding to changes in the magnetic field of the planet, guided by the sun and remembering the migration route for several years. Many birds, such as swans and geese, study the path with older individuals, so the route is passed from generation to generation.
Early Return Course
“In the spring, birds began to fly earlier. This is especially pronounced in those species of birds that traditionally returned late from wintering: Oriole, Streptopelia, Dubrovnik oatmeal and many other birds nesting in dense grassy or woody vegetation. But those that always arrived early, return from wintering to their usual time: these are nightingales, cuckoos, swifts and a whole species of insectivores. Compared with the indicators of 50 years ago, in the Voronezh region the average temperature increased by one degree, ”says Alexander Numerov.
The trend towards early arrival of birds is confirmed by researchers from the UK. Due to warming, migration and nesting patterns have changed. For example, over 20 years of observing a swamp sandpiper, it was revealed that these birds shifted the dates of spring arrival and nesting by almost two weeks.
As for the autumn migration, according to Alexander Dmitrievich, everything with it remains at the same level.
“The birds reluctantly and slowly fly to the places of wintering. In spring, on the contrary, the breeding goal arises, so the birds are in a hurry to return to their native lands, ”the professor says.
Temperature plus - population minus
Climate change affects bird populations. The numbers of many long-distance migratory birds are currently declining very rapidly.
According to researchers from the University of East Anglia, 25 million birds die annually. This number includes, among others, the victims of global climate change. However, there are other factors: reduction in the area of the bird’s natural habitat, human harassment, death on power lines, from collisions with vehicles and architectural structures, poaching, and collecting.
Also, do not forget that during the flight itself, about a third of the birds die, but the ornithologist Pyotr Vengerov calls this a completely natural phenomenon.
“If more birds died than survived, they would not migrate, but simply live in Africa,” the ornithologist jokes.
Which birds are in danger?
British and Russian scientists agree on one thing: global warming can lead to the extinction of many populations and species of birds. An increase in temperature conditions affected a decrease in activity in terms of mating and breeding of a number of meadow birds. According to researchers, in the coming years, their populations will be significantly reduced. Warming can damage the abundance of such bird species as the Lark, the white and yellow wagtail, the quail, and the lapwing.
Under the threat of extinction due to ongoing natural and weather changes was a small bustard. To create marital ties, the male bustard performs specific dances, supplementing them with trills. Given the temperature changes, scientists suggest that in the near future, birds will have to choose: either escape from the heat and seek shelter, or seek strength and opportunity to traditionally attract a female. The behavior of small bustards during mating depends on temperature. Warming even one degree negatively affects the mating activity.