Lan ying
Bird migration's reasons are very complicated. It is generally believed that this is an instinct of birds. This instinct is not only the result of genetic and physiological factors, but also the result of long-term adaptation to external living conditions, which is closely related to changes in living conditions such as climate and food. Migratory birds are very sensitive to climate change. As soon as the climate changes, they begin to migrate. In this way, we can avoid the cold in winter in the north and the heat in summer in the south. Climate change also directly affects the food conditions of birds. For example, after autumn, most plants in northern China withered their leaves, and insect activities decreased. After laying eggs, they successively burrowed into the ground to sting or die, and the number dropped sharply. The lack of food makes it impossible for birds that eat insects to sustain their lives. Only by migrating to the food-rich south can they survive the winter well, and insect-eating birds and small insect-eating birds also move south.
Weather, wind direction and wind force have great influence on bird migration. It is more suitable for sunny days with downwind of 3-5 winds. However, some birds migrating in spring sometimes rush to reach the breeding ground because the breeding season is approaching, so they will overcome difficulties and continue to migrate even under very unfavorable climatic conditions.
What's even more amazing is that birds can fly very harmoniously during migration, sometimes turning to the left, and sometimes jumping in the air like horses, which is very spectacular. Since ancient Roman naturalist Pirini recorded the observation of geese and other birds for the first time, people have studied and explored this phenomenon for 20 centuries, but there are still different opinions. At present, there are three explanations: one is the theory of "energy saving", according to the principle of "aerodynamics" or "runway", when birds fly in a "V" shape, they can save about 70% energy by putting their wings on the airflow generated by other birds, which is very important for geese with heavy bodies; The second is "information", which means that when birds fly, there are often one or several experienced leading birds leading the way, and the leading birds can provide reliable information on food sources and water sources for the birds. The third is the "safety" theory, which holds that when a large group of birds gather together, it is easier to find the enemy's injury than when there is only one bird or only a few birds, because when a group of birds fly or perch, as long as one of them finds the enemy's injury, it will quickly transmit this information to all the birds in the form of one bird spreading to ten, and the birds will immediately take emergency measures, or run away quickly, or sing together to scare away the enemy's injury.
Many birds have an instinct, the so-called "homing nature", which reflects their attachment to their birthplace, Zaoxiang, and their ability to find their hometown. It can help birds return to their nests smoothly in the second breeding season. Someone once caught a vulture owl. 13 years later, this free bird returned to the place less than 2 kilometers away from the old address. Birds can find their way from thousands of miles away, which has always been one of the mysteries of magical nature. What do they rely on to decide their own course? Polaris? The sun? The moon? Wind? Climate? Or geomagnetism? Where does their sense of direction come from? This has always been a mystery in nature. Through environmental recording, radar, flight tracking and remote sensing technology, scientists found that birds often rely mainly on vision to determine their flight direction through the positions of the sun, moon and stars in the sky. In addition, topography, rivers, thunderstorms, magnetic fields, polarized light, ultraviolet rays, etc. Are the basis for birds to fly thousands of miles without getting lost. Recent studies also show that there are nerve cells in the cortex of bird beak that can distinguish magnetic fields, and nerve cells called pineal gland play an important role just like vertebrates' sensory organs for light. Many electrophysiological experiments on mammals and homing pigeons show that some pineal cells can respond to small changes in magnetic field strength.
It is generally believed that birds that migrate during the day are located according to the sun, and birds that migrate at night are located according to the starry sky. Another view is that birds have keen eyesight to adapt to aerial observation. In the open environment, the visual radius of human beings is 9.6 kilometers, while the vision of birds flying at an altitude of 2000 meters is 100 kilometers. They can also remember the familiar features of vast areas as directional signs, which plays a key role in their migration from breeding grounds to wintering grounds.
The migration of birds is by no means easy. Usually, after flying over the vast sea and tall mountains, its weight will be reduced by half, and a large number of young birds born in that year can't escape the fate of dying during the migration or after reaching the migration terminal. During the migration, there is no time to feed, sudden storms, vast waters, etc. They devour these creatures all the time. At the same time, there is also a crisis in the migration time. Too early means that the living environment in the north is still covered with snow and ice, too late will be in danger of storms, and there will be countless human disturbances: tall buildings, radio antennas, lighthouses and chimneys, collisions with planes and so on. , are lurking in the long bird migration.
Edited on 20 15-06-27
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Why do birds fly south for the winter?
The living habits of migratory birds are an evolution to adapt to climate change in order to ensure population reproduction because of lack of food and low temperature.
1 1Zan 636 browse
Why do birds fly south in winter?
I don't know this myth,
The current research results show that many birds migrate seasonally. Of the 589 species of birds in Palaearctic realm, 40% breed on land, with a total of about 5 billion birds, which fly south to Zhaodong every year, and the wild goose is one of them.
Birds often migrate in a certain formation along a certain route. The distance of migration is near and far, from several kilometers to tens of thousands of kilometers. The longest journey is the Arctic tern, as far as1.8000 km. This bird breeds in the Arctic, but flies to the Antarctic coast for the winter. In the process of migration, birds generally don't fly too high, only a few hundred meters, and only a few birds can fly over Mount Everest. When moving, the flight speed is 40 ~ 50 km/h and the continuous flight time can reach 40 ~ 70 hours.
Many birds must store enough energy before migration. This is an adaptation to a long flight. The main way to store energy is to deposit fat. Fat not only provides energy for migratory birds, but also the water produced during fat metabolism can be used by the body. By storing fat, many birds greatly increase their weight and even double it. For example, the black-capped white-cheeked warbler in North America and the water reed warbler in Europe generally weigh about 1 1 g, but before migration, they can reach about 22 g, and the deposited fat can be used for their flight 100 hours.
Bird migration's reasons are very complicated. It is generally believed that the migration of birds is an adaptive behavior to the periodic changes of environmental factors. Seasonal climate change is the main reason for migratory birds' migration. Due to climate change, food shortages often occur in the cold winter and tropical dry season in the north, which forces some individuals in the bird population to migrate to other food-rich areas. This behavior was finally fixed by the power of natural selection and became an instinct of birds.
Migration has brought many benefits to birds, mainly in the following aspects: (1) Birds always live in the most suitable climate and have rich and diverse food sources, which is conducive to maintaining their vigorous metabolism; Migration can also create the most suitable conditions for raising offspring, because raising offspring requires a lot of food; (3) The north can hatch the most eggs, with a long season and abundant insects, so the parent birds can have the opportunity to fully collect food; (4) There are few enemies in the north, and the appearance of this annual fragile juvenile black will not promote the formation of enemy population; ⑤ Migration can greatly expand the activity space, which is conducive to reproduction and occupation; ⑥ It is beneficial to automatic balance and can avoid climate disparity; ⑦ Migration provides opportunities for birds to spread to new distribution areas, and also provides opportunities for different individuals to contact and mate, so it is also of great significance in evolution.
Many birds are born and can be learned. Harris's experiment of changing parents can prove this point. He exchanged the eggs of silver gulls and black-backed gulls, so he got 900 young birds raised by his upright relatives. The results of ring records of these young birds show that; The silver gull flew to France and Spain with its adoptive parents, while the black-backed gull moved to its wintering place on the European continent like its biological parents, although its adoptive parents stayed in Britain for the winter.
The migration behavior of birds is also produced in this process. Because the environment is constantly changing, nature has always been in the process of development and change. Even today, migration behavior still forms and disappears among these birds. For example, the wild canary was once a resident bird in the Mediterranean. In the past few decades, the distribution area has expanded to the Baltic region of continental Europe. Now this bird is still a resident in the Mediterranean, but it has become a migratory bird in the new distribution area.
82 browse
Why do birds fly to the south in winter? What is this phenomenon called? urgent
Migratory birds will fly to the south, which is called migration.
Many birds have the characteristics of seasonal migration along latitude. In summer, these birds breed in temperate regions with higher latitudes, and in winter, they spend the winter in tropical regions with lower latitudes. In late summer and early autumn, these birds move from the breeding ground to the wintering ground, and in spring, they return to the breeding ground and fly north. These birds that migrate north and south with the seasons are called migratory birds.
Why do migratory birds migrate?
Because: The advantage of bird breeding in temperate regions is that the days in summer are long and the nights in temperate regions are short, so that they can feed and nurse young birds for a longer period of time and avoid the competition between nests and food that they have to face when breeding in tropical regions with many species. In addition, in summer, the number of insects in temperate regions is more abundant than that in tropical regions, and at the same time, there are fewer natural enemies in temperate regions, and the predation pressure of natural enemies is relatively low. However, due to the cold winter climate, temperate regions often face the problem of food shortage. In tropical areas, on the other hand, the breeding season is faced with fierce competition between nesting sites and food resources, and the predation pressure of natural enemies is also relatively high, but the climate in winter is mild and the food resources in winter are much richer than those in temperate areas. Migratory birds breed in temperate regions in summer and winter in tropical regions in winter, and both places have advantages. In that case, why don't all birds become migratory birds? The answer is that immigrants must pay the price. For example, the migration process needs to consume a lot of energy, and may encounter bad weather, the migration direction is wrongly positioned, and it is necessary to adapt to an unfamiliar new environment and compete for resources with other migratory birds and residents in the region. At the same time, when all birds adopt a behavior pattern with high income (migration), the competition will become greater, and the behavior pattern with low income (non-migration) will become relatively favorable. Therefore, there will be different behavior patterns in evolution, and an evolutionary stability strategy (ESS) will be achieved. This is why some birds migrate and some birds don't. Furthermore, individuals of the same ethnic group who do not migrate in winter may have to endure the crisis of food shortage, but they can occupy better breeding nests as soon as possible before the next breeding season, thus increasing the success rate of breeding; On the contrary, migrating individuals can obtain more abundant food sources in warm wintering areas, but there are risks of migration and the possibility of poor breeding nests. Whether to migrate or not is a question of individual survival and reproductive strategy. If the reproductive success rate of migrating individuals is much higher than that of non-migrating individuals, evolution will tend to migrate. On the other hand, if the reproductive success rate of migrating individuals is much lower than that of non-migrating individuals, the evolutionary direction will not be conducive to migration behavior; If the reproductive success rate of the two strategies is similar, then both behavior patterns will remain in evolution. On the whole, we can summarize the following table according to the breeding and survival characteristics of birds in temperate and tropical regions. The success rate of reproduction is high in temperate regions, but the survival rate of adult and sub-adult birds is low in the face of severe winter climate. There is great competition in tropical areas, and the success rate of reproduction is low, but the survival rate of adult and sub-adult birds is high. Migratory birds have to pay a price in the process of migration, so the survival rate of adult birds and sub-adult birds is moderate. At the same time, because they will return to the north temperate zone to breed later than the local resident birds, good nests will be occupied by resident birds first, and the reproductive success rate is moderate (Gill 1990).
1 Zan 783 browse
Why do birds go to the south for the winter? In order to find the answer, let's "ask"
42 experts answered
Why do birds migrate?
Lan ying
Bird migration's reasons are very complicated. It is generally believed that this is an instinct of birds. This instinct is not only the result of genetic and physiological factors, but also the result of long-term adaptation to external living conditions, which is closely related to changes in living conditions such as climate and food. Migratory birds are very sensitive to climate change. As soon as the climate changes, they begin to migrate. In this way, we can avoid the cold in winter in the north and the heat in summer in the south. Climate change also directly affects the food conditions of birds. For example, after autumn, most plants in northern China withered their leaves, and insect activities decreased. After laying eggs, they successively burrowed into the ground to sting or die, and the number dropped sharply. The lack of food makes it impossible for birds that eat insects to sustain their lives. Only by migrating to the food-rich south can they survive the winter well, and insect-eating birds and small insect-eating birds also move south.
Weather, wind direction and wind force have great influence on bird migration. It is more suitable for sunny days with downwind of 3-5 winds. However, some birds migrating in spring sometimes rush to reach the breeding ground because the breeding season is approaching, so they will overcome difficulties and continue to migrate even under very unfavorable climatic conditions.
What's even more amazing is that birds can fly very harmoniously during migration, sometimes turning to the left, and sometimes jumping in the air like horses, which is very spectacular. Since ancient Roman naturalist Pirini recorded the observation of geese and other birds for the first time, people have studied and explored this phenomenon for 20 centuries, but there are still different opinions. At present, there are three explanations: one is the theory of "energy saving", according to the principle of "aerodynamics" or "runway", when birds fly in a "V" shape, they can save about 70% energy by putting their wings on the airflow generated by other birds, which is very important for geese with heavy bodies; The second is "information", which means that when birds fly, there are often one or several experienced leading birds leading the way, and the leading birds can provide reliable information on food sources and water sources for the birds. The third is the "safety" theory, which holds that when a large group of birds gather together, it is easier to find the enemy's injury than when there is only one bird or only a few birds, because when a group of birds fly or perch, as long as one of them finds the enemy's injury, it will quickly transmit this information to all the birds in the form of one bird spreading to ten, and the birds will immediately take emergency measures, or run away quickly, or sing together to scare away the enemy's injury.
Many birds have an instinct, the so-called "homing nature", which reflects their attachment to their birthplace, Zaoxiang, and their ability to find their hometown. It can help birds return to their nests smoothly in the second breeding season. Someone once caught a vulture owl. 13 years later, this free bird returned to the place less than 2 kilometers away from the old address. Birds can find their way from thousands of miles away, which has always been one of the mysteries of magical nature. What do they rely on to decide their own course? Polaris? The sun? The moon? Wind? Climate? Or geomagnetism? Where does their sense of direction come from? This has always been a mystery in nature. Scientists have found that birds often rely mainly on vision, with the help of ring marks, radar, flight tracking and remote sensing technology, and determine the flight direction through the positions of the sun, moon and stars in the sky. In addition, topography, rivers, thunderstorms, magnetic fields, polarized light, ultraviolet rays, etc. Are the basis for birds to fly thousands of miles without getting lost. Recent studies also show that there are nerve cells in the cortex of bird beak that can distinguish magnetic fields, and nerve cells called pineal gland play an important role just like vertebrates' sensory organs for light. Many electrophysiological experiments on mammals and homing pigeons show that some pineal cells can respond to small changes in magnetic field strength.
It is generally believed that birds that migrate during the day are located according to the sun, and birds that migrate at night are located according to the starry sky. Another view is that birds have keen eyesight to adapt to aerial observation. In the open environment, the visual radius of human beings is 9.6 kilometers, while the vision of birds flying at an altitude of 2000 meters is 100 kilometers. They can also remember the familiar features of vast areas as directional signs, which plays a key role in their migration from breeding grounds to wintering grounds.
The migration of birds is by no means easy. Usually, after flying over the vast sea and tall mountains, its weight will be reduced by half, and a large number of young birds born in that year can't escape the fate of dying during the migration or after reaching the migration terminal. During the migration, there is no time to feed, sudden storms, vast waters, etc. They devour these creatures all the time. At the same time, there is also a crisis in the migration time. Too early means that the living environment in the north is still covered with snow and ice, too late will be in danger of storms, and there will be countless human disturbances: tall buildings, radio antennas, lighthouses and chimneys, collisions with planes and so on. , are lurking in the long bird migration.
2 Zan 124 browsing
Why do birds have to go to the south in winter?
Many birds have the characteristics of seasonal migration along latitude. In summer, these birds breed in temperate regions with higher latitudes, and in winter, they spend the winter in tropical regions with lower latitudes. In late summer and early autumn, these birds move from the breeding ground to the wintering ground, and in spring, they return to the breeding ground and fly north. These birds that migrate north and south with the seasons are called migratory birds. Reasons for migration: The advantages of bird breeding in temperate regions are long days and short nights in summer, so young birds can be fed and nurtured in longer days, avoiding the competition for nesting sites and food when breeding in tropical regions with many species. In addition, in summer, the number of insects in temperate regions is richer than that in tropical regions, and there are fewer natural enemies in temperate regions, so the predation pressure of natural enemies is relatively small. However, due to the cold winter climate, temperate regions often face the problem of food shortage. In tropical areas, on the other hand, the breeding season is faced with fierce competition between nesting sites and food resources, and the predation pressure of natural enemies is also relatively high, but the climate in winter is mild and the food resources in winter are much richer than those in temperate areas. Migratory birds breed in temperate regions in summer and winter in tropical regions in winter, and both places have advantages. In that case, why don't all birds become migratory birds? The answer is that immigrants must pay the price. For example, the migration process needs to consume a lot of energy, and may encounter bad weather, the migration direction is wrongly positioned, and it is necessary to adapt to an unfamiliar new environment and compete for resources with other migratory birds and residents in the region. At the same time, when all birds adopt a behavior pattern with high income (migration), the competition will become greater, and the behavior pattern with low income (non-migration) will become relatively favorable. Therefore, there will be different behavior patterns in evolution, and an evolutionary stability strategy (ESS) will be achieved. This is why some birds migrate and some birds don't. Furthermore, individuals of the same ethnic group who do not migrate in winter may have to endure the crisis of food shortage, but they can occupy better breeding nests as soon as possible before the next breeding season, thus increasing the success rate of breeding; On the contrary, migrating individuals can obtain more abundant food sources in warm wintering areas, but there are risks of migration and the possibility of poor breeding nests. Whether to migrate or not is a question of individual survival and reproductive strategy. If the reproductive success rate of migrating individuals is much higher than that of non-migrating individuals, evolution will tend to migrate. On the other hand, if the reproductive success rate of migrating individuals is much lower than that of non-migrating individuals, the evolutionary direction will not be conducive to migration behavior; If the reproductive success rate of the two strategies is similar, then both behavior patterns will remain in evolution. Generally speaking, people can summarize the following table according to the breeding and survival characteristics of birds in temperate and tropical regions. The success rate of reproduction is high in temperate regions, but the survival rate of adult and sub-adult birds is low in the face of severe winter climate. There is great competition in tropical areas, and the success rate of reproduction is low, but the survival rate of adult and sub-adult birds is high. Migratory birds have to pay a price in the process of migration, so the survival rate of adult birds and sub-adult birds is moderate. At the same time, because they will return to the north temperate zone to breed later than the local resident birds, good nests will be occupied by resident birds first, and the reproductive success rate is moderate (Gill 1990). References:
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