How do homing pigeons get home?

Carrier pigeons fly thousands of miles to the nest, which is not only a subjective wish, but also a physiological function. In order to improve homing performance of homing pigeons, as an important subject of bionics, biologists and pigeon breeders have done a lot of research on the function of homing pigeons in a foreign land thousands of miles away. Through their own experiments, they put forward various navigation theories, such as "solar navigation theory", "geomagnetic navigation theory", "celestial radar navigation theory" and various sensory navigation theories, as well as the comprehensive effect of various factors. There is a consistent understanding that pigeons have a "compass" or "compass-like substance" in their bodies. Then there must be something like a map. So what is the navigation "map" of pigeons? Opinions vary. Recently, Kenneth Eibl of new york State University found that migratory birds use natural light to determine their own migration direction, and the pigeon community is very interested in this. Can you find the homing pigeon navigation "map"? Further research is needed.

Sun compass navigation theory

One of homing pigeon navigation theories. This is what Kama, a bird scientist at the Institute of Marine Biology in Pley, Germany, said. He found that pigeons have a "sun compass" so that they can see the compass based on the sun. He believes that the earth keeps circling all day, and pigeons can correctly correct the time and measure the changes of displacement and orientation by relying on their internal biological clocks, so as to determine their position and flight orientation.

Geomagnetic compass navigation theory

One of homing pigeon navigation theories. As early as a century ago, it was suggested that pigeons could navigate directly by the earth's magnetic field. But there is no strong evidence. Later, robert green and Charles Wilcock of new york State University did an experiment. They put coils around the pigeon's head, and they can control the magnetic field around the pigeon's head by tiny harmless current. If you change the direction of the battery placed on it, the current passing through the coil will change and the direction of the magnetic field will change accordingly. In the sky without sunshine, pigeons with loops facing south will fly to their homes, and pigeons with loops facing north will fly away from their homes. Once there is sunshine, they won't be fooled. Therefore, pigeons use the sun as a compass when they have the sun, otherwise they use the earth's magnetic field as a compass. But where on earth are pigeons sensitive to magnetism? It is still a mystery.

Ionosphere in magnetic navigation theory

One of homing pigeon navigation theories. It is considered that homing pigeon navigation has the same principle as modern radio communication. The transmitting station transmits the signal to the ionosphere 50 kilometers away, and the receiving station receives the signal from the ionosphere, thus increasing the communication distance from 200 kilometers to more than 2,000 kilometers. The same is true of homing pigeon navigation principle. The geomagnetic field in the nest is weakened by radio signals and even cannot be received. When the sunspot activity is strong, the radio will also lose contact. By comparing a series of phenomena like this with homing homing homing pigeons, the old geomagnetic navigation theory is supplemented and perfected. The founder of this theory is German pigeon racer Hansen. After many experiments, he questioned the existing navigation theory by negative induction, and then supplemented and improved the overturned magnetic navigation theory.

Genetic navigation theory

One of homing pigeon navigation theories. It is considered that the navigation performance of homing pigeons is a physiological instinct, just like migratory birds. It is determined by genetics, which was founded by a pigeon breeder in the former Soviet Union in the 1930s and 1940s. He works in Swan Farm. He found that swans, once migratory birds, changed their habit of migrating to the north after several generations of breeding. In autumn, he took the swans to a distance of 0/00 km from the training ground/kloc-and set them free when the wild swans flew by. Instead of flying south with the flock, they returned to the breeding ground in the north. Based on this, he concluded that migratory birds go north in spring and return south in autumn, which is purely physiological instinct and the crystallization of genetic variation for thousands of years. And homing pigeons have to go through several generations of artificial culture to complete.

IQ navigation theory

One of homing pigeon navigation theories. People think that the navigation ability of homing pigeons is related to their IQ. Practice has proved that homing pigeons released from other places are comprehensively analyzed and compared according to all kinds of information in daily life, surrounding environmental conditions, all kinds of significantly changed information and environmental conditions in other places. The internal biological clock and biological guide of public-private partnership compare the movement of the sun (the change of the position and height of the sun) and the direction and intensity of the geomagnetic field (including horizontal and vertical intensity) at home with those in other places, so as to judge the homing direction wisely and fly home gradually. Most of the excellent racing pigeons who have won many championships have developed the back of their heads. And some "silly blanks" always fly behind pigeons, and even can't find their hometown and lose their foreign land. Obviously, the IQ of homing pigeons is different, but the research in this area needs further development.

Memory navigation theory

One of homing pigeon navigation theories. This is the research result of homing pigeon lovers in China in recent years on the basis of summing up practical experience. Carrier pigeons have a good memory, which is recognized by carrier pigeon lovers as practical experience. Therefore, every race, the flight distance is always from near to far, and the training is required to be carried out in the same direction as the finish line. The racing pigeons saw the terrain along the way and left a memory in their minds. With this memory, they decided to return to their hometown. For example, if they take Shanghai as the end and Xining as the starting point 1900 km race, they will go to The Journey to the West for a southern tour, passing through Jiading, Changshu, Danyang, Xuzhou and Luoyang. After flying five stops, the homing pigeon left a memory in its mind, determined that its home was in the south, and finally arrived at the terminal. If pigeons are released after five training stops in the north and taken to Guangzhou in the south, although the distance is shortened to 12900 km, the result is likely to be wiped out. This is enough to prove that homing pigeons can fly home thousands of miles by training their memory and directional ability.

Celestial radar navigation theory

One of homing pigeon navigation theories. According to the aircraft tracking, most pigeons have just left the flying place and there is a "flying point deviation". The initial "deviation" flight direction is to gradually deviate from the correct homing direction along an arc, and then turn back to the correct course until it deviates about 25. Then hover in the sky and fly around, forming an oscillating flight mode. No matter how tortuous, you can always return to your hometown in the end.

Auditory navigation theory

One of homing pigeon navigation theories. Claudine, a researcher engaged in bird navigation instinct at Cornell University in the United States, believes that pigeons can detect low-frequency sounds below human hearing range, and can distinguish sounds as low as 0.5 cycles (that is, the bass below the central C 12 scale). These sounds are numerous on the earth. They come from jet air, waves, thunderstorms and many other natural features in the mountains. Many terrain targets, such as mountains, can produce consistent and identical low-frequency intervals in key signature. So pigeons can use it as a navigation object, just like airplane pilots use radio signals. In a word, pigeons' perception of low-frequency sound sources and their relative position when they release sound can locate themselves according to different and unique low-frequency sounds and decide the route to return home.

Skin navigation theory

One of homing pigeon navigation theories. Donald of the American Institute of Animal Medicine? Dr. Mike found that pigeon skin cells contain acetylcholine, a chemical that can transmit external information to the brain. He believes that the receptor of acetylcholine in carrier pigeon skin cells is particularly developed and sensitive, which is 60% more than that of all non-carrier pigeons, so the feelings and reactions are also colorful. Even if it is thousands of miles away from the pigeon house, it can show different dry humidity, temperature and wind direction from the environment. Depending on the change of feeling, it can track the direction of the pigeon house and go straight. Only when we get to the home with a radius of 50 kilometers can we know the pigeon house by using the hierarchical memory instinct of the eye pulse. Therefore, Dr. Mike asserted that a champion pigeon in a long-distance race will never be infected with skin diseases, nor will it cause diseases that affect the health of feathers. He reminded pigeon owners not to spray pesticides or detergents or stimulate sesame oil within 2-3 days before the game, because these things will destroy acetylcholine in the skin and the fiber cells will not let go of the outside world.

"Information" reaches the pigeon's brain, and many chemicals tend to fail because of their dullness. Dr. Mike also said that sand bath, water bath and sunshine bath of pigeons can not only promote the health of skin and feathers, but also enhance the maintenance of feather skin cells, accept the optimal selection of acetylcholine, and adjust the response of homing targets guided by long-distance flights. According to the research report, homing pigeons in flight will eventually get lost because of lack of acetylcholine, even though they have strong wings.

Visual navigation theory

One of homing pigeon navigation theories. Many people in the international and domestic pigeon circles believe that homing pigeons can fly back to their hometown from thousands of miles away, mainly by virtue of a pair of keen eyes to identify the direction. People who hold this theory can even judge whether this homing pigeon should fly in sunny days, cloudy days, all-weather racing pigeons, and long-distance racing pigeons or ultra-long-distance racing pigeons from the color of iris in its eyes. Experimental observation shows that the optic nerve of pigeon eye is composed of millions of optic nerve fibers, and there are more than 654.38+00000 neurons in the retina of pigeon eye. If microelectrodes are inserted into each nerve fiber and pigeon eyes are stimulated with various optical patterns, it can be found that the retina of pigeon eyes can detect the movement, intensity and color of the basic elements of the image. There is a comb on the back of the optic nerve in the posterior chamber of the eye, which can adjust the pressure of the eyeball with the help of volume change, so it takes great efforts to accurately detect moving objects. The muscle of pigeon eye is striated muscle, which is beneficial to quickly gather objects on retina during rapid flight, and change the shape of lens and the distance between lens and cornea through the contraction of ciliary muscle. At present, the convexity of cornea can also be changed, which is called "double tone". This ingenious quick adjustment function can instantly turn the "hyperopia" of head-up into "myopia" and accurately judge where you are and where you should fly.

Olfactory navigation theory

One of homing pigeon navigation theories. Bobby, a researcher at the University of Pisa in Italy, and Hans in France? Wolafur has the deepest research. People think that pigeons' sense of smell is the main reason for their homing. Carrier pigeons are sensitive to the changes of "air pressure data" caused by altitude differences and seasonal changes. Carrier pigeons have been raised in one place for a long time, and their circulatory system and respiratory system are accustomed to and familiar with the local geographical and climatic conditions, which naturally forms a map of the surrounding environment. Once I pick up the plane in a strange geographical location, I feel that the "air pressure data" is different and I am not used to it. After it is released, it carries out "double breathing" through airbags, blood vessels, lungs, etc. And the positioning is very sensitive, flying in the adaptive direction and returning to your home.

Leg and foot navigation theory

One of homing pigeon navigation theories. It is considered that there is a grape-shaped "corpuscle" near the interosseous membrane between the pigeon's leg, gaskin and fibula, which can feel mechanical vibration. The size of each "corpuscle" is about 0. 1×0.4 mm, and there are about 100 "corpuscles" on each pigeon's leg, which are dominated by a branch of sciatic nerve. These vibration "corpuscles" are very sensitive to tiny vibrations with a frequency of tens of weeks per second 1-2 thousand cycles. During the flight, homing pigeons are located according to the signal parameters proposed by these "small celestial bodies".

Flight retrograde positioning navigation theory

One of homing pigeon navigation theories. After a long flight training, the external factors of the environment play an important role through the pigeon body, and form the habit of flying back to "home" from the flying place. Carrier pigeons fly through many places, and the terrain differences on the way lead to different geomagnetic data signals, barometric data signals, colors and illumination signals, leaving different "traces" on the nerves, circulation and respiratory systems of pigeons. After being released from the destination, it will judge the direction according to these "marks" left on the way and fly back to the shed.