Birds have sharp eyesight. Publications. Beyond human perception
Vision is extremely important in the life of birds. There may be birds without a voice, but birds without eyes, blind, do not exist. There are no birds with underdeveloped eyes. And there are many species of birds in which the eyes are more developed than in other animals of a corresponding size. In a buzzard, for example, the volume of an eye is approximately equal to the volume of a human eye, and in a golden eagle, the eye is much larger than a human one. But the golden eagle is 30-40 times less than a human by weight. The weight of an owl's eyes is one third of the weight of its head.
The visual acuity of birds is amazing. The peregrine falcon sees small birds, the size of turtledoves, from a distance of more than one kilometer. Birds deprived of their sense of smell can search for their prey by hearing or by sight. The vulture notices its prey in the mountains - a fallen ungulate, sometimes from a height of two or three kilometers.
As you know, in birds, the head freely rotates on the neck up to 180 and even 270 degrees. They use it. In particular, owls love to turn their heads and look around. Owls cannot move their eyes from right to left; their eyeballs are tightly wedged in their sockets. And besides, their eyes, unlike other birds, are directed forward. Therefore, in the forest one sometimes has to observe such a strange picture at first glance: an owl sits on a tree with its back to the observer, and its head is turned upside down so that the beak is directly on the line of the middle of the back, and the bird's gaze is directed straight back. Owl is comfortable. She can, without making the slightest noise and without wasting time on turns, calmly inspect everything that is happening around her. Well, can a flying duck look back, especially if there is danger behind? A turn of the head, the slightest distraction from the flight for her can mean death. And it’s not easy for a running bird to look back.
What then to do?
Before answering this question, let's see how the eyes are located on the bird's head. With the exception of owls, the eyes of birds are located not in front of the head, but on the sides, and birds see more sideways than forward. Therefore, the total field of view of birds is very large. Passerine birds and pigeons can, without moving their eyes or moving their heads, immediately cover up to 300 degrees with their eyesight, only one sixth of the circle remains outside the visible. Enviable outlook! Let me remind you that a person has a total field of view of only 150 degrees.
There are more "happy" birds. In nightjars, the temporal edge of the eye is turned slightly backward and its field of vision is 360 degrees. This means that the nightjar can, without turning his head, completely freely notice what is happening in front of him, to the side and behind him. Advantageous position for this bird! After all, the nightjar catches its prey, small insects, in the air. If he chases only what he noticed in front, he will not be full. The flight of the nightjar is dexterous, nimble. What does it cost him, having noticed the prey flashed from the side or even from behind, immediately turn around and grab it with his wide mouth. For this, it is necessary first of all to notice this prey, that is, to see during the flight both in front and behind.
But one nightjar is so lucky. A woodcock can also see what is happening behind. Feeding, he sticks his beak into the soft ground, searches for food there by touch, forgetting, one might say, about everything around him. It's not good for him to look around. The lateral (and even slightly back) planting of the eyes completely allows him to notice the approaching danger without turning his head, without removing his beak unnecessarily from the feeding area of the soil.
Not all birds need such a wide field of view. Predators don't need it. Birds of prey, as a rule, feed on rather large prey, notice it in advance and, rushing towards it, must keep it vigilantly in their field of vision all the time. The eyes of the predator are directed forward, the general field of view is not so large (in the kestrel, for example, 160 degrees), but their binocular vision is better developed. But, of course, binocular vision is best developed in owls. But owls are inferior to humans in this regard.
The bird of prey does not see what is happening behind it, and it does not need to. She needs only front and partly lateral vision. And if you need to consider what is happening behind, the predator turns its head, like an owl, back, aiming its binocular vision at the object of interest to it.
The duck in this respect is the direct opposite of the hawk. It is useful for her to see what is happening behind, and to see, so to speak, in passing, without turning her head. Here she passes fat silt through her beak on the shore of a reservoir. There is nothing special to see here. Let your eyes follow what is happening behind. You need to see the duck from behind during the flight. What if there is a predator in the back? And the duck can actually spot it without turning its head. That's what a 360-degree field of view means!
In addition to the position of the eyes, the direction of the most acute vision of each eye is of great importance in birds. This direction depends on the anatomical structure of the eyes of different bird species and is never the same in them. The most acute visual perception in birds is usually directed laterally, beyond binocular vision, which allows a flying bird to have fields of clear vision to the right and left, but dependent on each other.
Indicative in this respect is the comparison of swallows and swifts. Both of them feed in the air on homogeneous food - air plankton, and the eyes of these birds are arranged differently. Strizh looks mostly forward. Another thing is the swallow. Her sharp visual perception is directed mainly to the side, and she perfectly notices every midge that flashes past her, whether it flew in front or from the side. The flying machine of the swallow is such that it can immediately make a turn and grab the flashing prey. The swallow's flight speed is not that great, and it makes turns on the spot very easily. The swift cannot make a U-turn on the spot, it flies too fast. Due to the peculiarities of his vision, the swift simply does not notice the midge that is behind, he only catches what is in front. What is the "best way" to hunt? As long as there is a lot of airborne plankton in the air, it's completely all the same. But when there is less food in the air, the swift is the first to get into a difficult position. The fact that he “plows” with his beak in the air in a straight line is no longer enough for him. Possible food to the right and left of it is hidden due to the peculiarities of vision. The swallow, on the other hand, excellently gets out of the situation, turning after every midge flashing from the side. Moreover, she can even, flying along a rock or wall of a house warmed by the sun, frighten away insects with her wing and immediately grab them. Therefore, the swift cannot stay with us for a long time until autumn, but the swallow can. The birds don't look up. For them, the main thing is what happens on earth. This also affects the arrangement of their eyes. In the retina of diurnal birds, its upper segment, the one that perceives the rays coming from the earth, is more saturated with the so-called bipolar cells and ganglia, to put it simply, it sees better, while the lower segment, reflecting the sky, is depleted in these formations. . So the bird has to, if it needs to take a closer look at what is happening in the sky (say, if a predator is flying), throw its head back and look up in this position.
What do the bird's eyes reflect, do they have an "expression"? The hawk has light yellow eyes, they leave an unpleasant impression, it seems that the hawk has an evil character. However, the point here is not at all in character, it’s just that the iris of this predator is yellow, and its eyes do not express absolutely anything. The eyes of old cormorants glow with a deep green tone and also do not express anything. All this is an external design of the eyes, not related to how the bird behaves.
Some types of birds need to see well in different environments. Merganser, for example, and a cormorant see well in the air and not a bit worse in the water. This requires an increased capacity for accommodation. Indeed, a cormorant is able to change the refractive power of the eye by 40-50 diopters, while a person is only 14-15 diopters. But here in owls the ability to accommodate is quite insignificant, some 2-4 diopters. As a result, they apparently cannot see anything in their immediate vicinity.
The question is sometimes asked whether birds have color vision. The answer to this question suggests itself. And why then do birds have bright colors, why colorful and often very original colors? Observations show that many details of the plumage of a bird have a signal value for them and are perfectly perceived by them. Another thing is whether birds see colors exactly as a person sees them. This remains unclear. But, apparently, the bird's eyes do not have any special differences in this regard. Birds can sometimes, for example, be trained for colors.
Cats are typical nocturnal predators. For fruitful hunting, they need to use all their senses as much as possible. The "calling card" of all cats without exception is their unique night vision. The cat's pupil can expand up to 14 mm, letting a huge beam of light into the eye. This allows them to see perfectly in the dark. In addition, the cat's eye, like the moon, reflects light: this explains the glow of the cat's eyes in the dark.
All-seeing dove
Pigeons have an amazing feature in the visual perception of the world around them. Their viewing angle is 340o. These birds see objects located at a much greater distance than a person sees them. That is why, at the end of the 20th century, the US Coast Guard used pigeons in search and rescue operations. Sharp pigeon vision allows these birds to perfectly distinguish objects at a distance of 3 km. Since perfect vision is the prerogative of mainly predators, pigeons are one of the most vigilant peaceful birds on the planet.
Falcon vision is the most vigilant in the world!
The most vigilant animal in the world is the bird of prey, the falcon. These feathered creatures can track small mammals (voles, mice, ground squirrels) from great heights and simultaneously see everything that happens on their sides and in front. According to experts, the most vigilant bird in the world is the peregrine falcon, capable of spotting a small vole from a height of up to 8 km!
The fish don't miss either!
Among fish with excellent eyesight, the inhabitants of the depths are especially distinguished. These are sharks, and moray eels, and sea devils. They are able to see in pitch darkness. This is because the density of rod placement in the retina in such fish reaches 25 million/sq.mm. And this is 100 times more than in humans.
horse vision
Horses see the world around them with peripheral vision because their eyes are located on the sides of their heads. However, this does not prevent horses from having a viewing angle of 350 degrees. If the horse raises its head up, then its vision will approach spherical.
high speed flies
Flies have been proven to have the fastest visual response in the world. In addition, flies see five times faster than humans: their frame rate is 300 images per minute, while humans have only 24 frames per minute. Scientists from Cambridge claim that the photoreceptors on the retina of fly eyes can contract physically.
Eagles have the best vision of all living creatures. They are able to see a hare from a height of 3 km.
Eagles have two pairs of eyelids that protect their unusually sharp eyesight. They use one pair when they are sitting still or on the ground. However, it is enough for them to fly into the air, as the second eyelids, or, more precisely, transparent blinking membranes, immediately fall on their sovereign eyes. Their task is to protect the eyes of the bird not only from the pressure of the air (when the eagle dives at great speed), but also to cover them from the branches of trees or shrubs, or from the prey itself. The sun can also create problems, especially at the heights reached by large birds of prey. Said membrane covers the eyes to keep them clear and unclouded.
Eagles have excellent eyesight.
They are characterized by both a wide field of vision and binocularity, that is, stereoscopic perception with two eyes. A bird, hovering hundreds of meters above the ground, is able to notice the movement of a tiny field mouse. The accommodation of vision in the eagle is very fast and precise both in terms of depth and sharpness. Its eyesight is so sensitive that the bird is able to search an area of 5 square miles (13 km2) with great care. The width of the eagle's field of view is 275 degrees. This allows him not only to observe what is happening from his side, but also to notice when someone is approaching from behind. At the time of the birth of an eagle chick, its eyes are far from being developed so strongly, and the vision of this magnificent hunter reaches perfection only as it matures and matures.
The eagle is able to easily identify potential prey from a distance of one and a half to two kilometers, and by additionally moving its head, it can almost double this distance.
The ability to gain great height brings the eagle a twofold benefit. Firstly, this allows him to notice a thunderstorm, storm and danger from a distance, and secondly, to see prey and a source of food. Birds such as crows or wild turkeys rarely fly high and have a limited field of view. The same is true with us.
Eagles distinguish colors - an unusual phenomenon in the world of wildlife. Moreover, in reality, they perceive color shades much more clearly than humans, due to which they better perceive the beauty of the earth. Eagle eyes also have another feature: inside the eyeball is a kind of comb that acts like a gyroscope, allowing for extremely precise navigation. The eyes of the eagle are placed far apart on the sides of the head, which allows him to feel the depth of space - to determine the height and distance. When a bird dives at a speed of 100 km / h, it must quickly and accurately estimate the distance to the ground - otherwise it will not escape trouble.
Birds are very interesting creatures, they are strikingly different from all other animals, and even from each other. Some birds spend almost their entire lives in the air, the second are generally devoid of wings and feathers and can only run on the ground, and still others prefer exclusively the water element ...
The biggest bird
It `s naturally, . The growth of the largest individuals of the African ostrich reaches 2.80 meters, with a weight of 170 kilograms.
The smallest bird
This record belongs to . The smallest hummingbird weighs only 1.5 grams with a body length of about 5 centimeters.
The fastest flying bird
There is simply no equal among flying birds. At a straight distance, the peregrine falcon is able to accelerate to 200 km/h, and in the so-called diving fall while hunting, the feathered predator can reach speeds of up to 325 km/h. By the way, the peregrine falcon is not only the fastest bird, but also the fastest animal on the planet.
The fastest running bird
It is probably no secret to anyone that they are the best runners among all birds. They are able to run at a speed of 80 km/h. With such a run, the step of an ostrich can reach up to 8 meters in length.
Heaviest flying bird
Here the first place is shared by the large African and dudak. Surprisingly, these birds weigh 18-20 kg.
longest living bird
Large yellow-crested cockatoo lives in captivity for about 80 years. However, it is believed that under natural conditions, the life expectancy of this parrot can be 100 years or more.
The sharpest vision
Second record. This bird has such good eyesight that it can recognize a mouse from a distance of 8 kilometers.
The largest wingspan
At wandering albatross this figure is 3.6 meters. Slightly smaller wingspan andean condor- a predator of the falcon family - 3 meters 20 centimeters.
longest beak
The longest beak relative to body size has sword-billed hummingbird. The length of the beak of this small bird can reach 10 cm, with a total length of 15 cm, i.e. their beak is 2 times longer than the body.
highest flight
Here it is actually very difficult to determine who is the real champion in this parameter. According to truly famous cases, the first place belongs to vulture Ruppel, this bird flew at an altitude of more than 11 kilometers.
The most voracious bird
Cuban tody per day eats several thousand insects, the total weight of which is about 60-65% of the weight of the bird itself.
The fastest bird or the maximum number of strokes per minute
Blue-tailed Amazonia- another record-breaking bird from the hummingbird family, makes 80 wing beats per second.
Best Floating Bird
Penguins are the best swimmers in the bird world. Stronger than other species stands out emperor penguin- he swims at a speed of 36 km / h, and what is generally unbelievable can dive to a depth of almost 500 meters.
The hardiest bird
polar duck able to withstand temperatures of -110 degrees Celsius. This makes it not only the hardiest member of the feathered family, but also the hardiest animal in general.
The loudest bird
indian peacock screams so loudly (and also ugly) that it can be heard for several kilometers.
Most Feathers
At swan more than 25 thousand feathers.
The most poisonous bird
Yes, birds are also poisonous! The most dangerous are representatives of the genus pitowy. The entire body and feathers are saturated with one of the most dangerous toxins in the world - homobatrachotoxin. This poison is deadly even for humans.
Eyes, nose, ears - in the wild, all organs are in the service of the survival of the animal. Eyes play a crucial role in the life of any living creature, but not all animals see the same way. Visual acuity does not depend on the size or number of eyes.
So, even the most vigilant among the many-eyed spiders, the jumping spider sees the victim only at a distance of 8 centimeters, but in color. It should be noted that all insects have poor eyesight.
Animals that live underground, such as moles, are generally blind. Poor eyesight in mammals that live in water, such as beavers and otters.
Animals hunted by predators have panoramic vision. It is extremely difficult to sneak up on a nightjar bird unnoticed. Her bulging large eyes have a wide slit that curves towards the back of the head. As a result, the angle of view reaches three hundred and sixty degrees!
It is interesting, for example, that eagles have two eyelids, and insects do not have eyelids at all and sleep with their eyes open. The eagle's second eyelid is absolutely transparent, it protects the eye of a bird of prey from the wind during a swift attack.
Birds of prey have the sharpest eyesight in the animal kingdom. In addition, these birds can instantly shift the focus of vision from far distances to near objects. .jpg)
Feathered predators eagles see their prey at a distance of 3 kilometers. Like all predators, they have binocular vision, when both eyes look at the same object, it is easier to calculate the distance to the prey.
But the absolute champions of vigilance in the animal kingdom are representatives of the falcon family. The most famous falcon in the world - the peregrine falcon or, as it is also called, the pilgrim - can spot game from a distance of 8 kilometers. 
The peregrine falcon is not only the most vigilant, but also the fastest bird, and in general a living creature, in the world. According to experts, in a swift dive flight, it is capable of reaching speeds of over 322 km / h, or 90 m / s. For comparison: the cheetah, the fastest animal of land mammals, runs at a speed of 110 km / h; the spiny-tailed swift, living in the Far East, is capable of flying at a speed of 170 km / h. But, it should be noted that in horizontal flight the peregrine falcon is still inferior to the swift.
peregrine falcon(lat. Falco peregrinus) - a bird of prey from the falcon family, common on all continents except Antarctica. During the hunt, the peregrine falcon plans in the sky, having found prey, it rises above the victim and dives rapidly down almost at a right angle, inflicting fatal blows to the victim with its paw claws.