The behavior of predators refutes the rules of natural selection. Ways to protect yourself from predators Protecting juveniles from predators
In the animal world of oddities and crazy facts - an endless amount. Today we will look at the defense mechanisms of animals and, as one would expect, we will find some rather strange (and sometimes simply disgusting) facts. From animals that will vomit all over your face to creatures that will literally knock you out with their scent, here are 25 animals with the strangest defense mechanisms imaginable.
25. Cuttlefish
Cuttlefish have amazing camouflage skills. These creatures have the ability to quickly change the color of their skin, allowing them to almost completely merge with any environment. They can even change their body shape to match the structure of their environment.
24. Texas Horned Lizard
The Texas horned lizard has one of the bloodiest self-defense mechanisms in the animal kingdom…literally. When it is in danger, the lizard constricts the sinuses until the blood vessels in its eyes burst, shooting blood from its eyes at the attacker!
23. Motyxia sequoia
During the day, this species of centipede resembles any other species of centipede, but at night, when they feel threatened, they become bioluminescent in an attempt to scare away predators. However, if this fails, centipedes secrete toxic cyanide and foul-tasting chemicals from small pores located on the sides of their bodies.
22. Skunks
An animal that releases a foul-smelling substance from its anus at predators deserves to be on this list. The skunk possesses two glands that create a mixture of chemical substances containing sulfur, characterized by an incredibly disgusting smell. The smell is so strong that it repels bears and can even cause temporary blindness.
21. Common Roller
The chicks of these colorful birds spew foul-smelling, liquid, orange vomit as a defense mechanism in case of danger.
20. Stick insects
As the name implies, stick insects look like sticks, but sometimes they can even look like leaves with mossy growths. But disguise is not the only defense of these animals. Some stick insects may also spray attackers with a defensive secretion that not only smells bad but also irritates the mouth and eyes.
19. Sea cucumbers
When threatened, the sea cucumber releases a sticky, poisonous toxin called holothurin. If that doesn't help, the sea cucumber will gut itself. This means that they will tense their muscles strongly until some of their organs come out through their anus. This misleads predators into thinking the sea cucumber is already dead.
18. Octopoteuthis deletron
Like most squids, the Octopoteuthis deletron is capable of secreting ink as a defense. But what makes this species unique is their ability to shed one of their tentacles in a process called autonomous tentacle. This not only minimizes tissue loss in the event of an attack, but also distracts the predator enough for the squid to flee.
17 Malaysian Exploding Ant
Malaysian exploding ants have large glands full of poison. When they sense danger, the ants tense their abdominal muscles, which explode the glands, from which a corrosive poison flies out.
16. Possum
Possums in danger fall into a comatose state that can last several hours - long enough for any predator to think the opossum is already dead. If that's not enough, opossums also excrete a foul-smelling green liquid.
15. Flying fish
Flying fish have an outstanding ability to fly or glide through the air for long distances to escape predators. To achieve this, the fish accelerates up to 60 kilometers per hour, thanks to which it can overcome the surface of the water. She then uses her large pectoral fins as wings, allowing the fish to fly. After it jumps out of the water, the fish can fly up to 200 meters.
14. Mixin
This ancient organism, which has existed for about 300 million years, secretes a disgusting, viscous substance when threatened. The substance mixes with water, expands and, if it enters the gills of fish, causes suffocation.
13. Colorado potato beetle
Colorado potato beetles have a hideous way of defense against predators. The larvae cover themselves in their own feces, which are poisonous and smell bad...bad enough to deter predators.
12 Boxer Crab
Don't let the charm of this defense mechanism fool you. Sea anemones attached to the claws of boxer crabs can be very dangerous... they can even kill some sea creatures.
11. Vulture Turkey
When turkey vultures feel threatened, they regurgitate the contents of their stomach (which is extremely disgusting... and let's not even talk about the smell). This allows the vulture to escape faster, as it becomes much lighter, in addition to the fact that the vomit with a disgusting smell will scare away the predator.
10 Japetella heathi octopus
Japetella heathi octopuses have evolved a defense mechanism that allows them to avoid two types of deadly predators - those who look for silhouettes from above, and those who use their own light to search for prey. In order not to create a silhouette, the octopus has become almost completely transparent. However, this makes it a good target for bioluminescent creatures. In order to avoid them, the octopus changes its color to red, greatly reducing the reflection. This effectively makes the octopus invisible to anglers and other fish with "lanterns".
9. Spiny newt
Spiny newts, found in the Iberian Peninsula and Morocco, have an alarming self-defense mechanism. When in danger, the newt advances its ribs through the skin and uses them as a weapon. The protruding bones are covered with a poisonous substance that can kill a predator.
8 Hairy Frog
Imagine if in any danger your only defense was to break your bones and use them as a weapon? Meet the hairy frog, a species from central Africa that, despite its name and furry appearance, is not hairy at all. When breeding, male frogs are covered on the sides with thin strips of skin resembling hair. These bands also, in theory, allow the frogs to get more oxygen while they watch their eggs. But the most interesting thing about this frog is its ability to break its bones and push them through the skin to form sharp claws that are good at scaring off attacking predators.
While it's not entirely clear what happens to the bones after the danger has passed, the researchers believe that the bones are pulled back under the skin when the frog's muscles relax.
7. Bombardier beetle
If you disturb this beetle, you will get a very unpleasant surprise. Bombardier sprays predators with a hot, poisonous mixture of body fluids directly from the anus. To do this, the beetle stores hydroquinones, hydrogen peroxide and a mixture of catalysts that set off an explosive reaction that fires almost at boiling point.
6. Silly
As with the rollers, fulmar chicks vomit on their predators. A jet of bright orange vomit has the smell of rotten fish, which will linger on the victim for a long time, no matter how hard they try to get rid of the aroma.
5. Large pygmy sperm whale
As one of the smallest toothed whale species in the sperm whale family, the great pygmy sperm whale has an absurd (but effective) defense mechanism. When threatened, the whale releases an anal "syrup" into the water. The sperm whale then churns the water to create a giant poop cloud in which it can hide.
4. Wine hawk
When this caterpillar senses the presence of a predator, it changes its appearance to resemble a snake by inflating itself and using its spots to form false eyes. Few predators want to mess with a snake.
3. African crested porcupine
Armed with long quills that can pierce the internal organs of predators, crested porcupines are an animal to avoid. In case of danger, the porcupine starts to run back or sideways to stick its needles into the predator. If they are chasing him, he suddenly stops, because of which the predator crashes into the needles with a run.
2. Sony
Adorable dormice have a very strange ability to elude a predator ... literally. The skin of the dormice's tail is very loosely attached and if a predator grabs the rodent by the tail, the skin peels off, allowing the dormice to escape. However, dormice do this only once in a lifetime, because after the skin is torn off, the remaining bone either bites off or falls off on its own.
1. Slow Loris
Slow lorises, as their name implies, are very slow moving creatures, making them vulnerable to predators. To cope with their lack of good speed, lorises have developed venom glands near their armpits. Lori covers her body and teeth with poison by rubbing her hands against these glands. As a result, the bite can cause anaphylactic shock in the predator.
What kind of defense mechanisms do not use animals to protect their skin from enemies. Some of them are downright incredible, while others are downright disgusting.
Suicide Ants
If they were a little larger, who knows what the fate of mankind would have been like. Insect soldiers are desperate and fearless, they do not run from enemies, but let them get closer to them, strain their abdomen and explode, spreading their signature neurotoxin around.
Sea cucumber
Holothurians lead a sedentary lifestyle and seem to be miserable, helpless creatures that cannot run away from danger. But they don’t have to, left alone with the enemy, the sea cucumber turns its insides inside out and releases a stream of poisonous digestive juice on the offender. Some species of these creatures can even throw out pieces of the intestine, which then quickly recovers.
Mixins
Unattractive sea creatures have an interesting way of self-defense, for which they have received the nickname "spitting witch". Having learned about the approach of a predator, the hagfish secretes a huge amount of sticky mucus, and the fish that accidentally swallow the polluted water will not be lucky. Her insides instantly stick together.
scorer beetles
Do not say hello to animals who wish to feast on this seemingly innocent beetle. At the first danger, he will douse them with poisonous boiling water. Of course, this does not mean that the centigrade liquid is contained in its abdomen, but there are special glands and two reservoirs of liquid, like a microemulsion. When the insect is frightened, the contents are squirted out of them, and enzymes are added to it at the exit, they catalyze oxidation and cause an increase in the temperature of the jet.
Roller chicks
Of all the birds and chicks, only they boast the most unusual way of protecting themselves from predators. In case of danger, the chicks regurgitate a foul-smelling liquid on themselves, which not only scares off potential enemies, but also warns the parents who have returned home that the danger is nearby.
Seeking shelter
Most species undertake searches for some kind of shelter to hide from sharp fluctuations in temperature, precipitation and predators. Sometimes an animal simply climbs into a cave, crevasse or tree, which does not lead to any significant change in the environment. However, in many other cases, it builds very complex nests or burrows, which entails significant changes in external conditions. Buildings are relatively permanent, like beaver dams, or temporary, like chimpanzee sleeping nests, in which they usually spend only one night. In many species, nesting is closely related to reproduction: when the time for the appearance of offspring is near, they start building a nest or significantly expand an existing nest.
Among invertebrates, the construction of shelters is most pronounced in insects. In species such as solitary wasps, each individual female digs a mink and stores food in it. However, in many other species, nests are very complex structures, and entire communities live in them. Examples are tall termite structures and bee nests.
The structure of the community is different for different species of bees, but they certainly have one queen and many working individuals. In the honey bee, a distinctive feature of the activity of working individuals in the construction and maintenance of the nest is functional specialization. Different individuals are engaged in the construction of combs, feeding the larvae, cleaning the cells, preparing honey, guarding the entrance and collecting pollen and nectar. At the same time, the functions of each individual worker bee change during its life: it starts with cleaning the cells and ends with the collection of pollen and nectar.
Choosing a place for a new nest in a honey bee is a very interesting process. At the end of spring, the queen and about half of the workers leave their old place for the daughters of the queen and form a swarm at a short distance from it. The bees remain in this swarm until a new location is chosen. The scout bees fly out of the swarm to explore the numerous places that are potentially suitable for building a nest. Returning to the swarm, they perform a "dance" containing instructions about where these places are. The intensity of the dance varies depending on the quality of the place. Particular importance is apparently attached to its size and protective capabilities. The dancing bees are recruiting new scouts. Based on the intensity of the dances and the reaction of the new scouts, the swarm “makes a decision”: in the end, the predominant part of the scouts indicates one specific place with the help of a dance, and then the swarm is removed and sent there.
In rodents, shelter-seeking or shelter-building behavior takes a wide variety of forms. Beavers build single-chamber burrows, or huts, in which a pair of adults and their last two broods live. Woodrats collect many twigs or twigs from which they build vast huts. The construction of nests by laboratory rats and house mice has been studied in detail. Both species make nests in the shape of goblets or bowls, using cotton wool, paper, rags, and other similar materials; sometimes nests are provided with a roof.
Chimpanzees, orangutans, and gorillas build sleeping nests in trees.
Avoidance of predators
Since most species serve as prey for at least a few other species, avoidance of predators is essential for survival and reproduction. The main methods of protection against predators are hiding from them, warning individuals of their own species, the presence of warning signs, flight and active resistance.
shelter
Many animals hide from predators in shelters - burrows, crevices and huts. In addition, the appearance of the animal itself can contribute to hiding from a predator. Protective coloration, due to which the animal merges with the background, is found in representatives of almost all taxonomic groups. Many particularly striking examples can be found in insects, among which there are forms similar to leaves, twigs, or even bird droppings. Often protective coloration is combined with a special behavior: the animal is located in relation to the environment in a certain way, usually remaining motionless.
Rice. 4.1. Frequency spectra of calls made by various birds
Warning other animals
Whatever the species-specific reaction to predators may be, the prey must first of all be able to detect their presence. Various features of movement, in particular periodic surveys of the area and a certain orientation (for example, in relation to the wind), facilitate the detection of predators. Often animals graze in mixed herds, for example, baboons along with antelopes. Baboons have very sharp eyesight, and antelopes have a particularly developed sense of smell. Both react to alarm signals given by individuals of the other species, and therefore it is difficult to take them by surprise.
Many species react to the cries of alarm given by birds. As a rule, such cries are relatively pure tones, without sharp breaks; such sounds are difficult for a predator to localize (Fig. 4.1).
Warning signs or actions
Some animals have an unpleasant taste for a predator. If, for example, a blue jay eats a large, brightly colored Danaus plexippus butterfly, it will soon induce vomiting. Such a bright color "warns" the predator that the victim is unfit for food. In the process of evolution, numerous edible species have acquired similarities with inedible ones, which gave them a clear advantage; predators began to avoid them. This phenomenon is known as Batesian mimicry.
A variety of active actions are also used to warn predators. Examples are the sounds made by the rattlesnake and the aggressive postures adopted by many mammals. Birds have a well-known "shouting" reaction to immobile predators, such as hawks or owls: birds fly quite close to them, emitting loud cries and performing various kinds of demonstration actions. The sounds emitted at the same time are characterized by a wide frequency range and a pronounced beginning and end, and therefore they are easy to localize (Fig. 4). The advantage that the animal gains by drawing attention to itself is obvious in such cases.
Escape
Speed and agility are the best and probably the most common means of escape from predators. Many species, fleeing, supplement their locomotor movements with display behavior in order to divert the attention of a potential predator or frighten him. Others, on the contrary, hide in order to reduce the likelihood of an attack.
Active resistance
As a last resort, the prey may actively resist the predator. In doing so, it may strike, grab, or bite the predator. Skunks and many species of arthropods, such as centipedes, release chemicals that deter predators. Other animals protect themselves from predators by their dense or poisonous integuments, hard shells, or outgrowths such as spines and spines.
Almost all animals, with the exception of some large predators, are forced to constantly beware of enemies. Even the slightest carelessness can lead to their death. In this regard, some animals have developed special protective "weapons", such as needles, claws and pincers, which they can use in case of danger.
Others unite in groups, packs or herds, which allows them, in case of danger, to act like one big living organism, before which the enemy retreats. Some animals use "chemical" weapons for protection - they emit, for example, strong-smelling substances, warning their relatives about the danger.
Group security
Starlings, gathering in huge flocks and maneuvering in flight, make a frightening impression. Many predators take the flock for a huge animal and do not dare to attack it.
scorpion sting
There are more than 1500 species of scorpions similar in structure. Each of them has eight legs and two large claws on the front of their elongated torso. With these claws, the scorpion grabs the victim and tears it apart. A dangerous sting at the end of a scorpion's tail protects it from attack by enemies.
prickly ball
Almost everyone in Europe is familiar with such a forest dweller as a hedgehog. It can also be found in gardens and parks. This friendly creature has an excellent defense weapon. In case of danger, it curls up into a ball, hiding a delicate abdomen and exposing thorns. And if the enemy does not retreat, he will receive a rather painful lesson.
escape flight
Impalas (antelopes of the bovid family) graze in herds. With their sensitive ears, they constantly listen to see if a predator is approaching them. In case of danger, they can only quickly run away, but before doing this, the first of them make a huge jump, clearly visible to the rest of the animals. In addition, they have a special gland at the back, which, at the moment of danger, releases a strong-smelling substance, which, like jumping, is a warning to the entire herd.
Owl
This young long-eared owl has already learned to ruffle its feathers in case of danger so that it looks much larger and more terrible than it really is. Only in this way can she scare off many of her enemies.
schools of fish
The smallest fish prefer to huddle in dense schools or schools that move like one big living organism, and such an accumulation confuses attackers who can no longer notice and grab an individual fish.
found in North America, Western Europe and the USSR.
A predator is an animal that kills other animals and feeds on them, and its actions are called predation. Domestic cats are also predators, they catch mice; the life of predators is a world-famous game of cat and mouse, it is constantly and everywhere repeated in ecosystems, millions of animals participate in it, each in its own way.
Lions, cougars, wolves, eagles, hawks, herons, crocodiles, sharks, pikes are indisputable predators. Toads and frogs are also predators, although not as obvious. Predators and all insectivorous birds. And tiny shrews. And a wasp carrying a caterpillar to its larva. And water beetle larvae sucking out a tadpole. And the tadpole himself. Even a whale that feeds on marine zooplankton is a predator. Man, a universal predator, is no exception, possessing both cunning, dexterity, and the greatest destructive power.
Production range.
There is an upper limit to the size of prey - a predator cannot cope with very large animals; and the lower limit - there is no point in hunting for small fry, wasting time and effort on it. Between these limits lies the prey range of the predator. A predator can only be seduced by game of the wrong size during periods of hunger, when there are very few animals in its range. Thus, European buzzards and golden eagles feed on the chicks of small songbirds when there are very few hares, rabbits, partridges and voles (their usual prey).
It happens that a predator for some time preys on only one species from its range of prey: when this species has multiplied strongly and has become easily accessible. For example, white storks that follow swarms of locusts in Africa; skuas hunting lemmings in Alaska; short-eared owls that settle in places where voles invade, or herons and otters that feed exclusively on frogs during their mass exit from ponds at the end of summer.
Harrier chicks in a defensive posture. Defending themselves from the enemy, they fall on their backs and fight off with clawed paws.
Does the predator get tired of the abundant food that he feeds on day in and day out? Watching the European tit, you come to the conclusion that it is boring. This bird, similar to the North American chickadee, was studied by Luke Tinbergen in the pine forests of Holland while rearing chicks. Various caterpillars served as food for these tits. When the caterpillars had just appeared, the tits did not eat them very willingly for the first days. Then suddenly they attacked them with greed. Tinbergen decided that the tits gradually developed a specific visual image of the new prey. Simply put, their eyes were getting used to the sight of the new food. There were more and more caterpillars, and then the appetite of tits began to weaken, as if this food began to bore them. Since then, any kind of caterpillars has been only half the diet of tits. This observation shows that tits prefer mixed food, even if it takes more time and effort to find it.
In the case described above, the tits had so much food that they could be picky. But in general, it is difficult for tits, wagtails and our other birds to feed their chicks. Parents have to fly up to the nest almost every minute, and they cannot acquire large families if there is no plentiful food near the nest. The predator did not always go and kill the game as soon as he got hungry. Sometimes he's lucky, and sometimes he's not.
Hard and easy ways.
Not all predators are equally agile and agile. One male Short-eared Owl will miss fourteen times before having lunch, another only four. Some crows in a nesting flock perform parental duties much better than their relatives: they are the best getters, that is, the best hunters and the best breadwinners.
preys mainly on lowland animals: antelopes and zebras. A lion with several relatives forms a family called a pride. Lionesses, unlike lions, do not have a mane, they are smaller and more graceful.
Misses and failures of a predator can be explained by his youth and inexperience. But the sensitivity of the prey must also be taken into account, because the sensitivity of prey animals is as important as the swiftness of predators. the victim has a wealth of life experience. A fox may be left with a handful of feathers in its mouth instead of a bird, or with the wriggling tail of an escaped lizard. Lions often do not kill large ungulates, but only injure them. Many adult salmon caught by fishermen show evidence of tooth or claw marks. This means that the salmon once managed to slip out of the mouth of a predator - a seal.
Why did the predator kill this particular animal this time, and not some other animal? The shortest answer is: it just happened. A prey of suitable size was at the right moment in an accessible place and fell into the clutches of a predator. It is necessary not only the presence of the victim - it must be within reach. It depends on many things: the ability of the animal to disguise itself, its age, state of health, the speed of its legs and its position in the group. Other factors that apply individually to the predator also play a role; first, the weather: rain, frost, deep snow, wind strength and direction; then sounds: the sound of a forest, a nearby river or waterfall; as well as the ability of a predator to withstand competition.
likes to build nests under the canopy of hedges and in dense bushes.
What the prey tastes like is not the main factor, it only plays a role if the predator has a very real choice. The fox, apparently, prefers the pheasant to the rat, but she will not scour half the night in search of a delicacy when rats are swarming underfoot. Sometimes a predator kills an animal that he does not like at all: in the heat of the hunt, he takes the pursued game for someone he would eat with pleasure. A cat, for example, kills shrews but does not eat them. Apparently, she mistakes them for mice and discovers the mistake when it's too late. Shrews, having once made a mistake, do not repeat the mistake again and do not kill “tasteless” game, remembering its smell. No one knows how often mammals make such mistakes and how quickly they learn to recognize inedible animals. Shrews are generally inedible due to their unpleasant odor to all mammals, although some do eat them if nothing else is available. But what is poison for one, says the proverb, is honey for another. Hawks and owls will not miss the opportunity to catch a shrew and eat it with pleasure.
A predator that feeds on a particular species encounters individuals of that species in a wide variety of situations. The pursued animal can run into the thicket, where it is not visible, or, conversely, into the woodlands, where it is more difficult to hide and where it is more accessible to the predator. It is easier for an experienced adult animal to run away from a pursuer than for a young and inexperienced animal, because an adult animal knows the tactics of the pursuer, the terrain and possible escape routes better.
Very young and very old, mutilated by predators, sick or hungry are more easily prey than healthy animals in their full bloom. An important factor is the position of the animal in the group: there are parties among the animals, they graze on the worst pastures, where there is little food and there is no good shelter from enemies. The age and experience of the predator, that is, the speed of his legs and cunning, also matter.
These factors play a role wherever there is a predator-prey relationship, but in different situations one or another factor or even a group of factors can become of great importance.
Choice of prey.
What all situations have in common is that the predator attacks the one who is easier to grab at the moment. If there are two types of prey animals and both are equally accessible, the predator preys on both species, and the number of victims will be proportional to the number of animals of each species. If one species is easier to hunt, the predator will prefer that species until the situation changes. A good example of this is the Scottish marten. She feeds on voles and wood mice; voles suffer from it more than wood mice, although there are fewer voles in its territory. In the traps placed there, wood mice came across more often, which means that it is easier for the marten to catch voles. This may be due to the fact that wood mice are more cautious, they run and jump well, while voles are slow and not so nimble.
The European mole is another example of this selectivity. Moles feed mainly on earthworms. When there are a lot of worms, the mole catches them in abundance, cripples them and stores them for future use. Such warehouses of moles have been repeatedly studied; they tend to be dominated by one type of worm, although its grounds are home to a large number of other types of earthworms. Why this happens is still unknown. It can be assumed that the mole stores the type of worm that is easier to catch.
on the hunt. A wolf pack usually includes a male, a female, wolf cubs, sometimes two or three more wolves join them.
Predators also choose within this species, and do not at all rush in pursuit of the first animal that comes across. North American wolves, on the heels of chasing caribou herds, kill calves, old deer, sick and wounded animals. The Zambian wild dog hunts hartebeest antelopes, but is very picky. Most of all, she kills calves that are not a year old; there are slightly fewer one-year-olds, even fewer old animals, and very few healthy adults. Lions, on the other hand, kill age groups in proportion to their number in the herd - also a kind of selectivity. Hyenas hunting antelope in the Serengeti kill only calves - another kind of selectivity.
The European Sparrowhawk and the Peregrine Falcon have been observed to frequently kill those birds that stand out in some way from the flock. Five of the twenty-three birds killed by the hawk turned out to be some kind of aberration. One day a sparrowhawk snatched a lame tit from a flock of twenty-six healthy tits. In Germany, it was recorded: of the seventeen domestic pigeons caught by the peregrine falcon, fifteen were either somehow different from other pigeons or were strangers in the flock. In Poland, they saw how a hawk snatched a white dove from a flock of gray and blue-gray from a flock of whites.
Rivalry.
A man, an outside observer and a predator himself (addition from the site: if this person is the owner of the psyche of the animal type, which is a violation, because all the same, the Human is predestined from above to have a different type of psyche, different from the animal) , is inclined to consider wild predators, hunting game that he himself needs, as his rivals. General hostility to predators (addition from the site: among the "humanoid predators") this is explained; the above examples, which can be multiplied, show that such an attitude towards predators is hardly fair. As a rule, the number of game does not depend on the number of predators, but vice versa. A loaf of bread can only feed a certain number of mouths.
In Scotland, the number of partridges has declined sharply in recent years. This phenomenon has been investigated and interesting findings have been made regarding predation; the most important: predators in the disappearance of the grouse are innocent, the reason for this is the behavior of partridges.
valuable feathered game. It is found in moorlands and mountain slopes. The partridge needs thick, well-leafed heather for both food and shelter. The most aggressive male takes the best territory. A person artificially maintains the habitat necessary for partridges, periodically burning out the old heather.
A bird that lives in a certain area; she feeds on heather, lives and breeds on the moors. The male owns a certain territory, which he defends from other males. The most aggressive males have the best territories, the less aggressive ones have the worst territories, and so on; in the end, all the land is divided among the married couples. Birds that could not capture any territory become "outcasts", content with the worst marginal lands: bare slopes, floodplain meadows, areas with poor cover, on which there is little food and it is difficult to hide from enemies. These outcasts are six times more likely to be preyed upon, with many dying from starvation or disease. Some move to other places in search of territories; the number of eaters is decreasing, and now the moorland can feed everyone. An ecologist would say that this struggle for territories is a kind of buffer between the bird population and the amount of food.
In August, partridge hunting begins, and the whole system of division of territories is violated. Young broods are equally threatened by wild predators and humans. Human predation causes great damage to the population of partridges, although a person does not always exterminate the entire annual offspring without exception, that is, he does not kill as much as he could. And in the fall, when the birds divide the territory again, outcasts again remain, for whom there was no good land.
Once again, wild predators kill many more outcasts. And again, many die, and many go to other places. Some still remain, taking advantage of the territory, for one reason or another, found itself without a master. Scottish partridges regulate their own population, and a prudent attitude to heather lands does not require the extermination of predators, but care for the protection of the vegetation cover.
"Fixed capital" and interest from it.
The predator feeds on its victims without reducing their population: it regulates their numbers. The predator lives, so to speak, not at the expense of fixed capital, but at the expense of interest from this capital. The mole, which feeds almost exclusively on earthworms, does not have any noticeable effect on the number of worms living in its territory. And the ermine, which hunted rabbits while they were found in Europe, did not pose a threat to the population of these rodents. In the barn owl, which lives in Palestine, in the Levant, half of the diet is voles: the number of all voles eaten, however, is relatively small; barn owls not only do not affect the "fixed capital", which is a population of 25,000 voles, but almost do not even spend interest on capital. In the same way, all the cats of the world can do nothing with the mouse people that are prosperous to this day.
Owl hunts all night, from dawn to dusk; her food is small rodents: voles, mice, rat pups. It happens that an owl will catch and eat a small bird. Owls do not build nests, they live in hollows and abandoned nests of other birds: crows, magpies or kestrels.
And yet it happens that a small predator causes serious damage to the population of its prey. A tiny weasel, for example, has access to the burrows of mice and voles, and once in such a burrow, it can cause real havoc among its inhabitants. The Americans McCabe and Blanchard report that the weasels, having found themselves in an area where there were many deer mice, walked along their minks and destroyed the mice almost without exception.
Insectivorous birds can sometimes delay insect breeding, but in the case of the European tits described by Tenbergen, raptors ate the most caterpillars when there were not so many of them. Birds, as a rule, cannot cope with hordes of insects. The fact that birds at some stage can inhibit the reproduction of insects is very important for humans. In Germany, this was understood long ago; there, everywhere in the forests, small houses are hung, like birdhouses, in which tits arrange their nests. Feathered tenants help people protect the forest - biological protection instead of chemical.
And what about the big predators? Do they control big game populations? In some cases, no doubt, as evidenced by the facts, though still few. A vivid illustration of this is the story of the black-tailed deer living on the Kaibab plateau. At the beginning of the 20th century, a herd of 4,000 black-tailed deer lived on the Kaibab Plateau in Arizona. They shared this habitat with predators: wolves, cougars, coyotes, lynx and a few bears. Herds of domestic animals - sheep and cattle grazed here. The deer population in these conditions did not grow and did not decrease, remaining from year to year within 4000 heads. This area, however, could feed a much larger herd of deer; no one had any doubts: predators were to blame for the small number of deer. And in 1906 the territory was declared a state reserve. To increase deer pasture, livestock grazing was banned; hunters were invited to fight the predators. Over the decade, 600 cougars were shot. In sixteen years, 3,000 coyotes have been exterminated. By 1926, the wolves were completely destroyed. The number of deer began to grow, at first slowly, then faster , by 1920 the herd of deer had grown to 60,000 heads, and by 1924 to 100,000 heads. This monstrous figure proved fatal. The plateau could not feed so many black-tailed deer. They multiplied menacingly and trampled pastures clean. In the next two winters, 60,000 deer died. By 1929, the number of deer had dropped to 30,000, by 1931 to 20,000. And in 1939, only 10,000 black-tailed deer grazed on the Kaibab Plateau.
This is an instructive story. Predators obviously held back deer population growth thus protecting natural pastures. The destruction of predators led to the fact that the deer multiplied catastrophically and destroyed the pastures on which they fed.
The same balance exists in nature between lions and the topi antelope, which lives in the Ruin di Rutshuru valley in the former Belgian Congo. From 1918 to 1929, lion hunting in the area was particularly intense; the number of large predators has sharply decreased, and the number of marsh antelopes, as one would expect, has increased greatly.
Close relatives.
Competition between predators of different species living in the same area is more apparent than real, even if several species prey on the same animals periodically or constantly. Changes in habitat, in the number or ratio of animals that feed predators, can tip the balance in favor of one predator or another. Some predators thus benefit, others suffer.
(lat. Mustela erminea) - a small predatory animal of the weasel family, a typical marten appearance with a long body on short legs, a long neck and a triangular head with small rounded ears. The body length of the male is 17-38 cm (females are about half as long), the tail length is about 35% of the body length - 6-12 cm; body weight - from 70 to 260 g. It looks like a weasel, but somewhat larger in size.
These relationships have been well studied in the case of weasels and stoats living in the Northern Hemisphere. In England, weasels and stoats often live side by side in the same territory; and as long as each species hunts for its prey, there is no rivalry between them. Weasels are much smaller than stoats, the male weasel weighs only 150 grams, and the male stoat 350 grams. If there are a lot of rabbits, the ermine preys mainly on them, while weasels feed on voles. In such a situation, both predators thrive. If the rabbits are struck by myxomatosis, which mows down these rodents without exception, the number of stoats decreases markedly, but this does not affect the weasels at all. The disappearance of food upsets the balance of the ecosystem to the detriment of the stoat, without affecting the weasels in any way.
Young forest plantations in temperate countries are ideal habitat for voles, which are very fond of dense, tall grasses. In such a biocenosis, both weasels and ermines feed on voles. The relationships of these animals have been well studied in Scotland. Weasel, due to its diminutiveness, can hunt for voles underground, in their minks. An ermine will not crawl into a mouse hole and is content with random prey, that is, those voles that it catches on the surface. For affection, we also reach the main capital: by destroying voles underground, weasel reduces the amount of accidental prey of ermine; but as long as the number of voles does not fall below a certain critical figure, hunger is not terrible for both predators. However, the number of voles is subject to sharp fluctuations, and if there are less than forty-five of them per acre, stoats leave their homes. Weasels continue to exist carelessly in this territory until the number of voles drops to eighteen per acre. With the departure of ermines, the number of voles begins to grow. In the end, there are so many of them that the stoats return again.
, or common weasel (lat. Mustela nivalis) - a predatory mammal of the mustelid family, a species of the genus Weasel and ferrets (Mustela). It is found on all continents of the Northern Hemisphere.
And here is another example of the coexistence of weasels and stoats, this time brought to the Dutch island of Terschelling. On this island, in the early 1930s, water voles began to cause great damage to the forest. They decided to apply the biological protection of the forest and in 1931 102 weasels and 9 stoats were brought to the island. Three years later, there were no weasels left on the island. Five years later, stoats completely destroyed the water voles and drastically reduced the number of rabbits that lived on the island. Now it was necessary to take urgent measures against stoats, which quickly multiplied and began to feed on all kinds of birds: wild, domestic and even waterfowl. Natural equilibrium was reached only by 1939. Stoats have survived on the island, but have ceased to be a problem. In this case, the ermines were in an advantageous position, and the weasels, unable to withstand the rivalry, died.
The USA has its own weasels and its own stoats; the American weasel is no different from the European one, while the American ermine, unlike the European one, can be both a very small animal and a larger one: different types of ermines live in different parts of the country. The largest is distributed in the United States in the eastern and northwestern regions up to Alaska. He shares his habitat with affection. In the west of North America, only a small ermine lives, no larger than a weasel; and it turned out that in these places weasel is not found at all. She can live in the neighborhood with large ermines, but she cannot stand the competition with the "kids". This example proves that the small species of ermine is a kind of taboo for affection, it can only live where they do not exist.
Reference supplement to the book.
Distribution area of Ermine.
