Which bird lays its eggs? Did you know: Why the cuckoo throws eggs into the nests of other birds

Little cuckoo chicks always hatch from eggs earlier than other chicks, and they are born stronger and more cunning, getting rid of their “step” brothers and sisters. How does a mother cuckoo pass on secrets to her unhatched heirs in a game of survival? Why don't the deceived birds realize the substitution? And how do inventive cuckoo birds manage to spend a well-fed and happy childhood in someone else’s nest? But first things first…

Express development of the cuckoo

Back in the 18th century, researchers discovered that cuckoo egg embryos are at an advanced stage of growth, which is as follows. In ordinary birds, the process of laying eggs begins within a day after fertilization, and the embryo develops in the egg within six hours, but cuckoos have a secret.

After fertilization, unfortunate mothers leave the egg in the oviduct for another whole day. If we add to this the fact that the temperature of these additional 24 hours inside the cuckoo’s body is 40 degrees Celsius, this means that the development of the chick proceeds even faster than under the wing of its parents. In total, the cuckoo chicks have 31 hours to hatch and attract the attention of their new parents. In this, future chicks give a head start to other yellowthroats.

It is also interesting that cuckoos specialize in throwing eggs to a certain type of bird, selecting camouflage by color and size.

How does the egg tossing process take place?

Sometimes the male cuckoo also takes part in such sabotage: he sits in a visible place and distracts the attention of the birds with his screams, and the female does the same thing - in just a few seconds she lays an egg in someone else’s nest and disappears among the trees. Thus, in one summer a pair of cuckoos throws about two dozen chicks into the nursery.

How do “aliens” live in other people’s families?

The hatched cuckoo, although it weighs about 3 grams, is strong enough to lift twice its own weight. This is no coincidence, because this ability helps him throw his rivals out of the nest.

The cuckoo chicks do this not out of malice; on a subconscious level, when they touch the sensitive back of the chick, it reflexively takes the “throwing out” position. The reflex is valid only in the first four days of the cuckoo’s life, therefore, if it does not meet the deadline and does not push its rivals out of the nest, it will not have any more chance of survival.

The foster parents do not notice the substitution, and continue to feed the uninvited guest as if they were their own chick, thanks to the little guest’s ability to imitate sounds. The cuckoo makes the same sounds as real chicks of the species it came into contact with. But how does a newborn chick know all these sounds? When throwing eggs or newborn birds out of the nest, cuckoo chicks do not hear the sounds that they then imitate! The fact is that the color, size of the eggs and the sounds that the baby needs to make are already included in the female’s “program”. And the chicks understand everything intuitively.

But this is not the limit. If a young cuckoo makes a mistake and throws an egg into the wrong nest, her little cuckoo will not be confused, and will correct its “vocals” if it understands that with such screams it will not get food.

Cuckoo chicks are incredibly voracious, so new parents have a hard time. In addition, the open beak of the adopted child is large and orange-red; this fact cannot leave the breadwinners indifferent, so the cuckoo gets the most a large number of stern. This continues for three weeks, and then the cuckoo chick flies out of the nest, but for another month and a half it visits its parents to feed. Towards the end of summer, the young bird goes to India or Africa for the winter.

Some mother cuckoos do not forget about their children and feed the chicks along with the adopted birds.

Not everything fits the same line...

Observations of cuckoos show that in nature males can build nests, arrange mating dances, calling females to live together, which the latter, of course, do not plan.

Besides, African species On the contrary, they do not throw eggs to other birds. They diligently build family nests, and the entire flock (about 20 individuals) lays eggs there, and older and experienced birds take part in incubation.

The cuckoo is a bird of the cuckoo family. Body length various types these birds are from 14 to 80 cm. Long, stepped tails and long beaks curved down are one of the main distinctive features kind.

Cuckoos live on all continents except Antarctica. Most cuckoos live in forests and are bush or arboreal birds. Some species prefer to make nests directly on the ground.

Cuckoos feed mainly on insects. They also eat small lizards, eggs, other people's chicks, some berries and fruits. It seems like a completely normal diet, but there is one nuance: the “favorite dish” of cuckoos is not simple insects, but the most harmful ones: mole crickets, weevils, caterpillars of the ocellated hawkmoth, longhorned beetles, May beetles, white moths and caterpillars of oak and pine silkworms . All insects listed on the “menu” are extremely harmful to Agriculture, and many of them are also poisonous. Few birds eat them.

Most cuckoos are monogamous. During the mating season, they form pairs, build nests and raise their vocal offspring. Other species of cuckoos are polygamous. And thanks to them, the people have formed the opinion that cuckoos are bad parents and abandon their children. But it's not that simple.

Different types These birds behave oh, how differently! There are those who forget about their children as soon as they lay eggs in someone else's nest. Having thrown all its eggs into several different nests, one or two in each (and a total of 10 and 20 eggs), the cuckoo calmly goes to South Africa for the winter.

It is interesting that cuckoos never lay eggs in closed nests - they place it somewhere nearby on the ground, and only then transfer it in their beak to the place they like.

Each of the cuckoos, when choosing a nest - an incubator for its future chick, specializes in certain types of birds. Some lay eggs only in flycatcher nests, others prefer warblers or redstarts. The most amazing thing is that the eggs of such cuckoos are identical in shape and color to the eggs of the birds they choose.

Moreover, the methods of throwing eggs into other people's nests are very diverse. Some cuckoos rush past the nest or hollow they like at high speed, pretending to be a hawk (they actually look like hawks in the color of their plumage and the outline of their body) and thereby scaring away the legal residents. And while they are hiding in the grass and bushes, the false hawk quickly lays eggs in someone else's nest and flies away.

Sometimes a pair of cuckoos act together. The male distracts the birds and leads them away from the nest, teasing and bullying - at this time the female pushes away with her beak the previously laid eggs of others and places her own between them. Sometimes cuckoos throw out other eggs if they think that the “living space” is too small for their own. However, the apple does not fall far from the tree: grown cuckoo chicks often throw their half-brothers and sisters out of their nests.

The cuckoo chick is born a couple of days earlier than the other chicks. Thus, he has enough time to get comfortable in the nest and feel like a full-fledged owner. He is still completely naked and blind. And it weighs only 3 grams. But from the first days the baby begins to fight for survival. He can lift twice his own weight. And he uses his power, throwing out from his hospitable house everything that he touches with his bare back, be it an empty shell, an egg or a chick. Ornithologists call this the ejection instinct. It is effective in foundlings for only 4 days after birth, but this is quite enough to reduce competition in the fight for food brought by “foster parents”.

And these parents seem to not notice what is happening. They feed one chick instead of several. Aristotle wrote about this strange phenomenon: “The cuckoo is so beautiful that its breadwinners begin to hate their own children.” What is the real reason for this behavior of birds?

Only recently has it been proven that the yellow mouth and bright red throat of the cuckoo chick are an exceptional signal that forces not only the “foster parents,” but also all the birds that are close to the nest to bring food to the vocal cuckoo chick. At the same time, no one pays attention to the strange size of the chick. The feeders often sit on the back or even on the head of their adopted child and thrust their entire heads into its wide-open mouth.

For example, the Guira and Ani cuckoos breed their offspring independently. Well, almost always. Sometimes they lay eggs in the nests of other cuckoos and consider themselves completely free from parental obligations. But some American species of cuckoos, although they lay eggs in other people’s nests, hatch and raise the chicks themselves. For African cuckoos, things are even more complicated. These sweet parents wait patiently for the “nanny” they have chosen to sit and feed both their own and their adopted children. But when the chicks grow up, the parents begin to feed them and protect them from the dangers lurking around them. So not all cuckoos behave like... cuckoos))

Cuckoo chicks always hatch from eggs, ahead of their half-brothers and sisters, and are born stronger, and manage to get rid of extra mouths, excuse me - beaks, in the nest. How does the cuckoo give its unhatched heirs a secret trump card in the game of survival? How do deceived birds not realize the substitution? And what do the cuckoo babies themselves invent for the sake of a well-fed and happy childhood in someone else’s nest? First things first!

Cuckoo eggs

As early as the 18th century, researchers knew that cuckoo egg embryos were at an advanced stage of growth when they were laid. They suggested that the secret of the cuckoo lies in internal incubation, but no one has undertaken to check and prove this until our time. Research from the University of Sheffield, after studying the embryos under a microscope, confirmed this fact, surprising for the avian world. What's unusual about it? The thing is that birds usually cannot hold eggs in themselves when they are ready for the laying process. In most species, egg laying occurs one day after ovulation and fertilization of the egg, and the embryo begins to develop six hours later.

After a day, the egg is ready - the white and shell are already formed. By the time a bird lays an egg, the embryo contains only about 10 thousand cells. Two days after the start of incubation, the embryo developing behind the walls of the shell could barely be seen with the naked eye.

Research has shown that cuckoo eggs go through similar developmental stages at the same time intervals. However, the cuckoo has proven its right to be considered an exception to the rule: it leaves the egg in the oviduct for another whole day. Add to this the fact that the temperature of these extra 24 hours inside the cuckoo's body is 40 degrees Celsius, and development occurs even faster than under the parent's wing, where the embryos receive only 36 degrees. In total, cuckoo chicks have 31 spare hours to hatch and attract the attention of their new parents. That is why future chicks are able to give odds to any other yellowthroats!

Moreover, each cuckoo specializes in throwing eggs to certain types of birds, and camouflages them both in color and size. Moreover, taking into account the weight of an adult bird, which is approaching 100 grams, and the advanced development of embryos, it is incredible that the mass of eggs laid does not exceed 2-3 grams, and if necessary, the size can approach the modest dimensions of sparrow eggs.

Sabotage at the edge

When a cuckoo is about to lay an egg in someone else's nest, it scares away the brood birds. She is helped in this by the external similarity of coloring, size and manner of flying like a sparrowhawk. In addition, the cuckoo in our area adequately replaces tropical parrots, even managing to imitate the calls bird of prey. Flying over the grass, almost touching it, or over the edge of trees, the inventive bird flaps its wings, and the hens, alarmed by the sight of the “huntress,” flee. The cuckoo is just waiting for this in order to quickly toss the egg - after all, a long delay will deprive the cuckoo chicks of all advantages, and they may not even wait until the end of hatching. Sometimes it is difficult for a bird burdened with a precious burden to reach the nest, or it is simply too small for it - then the cuckoo brings a freshly laid egg in its beak - and always takes one real one in the same way, so that the parents do not guess about the substitution.

Sometimes the male also participates in sabotage: he flies over the nest, sits in a visible place and distracts the attention of the birds, who are trying to drive him away with screams. Meanwhile, the female lays an egg in just 5-8 seconds and disappears among the greenery. So in one summer, one pair of cuckoos leaves offspring in two dozen other people’s nests.

The alien has arrived!

The hatchling cuckoo weighs only about three grams, but is so strong that it can lift twice its weight. He uses this ability to throw the “natives” out of the nest. The cuckoos do this not out of malice - they subconsciously carry out such a program. It's all about the sensitive back of the chicks - as soon as you touch it, they reflexively take the “throwing out” position, and this instinct only works for the first four days, after which it disappears without a trace. If during this time the cuckoo does not get rid of other contenders for food, it will never do so again.

Why do foster parents continue to feed the uninvited guest as if they were their own chick? Here, relatives of parrots (in spirit) are helped by their ability to imitate the sounds made by real chicks of the type of bird to which the cuckoo came. But the most amazing thing is not even this. The fact is that when throwing eggs or newborn birds out of the nest, cuckoo chicks do not hear the sounds that they then imitate! Just as the color and size of the eggs are already included in the female’s “program,” the chicks understand the sounds that need to be made intuitively. Moreover, having turned into adults, all cuckoos “sing” the same way: females emit something like “kli-kli” and a kind of laughter, but cuckoo in fact, we are only pleased with the males. But this is not the limit of their capabilities: sometimes a young cuckoo makes a mistake, or there are no suitable nests nearby, and the cuckoo ends up with the wrong bird species as intended by nature. As a result, the chick makes characteristic sounds of its new parents, experimenting and adjusting its “vocals” if they realize that they are not getting enough food.

The little cuckoo is very voracious, and from dawn to dusk the baby has to be fed every now and then. Moreover, the open beak of this chick is so large and orange-red that often other birds cannot remain indifferent, and feed the cuckoo. This continues for three weeks - then he leaves the nest for another month and a half, “eating” with his parents, and in August the young bird usually goes to India or Africa for the winter.

But some cuckoo mothers do not forget about their offspring and feed the cuckoos along with their adoptive parents.

Observations of these birds in natural conditions prove that cuckoos did not always lead such a cunning lifestyle. For example, when courting a female, the male sometimes brings her twigs and blades of grass, hinting at the joint construction of a nest, which the cuckoos, of course, do not plan. It turns out that ritual mating dances still retain echoes of the past.

Besides, in tropical Africa There are cuckoos with opposite instincts: they do not throw eggs to other birds. On the contrary, they build a family nest, where the whole flock of about twenty individuals lays eggs, and older birds hatch them while the young frolic in the banana thickets!

Throwing eggs into other people's nests. On the one hand, it is absolutely unfair and even vile. But have you looked at the situation from the cuckoo's point of view? Unlikely...

Reasons that motivate cuckoos to behave in such an unusual way

There are two reasons for this. The first is that male cuckoos calmly feast on eggs, not paying attention to their identity. Yes, something like cannibalism is characteristic of this type of bird. The second reason is even stranger. The fact is that the cuckoo is a conveyor belt for laying eggs. As soon as one hatches, the second is already on the way.

The problem is that the eggs need to be hatched, and the cuckoos need to be fed. And doing these two things at the same time is physically impossible. That's why the cuckoo throws its eggs into other people's nests - let other birds take on at least part of its worries.

Moreover, it is not just “find any nest, fly in, lay an egg, fly away.” Birds are not so stupid and are able to get rid of completely unusual and alien eggs. Therefore, the cuckoo masters “specialization.” That is, they purposefully look for the nests of certain species of birds, and only then throw eggs there. Sometimes you even have to put it aside first, and then, after waiting for the right moment, transfer it in your beak to the “hatching place.” And if this is not specific concern for the offspring, then what?

Why is this normal and even useful?

American larva-eating cuckoos solved the problem by organizing a “communal apartment”. That is, joint incubation of eggs and joint feeding of hatched chicks. Some sit in the nest, others fly away in search of food. And the American ground cuckoos in their behavior they are more reminiscent of penguins - they form strong pairs in which the partners take turns hatching eggs and flying out to hunt.

We also believe that it would be useful for you to learn about other animals with. Even more unusual than cuckoo behavior and gluttony.

The weight of the bird does not exceed 100 grams, and the body length is 40 centimeters. They have a very strong torso and legs. The length of the tail reaches 20 centimeters, the wings are almost 30. In flight, the bird looks quite large. The feathers on the back are ash-gray, on the chest - with dark stripes. The female is different in color; her back has a rather reddish tint.

Cuckoos live everywhere, except in Antarctica and the Arctic. With the first cold weather, they leave their native lands, flying somewhere to northern Africa. Birds living closer to the south are considered sedentary; they stay in their vicinity all year round.

The main diet of the cuckoo consists of:

• amphibians: frogs and lizards;
• insects: caterpillars, weevils, hawk moths, white moths, butterflies, silkworms, beetles, spiders;
• eggs;
• berries and fruits;
• other people's chicks.

For workers in rural fields, cuckoos are considered saviors, since many insects included in the bird’s “menu” are considered harmful and poisonous to crops.

To whom does he throw it and how?

In central Russia, cuckoos lay eggs to different families of birds: kinglets, nightingales, swifts, sparrows and many others. In Europe, they mainly go to redstarts, wagtails, shrikes and warblers.

There are several varieties of cuckoos, which differ in the number of offspring they throw. Thus, a crested female leaves from 2 to 4 eggs in someone else’s nest, while an ordinary female leaves only one. From May to July, the cuckoo lays about 10-20 eggs.

The tossing process also occurs differently. Some individuals throw out the egg in flight, others lay it on the ground and then carry it in their beak. Before the cuckoo flings its baby, it scares the brood bird away from the nest. Sneaking under the treetops, she loudly flaps her wings or imitates the cries of birds of prey. The foster mother flees for her life, while the cuckoo throws an egg into her house. The unfortunate mother takes the real egg with her or eats it so that the parents do not notice the trick.

Birds throw eggs into different nests, having previously selected the size and color so that the stranger is not detected. This is not difficult to do, as their colors are varied: white, blue, pink, light blue, brown, speckled, intricate patterns. And the dimensions are small: about 20 by 15 cm. And yet, sometimes foster carers find an egg that is “not theirs” and throw it away, dooming the chick to death.

Interesting facts

It is interesting that the cuckoo chooses adoptive parents similar to those in whose nest it once grew up. In an emergency, she can throw an egg into the first nest she comes across.

If the selected clutch is already well hatched, the pest bird can ruin it. Thus, she provokes the victim to re-lay eggs with further replacement.

Two centuries ago, ornithologists discovered the following: cuckoo chicks develop twice as fast as other birds. This is due to the fact that in other birds the egg is born a day after fertilization. And cuckoo eggs, after being thrown into the nest, hatch after 6 hours. What is their secret?

After mating, the cuckoo is in no hurry to remove the egg from the oviduct. They keep him inside for a day, where the temperature is 39 degrees. That is why the development and growth of the chick occurs twice as fast, as in an incubator. After that, she throws her child into someone else's egg, where on the same day he hatches and becomes comfortable.

Why does the bird behave this way and the life of the chicks

Ornithologists explain the behavior of the cuckoo by saying that it is trying to protect its offspring from their own fathers. Males love to feast on fresh protein and can easily eat their children. Other scientists prove that cuckoos are not capable of hatching eggs. This is due to the structural features of their chest. There is a third theory - the egg follicles do not mature at the same time, so if a cuckoo lands on a nest where there are other chicks, it will crush them.

In appearance, cuckoo chicks are practically no different from their adopted brothers and sisters, but they are ahead of them in growth and development. The chicks imitate the squeak of the chicks in whose nest they find themselves. They are born blind, naked and with a great appetite. They are very picky about food. Often the foster parents cannot cope with feeding them; at such times other birds come to the rescue.

A strange feature of the chick is that already half a day after birth, it begins to shed eggs. This is due to the fact that the cuckoo’s bare skin is very sensitive and any touch of objects irritates it. When a small chick touches his back, he squeezes him in the sacral recess and drags him outside the nest. They become independent after 12 days and fly away from the nest.