Caring for the offspring of birds, in addition to feeding the chicks, also includes active protection of the nest and children from various enemies: predatory animals and birds, hunting dogs. It manifests itself in different ways: some birds pretend to be sick, wounded and take the enemy away from the nest, while others boldly defend him.

Large birds - eagles, eagle owls, herons and others - often resort to a direct attack of a disturber of their peace that has appeared near the nest.

Gray herons bravely defend their nests. An angry stork can “reward” with blows of wings and a sharp long beak. Swans selflessly protect their nests. The white partridge is a quiet and modest bird, which tricks it just doesn’t go for when you need to take the enemy away from the nest. In spring, the female will lay about a dozen eggs under a bush and incubate them. The male takes care of her and feeds her. In case of danger, he takes the enemy away from the nest.

— Aw-aw-aw-aw! - the partridge shouts loudly, dragging the hunter along with it. Or climb on a stump and sit. Only the hunter takes aim, and the kurapat is already falling from the stump, and the charge hits an empty place.

Known for great attachment to their nest of quails. They also have to go to all sorts of maneuvers to distract the hunter from their nest. The bird is forced to pretend either to be wounded or weak.

The little gray flycatcher is a trusting and inconspicuous bird. But for the sake of protecting the chicks, it becomes very bold. She is all fluffed up, the feathers on her head rise, small black eyes menacingly look at a potential enemy. One more minute and watch out. With a squeak, trembling in the air, she will rush at the offender and vigorously attack him.

Caring for offspring, protecting chicks is a top priority for many species of birds. Sometimes the defenses are just amazing.

An original way to protect the nests of our northern birds, fulmars or fulmars. A fool is almost not afraid of a suitable person. He, as it were, looks at the stranger with interest and trust, stretching his neck towards him. An unsuspecting person, perhaps, can be moved at the sight of such gullibility and selflessness of a bird that does not leave its nest in moments of danger and is ready to suffer for it. But a few seconds pass, and a person turns out to be the victim.

The silly, deftly aiming, douses him with the force of a jet of liquid ejected from his beak. And the most unpleasant thing here is that this liquid smells disgustingly of rotten fish. Here's to you stupid!

Taking care of their offspring, hornbills living on the Malay Islands act as follows: a female hornbill, having laid 5-6 eggs in a tree hollow, sits on them. The male covers the hole in the hollow with clay, leaving only a small hole through which the female sticks out her beak to take the food brought by the male. During the entire period of incubation of eggs, the male carefully feeds his “soul mate”.

Material selection: Iris Revue

Birds have a very developed care for offspring, which manifests itself, in addition to building a nest and incubating masonry, in feeding chicks, in warming and protecting them from weather conditions, in cleaning the nest from excrement and more or less active protection from the enemy.Usually, in polygamous birds, the male does not take part in caring for the offspring. And in monogamous species, on the contrary, the male fully participates in it along with the female.Eggs are most often incubated by females, less often by both birds from a pair, very rarely by only males. Incubation usually begins after the laying of the last egg in the clutch, but sometimes earlier, in the middle of the laying period or after the laying of the first. eggs (gulls, shepherds, etc.). Long-legged, predatory and owls, parrots and a number of other birds begin incubation immediately after laying the first egg. In small birds, the incubation period is much shorter than in large ones; among the latter, some incubate for more than a month. When birds incubate, fluff falls out on parts of the abdomen and chest and a perched spot is formed, which provides more intense heating of the eggs with body heat.

Depending on the duration and complexity of embryonic development, birds are divided into two classes - brood and chicks.Brood birds (tinamu-like, ostrich-like, anseriform, chicken-like, except for hoatzin, bustards, many waders, etc.) - whose chicks hatch from the egg fully formed, covered with down and able to find food. They immediately leave the nest, although for a long time they follow their parents, who protect them and help them find food.Nestling birds (copepods, woodpeckers, swifts, parrots, some crustaceans and passerines) - whose chicks hatch from an egg unformed, naked, blind and

Meeting 42. HOW DO BIRDS TAKE CARE OF THEIR OFFspring?

Target: tell students about the features of the life of birds, about how birds take care of their offspring; develop observation, speech, thinking, memory; teach the rules of behavior in nature.

During the classes

I. ORGANIZATIONAL MOMENT

II. UPDATE OF BASIC KNOWLEDGE

1. Frontal survey

What is the structure of birds?

What is the significance of the structural features of birds for flight?

How do birds get the energy to fly?

Research: What do the birds you see in your area eat? Give examples.

What fairy tales or songs about birds do you know? What features of these animals are they talking about?

2. Work on the table

Fill the table. Give examples.

Insects

III. MESSAGE TOPICS AND LESSON OBJECTIVES

Today in the lesson you will learn more about the life of birds and the rules of human behavior in nature.

IV. STUDY NEW MATERIAL

1. Work on the textbook (pp. 112-113)

- Remember! Or are fish worried about their offspring?

- Remember!

In the life of birds during the year, several periods can be distinguished. For migratory birds: spring arrival, nesting and breeding, preparation for departure and autumn departure.

Work in pairs

Look at the pictures on page 112 and name which of the birds are migratory and which are sedentary?

The most responsible for birds is the spring period, when it is time to hatch chicks. In spring, birds do not arrive at their homeland at the same time. Males appear at nesting sites earlier than females in order to find and secure a certain nesting territory. They designate it with the help of singing. During incubation, parental responsibilities between dad and mom are distributed differently. In woodpeckers, jays and nightingales, the female incubates the eggs during the day, and the male at night. But in drakes, only the mother duck takes care of the offspring. The females of the hawk, falcon, and eagle also incubate themselves, but the males bring them food. They do this very carefully so as not to betray their nest to enemies or fidget kids.

Look at the pictures on page 113. Explain what they show.

conclusions

Birds take care of their offspring.

The most important spring care of birds is breeding chicks. At this time, they should not be disturbed.

2. Physical education

V. GENERALIZATION AND SYSTEMATIZATION OF KNOWLEDGE

1. Work in groups

Listen to interesting information and think about why small animals - such as insects, fish, amphibians, reptiles - lay a lot of eggs and eggs? Why the larger the animal, the greater the number of its descendants?

Informant. Bedbugs lay 70-100 eggs, Colorado potato beetle - 700, butterflies 100-400. The number of eggs in carp, pike reaches tens of thousands, and large sturgeons “throw out” several million eggs. Reptiles have 10-20 eggs per clutch, which they bury in sand and soil. Birds lay up to 10 eggs. In animals, the birth rate of cubs is the lowest: squirrel - 3-10, cat - 2-6, dog - 2-10, lynx - 1-4, bear - 1-3, elephant - 1, whale - 1.

2. Testing

1. Where does the caterpillar come from?

a) hatch from eggs

b) is born from a pupa. (+)

2. How is a tadpole different from an adult frog?

a) Size only

b) tadpoles have tails and no legs. (+)

3. Where do reptiles lay their eggs?

a) in dry soil; (+)

b) in nests.

4. Do reptiles take care of their offspring?

a) Yes, they care;

b) no, they don't care. (-)

5. Do birds take care of their offspring?

a) Yes, they care; (+)

b) no, they don't care.

Mutual review (in pairs).

3. Challenge

A gray partridge has 20 children, a long-tailed tit has 8 fewer children than a partridge, and a siskin has 7 children less than a titmouse. How many babies are born to a tit and a siskin?

VI. SUMMARIZING. REFLECTION

What animals are called birds? Give examples.

Is the sign of birds significant?

How do birds take care of their offspring?

VII. HOMEWORK

Make the rules of behavior in nature during the period of breeding by birds.

Imagine that you need to tell the inhabitants of a fairy-tale planet about birds, where only insects live. Plan your story.

and different "output" of the process in the form of different quality of young

Recently I realized that the systems of relationships “parents-offspring” and between cubs in birds and mammals are sharply different, and I was able to formulate exactly what.

The difference is that relationships in the context of caring for offspring (within the brood on the one hand, between parents and offspring on the other) are organized in the opposite way, so that they give the opposite result in the form of polar levels of different quality of the young. That is, at the moment of transition to independence during the breakup of a brood in birds, the settlement of young animals in mammals, fledglings from one brood are so different that they are distributed according to two opposite strategies (conditionally “ fast" And " slow”, see below), but young mammals, on the contrary, in behavior represent some variation around the average norm created by the organizing influence of the mother on the formation of the behavior of the cubs (Kruchenkova, 2002).

In birds, the interactions of chicks in the brood and parents with chicks are organized in such a way that the behavioral heterogeneity of the offspring is purposefully enhanced by social means beyond the level that is set by the biological diversity of the chicks themselves. The mutual competition of chicks for food leads to the differentiation of two alternative strategies, conditionally "fast" and "slow", which are most clearly manifested in the two "extreme" chicks (the most mobile and quick-witted and "the most stupid, stereotyped" according to Berndt Heinrich's description of chicks crow Corvuscorax), and all the others are distributed among them. Reinforcement from parents (positive - in the form of food, negative - in the form of the periodic presentation of a song that makes one alert and alarms that make one lie low) affects the chicks in such a way that it reinforces the differentiation of strategies of different chicks and stimulates each chick to further specialize in a once chosen strategy, do not stop and do not change it. The details of the process are described in detail in the studies by S.N. Khayutin and L.P. Dmitrieva (1981, 1991), carried out mainly on the pied flycatcher ficedulahypoleuca .

As a result, by the time of departure, the behavioral heterogeneity of chicks is maximum and, on the whole, corresponds to that of adults in the breeding population.

In the broods of mammals, above the organization that birds have, interactions of a different level are superimposed, associated with social support for the development of specific forms of activity of cubs on the part of the mother. The behavior of the mother is characterized by maximum responsiveness to immature manifestations of activity of the cubs - in response to them, the mother is involved in joint activities with the cub, so that the "ripening" of specific forms of activity in the offspring occurs not autonomously, as in birds, but in the course of joint activity with the mother. Being formed, the behavior of the young is gradually freed from dependence on joint activities with the mother and begins to manifest itself (governed) under the influence of its own mechanisms (Kruchenkova, 2002).

In primates and many other species (carnivores, some monogamous ungulates), the joint activity of cubs with the males of the group (not necessarily fathers) has the same formative influence on the maturation and specialization of the behavior of the young as joint activity with the mother. On the other hand, the behavior of young mammals is also more sensitive to social stimulation than mature ones, and responds to stimulation with similar adult behavior with maturation, specialization, differentiation of forms, and not “just a reaction”, as in birds.

In this case, the mother in mammals sets the rate of development of the behavior of the cubs, accelerating or restraining it, according to the situation, in the same way and for all at once. Accordingly, the mother (and father/other males) here has a leveling effect on the brood, so that the heterogeneity of the young is reduced as much as possible - the aftereffect of organizing influences from the mother significantly exceeds the differentiating effect of competition within the brood (Kruchenkova, 2002). Moreover, the results of the latter in the form of a stable distribution of roles manifest themselves mainly when the behavior of the young is already formed and freed from maternal influence. And at this moment, all “puppies of the same litter” are on average similar to each other in essential behavioral characteristics, so their individual behavior is a certain deviation from the “brood” average.

In birds, the opposite is true: in the course of interactions in the nest, the chicks compete for the primary food, and in the course of competition, two opposite strategies are differentiated, relatively speaking “fast” and “slow”. "Fast" chicks are strong, active, not afraid of novelty (including ready to receive food, not being afraid of the parents' alarm cries, rustling, nest shaking, etc.). They are the first to break through to the notch, moving through the entire bottom of the nest box, they are the first to receive food, eat and fall asleep, freeing up space.

It is, so to speak, competitive strategy: the chick itself, to the best of its ability, forms the most favorable circumstances for obtaining food, not being afraid of the variability and instability of the outside world. Alternative strategy - tolerant: chicks that lose all attempts to rush and take food first, and gradually get used to making the most of those periods of time for taking food when the most competitive chicks have already eaten and freed the entrance or the edge of the nest. To do this, they do not move and almost all the time they sit under the entrance, that is, they passively wait for favorable circumstances and, when the appropriate stimulation occurs (the parent arrives with food), they react stereotypically to the impact.

At the beginning of the rearing period, the competitive strategy is much more profitable than the tolerant one, and the second chicks are strongly lose weight. But then the situation levels off and by the time of departure, the representatives of all the chicks have approximately the same weight, but the behavioral strategies (begging for food and responding to parental signals) turn out to be maximally differentiated. Much more than can be expected, based on the biological heterogeneity of the chicks at the beginning of the rearing period.

A kind of “carousel” arises, a continuous “circulation of chicks in the nest”: individuals successively replace each other at the nest, almost without entering into a physical collision, so that representatives of “more tolerant” strategies use periods of rest and satiety of chicks of “more competitive” strategies. Since parents actively support this system, reinforcing every step along the path of differentiation with food, it is logical to assume that the heterogeneity of chicks, reflected in the differentiation of strategies, was not given initially, but was created by social means. This constant “circulation of chicks in the nest” leads to the fact that the space inside the nest turns out to be anisotropic and chicks with different strategies occupy different “positions” relative to the center of food intake - the entrance or the edge of the nest. The “faster” the strategy of the chick, the further it is from the entrance when full, and the faster it makes its way to it when it is hungry. "Slow" individuals are under the entrance all the time.

This “circulation”, which differentiates chicks, was first shown for the hollow nest of the pied flycatcher, whose chicks are in nest boxes, where there is one clear center for eating - the entrance hole and it is possible to give a clear signal about the arrival of the parents by reducing the illumination from the closing of the entrance hole and shaking the walls from hitting the hollow. But in open-nesting birds, the same differentiation of chicks into “fast” and “slow” takes place. Immediately before the flight, a “smart and nimble” chick stands out, ready to climb into everything and explore everything, its opposite is the dumbest chick of the brood, afraid of novelty and stereotypically reacting to stimulation. And the rest of the chicks are in the middle. In particular, this is described for crow chicks by Berndt Heinrich (1994).

These behavioral differences in chicks persist but do not increase in adult birds, manifesting themselves as an alternative of "fast" and "slow" bird phenotypes in natural populations. On big tits (Parus major) it has been shown that in terms of indicators of locomotor mobility and mobility response to novelty, the same strategies are distinguished in the breeding population as in nestlings. In "fast" individuals, in response to novelty, mobility and exploratory reactions increase, in "slow" individuals, on the contrary, they are suppressed ( Drent et al., 2003; Dingemanse et al., 2002, 2003; Dingemanse, 2007).

"Fast" and "slow" phenotypes in tits can be separated, for example, by testing in an "open field" according to the method Dingemanse et al . (2002), or using the “doubling the enclosure” method, when the behavioral strategy of an individual is manifested in the speed of mastering a suddenly appeared new space (Ilyina et al., 2006).

In double enclosures, the probability of reproduction was higher in the "fast" individuals, who actively mastered a new adjacent room. In males, the rate of development of a new territory positively correlated with the result of testing in the "open field". In contrast to the probability of breeding, its success and timing did not depend on the size of the enclosures (single or double), but were associated with the results of testing in the open field, that is, with the dichotomy of "fast" and "slow" phenotypes. "Fast" females earlier slow began to show reproductive behavior, but Later started laying eggs and worse hatched the laid eggs. The phenotype of the male also influenced: the partners of the “fast” males showed reproductive behavior earlier, while the “slow” males began to incubate the clutch earlier. Finally, the superiority of the male over the female in terms of testing in the “open field” increased the likelihood of manifestations of male reproductive activity in the pre-nesting period (Ivankina et al., 2006).

That is, in the social interactions of animals in the community, “fast” individuals stimulate their partner better, but perform their social role worse (less accurately, with a higher probability of errors and failures). And in reproduction and social communication, the accuracy of the implementation of specific forms of signals and forms of relationships is no less important than the strength and intensity of stimulation between partners. The division into "fast" and "slow" individuals in the population is in good agreement with "my" division of individuals into those committed to competitive and tolerant strategies as two mutually exclusive alternatives. The former prefer high social density and are sensitive to environmental stress, the latter prefer low density, uncompetitive under conditions of social stress.

It was also shown in the Dutch population of great tits that the alternativeness of "fast" and "slow" phenotypes is also associated with the alternativeness of strategies for social, foraging and reproductive behavior - everything that requires a reaction to novelty, the ability to control the situation without fear of the risk associated with this novelty itself (or vice versa, avoidance of novelty and self-restraint by an environment where one can only behave stereotypically), cf. Drent et al., 2003; Dingemanse et al., 2003.

The authors, who studied only adults, believe that the dichotomy of "fast" and "slow" phenotypes is hereditary. Heritability was determined indirectly and amounted to 0.22-0.41 according to the regression method "parents-offspring", according to the analysis of siblings 0.37-0.41 ( Dingemanse et al., 2002).

However, studies of ontogeny show that both alternative strategies are not innate, but “made”, the differentiating effect of signal heredity, social influences within the brood and from parents here “mimics” the effect of genetic heredity. On the one hand, competitive interactions in the brood are organized as follows that create the "embryo" of differentiation strategies in the form of situational deviations of behavior in one direction or another in chicks, by chance found themselves in a certain role. On the other hand, parents with positive and negative stimulation (bringing food, making them move - singing, making you alert - an alarming cry, making you hide) affect the differentiating behavior of the chicks in the direction of "increasing fluctuations", designing and fixing them in the form of differentiated strategies, following which as specialization deepens, it turns out to be more profitable for each chick (= more efficient in terms of obtaining food and minimizing the overall risk of ruining the nest) than adjusting and changing the strategy. This reinforces and reinforces the overall pattern of differentiation within the brood.

If the parental behavior in birds, as it were, "pushes" the chicks according to different strategies that differentiate in competitive interactions within the brood, acts as a kind of diversifying influence, then in mammals, the influence of the mother and father on the cubs is directly opposite, leading their behavior to a certain general norm. . The differentiation of individual behavioral roles here occurs relatively late, when the mother ceases to be the organizer of the behavior of the cubs, and all forms of activity of the cubs have reached maturity and are associated with the interactions of the cubs with each other without the participation of parents. At earlier stages, the influence of the mother lies in the fact that with immature manifestations of various forms of activity of the cub, the mother (and the father, where he interacts with them) is included in the joint activity of the cubs, which leads to the maturation of the corresponding form of behavior and emancipation from the organizing influence of the mother . That is, the maturation of species-specific behavior in mammals always requires the social support of parents (i.e., zone of proximal development principle L.S. Vygotsky per person can be extended to all mammals, but not on birds!) and at the same time, the leveling influence of the mother on different cubs is naturally. In birds, parents do not engage in social support, chicks organize their interactions themselves, and parents organize only reinforcement and selection.

Accordingly, the broods of birds work as diversifying systems that create and reinforce the differentiation of the behavioral roles of the young between the two poles of alternatives that are essential for a given species and population. Broods of mammals act as levelers, the differentiation of roles occurs later, during the period of growing up and mutual games of grown puppies. The low activity of the cub stimulates the mother's initiative, and the activity of the cub above a certain level inhibits the initiative of the mother. The same is true of the maturation (specialization) of different forms of behavior. In birds, under the influence of parents on the corresponding process, a positive feedback occurs, encouraging the deviation of behavior patterns from the average at each of the successive stages of maturation (primarily, motor activity, begging and hiding behavior, with appropriate vocalization). In mammals, a similar effect forms a negative feedback, leading all puppies to the “average developmental norm” set by the parental behavior of the mother (and father, other males - where they are supposed to be).

For example, agonistic interactions in wolf cubs not only build a social hierarchy in a group of individuals, but have a much longer-range effect. The division into dominants and subordinates created by them forms the basis for the subsequent distribution of roles between wolves when they attack the prey. Depending on the social status, young wolves during group hunting choose different ways of pursuing themselves, attacking different parts of the victim’s body, etc. there is neither differentiation of roles when attacking a prey, nor effective interaction of wolves when mastering it (Badridze, 2003).

Sources

Badridze Ya.K., 2003. Wolf. Issues of behavior ontogenesis, problems and method of reintroduction. M.: publishing house GEOS. 117 p.

Ilyina T.A., Ivankina E.V., Kerimov A.B., 2006. Influence of the spatial factor and individual characteristics of behavior on the reproduction of great tits in captivity - Report on XII All-Union Ornithological Conf. in Stavropol.

Kruchenkova, E.P., 2002. Principles of the mother-calf relationship in mammals. Abstract and manuscript of diss. doctor of biological sciences M. 409 p.

Khayutin S. N., Dmitrieva L. P., 1981. Organization of the natural behavior of nestlings. - M.: Science. 136 p.

Khayutin S.N., Dmitrieva L.P., 1991. Organization of early species-specific behavior. M.: Science. 221 p.

Heinrich B., 1994. Raven in winter. M.: "Mir". 522 p.

Dingemanse N.J., Both C., Drent P.J., Van Oers K., Van Noordwijk A.J. 2002.Repeatability and heritability of exploratory behavior in Great Tits from the wild// Anim. behavior. Vol.64. P.929-938

Dingemanse N.J., Both C., Van Noordwijk A.J., Rutten A.L., Drent P.J. 2003.

Every year, in order to raise offspring, the vast majority of birds build nests. In temperate latitudes and in cold countries, nesting begins in spring and ends in summer, when the chicks are compared in size with adult birds. But this is not the case everywhere. After all, there are many places on the globe where there is no change of seasons. In some tropical countries, summer lasts all year, in other places there is an annual change of dry and rainy seasons.

How, then, to determine the time of reproduction of birds? For the entire globe, the rule is general: birds begin to nest at such a time that the feeding of the brood and the first days of the life of the chicks outside the nest falls on the most food-rich time. If we have it in spring and summer, then in the savannahs of Africa, most birds nest immediately after the start of the rains, when the vegetation develops violently and many insects appear. The exception here is birds of prey, especially those that feed on terrestrial animals. They nest only during drought. When the vegetation burns out, it is easy for them to find their prey on the ground, which has nowhere to hide. Birds nest in tropical forests throughout the year.

It is generally believed that all birds, when hatching chicks, build special nests for incubation of eggs. But this is not so: many birds nesting on the ground do without a real nest. For example, a small brownish-gray nightjar lays a couple of eggs directly on the forest floor, most often on fallen needles. A small depression is formed later, because the bird sits in the same place all the time. The circumpolar murre also does not build nests. She lays her single egg on the bare rock ledge of the bluff. Many gulls and waders need only a small depression in the sand, sometimes they use the footprint of a deer hoof.

Nightjar bird nests right on the ground. The whitening shell near the nest helps parents find their chicks in the dark.

Birds that raise chicks in hollows and burrows do not make a real nest. They are usually content with a small litter. In hollows, wood dust can serve as litter. In the kingfisher, the litter in the hole consists of small bones and scales of fish, in the bee-eater - from chitinous remains of insects. The woodpecker usually does not occupy the finished hollow. With his strong beak, he hollows out a new hollow for himself. The golden bee-eater for about 10 days digs with its beak in the soft clay of a cliff of one and a half and even two meters, which ends with an extension - a nesting chamber. Real nests are made by birds nesting in bushes and trees. True, not all of them are skillfully made. The dove, for example, folds several twigs on tree branches and somehow fastens them.

Thrushes build solid cup-shaped nests, and the song thrush smears it with clay from the inside. Birds, working from morning to late evening, spend about three days on the construction of such a nest. The finch arranges a warm, felt-like nest, moreover, with a soft lining, masking it from the outside with pieces of moss, fragments of lichen, and birch bark. Golden-yellow oriole hangs its nest - a skillfully woven basket - from a horizontal branch of an apple tree, birch, pine or spruce. Orioles sometimes tie the ends of two thin branches and place a nest between them.

Among the birds of our country, the most skillful nest-builder is undoubtedly the Remez. The male remez, having found a suitable flexible branch, wraps its fork with thin plant fibers - this is the basis of the nest. And then, together - a male and a female - they build a warm hanging mitten from vegetable fluff with an entrance in the form of a tube. Remez's nest is inaccessible to terrestrial predators: it hangs on thin branches, sometimes over a river or over a swamp.

In some birds, nests have a very peculiar appearance and complex structure. Living in Africa and on the island of Madagascar, the shadow heron, or hammerhead, makes a nest in the form of a ball of twigs, grass, reeds, and then closes it up with clay. The diameter of such a ball is more than a meter, and the diameter of the side tunnel, which serves as the entrance to the nest, is 20 cm. The Indian warbler-dressmaker sews a tube of one or two large woody leaves with vegetable "twine" and arranges a nest in it from reed fluff, cotton, wool.

The small salangan swift, living in Southeast Asia (and on the islands of the Malay Archipelago), builds a nest from its very sticky saliva. The layer of dried saliva is strong, but so thin that it shines through like porcelain. This nest is built for a long time - about 40 days. Birds attach it to a sheer rock, and it is very difficult to get such a nest. Salangan nests are well known in Chinese cooking under the name of swallow nests and are highly valued.

A relative of the salangana already known to us, the kleho swift attaches its small, almost flat nest to a horizontal branch only at the edge. A bird cannot sit on such a nest: it will break off. Therefore, the kleho incubates the egg, sitting on a branch, and only leans on it with its chest.

Chiffchaff feeds chicks that have just flown out of the nest.

The South American stove-bird builds its nest almost exclusively from clay. It has a spherical shape with a side entrance and really resembles the ovens of the local Indians. It is not uncommon for the same pair of birds to use a nest for several years. And many birds of prey have 2-3 nests, using them alternately. There are also species of birds in which several pairs make a common nest. Such, for example, are African weavers. However, in this common nest under one roof, each pair has its own nesting chamber and, in addition, there are also sleeping chambers for males. Sometimes uninvited "guests" appear in the common nest. For example, one of the chambers in the nest of weavers can be occupied by a pink parrot.

There are many species of birds in which nests are grouped very closely, in colonies. One species of American swallows builds clay bottle-shaped nests on cliffs, which are so closely molded to each other that from a distance they look like honeycombs. But more often the nests in the colony are separated from each other by a meter or more.

Remez's nest is built very skillfully.

Bird colonies in the north are huge - hundreds of thousands of pairs. These so-called bird colonies are inhabited mainly by guillemots. Small colonies are also formed by gulls and petrels nesting on the ground. Cormorants, pelicans and gannets nest in colonies on islands along the western coast of South America. Their nests have accumulated so much droppings over the centuries that it is being developed and used as a valuable fertilizer (guano).

Large colonies are usually nested by those birds whose food is located near the nesting site, and, moreover, in large numbers. Cormorants on the islands of South America feed, for example, at the expense of large schools of anchovies, three-toed gulls from the bird colonies of the Barents Sea catch capelin without much difficulty. But often birds nest in colonies and fly far for food. Such birds are usually good flyers - these are swallows, swifts. Scattering in all directions, they do not interfere with each other to get food.

The forest horse arranges a real nest in the grass from dry blades of grass.

Those birds that do not have good flying abilities, and collect food by midge, by grain, nest far from each other, since when nesting in colonies they will not be able to collect enough food. These species of birds have feeding or nesting areas near their nests, where they do not allow competitors. The distance between the nests of these birds is 50-100 m. It is interesting that migratory birds usually return in the spring to their last year's nesting site.

All these features of bird biology should be well remembered when hanging artificial nests. If the bird is colonial, like a starling, nesting boxes (birdhouses) can be hung often, several on one tree. But this is not at all suitable for a great tit or a pied flycatcher. It is necessary that within each nesting site of tits there should be only one nest.

Chicks hatch in the nest of the redwing thrush. They are helpless for a long time, as in all nestling bird species, and fledge just before leaving the nest.

Some birds of prey, including owls, do not build nests at all, but capture ready-made strangers and behave in them like at home. A small falcon takes away nests from a rook or a raven; The saker falcon often settles in the nest of a crow or a heron.

Sometimes the nesting site is very unusual. Some small tropical birds hollow out caves for their nests in the nests of social wasps or even in termite mounds. A small loten nectary, living in Ceylon, looks for a network of a social spider in the bushes, squeezes out a depression in its densest part, makes a small lining, and the nest for her 2-3 testicles is ready.

Our sparrows often breed chicks in the walls of the nests of other, larger birds, such as a stork or a kite. Skillfully diving grebe (crested grebe) arranges a nest on the water. Sometimes its nest is fortified at the bottom of a shallow reservoir and rises as a small island, but more often it floats on the surface of the water. Surrounded by water and a coot's nest. This bird arranges even a gangway - on them the chicks can go down to the water and return to the nest. Small jacanas sometimes nest on the floating leaves of tropical aquatic plants.

Some birds make nests in human buildings. Sparrows - on the cornices and behind the window frames. Swallows nest at windows, jackdaws nest in chimneys, redstarts nest under canopies, etc. There was a case when a heater made a nest in the wing of an airplane while it was at the airfield. In Altai, a wagtail nest was found, twisted in the bow of a ferry boat. It “floated” every day from one shore to another.

Hornbills live in the tropics of Africa and South Asia. At the beginning of nesting, rhinos - male and female - choose a hollow suitable for the nest and cover up the hole. When there is a gap through which the bird can barely squeeze through, the female climbs into the hollow and already from the inside reduces the inlet so that she can only stick her beak into it. The female then lays her eggs and begins incubation. She receives food outside from the male. When the chicks hatch and grow up, the bird breaks the wall from the inside, flies out and begins to help the male get food for the growing brood. The chicks remaining in the nest restore the wall destroyed by the female and again reduce the hole. This nesting method is a good protection against snakes and predatory animals climbing trees.

No less interesting is the nesting of the so-called weed chickens, or big-footed ones. These birds live on the islands between South Asia and Australia, as well as in Australia itself. Some weed hens place their eggs in warm volcanic soil and don't take care of them anymore. Others rake up a large pile of decaying leaves mixed with sand. When the temperature inside the heap rises sufficiently, the birds tear it open, the female lays eggs inside the heap and leaves. The male restores the pile and stays near it. It does not incubate, but only monitors the temperature of the heap. If the heap cools down, it enlarges it; if it heats up, it breaks it. By the time the chicks hatch, the male also leaves the nest. Chicks start life on their own. True, they emerge from the egg with already growing plumage, and by the end of the first day they can even fly up.

In Great Grebe, as in all brood species of birds, chicks become independent very early. They have long been able to swim, but sometimes rest on the back of an adult bird.

When building a nest, not all birds have a male and a female working the same way. Males of some species arrive from wintering earlier than females and immediately start building. In some species, the male completes it, in others, the female completes the construction, or they build together. There are species of birds in which the male only carries the building material, and the female puts it in the right order. In goldfinches, for example, the male is limited to the role of an observer. In ducks, as a rule, only females build a nest, drakes do not show any interest in this.

Some birds (petrels, guillemots) lay only one egg each and nest once per summer. Small songbirds usually lay 4 to 6 eggs, and the great tit - up to 15. Many eggs are laid by birds from the hen order. The gray partridge, for example, lays 18 to 22 eggs. If for some reason the first clutch fails, the female lays another, additional one. For many songbirds, 2 or even 3 clutches per summer is normal. In the Thrush warbler, for example, the first chicks have not yet had time to fly out of the nest, when the female starts building a new nest, and the male alone feeds the first brood. In the water moorhen, the chicks of the first brood help their parents feed the chicks of the second brood.

In many species of owls, the number of eggs in a clutch and even the number of clutches varies depending on the abundance of food. Skuas, gulls, snowy owls do not hatch chicks at all if there is very little food. Crossbills feed on spruce seeds, and during the harvest years of spruce cones they nest in the Moscow region in December - January, not paying attention to frosts of 20-30 °.

Many birds begin incubation after the entire clutch has been laid. But among owls, harriers, cormorants, and thrushes, the female sits on the first laid egg. The chicks of these bird species are hatched gradually. For example, in the nest of a harrier, the eldest chick can weigh 340 g, and the youngest - the third one - only 128 g. The age difference between them can reach 8 days. Often the last chick dies due to lack of food.

As a rule, most often the female incubates the eggs. In some birds, the male replaces the female from time to time. In a few species of birds, for example, in the phalarope, painted snipe, three-fingered, only the male incubates the eggs, and the female does not show any concern for the offspring. It happens that males feed incubating females (many warblers, hornbill), in other cases, females still leave the nest and leave eggs for a while. Females of some species go hungry during incubation. For example, a female common eider does not leave the nest for 28 days. By the end of incubation, she becomes very thin, losing almost 2/3 of her weight. The female emu can starve during incubation without much harm to herself for up to 60 days.

In many passerine birds, as well as woodpeckers, kingfishers, storks, chicks are born blind, naked and helpless for a long time. Parents put food in their beaks. These birds are called chicks. As a rule, their chicks fledge in the nest and fly only after leaving the nest. Chicks of waders, ducks, gulls emerge from eggs sighted and covered with down. Having dried a little, they leave the nest and are able not only to move independently, but also to find food without the help of their parents. These birds are called brood. Their chicks grow and fledge outside the nest.

It rarely happens that an incubating bird, or especially a bird at the brood, tries to hide unnoticed at the moment of danger. Large birds, protecting their brood, attack the enemy. A swan can even break a person's arm with a blow of its wing.

More often, however, the birds "take away" the enemy. At first glance, it seems that the bird, saving the brood, deliberately distracts the attention of the enemy and pretends to be lame or shot. But in fact, the bird at this moment has two opposite aspirations-reflexes: the desire to run and the desire to pounce on the enemy. The combination of these reflexes creates the complex behavior of the bird, which seems conscious to the observer.

When the chicks have hatched from the eggs, the parents begin to feed them. During this period, only one female walks with black grouse, capercaillie and ducks with a brood. The male does not care about the offspring. Only the female incubates at the white partridge, but both parents walk with the brood and “take away” the enemy from it. However, in brood birds, parents only protect the chicks and teach them to find food. The situation is more complicated in chicks. As a rule, both parents feed here, but often one of them is more energetic and the other is lazier. So, in a large spotted woodpecker, the female usually brings food every five minutes and manages to feed the chicks three times until the male arrives with food. And in the black woodpecker, the chicks are fed mainly by the male.

In the sparrowhawk, only the male hunts. He brings prey to the female, who is inseparably at the nest. The female tears the prey into pieces and gives them to the chicks. But if the female died for some reason, the male will put the brought prey on the edge of the nest, and in the meantime the chicks will die of starvation.

Large birds cormorants usually feed chicks 2 times. per day, herons - 3 times, albatrosses - 1 time, and moreover at night. Small birds feed chicks very often. The great tit brings food to the chicks 350-390 times a day, the killer whale - up to 500 times, and the American wren - even 600 times.

The swift sometimes flies as far as 40 km from the nest in search of food. He brings to the nest not every caught midge, but a mouthful of food. He glues the prey with saliva. a lump and, having flown to the nest, deeply sticks balls of insects into the throats of the chicks. In the first days, the swifts feed the chicks in such enhanced portions up to 34 times a day, and when the chicks grow up and are ready to fly out of the nest, only 4-6 times. While the chicks of most bird species, having flown out of the nest, still need parental care for a long time and only gradually learn to find and peck prey without the help of their parents, the chicks of the swifts feed and fly on their own. Moreover, departures from the nest, they often immediately rush to the south. Sometimes the parents are still hovering over the houses, collecting food for their chick, and he, feeling strong enough, is already heading south without even seeing his parents goodbye.