Everyone sooner or later thinks about their offspring, and the animal world is no exception. Every year, in order to give the world new birds, adults arrange nests. In cold countries, as well as in latitudes with a temperate climate, birds begin to nest in the spring and finish in the summer. On the whole planet, this happens in different ways and depends on many factors - climatic and geographical. Somewhere the summer lasts all year round, and somewhere often there is a change of season.
Regardless of these factors, the rules are the same for everyone - adults, regardless of their habitat, begin to think about offspring precisely at a time when there is a great variety of food. The first days of feeding are especially important, so you should approach this issue very responsibly. For example, if in our strip birds do this in the warm season, then somewhere in the African expanses the birds begin to nest immediately after the rainy season passes, because it is at this time that the rapid development of greenery begins and great amount insects. An exception to the rule are birds of prey, whose diet consists of small animals. Predators begin to build nests during the dry period, when finding food is not difficult for anyone - the vegetation burns out, and the whole earth seems to be bare.
Caring for offspring in birds is a very complex and responsible process. But not everyone knows about the intricacies of this event. For example, many believe that all birds, in order to show offspring to the light, build special nests in which they incubate eggs. But it is not so. Most birds do without a nest, for example, the nightjar, as a rule, lays its eggs directly on the forest floor, and chooses soft needles for this. And the recess appears much later, over time, from the fact that the feathered mother constantly sits in one place. Guillemot also does not build nests, but lays its egg right on a ledge of bare rock, and seagulls need only a small depression in the sand.
According to the degree of maturity of chicks, birds are divided into two types: brood and chicks. In brood children, after birth, they are immediately ready for independent living and getting food. Chicks are not able to control their body temperature and need constant warming. The only thing they can do is raise their head a little while feeding.
If we talk about birds that still build nests, then first of all it is worth mentioning the thrush, which builds an incredibly complex structure in the form of a bowl and smears it with clay from the inside. The bird spends about three days building such a house, and works from early morning until late at night.
After the preparation and construction is completed, the responsible time comes to feed the little bird. The offspring of different birds is also different, someone has one offspring, and someone has a whole brood.
How do birds take care of their offspring? For example, a duck, capercaillie or black grouse approach this issue as follows: only the female deals with the fate of the children, and the father does not take any part in the life and development of his children. Only the mother hatches at the partridge, but both parents take care of safety and scare off enemies. Both parents feed the woodpecker, but, as a rule, the female does it more vigorously. By the time the father arrives with food, the mother already has time to feed up to three or four times. Only the male gets food from the hawk, and brings food to the female, who then feeds the children. Mom does not leave the nest while raising children. However, there are also parents who do not bother themselves at all and do not worry about their children. For example, if bad weather happens, then swifts can shamelessly leave the nest for several days. As you can see, the feeding of chicks in different individuals also occurs in different ways.
A variety of living conditions and different habitats form a perfect various forms existence, behavior and feeding. On our planet there are a great many species that are quite different from each other.
Large individuals, such as cormorants, feed their children several times a day, and albatrosses and herons generally once a day, and moreover at night. Small ones, on the contrary, do this very often, the tit brings food about four hundred times, and the swallow five hundred!
In search of the necessary food, parents can fly very far from the nest, as, for example, the swift does. In order to find the necessary food, adult bird can fly forty kilometers. The parent brings not one midge, but a whole beak of food. In the first days of life, the swift feeds its children up to forty times a day in very large portions, and when the chicks are already large and ready for independent flights, the amount of feeding is reduced to five times.
After the chick has hatched from the egg, passed the necessary period of feeding and maturation, and for the first time tried to make the first independent flight from the nest, a very important and crucial moment comes to enter adulthood. In order to try to start an independent life, many of them still need parental care and guardianship for a long time, and the process of adaptation occurs gradually. It also happens that after the first departure from the nest, the children immediately rush to the south, and the parents do not even suspect that their child is going to leave his father's house. In fact, no farewell occurs, and the children do not feel any attachment to the place of birth, and even more so to their parents, as well as the parents themselves quickly forget this fact and do not yearn for the children who left the nest so early.
Take care of our nature, be attentive to those who surround us on earth and soar high in the sky. Every life is complex and priceless. Nature has created everyone so different and at the same time similar. A person is obliged to take care of the inhabitants of nature and protect a priceless life.
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.
Boldly defend their nests gray herons. 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
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.
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Insects |
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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.
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. At 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 
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), while young mammals, on the contrary, in their behavior represent a certain 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 development specific forms activity of cubs from the mother. The behavior of the mother is characterized by maximum responsiveness to immature manifestations of the activity of the cubs - in response to them, the mother is included in joint activities with the cub, so that the "ripening" of specific forms of activity in the offspring does not occur 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 variability and instability 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 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. It reinforces and reinforces general scheme 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 effect of the mother and father on the cubs is exactly the opposite, leading their behavior to some 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).
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.
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