These mysterious feelings
Organs of taste and smell in birds
The organs of taste in birds are represented by taste buds located in some parts of the beak and tongue, near the ducts of glands that secrete a sticky or liquid secret, since the sensation of taste is possible only in a liquid medium. A pigeon has 30-60 of these taste buds, a parrot has about 400, and ducks have a lot of them. For comparison, we point out that in the human oral cavity there are about 10 thousand taste buds, in a rabbit - about 17 thousand. Nevertheless, birds well distinguish between sweet, salty and sour, and some, apparently, bitter. Pigeons develop conditioned reflexes to substances that create such sensations - solutions of sugar, acids, salts. Birds have a positive attitude towards sweets.
Smells are not as indifferent to birds as previously thought. For some of them, they play a very significant role in the search for food. It is believed that corvids, such as jays and nutcrackers, search for nuts and acorns under the snow, focusing mainly on smell. Obviously, petrels and waders have the best developed sense of smell, and especially the nocturnal New Zealand kiwis, which, apparently, get food, guided mainly by olfactory sensations. Features of the microstructure of the olfactory receptors of birds led some researchers to the conclusion that they have two types of odor perception: on inspiration, as in mammals, and the second on exhalation. The latter helps the odor analysis of food already collected in the beak and formed a food portion in its back. Such a lump of food in the choanal area is collected before swallowing in the beak of chickens, ducks, waders and other birds.
Recently it has been suggested that the olfactory organ plays a role in the period preceding reproduction. Along with other rearrangements in the body of birds at this time, there is a strong increase in the coccygeal gland, which has an odorous secret specific to each species. In pre-nesting time, members of the same pair, along with other ritual postures, often take a position in which they touch each other's coccygeal gland with their beak. Perhaps the smell of her secret serves as a signal that triggers a complex of physiological processes associated with reproduction.
The olfactory abilities of birds are questioned by many. The differences in the complexity of the organization of the organs of smell in birds and mammals are too great for them to use this sense equally. Still, many ornithologists admit that tropical honeyguides find wild bee hives in part by the peculiar smell of wax. During the breeding season, many tube-noses often burp a dark, sharp-smelling liquid from the stomach - "stomach oil", which often stains nests and chicks. It is believed that in a dense colony, individual differences in the smell of this receptor help them find their offspring. The South American nightjar guajaro detects the fragrant fruits of trees, probably also by smell.
The olfactory analyzer is developed in different birds to varying degrees. But the mechanism of its functioning is largely the same as in other vertebrates. This is confirmed, in particular, by electrophysiological studies.
Didn't I believe?
The organs of taste in birds are represented by taste buds located in some parts of the beak and tongue, near the ducts of glands that secrete a sticky or liquid secret, since the sensation of taste is possible only in a liquid medium. A pigeon has 30-60 of these taste buds, a parrot has about 400, and ducks have a lot of them. For comparison, we point out that in the human oral cavity there are about 10 thousand taste buds, in a rabbit - about 17 thousand. Nevertheless, birds well distinguish between sweet, salty and sour, and some, apparently, bitter. Pigeons develop conditioned reflexes to substances that create such sensations - solutions of sugar, acids, salts. Birds have a positive attitude towards sweets.
Smells are not as indifferent to birds as previously thought. For some of them, they play a very significant role in the search for food. It is believed that corvids, such as jays and nutcrackers, search for nuts and acorns under the snow, focusing mainly on smell. Obviously, petrels and waders have the best developed sense of smell, and especially the nocturnal New Zealand kiwis, which, apparently, get food, guided mainly by olfactory sensations. Features of the microstructure of the olfactory receptors of birds led some researchers to the conclusion that they have two types of odor perception: on inspiration, as in mammals, and the second on exhalation. The latter helps the odor analysis of food already collected in the beak and formed a food portion in its back. Such a lump of food in the choanal area is collected before swallowing in the beak of chickens, ducks, waders and other birds.
Recently it has been suggested that the olfactory organ plays a role in the period preceding reproduction. Along with other rearrangements in the body of birds at this time, there is a strong increase in the coccygeal gland, which has an odorous secret specific to each species. In pre-nesting time, members of the same pair, along with other ritual postures, often take a position in which they touch each other's coccygeal gland with their beak. Perhaps the smell of her secret serves as a signal that triggers a complex of physiological processes associated with reproduction.
The olfactory abilities of birds are questioned by many. The differences in the complexity of the organization of the organs of smell in birds and mammals are too great for them to use this sense equally. Still, many ornithologists admit that tropical honeyguides find wild bee hives in part by the peculiar smell of wax. During the breeding season, many tube-noses often burp a dark, sharp-smelling liquid from the stomach - "stomach oil", which often stains nests and chicks. It is believed that in a dense colony, individual differences in the smell of this receptor help them find their offspring. The South American nightjar guajaro detects the fragrant fruits of trees, probably also by smell.
The olfactory analyzer is developed in different birds to varying degrees. But the mechanism of its functioning is largely the same as in other vertebrates. This is confirmed, in particular, by electrophysiological studies.
In general, the sense of smell in birds is very poorly developed. This correlates with the small size of their olfactory lobes and the short nasal cavities located between the nostrils and the oral cavity. The exception is the New Zealand kiwi bird, in which the nostrils are at the end of a long beak and the nasal cavities are elongated as a result. These features allow her to stick her beak into the soil, sniff out earthworms and other underground food. It is also believed that vultures find carrion with the help of not only sight, but also smell.
The taste is poorly developed, because the lining of the oral cavity and the integument of the tongue are mostly horny and there is little space for taste buds on them. However, hummingbirds clearly prefer nectar and other sweet liquids, and most species reject highly acidic or bitter foods. However, these animals swallow food without chewing, i.e. seldom hold it in the mouth long enough to subtly distinguish the taste.
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Sense organs in birds. Tactile, temperature, pain sensitivity and hearing are well developed in birds. They perceive sounds with a frequency of oscillations from 200 to 20,000 Hz per second (absolute thresholds in chickens are in the range of 90-9000 Hz), the sound strength should not exceed 70-85 dB, although they can adapt to sound strengths up to 90 dB ( stronger sounds negatively affect the state of the central nervous system and productivity).
Sound alarm. In chickens, 25 sounds are described that they make "when communicating." This is more than in cats and pigs. Only seven varieties of danger signals were found in them.
It has been established that chick embryos communicate with each other by “tapping”, making clicking sounds. Following the example of the leader who first gave the sound, his brothers also begin to try the voice and switch to lung breathing, which accelerates their growth and formation. Sound signaling during the period of embryonic development of birds ensures synchronization of the hatching of chicks from eggs, allowing them to leave the shell together even under conditions wildlife the whole family quickly leave the nest, avoiding encounters with predators. For better synchronization of the output of chickens, an incubator is sounded using an electronic device. The apparatus is turned on on the 17th day of egg incubation. It broadcasts clicking sounds recorded from embryos, which allows you to reduce the hatch of chicks from a batch of eggs received from different laying hens to one day. The additional connection of the imitation of the voice of the mother hen, calling the chickens, speeds up their exit from the trays and the desire to move to the call of "mother" - "follow me".
The organs of vision in most species of poultry (pigeon, goose, duck, turkey) play an important role and are therefore relatively well developed. The structure of the eye is somewhat different from the structure of the eye of mammals. So, the eyeball in a bird is not spherical, but flattened in front and behind, while in ducks it has a conical shape. The most convex cornea in predators, the least convex in waterfowl. The cornea and bone plates do not allow the eyeball to deform under air pressure during flight, under water pressure when immersed in it, or under the action of oculomotor muscles.
The eye of a bird is distinguished by unusually fast and precise accommodation, especially developed in predators. Accommodation is carried out not only by changing the curvature of the lens, but also by changing the shape of the cornea. The next feature of the eye is the ridge. This is an irregular quadrangular plate, located in the thickness of the vitreous body at the entrance of the optic nerve. The crest is credited with the function of nourishing the vitreous body and retina. It is also suggested that the ridge regulates intraocular pressure (which changes with rapid accommodation) and serves as an auxiliary device for observing moving objects. He is also credited with the function of heating the eyeball, which is important mainly for birds flying at high altitudes. In birds, as in mammals, a layer of cones is located in the visual part of the retina (there are especially many of them in diurnal birds). The cones provide visual acuity. They contain oily colorless, blue, green, orange and reddish droplets that determine color perception. The zone of best vision in the retina of the mammalian eye is only one, while birds can have two or three of these zones. This is due to the nature of the location of the eyes, which in most birds are turned in opposite directions. This arrangement of the eyes limits the area of binocular vision to a very small area at the level of the continuation of the beak, where the visual field of the left and right eyes overlaps. The visual field of each eye produces a predominantly flat image. It is very large: birds can see objects behind them. In pigeons, the angle of view of each eye is 160 °. The bird compensates for the lack of three-dimensional (binocular) vision by changing the position of the eyes when turning the head. Birds have a well-developed third eyelid - the nictitating membrane, which is usually collected in the inner corner of the eye, but can cover the entire visible part of the eyeball.
Different types of birds have different visual acuity. Geese recognize individuals of their own species at a distance of up to 120 m, ducks - up to 70-80 m. To peck the grain again, the chicken must increase the distance between the grain and the eye by at least 4 cm. Birds of all species, when choosing food, pay attention primarily to the size of its particles. They have an innate sense of proportion regarding the size of a particle that they can easily swallow. This measure changes with age in proportion to the increase in the size of the esophagus and beak. The shape of the chick feed particles is not important. Only during their life they learn to recognize the shape of food objects.
Hearing. Birds do not have an external ear; instead, most species have a skin fold or a bundle of thin feathers surrounding the entrance to the external auditory meatus. In a waterfowl, the feathers at the entrance to the external auditory meatus are located so that during their stay under water they completely close it. The external auditory canal is short, wide and covered by the tympanic membrane. The connective tissue membrane does not have its own bone base, but is attached directly to the cranial bone. Sound waves are perceived by the tympanic membrane and transmitted as vibrations through the column (the only auditory ossicle) to the perilymph and endolymph of the inner ear. The inner ear consists of a bony canal and membranous labyrinths located inside it, divided into an organ of hearing and an organ of balance. The organ of hearing is formed by the cochlea, the organ of balance - by the vestibule and semicircular canals.
The bird's hearing is very well developed. Predator birds they hear the squeak of a mouse even at a distance of 60 m. Of poultry, hearing is best developed in chickens, whose ancestors lived in virgin forests, where good hearing was in dense bushes the best remedy protection than sharp eyesight. The good development of hearing in chickens is also evidenced by the fact that the chick in the egg already a day before hatching reacts to changes in external environment frightened squeak, but subsides when the mother hen calms him down with a deep cluck. Immediately after hatching, the chicks can hear their mother in the dark at a distance of up to 15 m. By their characteristic clucking, they individually recognize the mother and run to her, not paying attention to other hens sitting near her. Mother hens can also recognize their chicks by squeaking at the same distance, even if there are other noise sources within a radius of 1 m around them. The mother's voice attracts the chicks more effectively than her appearance, even at a distance of about 50 m to the sound source. Chickens recognize a familiar bird distributing food only from a distance of 25 m. If sounds come from above, in front and behind, then chickens and adult birds are not able to establish the direction of sound sources, since sound waves come from these sources at the same distance.
If the chick has lost its brood, it makes piercing plaintive sounds, to which the hen responds with increased frequent clucking. The chick determines its location by running quickly in different directions and listening to the signal of the hen from different points. He determines the correct direction when sound waves are perceived successively by the right and left ears. The absence of an auricle, which improves the location of sounds, is apparently compensated for by the high flexibility and mobility of the neck, which makes it possible to quickly turn the head in different directions.
Everyone is familiar with the calls of birds that serve as an alarm signal; they were recorded and even managed to be used to protect crops from crows and fisheries from seagulls. With their cry, the sentinels even inform about what kind of enemy is approaching, and from the ground or from the air it is necessary to wait for him. After the signal, all the birds freeze in immobility and are silent, especially the chicks, which immediately stop squeaking. Cubs, feeling hunger or fear, yell with might and main, and sometimes (more often chickens and ducklings) make a sound expressing, as it were, pleasure. Everyone knows the call of a chicken. With it, you can call the chickens to the speaker through which it is broadcast; therefore, it is not necessary for the chicks to see the hen. In the same way, a mother can be attracted by the inviting sound of a chicken; but put a chicken under a soundproof glass jar, and the chicken, seeing it perfectly, will pass by indifferently.
skin feeling in birds, it is carried out mainly by tactile bodies located on non-feathered parts of the body, especially in the beak wax. However, sensitive nerve endings, closely adjacent to epithelial cells, penetrate the skin of other parts of the body. They also contribute to the perception of heat and pain sensations. Much more often in birds, there are organs of touch that lie under the epidermis of the connective tissue (Herbst's bodies), under large feathers (tail and flight feathers), as well as in the skin of the paws and thighs. They are credited with the ability to respond to changes in pressure. Large bodies of this type, embedded in the mucous membrane of the tongue and along the edges of the beak, make it possible to determine the size, shape, texture and degree of hardness of food objects.
Birds constantly groom their feathers. This is especially important for waterfowl, which ensure that the feather is not wetted by lubricating it with the secretion of the coccygeal glands.
Composition and properties of the secretion of the coccygeal gland. On visual examination, the secret of the coccygeal gland can be characterized as a thick liquid of light yellow color with a faint smell of goose fat. In a biochemical study, it turned out that the content of dry substances in the secretion of the coccygeal gland is 37.30-44.2%. The reaction of the secret is slightly alkaline. Most of the secret consists of lipids. The secret of the coccygeal gland contains a number of minerals. Interestingly, the amount of some components of the secret in drakes and ducks differs. For example, ducks have 16.9 mg/g more total protein and 0.97 mg/g more sodium than drakes.
It was found that when cultivating Staphylococcus aureus and Escherichia coli on agar in the zone of application of discs moistened with the secretion of the coccygeal gland, a clearing zone of 15 mm for Escherichia coli and 10 mm for Staphylococcus aureus is formed. This confirms the bacteriostatic properties of the secretion of the coccygeal gland in relation to both gram-positive and gram-negative microflora. The relative mass of the coccygeal glands depends not only on age, nutrition, but also on the intensity of contact of ducks with water. With prolonged restriction of access to water for bathing, the relative weight of the oil glands in Peking ducks decreases by 0.02-0.03% of body weight. Extirpation of the coccygeal glands in Peking ducks, both at an early age and in adults, does not cause emaciation and rickets. After extirpation of the coccygeal glands in Peking ducks, there are no changes in the number of erythrocytes, leukocytes, blood volume, hemoglobin concentration, hematocrit, and acid capacity of the blood. Extirpation of the coccygeal glands in Peking ducks entails significantly pronounced changes in the concentration of proteins, lipids, glucose, and inorganic phosphate in the blood.
The organs of taste in birds are poorly developed. The organs that perceive taste stimuli are either barrel-shaped formations (like the taste buds of mammals) or low, highly elongated formations equipped with a relatively powerful layer of supporting cells (as, for example, in lamellar beaks). The tongue and hard palate are covered with a powerful stratum corneum, in which taste buds can hardly be located. Taste bodies are located in the root of the tongue on its sides and at the bottom of the oral cavity, in the soft palate and near the larynx. Birds of all kinds distinguish between salty, sour, bitter and sweet, and the sensitivity to bitter in domestic birds is only slightly developed. Waterfowl, however, reject bitter solutions in concentrations that are unpleasant to humans. Sensitivity to sweets is also poorly developed in birds. Malt and milk sugar are practically tasteless to birds, and artificial sweet substances, such as saccharin, are perceived by them as sour rather than sweet. The taste of glycerin, which a person evaluates as sweet, is also perceived by birds, the same can be said for weak salty-bitter solutions. However, it remains open question what taste these substances have for birds - sweet or bitter. Sensitivity to bitter in all species of birds is similar to that of humans. In chickens, taste plays a very small role in food selection. Although chickens prefer certain foods over others, they are guided by visual or tactile perception.
The organs of smell in birds are very poorly developed. Goblet-shaped sensory cells dotted with very short hairs are located in the epithelium of the nasal mucosa lining the dorsal concha and septum. The bird has no structures that perceive smell at all. In numerous experiments, it was not possible to teach the pigeon to distinguish between the smell of anise and rose oils. The weak development of the bird's sense of smell is also evidenced by the fact that laying hens drink slurry. The smell of spoiled eggs does not bother them, and they often peck at strong-smelling substances such as manure, compost, etc.
The bird's memory is poorly developed. It depends on the species of birds, age, duration and intensity of stimuli, and many other factors. It takes about 100 repetitions to teach a chicken to peck the larger of two grains of corn. To restore a skill after a seven-month break, 24 repetitions are required, and after the next four-month break, 15 repetitions. Adult chickens, if they are not let out for walking for two weeks, no longer remember that the attractive-looking sorrel is almost inedible for them. On the other hand, hens prefer grains of corn for many months if they received it for at least two days and had to learn to peck it, despite the large size of the grains. The bird remembers familiar places very badly. The hens remember the placement of the feeders in which they received their favorite food for three weeks; in chicks, this time is shorter - until 10 weeks of age, chicks, as a rule, do not remember their own favorite place on a walk. They quickly find other similar places and just as quickly forget them. Pullets remember their former premises or walking for about three weeks, and after four weeks they treat them as strangers. An adult chicken finds its place in the old environment after 30 days, after 50 days it does it with difficulty, and after 60 days everything is new for it here.
The duration of the period after which the members of the flock still recognize the temporarily removed individual after its return was studied. It turned out that if young males that grew up together in a herd with an established social hierarchy are returned there after their two-week absence, then the members of the group perceive these individuals as strangers, since social order in the herd during this time has changed. The period of habituation of adult birds to each other is on average 3-4 weeks. The duration of the habituation period depends on the breed, physique, social status and individual characteristics of the individual. Light breed roosters renew their relationship by fighting in as little as 14 days, while heavy breed roosters take a month or more to do so. There is nothing surprising in the fact that the rooster does not forget his defeat even after six months, especially in cases where he was persecuted by a despotic individual.
group behavior. All types of poultry are social, and the behavior of each individual is influenced by its relationship with other members of the flock. In ducks, at the end of winter, the sexual instinct intensifies, which entails a spring increase in pugnacity among both drakes and ducks. Weak individuals submit to stronger ones after repeated defeats. After that, all individuals are guided in their relations by newly emerged social ties. By the end mating season this order disappears, and the ducks rarely interact with each other. The superiority of stronger individuals does not remain strong due to the frequent resistance of subordinates. Therefore, individuals that dominate mainly during feeding and mating can often be replaced.
In geese, the goose is the leader of the herd, all other individuals obey him. He and other high-ranking individuals provide themselves with certain advantages in obtaining food and in conflicts with other herds. The social unit is the family, where natural conditions goslings usually grow under the supervision of their parents. Upon reaching puberty, new hierarchical bonds are formed between the goslings. High-ranking individuals use their superiority not only when feeding, but also in all other cases when subordinate individuals try to counteract them.
A flock of birds is not an unorganized collection of individuals whose behavior is determined by random circumstances. There is a strict hierarchy here. The whole group obeys the leader. An individual is considered dominant if it is more aggressive than others in the group and enjoys advantages in reproduction, feeding and movement.
When they counted the beak blows that young cockerels reward each other with, they found out that among them there is an “alpha”, which pecks everyone, while no one dares to touch it, and an “omega”, which everyone pecks and sometimes pecks to death - he doesn’t even trying to defend himself. The first three days after hatching from the egg, any moving object puts the chicken to flight: he hurries to take refuge under the wing of his mother. A week passes, the chickens begin to run around poultry yard in all directions, spreading the wings; from the second week, semblance of battles arise between them: two chickens jump on each other exactly like adult roosters, but they still do not use their beak.
Between the fifth and sixth weeks, the fights become more serious, the opponents are already putting their beak into action, although not too hard; one of the combatants may retreat, then return and again beat the opponent with his beak.
Fights, during which relations of domination and subordination are established, begin later. At what age, it is difficult to determine: it depends to some extent on external conditions, on the characteristics of the group, etc.
Apparently, chickens recognize the birds of their breed - in leggorns this ability manifests itself at ten days of age. Hens are much less aggressive than males, which also attack females; however, by the time of puberty, roosters stop attacking chickens.
In chickens, a special hierarchy is also established, and a certain order is finally formed for them by the ninth week, while for males by the seventh. This order is not so unshakable; changes are possible due to the fact that not all individuals develop at the same pace. Such changes can be controlled by temporarily isolating individual birds, and they are able to recover from beak blows.
Hens can be isolated from the day of birth, and rejoin the group only after the control individuals growing in the group have already established order in themselves.
Bettas are another matter: when they are brought together after being kept in isolation, they quickly establish new order, proving in this way that they do not have to live together with early age. Isolated bettas after association turn out to be even more aggressive than those raised in a group.
Interestingly, the introduction of male sex hormones to young bettas almost does not change the established relationship of submission and dominance, while with the introduction of female hormones, they apparently become more "phlegmatic" - they avoid fights and do not tend to respond to blows with their beaks. Similar results were obtained in chickens: those that receive male hormones "raise in rank" somewhat (however, the difference from control birds is very small); the female hormone acts much more strongly, significantly reducing the "rank" of the individual. After order has finally been established in a group of young chickens, some of them can be transferred to another group, and then returned to the first group after a few days. The same individuals in different groups may be at different levels of the hierarchy.
Especially strong relationships of superiority and submission are found in chickens. Here, each individual has its own specific place and recognizes it without resistance (unlike what we see in ducks and pigeons). How relationships are formed in the herd can be judged on the basis of observations of the behavior of growing chickens. In the first days after being transferred to the poultry house, the chickens show signs of social instinct: they run among other chickens and seek their company. At the same time, their behavior is not related to the behavior of partners: each chicken does everything on its own. Only when he notices that he was left alone, he begins to squeak plaintively, looking for partners or a hen. In relation to strangers, chickens are indifferent as long as there are no too sharp age differences between them. At the age of 2-3 weeks, the older ones begin to peck the younger ones in the head, in the tail, etc.
The tendency for the formation of social ranking occurs in chicks at the age of 2-3 weeks, when fights begin to occur between them, while still in the form of a game. These encounters, which involve both males and females, give them the opportunity to get to know and appreciate each other. After a short time, such tests of strength cease and a free union is formed, which lasts until puberty.
With the onset of puberty, new, more serious, often bloody fights for dominance begin, the consequence of which (at the age of 8-10 weeks) is the emergence of a social hierarchy. This is a very strong order, which allows individuals of higher ranks to drive low-ranking birds away from feeders, drinkers, nests, peck them, etc., or to prevent low-ranking males from mating. As soon as the social hierarchy is established, the number of attacks in the herd usually decreases, with the help of which individuals previously sought to strengthen their position. This period of formation of the hierarchy continues in newly formed communities or flocks for 2-3 weeks.
As long as the number of chickens reared together remains within natural limits (50-100 per group), the birds are able to individually identify each other, and social status each is completely regulated. Among roosters, social ranking is more pronounced than among hens. While the stronger hen is usually content to drive the lower hen away from the food with a peck or a sudden movement, the rooster does not tolerate his opponent at all in his vicinity and drives him out of his sphere of activity with a radius of about 5 m.
Feeding behavior of birds. Birds' evaluation of food, i.e., the preference given to certain food over others, is a product of optical and tactile perception. This preference depends on the type of food offered and the amount of time the bird has to consume it. Turkeys and chickens require significantly more time to satiate when eating mealy feeds than when eating grains or pellets (turkeys, for example, take 16 minutes to saturate with pellets, 136 minutes with mealy feeds).
The palatability of food is largely influenced by the structure of the beak. The small and pointed beak of chickens and pigeons is adapted for grasping relatively small hard grains. Geese with their hard and flat beaks equally easily nibble grass and grab grains. The wide and long beak of ducks is adapted for capturing soft wet food, consisting mainly of aquatic plants and animal organisms. Therefore, it is difficult for ducks to pick up individual small grains of 3-4 mm, while chickens and pigeons can peck at gravel grains of 0.5-1 mm. Given a choice, they prefer 1.5-2 mm grains. The optimal particle size for poultry feed is determined primarily by the size of the beak and the width of the esophagus.
In chickens and geese, wheat grains satisfy these parameters, in pigeons - hemp, in ducks - corn.
Granular feed of the appropriate size is usually consumed immediately by the bird; in the absence of feed with particles of the required size, preference is given to smaller particles. To eat large grains, the bird must be accustomed, for which it usually needs to starve. If the bird overcomes the initial dislike, then later on it always chooses the largest grains from the feed first of all. Only with the onset of saturation does she begin to eat more small grains, which are easier for her to swallow.
The condition also plays an important role. environment. With an increase in ambient temperature, the palatability of feed decreases rapidly. If at the same time the body temperature rises above 42 ° C, the chickens stop pecking at the food, get worried and excitedly run from place to place. It is of interest to observe the rate of feed consumption with different methods of distribution in the conditions of cage keeping of chickens. Cage batteries with a chain feeder are switched on automatically at regular intervals in most cases. The hens become so accustomed to these intervals that already a few minutes before the feeder is turned on, they stick their heads out of the cage and rarely take the feed that is in the feeder. As soon as the chain starts to move, all the hens start pecking at the same time, although there was the same feed in the feeder before the chain was turned on. Something similar happens with the distribution of feed by straddle carriers. The hens begin to peck the feed mainly after the passage of the loader, even in cases where an empty cart passes, which does not supply any feed to the feeders.
The speed of feed intake also depends on whether the bird has free access to feed or this access is limited in time. Changes in the form of feed (loose mixture, granules, grains) also caused its increased consumption if the bird got used to a new type of diet. So, when the granules are replaced with a loose mixture for a bird that was constantly receiving granular feed, the palatability of the latter decreases and rises again only after getting used to it (after a few days). When placing feeders and drinkers in the poultry house, it is necessary to remember the tendency of birds to form groups, for which it is necessary to provide areas of about 12-15 m in size. In order not to force the hens to leave their site, a feeder, a drinker and nests for oviposition are placed in it. Therefore, the distance between these points should not exceed 3-5 m.
Relations of social superiority are clearly manifested in the lack of fronts for feeding and watering. So, interesting results were obtained from observations of laying hens placed on a slatted floor. For the distribution of feed, two belt conveyors were used, which were switched on 4 times a day, and thus there was 7.62 cm of feeding front per laying hen. When distributing the wet mixture, the hens crowded around the feeders, and here the strongest pushed the weakest, who later, after the saturation of the strongest, did not dare, as a rule, to approach the feeders. With this method of feeding, the average egg production for the last week was 2460 eggs. After the frequency of feeding increased to 7 times a day, the hens no longer crowded at the feeders, and weaker individuals approached the feed. As a result, egg production gradually increased. After 3 weeks, when the frequency of feeding was again reduced to 4 times a day, egg production began to decline, reaching a level below the original.
Along with habituation, the frequency of feeding is also important in cases where chickens do not have constant access to feed. When hens were chain fed 6 times a day, the average monthly egg production was 22.8 eggs at a feed intake of 122 g per bird per day. Since a significant part of the feed was returned back to the silo, the frequency of feeding was reduced to 2 times a day. In this case, part of the feed was also returned to the bunker. However, the movement of the feeder chain encouraged the birds to increase feed intake, and the average feed intake during the month was 103 g per bird per day. Due to reduced feed consumption, egg production dropped to 19.4 eggs per month. With a repeated increase in the frequency of feeding, it increased to 21.9 eggs, which was accompanied by increased feed intake.
For chickens and adult birds, a certain rhythm in feed consumption is characteristic, which depends on the intensity of metabolism, the time of emptying the goiter and stomach. Chicks eat better with constant access to feeders; this creates an equal opportunity for fast feeders and slow eaters. It is also important whether the chicks approach the feed singly or in groups. In an adult bird, under natural conditions, one can observe a special rhythm of alternating periods of increased activity and rest.
Pullets are most active between 04:45 and 06:45, 10:45 and 12:45, 16:45 and 18:45.
Hens older than 12 weeks significantly limit their activity and approach feed less often than drinkers. In their free time, they find perches and sleep on them.
After the establishment of the social hierarchy, the hens of the lower ranks remain sitting on the roosts and begin to search for food later, when the individuals of the higher ranks return to the roosts.
2 Object of study, materials and equipment: 1. Chickens, goslings, ducklings, chickens of both sexes, geese and ducks. 2. Drawings and diagrams on the topic. 3. Ethogram forms, pen (pencil); camera, film or video camera, tape recorder; clock, a device for measuring the intensity of movement (pedometer), measuring and recording equipment for telemetry; kit different types grain and flour feed; areas in the house with different air temperatures, with different air speeds.
A team of biologists has determined that the sense of smell is just as important to birds as sight or hearing. In addition, scientists were able to find out that sensitivity to odors depends on the habitat of birds: than more important role smells to search for food in a given area, the more “subtle” is the sense of smell of birds. The researchers' work was published in Proceedings of the Royal Society B.
In their work, an employee of the Ornithological Center at the Max Planck Institute Silke Steiger (Silke Steiger) and her colleagues compared the representation of olfactory receptor genes in various kinds birds.
Olfactory receptors located on sensory neurons of the olfactory epithelium are responsible for the perception of odors. It is believed that the number of genes for these receptors correlates with the number of odors that a given organism can distinguish from each other.
In their research, biologists determined the number of olfactory receptor genes in nine species of birds. They found that their number can differ several times from species to species. So, in the DNA of the southern kiwi, there are six times more genes for olfactory receptors than in the DNA of blue tit or canary.
The scientists also tested how many of these genes are functional. In organisms where the importance of smell for survival is reduced, mutations accumulate in the genes of these receptors, which eventually turn them off. So, in humans, up to 40 percent of the olfactory receptor genes are inactive. As Steiger and colleagues found, most of the receptor genes in birds are functional, which may indicate the importance of smell for their life.
Another difference between the studied species of birds, scientists found in their brains: the more olfactory receptor genes a bird carried, the larger was the size of its olfactory bulb, the brain structure responsible for processing information about odors.
Scientists have suggested that in birds, as in mammals, the number of olfactory genes may depend on their habitat. For example, the flightless southern kiwi finds food on the ground. Kiwis are found only in New Zealand. Northern kiwi (Apteryx mantelli) inhabits the North Island, common (A. australis), large gray (A. haasti) and rowi (A. rowi) - the South island, while small kiwi (A. oweni) is found only on the island Kapiti, from where he is settled on some other isolated islands. Due to the secretive lifestyle, it is very difficult to meet this bird in nature.
Biologists believe that for this bird, the sense of smell can play the same, if not more, role than vision. Kiwis do not mainly rely on sight - their eyes are very small, only 8 mm in diameter - but on developed hearing and smell.
Among birds, condors also have a very strong sense of smell. In search of food, condors mainly use their excellent eyesight. In addition to searching for prey, they also carefully observe other nearby birds - ravens and other American vultures - turkey vulture, large and small yellow-headed catharts.
Catharths, with the help of their good sense of smell, find carrion, their main prey.
With catharts, condors have developed a so-called symbiosis, or mutually beneficial existence: catharts have a very subtle sense of smell, capable of smelling from afar the smell of ethyl mercaptan, a gas released during the first stage of decay, but their small size does not allow them to tear the strong skin of large prey as effectively as it can Andean condors.
According to scientists, their results prove that the importance of the sense of smell in birds has so far been underestimated.