Reproduction, organ structure and development of birds (biology, grade 7)

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The middle zone is characterized by spring breeding and development of birds. In the spring, insects appear, it becomes warm, and building material for the nest is found. Ideal conditions are created for raising offspring.

Reproductive system

Birds are oviparous dioecious animals. Sexual dimorphism is most often pronounced. Males are more attractive than females.

The reproductive system of females is represented by the left ovary (the right one is reduced) and the oviduct. The absence of the right ovary is due to two reasons:

• one ovary significantly lightens the weight of the bird, which is important for flight;
• Only one large egg can pass through the narrow oviduct.

By the beginning of reproduction, the ovary swells with numerous follicles and takes on the appearance of a bunch of grapes. The oviduct - a long tube with internal glands - extends like a funnel from the ovary, passes into the extension (uterus) and opens outward into the cloaca, through which fertilization and release of the egg occurs.

Follicle is a structural part of the ovary, consisting of an oocyte and an epithelial layer. After maturation, the oocyte produces an egg, which passes from the ovary into the oviduct.

Males are characterized by the presence of paired testes, from which vas deferens extend, ending in a cloaca. Most birds do not have an external male genitalia. The exception is ducks, which have a spiral-shaped penis. Also, some species of birds (ostriches, geese, craxes) have a copulatory organ that extends from the wall of the cloaca.

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Biology (8th grade): Birds

The structure of the internal organs of birds

Rice. 1. The structure of the reproductive system of birds.

Mating Features

Most bird species have similar reproductive patterns. But still, each representative has its own individual characteristics.

The mating process can be examined in more detail using the example of chickens. Although it should be noted that females of this species can lay eggs without males . In this case, the egg comes out unfertilized.

At a certain period, the testes of males begin to rapidly increase in size. At this time they are ready to mate. A few days later the female lays eggs. Their number differs among individual species.

The mating period for different individuals can occur at different times. Some species will be ready to breed in the spring or summer, while others will wait until early autumn before laying eggs that will produce chicks.

Egg structure

The egg itself (ovum) - the yolk - is fertilized in the upper part of the oviduct and, passing from the ovary through the uterus to the cloaca, is covered with protein, films, and a calcareous shell. It takes 12-48 hours for the formation of an egg in the oviduct in different species of birds. The internal structure of the egg is described in detail below.

• Yolk . Consists of nutrients and water necessary for the development of the embryo. In the upper part of the yolk there is always a germinal disc or blastodisc - a small accumulation of cytoplasm with a nucleus. The blastodisc is isolated and stands out on the yolk as a light spot. An embryo develops from it. The yolk is covered by a membrane that separates it from the white.
• Protein . Protects and provides the embryo with water. The protein is surrounded on top by two dense shells, which separate at the blunt end, forming an air chamber. As the embryo grows, the chamber enlarges and the chick begins to breathe with a supply of air.
• Chalazy . Protein cords (clumps of protein) extending from the inner shell and holding the yolk suspended in the middle of the egg. The cords protect the embryo from shock and damage.
• Shell . The upper hard shell is permeated with numerous pores through which gas exchange occurs. The shell can be painted with a special pigment for camouflage in open nesting conditions. A thin shell covers the top of the shell.

Rice. 2. Internal structure of the egg.

The importance of birds in nature

Birds play an important role in biogeocenosis. They take part in many biological circuits. Herbivorous species eat fruits, seeds and shoots of plants. Some representatives store food, carrying it for many kilometers. Along the way, some of the seeds may be lost. This helps plants spread over large areas.

Insectivorous species are also important . With their help, insect populations are controlled. Without these birds, a person would not be able to get a good harvest from the sown fields.

People are trying to help birds survive difficult winters. They set up temporary nesting sites everywhere, where blue tits, flycatchers, and tits move in. During the cold period, birds feel a lack of food, so they need to be fed with bread crumbs, seeds or small fruits.

Some species are commercial. For example, these are black grouse, ducks, hazel grouse, and geese. They are considered quite valuable to humans. There are also birds that are used for sporting purposes. These are waders, snipe and woodcock.

Thus, birds, despite many differences in appearance, lifestyle, etc., have a large number of similar features and are very important in nature.

Emergence and development of chicks

Speaking briefly about the reproduction and development of birds, four behavioral features should be highlighted:

• pair formation;
• pairing;
• nesting;
• caring for offspring.

Males attract females for mating by organizing mating games. Birds singing, male fights, nest building, decorations and gifts are attributes of courtship or mating with a female. Depending on the species, males may seek a mate for life or seasonally.

After mating, the birds nest. They build their nests independently from clay, branches, pebbles, or occupy other people’s houses. Birds lay 1-20 eggs.

For the development of the embryo, high temperature (38-39°C) is required. Therefore, birds incubate the eggs, periodically turning them over. The formation of the embryo ends on days 16-40, depending on the species.

Rice. 3. Development of the bird embryo in the egg.

After the birth of the offspring, the birds show care for some time in pairs or individually. Based on the duration of development, chicks are divided into two groups. The characteristics of the groups are described in the table.

How many hens per rooster?

Having one male per dozen chickens, these birds reproduce quite successfully. A male with strength will simply torture 2-3 laying hens, and cockfights for the right to trample hens are guaranteed. If eggs and not offspring are needed, the rooster is isolated.

In males, the genital organs are a pair of yellowish-white testes with thin spermatic ducts that empty into the cloaca.

Roosters are quite loving birds if they are completely healthy and are not bothered by the molting period. The less the rooster has intercourse per day, the more “live” eggs there will be. Accordingly, the survival rate of chickens will increase. In general, try to have about 10-12 “ladies” per “gentleman”, and then the roosters and hens will get along peacefully with each other.

Before starting poultry farming, a farmer must decide why he needs chickens: to produce eggs for sale or to increase the number of birds themselves. Despite the fact that the rooster does not have a male organ as such, he behaves in the flock like a real alpha male.

After all, everyone knows that a rooster does not have a penis. The reproduction of chickens directly depends on the social structure of the flock. After all, chickens never live alone. There should be one rooster and many hens. If another male appears in the pack, then fights for leadership begin to arise until the complete victory of one of the contenders. In a fertilized egg, a blood clot can be seen in the yolk. And to look into the egg without damaging the shell, farmers use an ovoscope. To do this, they are placed in a separate room and are not allowed into the yard to see the rooster. You can close the rooster, but then fertilization in birds not affected by the claws will also stop.

Knowledge of how the reproductive organs of roosters and hens are structured will help keep the reproductive process under control. The reproductive organs of a chicken differ in that they are represented by only one ovary - the left one, since the right one atrophies over time.

Natalia, Brama chickens are generally late-ripening, the average age is 7-9 months, so we think it’s worth the wait. It is not difficult to keep chickens; they can eat table scraps. Compound feed is also needed, but it also pays off.

The rooster should be left confident. He must sing the loudest, but at the same time he should not fight for primacy, because with the help of his singing he already shows who is in charge here.

Birds reproduce with the support of the cloaca, which opens under the tail. A strong rooster can carry out up to 22 matings daily; this sign can decrease due to the period of the year and the activity of the birds. The quality of its seed depends on the frequency of mating. On the contrary, with a small number of matings, the quality of the seed improves.

How do chickens reproduce?

Hens and roosters reach sexual maturity at about the same time, and their first mating occurs after 25 weeks from the moment they hatch from the egg. But this is on average. The age of puberty depends on the breed. Large individuals of the meat breed mature a little later than egg-laying ones. Sexual activity of cockerels also depends on the breed. A “meat” cockerel can mate with ten hens; for him, a maximum of 20 females are kept in the chicken coop. For an egg breed cockerel, you can keep up to 25 hens.

On a note! The timing of sexual maturity also depends to a large extent on the conditions of keeping and nutrition of the bird.

Young males tend to be less decisive and when an older male is in the pen he will have the advantage. He will trample the females.

Having figured out whether chickens lay eggs without a rooster, you need to decide how many males to let into the chicken coop. The optimal ratio of hens and cockerels is 10:1. If there are more than ten females, the likelihood that some hens will lay dummies increases.

Attention! If there are less than ten hens per rooster in the chicken coop to satisfy their biological needs, he will simply torture the hens, this will negatively affect their egg production. In order for the number of flock to be constant, while guaranteeing a high degree of fertilization of eggs, it is necessary to experimentally establish the required number of roosters in the flock

It has long been noticed by those involved in poultry farming: if you follow the recommended ratio of cockerels and hens in the chicken coop, laying hens feel much calmer. And if they sense a male presence, egg production increases

In order for the number of the flock to be constant, while guaranteeing a high degree of fertilization of the eggs, it is necessary to experimentally establish the required number of roosters in the flock. It has long been noticed by those involved in poultry farming: if you follow the recommended ratio of cockerels and hens in the chicken coop, laying hens feel much calmer. And if they sense a male presence, egg production increases.

Roosters fight

A rooster can be aggressive and fight with other roosters, or attack a person, as early as nine weeks of age. Various factors influence why anger appears: a natural impudent and pugnacious disposition; if the rooster protects and also wins back its territory (yard) when the bird is in danger; if it shares territory with numerous roosters in the flock; if there are few chickens on the farm; when the rooster seeks a place at the feeders, drinkers, or wants to occupy a certain perch in the chicken coop.

External reasons include: cramped chicken coop, presence of irritating noises and sounds. Roosters also get angry if the lighting around them is too bright or very dim.

If a rooster often attacks and fights, this gradually reduces his body weight, he loses weight, loses strength, which, in turn, has a bad effect on his reproductive function, especially since it acts as a distraction from trampling hens.

When a rooster attacks chickens, the owners of the bird should figure out why this is happening and urgently take action, since such behavior cannot be called natural. It is necessary to prevent deaths among birds.

https://youtube.com/watch?v=Gm-snGPgyNY

How to distinguish a hen from a rooster

Let's make a reservation: nature still endowed the rooster with a penis - a rudimentary one. So how do a rooster and a hen mate? Cock care suddenly stops during molting. But as soon as the bully’s feathers are renewed, his “politeness” returns to the rooster, and he again begins to trample his girlfriends. This happens again and again as long as the male has the rights of leader.

However, to an even greater extent, the survival and productivity of subsequent generations in the herd depends on the characteristics of the cockerel itself. But, of course, for good fertility they must first of all be active and healthy. A good individual mates with representatives of its “harem” willingly and confidently.

https://youtube.com/watch?v=i_pjhwUXSGQ

Meanwhile, as you know, due to their activity, these birds love to measure their strength. Moreover, in a fight they sometimes cause serious damage to each other.

The entire chicken collective, which lives in one room, completely obeys and obeys the most stately and strong male, who is a kind of leader. But there may be exceptions to the rules, in which chickens listen to a small rooster, but with a very lively character

But this does not always happen, because the rooster often behaves completely differently (wriggles around every female individual, showing all his gallantry and increased attention)

The leader has the right to copulate with any female whenever he wants. True, these processes are disrupted during molting. The picture of sexual intercourse itself is quite rigid; fertilization in birds is a unique process. Having a whole closet of so much beloved shoes, you have to walk around in shapeless moccasins and trampled ballet flats. Then the shell becomes hard and turns into a full-fledged shell, after which the egg comes out.

How many eggs does she produce per day? It all depends on the breed, proper feeding, etc. Many people believe that the only thing Petka does in the chicken coop is “trample” the chickens. However, this is by no means true and it has enough functions.

Many males mean fierce competition, constant fights and too much trampling of hens. Which is also not desirable for their psyche and health. When introducing a rooster into a chicken flock, you need to take into account such an indicator as its age

Chickens that are not attracted to the attention of a rooster gentleman have practically no brooding instincts. An ultrasound is experimentally selected whose tone would be attractive to females, but unpleasant to males.

Love ritual

Chickens are a herd bird. They live only in groups. In each group there is a leader - the largest and strongest male. At the slightest attempt at primacy in the pack, fierce fights occur between competitors, leading to blood. The leader has the right to mate with any female at any time.

Flirting, the rooster walks around the hen and scratches the lowered wing with his foot. He always shares his prey with the female he likes and generally shows her all kinds of attentions provided for by bird love etiquette.

During the molting period the situation changes. The chickens are left to their own devices. The male hits and drives the females away from the “table”. As soon as the molting stops, peace returns to the large chicken family.

The chicken has a hole on its back, and the rooster tries to find it by moving his paws. People say “the rooster tramples the hen.” In general, sexual intercourse among chickens is a harsh spectacle and absolutely devoid of erotic elements. During mating, the rooster is on top and holds his girlfriend by the back of her head with his beak.

Mating in birds is a short-term and often repeated process. With abnormally increased sexual activity of roosters (up to 22 matings per day), the amount of seminal fluid and its concentration in males decreases by 2 times. Limiting the number of copulations, on the contrary, increases the percentage of egg fertilization and the viability of chickens.

The rooster is pecking

Aggressive roosters can peck painfully not only at birds, but also at humans, which is especially dangerous if there are children nearby. If the male gets angry, his beak and spurs can be wounded until they bleed; a person’s legs after an attack by a bird can be left with bruises and abrasions, which cannot be treated quickly. They rarely peck the eye. They can attack from behind or from above.

Why a bird attacks and pecks depends on various reasons. If the male was acquired as a teenager or as an adult, his character has been formed and he will not be able to accept the fact of his master’s authority. If he was previously oppressed by stronger brothers or people, this negatively affects his character, so he often shows anger.

There are many measures to correct the situation; if all else fails, the male chicken is slaughtered. But it's still worth a try. For example, you can dip the rooster's head in a container of cold water, or trim the beak.