Schematic of a chicken egg

Розділ I

Птахи

Навчальний посібник та лабораторно-методичний комплекс для вивчення текстів спеціального призначення

Зміст:

- 1 Мета та завдання комплексу.

- 2 Загальна характеристика птахів.

- 3 Особливості будови птахів.

- 4 Пристосування для польоту та стилі польоту.

- 5Харчування птахів. Особливості травної системи птахів.

- 6Полювання птахів.

- 7Період парування птахів.

- 8Висиджування яєць і вигодовування пташенят.

- 9Сімейне життя птахів.

- 10 Прийоми та засоби побудови гнізд.

- 11 Догляд за пір’ям.

- 12 Стислий огляд вивченого.

- 13 Вправи та завдання. Роздатковий матеріал.

- 14 Тести досягнень.

- 15 Словник.

- 16 Словник назв птахів з ілюстраціями.

- 17Словник фразеологічних одиниць.

- 18 Глосарій.

- 19 Відео матеріали.

- 20 Прислів’я та приказки про птахів.

- 21 Веб-сайти про птахів.

Part I

Birds

Complex lab-arrangement of ESP- texts for study

Contents:

- 1 Objectives (Birds)

Objectives

Birds

After completing the section, you should know:

- general characteristics of birds

- the structure of feathers, bones and how wings work

- birds’ styles of flight, landing

- what kind of food birds eat and their food storage

- the ways birds use to catch fish

- the phases of mating period, laying eggs and family life

- the ways and materials birds use to build their nests

- ways of bathing, oiling, preening the feathers

What is a bird?

Birds are the most successful flying animals that have ever existed. They make up the scientific class Aves, distinguished from other animals by one feature: feathers. Birds almost certainly evolved from small, predatory dinosaurs called theropods more than 150 million years ago. Over time, the theropods’ scales were transformed into feathers, their front legs stretched and became wings, their bony tails withered away, and their snouts and teeth were replaced by lightweight bills. Evolution made them masters of the sky, and they soon spread across the planet.

A coat of feathers.Birds are the only animals with feathers. These are not just for flight – they also provide a warm coat to trap heat in the body. Birds are warm blooded, which means they maintain a constant internal temperature, rather than warming up and cooling down with the surroundings, as happen in reptiles.

Fitting the bill. Bills (or beaks) evolved because they are lighter than toothed jaws and so make flying easier. They are also simpler than jaws, consisting merely of thin bone coated with the tough protein that forms human fingernails. As a result, evolution can change their shape relatively easily, giving each species a design adapted to its way of life. Flesh-eaters, for example, have hooked bills for tearing flesh.

Digestive system. Since they have no teeth, birds must break up food inside their bodies. They have a special stomach chamber called a gizzard, with powerful muscular walls that squeeze and grind the food. Less frequent flyers swallow grit or stones to help the gizzard do its job .Many birds also have a food storage chamber, or crop, in the throat. This helps them to wolf down food quickly and then bring it up again later to feed their chicks or to lose weight when fleeing danger.

Senses. Vision is the most important sense in birds. Many can see colours invisible to our eyes or tiny details that we would need a telescope to notice. When they sleep, birds can keep one eye open and half the brain stays awake, wary for danger. Most birds have a poor sense of smell but excellent hearing. What sounds to us like a single note of birdsong might be heard by a bird as 10 separate notes.

Global domination. Flight has allowed birds to colonize almost every environment, from deserts and cities to remote islands, mountain peaks, and the freezing wastes of Antarctica. Birds can endure colder weather and thinner air than any other animals. The only habitat they haven’t conquered is the deep sea.

Reproduction. While mammals carry babies inside the body, birds lay eggs, like their reptilian ancestors. But, unlike most reptiles, which simply abandon their eggs, birds care for both eggs and chicks. Usually both parents cooperate to keep the young warm, and to protect and feed them.

External anatomy of a bird:

External anatomy of a bird:

1 Beak 12 Vent

2 Head 13 Thigh

3 Iris 14 Tibio-tarsal articulation

4 Pupil 15 Tarsus

5 Mantle 16 Foot

6 Lesser coverts 17 Tibia

7 Scapulars 18 Belly

8 Median coverts 19 Flanks

9Tertials 20 Breast

10 Rump 21 Throat

11 Primaries 22 Wattle

Built for flight

Almost every part of bird’s body has been shaped by evolution to meet the demands of flight. Wings and feathers are the most obvious features – they provide the “lift” to overcome gravity. Most birds also have a streamlined shape with weight concentrated in the middle for balance. The bones are riddled with hollow spaces to save on weight, and many are rigidly fused together to reduce the need for heavy joints or unnecessary muscles. The flight muscles are huge and powerful, but they need plenty of oxygen, so birds have special lungs to extract as much oxygen as possible from the air.

Feather light. Feathers are made of fine, lightweight fibres of keratin, the protein that coats bills. Flight feathers have a stiff central shaft, called a quill, with hundreds of side branches called barbs. The barbs bear thousands of tiny branches called barbules, which lock together to form a flat, streamlined surface.

The bare bones. A bird’s skeleton has the same basic plan as a human skeleton, but the details are very different. Birds have only three “fingers” (digits), and these are fused to form a strut supporting the wing. The wing pivots at the shoulder, and the elbow and wrist can bend only horizontally to fold or extend the wing. The tail bones are fused into a stump, and sidebars on the ribs overlap to form a solid cage. An enormous bone called the keel provides an anchor for the powerful flight muscles.

On the wing. The bird’s most important feathers are its flight feathers, found on the wings and tail. Most of the lift required for flight is generated by the primary and secondary flight feathers in the outer part of the wing. There are usually 9-12 of these on each wing. Other parts of the body are covered with small “contour feathers”, which give the bird a streamlined surface, or fluffy down feathers, which keep the bird warm.

How wings work. Wings lift a bird in two main ways. During flapping flight, they push air backwards and down, causing the bird to move forwards and up. Once a bird has picked up speed, the wings catch the wind like sails and create higher pressure underneath, pushing the bird up.

Wingspan. Wings work best when air flows swiftly over them. If the air moves too slowly, turbulent whirlpools develop around the wings and they stop generating lift. The result is a stall: the bird loses its balance and tumbles. Slow-flying birds, such as eagles that soar on thermals, spread out the feathers at the wingtips. This way, each feather acts as a tiny wing, generating extra lift and stabilizing the airflow.

Oxygen supply. Birds’ lungs are far more efficient than ours. When we breathe, air flows in and out of our lungs in two directions. Our lungs don’t empty entirely, so stale air stays behind after each breath. In birds, air circulates through the lungs in one direction only, thanks to a complex arrangement of air sacs around the lungs. Fresh air continually enters the lungs, flushing out stale air and providing a rich supply of oxygen.

Keeping clean. Feathers need a lot of care. The tiny barbules that keep them flat can come unzipped. Birds run their bills through the feathers to zip the barbules back together. Many birds also rub oil from a gland in the rump into the feathers to waterproof them. Some also bathe in puddles or dust to keep the feathers in shape.

Hollow bones. If you are ever picked up the skeleton of a dead bird, you’ll know how light a bird’s bones are. In fact, the feathers weigh up to three times more than the skeleton. The bones are light because they contain a honeycomb of air spaces, criss-crossed by solid to provide strength.

Up and away

Birds move through the air with such grace that flying looks effortless to our eyes. But it takes tremendous effort to overcome the force of gravity and travel on nothing but air. For most birds, getting off the ground is the hardest part. Wings work best when air is blowing over them, so until a bird has built up speed it relies on muscle power alone. Once they get going, birds can conserve energy by catching the wind, gliding on air currents, or taking brief rests.

Flight patterns. Birds differ a great deal in their style of flight. Small birds tend to flap intermittently and close their wings for barely perceptible rests. As a result, their flight paths move up and down. Ducks and geese are non-stop flappers. They are fast and have enormous stamina, but they use up energy quickly. Long-winged birds like vultures and albatrosses are gliders. They conserve energy by riding on thermals or catching the wind.

Flocking together. Flying in a flock has several advantages. If each bird flies slightly to the side of the bird in front, it gets a lift from currents blowing off the leading bird’s wings. This is why ducks and geese fly in V-formations. Flocks also make finding food easier and give protection from predators. Starlings sometimes flock by the thousand, forming dark clouds that twist and pulse as the birds swoop past each other in prefect co-ordination.

Landing. Landing takes less effort than taking off, but it requires skill – especially in birds that land on a small perch. To lose speed, birds bring their wings into a more vertical position and lower their tails. Many birds have a special tuft of feathers (the alula) on the bend of the wing that helps stabilize airflow over the wings as they slow down, keeping them balanced.

Getting airborne. It takes tremendous effort for a swan to get into the air. Its wings, like the wings of an aircraft, only generate sufficient lift when a fast stream of air is flowing past them. So to overcome gravity, the swan must sprint with all its strength, using the surface of the water as a runway. Facing the wind helps, but in still air a heavy swan has to reach about 48kph to take off.

Partners and parasites. Sometimes it pays for a bird to form a special partnership with another species. By teaming up, they might be able to find food that neither could reach alone nor defend themselves against a predator. Different bird species sometimes cooperate to drive away birds to prey; for instance small birds might “mob” an owl. In Africa, honey-guide birds team up with people to find and raid bees’ nests. When both partners benefit like this, the relationship is called symbiosis. Not all close partnerships work out so fairly, however. Often one partner takes advantage of the other: it becomes a parasite.

Bird food

Rich, easily digested food makes up the bulk of most birds’ food. Because they need lots of energy, but have to keep their weight down for flight, very few birds eat bulky plant food such as grass or leaves. The majority are omnivores, taking a mix of seeds, fruit and small animals including insects. Without teeth to grind and chew, birds must make do with their bills and their muscular stomach. And they must digest their meals as quickly as possible to get rid of any excess weight.

Insatiable appetite. Small birds burn energy at an amazing rate and must eat vast amounts just to stay warm, let alone fly. In winter, a blue tit can spend 90 per cent of its waking hours feeding to stay alive. Hummingbirds use up fuel at 10 times the rate humans do.

Dropped from a height. Foods encased in a shell can be problematic when a bird’s bill lacks the power to crack them. One solution is to drop them from a height. This tactic is used by herring gulls on mussels, by lammergeiers to break bones, and by crows to smash eggs.

Feat of memory. Food is hard to find in winter, so some birds build up a secret stash during the autumn glut. Jays bury thousands of acorns, hiding each one in a different part of the forest and memorizing its location. Nutcrackers bury up to 100,000 nuts and seeds each year and can remember their locations nine months later.

Pigeon milk. Pigeons and doves are unique among birds in that they produce a kind of milk from the crop to feed their young. Crop milk, a thick soup of protein and fat, is made for the first three weeks of the chicks’ lives. After that the mother weans them onto solid food by swallowing mouthfuls of seeds and storing them in the crop, where they soak in the milk to form porridge.

Quick digestion. An average meal takes half an hour to pass through a bird’s body (compared to 24 hours in humans). A turkey vulture, for instance, can digest a whole snake in 90 minutes; the reverse process (a snake digesting a turkey vulture) takes weeks.

Eat dirt. Small birds hull their seeds to avoid carrying extra weight, but bigger seedeaters such as farmyard chickens swallow seeds, husks and all. They grind up their meals in the gizzard, a muscular stomach that contains swallowed grit and stones to mash the food. A wood duck’s gizzard can puree walnuts, and an eiderduck’s can crush mussel shells. Turkeys are said to be able to grind steel needles in theirs.

Fisher kings

To catch a fish you need patience, a sharp eye, and lightning reactions. But most of all you need the element of surprise. For some birds, this means standing motionless in water until a fish blunders into range. Others attack from the air, performing a spectacular plunge-dive and striking before the victim has time to react.

Fish scoop. The brown pelican uses two tricks to catch fish. First, it plunge-dives into the water, dropping from a height of 10 m and hitting the surface with a terrific splash. Then it uses an enormous throat pouch to scoop up fish. The pouch also takes in lots of water, so the pelican must rest on the surface afterwards to let the water out before swallowing its catch.

Kingfisher. The European kingfisher sits by a river as patiently as a fisherman, watching for prey to swim into striking range. At the sight of a small fish, it springs off its perch, hovers for a few seconds, and plunges into the water to snatch the fish with split-second precision. A powerful beat of the wings lifts it clear of the water again, firmly gripping its prey. A kingfisher may need to catch up to 50 fish a day to feed its young.

Dive bomber. Gannets and boobies hit the water like missiles. They dive from amazing heights, accelerating as they plunge and folding their wings right back at the very last moment to form a streamlined torpedo. They strike the water at up to 95 kph and often shoot straight past the shoal they are targeting. When that happens, they simply turn around and swim back up, snapping at fish on the way.

The mating game

Birds, like all animals, are driven by the urge to reproduce. Choosing the right partner is of vital importance, so birds have evolved rituals and displays that help them assess the opposite sex. Usually the female gets to choose and the male strives to impress her. She has to choose a partner of the same species, and this is why most birds, especially males, have distinctive calls and markings. Next, the male must prove he is a good catch using every trick, from bringing gifts to singing love songs, dancing, or battling with his rivals.

Fighting fit. Male birds don’t win mates simply by looking beautiful – they have to prove their superiority over rivals, even if it means a fight to the death. Male golden pheasants slash at each other with the vicious spurs on the feet, but they usually settle their disputes without serious injury.

Building a bower. As a substitute for showy feathers, bowerbirds collect colourful objects and arrange them around a stack of twigs. Satin bowerbirds are particularly choosy, collecting only blue objects. Females mate with the males who produce the most artistic displays.

Gift giving. Some male birds give presents to prospective mates. Male herons bring nest material, offered with much ceremonial bowing, and snowy owls offer freshly killed lemmings. Gifts of food are of more than symbolic value. They allow the female to assess how well her partner will feed future offspring, and they provide her with the valuable nutrients she needs to produce eggs.

A brief affair. Courtship is often a long and complex affair, but mating itself is usually very brief. The male flutters onto the female’s back and the two birds press their genital openings together, allowing sperm to pass from male to female.

Eggs

All birds lay eggs rather than giving birth to live young as mammals do. This is because birds need to keep their weight down in order to fly, so mothers must get rid of their offspring as soon as they can. An egg, therefore, serves as an external womb, containing all the nutrients that a chick will need to develop. Parents simple keep their eggs warm, protect them from predators, and wait for them to hatch. We think of eggs as fragile, but in fact they are surprisingly tough: ostrich eggs are strong enough to stand on.

Inside an egg. A freshly laid egg consists of little but egg white and yolk. At first the chick is a tiny pink speck on the yolk, called a germ spot or embryo. Drawing on the food in the yolk and the water in the egg white, the embryo grows and a recognizable chick begins to take shape.

Extraordinary eggs. Eggs are surprisingly varied and many are very different from the chicken eggs we eat. They range in size from hummingbird eggs the size of your little fingernail, to ostrich eggs, which are bigger than pineapples. Shapes range from cones to spheres (spherical eggs are strongest), and textures vary from rough and chalky to smooth and shiny. Many eggs are coloured or speckled, either for camouflage or so that the mother can tell her own eggs from impostors, which other birds may have sneaked into her nest.

A difficult lay. Although the largest birds lay the largest eggs, small birds lay big eggs in proportion to their body size. An ostrich’s egg is a hundredth of its weight, but a hummingbird’s is more than a tenth of its weight. Kiwis lay proportionately the biggest eggs, at a quarter of the adult bird’s weight.

Hot seat. Birds appear to be doing little while sitting on their eggs, but they are expending up to 25% of their energy just keeping the eggs warm. Incubating eggs is especially important for birds in cold places, such as snowy owls. Their bellies have a special patch of almost bare skin which they press against the eggs to keep them warm.

Belly blanket. Male emperor penguins balance an egg on their feet and tuck a paunchy flap of belly over the top to keep it from contact with the icy ground or air. They can go for months without eating while the mothers are away looking for food.

Hatching out. Breaking out of an egg is such hard work that it takes hours or even days. To make the first crack, the chick pushes its “egg tooth” – a hard spike on its beak that it loses after hatching – against the shell with all its might.

Schematic of a chicken egg

1. Eggshell; 2. Outer membrane; 3. Inner membrane; 4. Chalaza; 5. Exterior albumen (outer thin albumen); 6. Middle albumen (inner thick albumen); 7. Vitelline membrane; 8. Nucleus of pander 9. Germinal disk (blastoderm); 10. Yellow yolk;11. White yolk; 12. Internal albumen; 13. Chalaza; 14. Air cell; 15.Cuticle (Bloom)

Family life

In some ways, the family lives of birds are much like our own. More than 90 per cent of bird species are “monogamous”, which means that males and females form stable couples that work together to raise a family. In some species, such as swans, couples may stay together for life. But despite the appearance of stability and harmony, family life among birds is full of hardship, deceit, and even cruelty. Birds almost always lay more eggs than will reach adulthood, and from the moment they hatch, chicks face a struggle to survive that only the strongest can win.

Divorce rate. Family life in birds can be as complicated as in humans. Swans might appear to be a model of the perfect family, but DNA tests reveal that parents often cheat on their partners and lay eggs “out of wedlock”. And if a couple has problems breeding they may get “divorced” so each can try mating with a different partner.

Growing-up. Young birds fall into two main types. Ground-nesting birds such as ducks and geese have “precocial” young, which are downy and can walk and feed themselves within hours of hatching. In contrast, tree-nesting birds have “altricial” young, which are tiny, naked, and helpless. Their parents face the exhausting challenge of feeding the young until they can leave the nest.

Imprinting. Newly hatched ducklings follow their mother, whose voice and appearance become permanently “imprinted” in their brains. If the mother isn’t present, ducklings imprint on whatever else they can follow.

Programmed to kill. Young birds learn some survival skills from their parents, but most knowledge is instinctive. A cuckoo never meets its parents, yet it knows how to kill the other chicks in the nest within hours of hatching.

Sibling rivalry. Birds of prey often have more chicks than can survive. The parents give most of the food to the strongest chick and turn a blind eye when it begins to bully the others. Often the well-fed chick ends up killing and eating its brothers and sisters, but sometimes the parents eat the weakest or most sickly chicks themselves.

Insatiable appetite. Birds that feed their young work non-stop to meet their chicks’ needs. A wren may make 1.000 feeding trips in a single day, and a swift may fly 1.000 km daily to gather enough food. Black terns spend three or four weeks flying to and from their nests, which are hidden on rafts of floating vegetation in lakes.

Master builders

With only instinct to guide them and only bills to serve as tools, birds construct nests of amazing complexity. A nest may take weeks to build and involve thousands of flights in search of suitable material. Some birds use whatever comes to hand – even string, nails, plastic bags, or old clothes. Others are much fussier. Hummingbirds build nests from spider’s silk one strand at a time, while swallows collect a certain kind of mud from the edge of puddles.

Cup nest. Most birds use a sequence of movements to create a cup-shaped nest with a snug hollow in the middle. First, they roughly organize the material, with softer items like feathers on the inside. Then they sit in the nest, and turning round and round, push themselves against it to form a perfectly sized cup.

Three houses. Woodpeckers make their homes by drilling holes in trees with their chisel-like bills. Boring through solid wood is hard work, so males and females work together, taking up to a month to complete the task. Instead of lining the nest with soft feathers or leaves, they finely chip the inner wall to make a cushion of sawdust.

Less is more. For many seabirds, a nest is little more than a scrape in the ground or a rocky ledge on a cliff. Gentoo penguins build simple mounds of pebbles, sticks, and grass. To impress their mates, the males collect pebbles of the same size and colour and arrange them in a neat ring around the nest.

Mud hut. Providing it stays dry, mud is an excellent nesting material. Ovenbirds use a mixture of mud, dung, and straw that sets rock hard under the sun, keeping out all but the strongest egg thieves. Their dome-shaped huts always face away from the wind and have an ingenious barrier inside the entrance to block draughts.

Body care

All birds have feathers, and this common feature requires that they spend much of their time maintaining their plumage. Birds have surprisingly similar ways of bathing, oiling, and preening their feathers.

Preening is the behaviour in which a bird slides its beak over individual feathers in such a way that it connects the individual barbules (hooks) of the feather vanes together. Small birds, such as sparrows, may have 2.000 feathers, while larger birds, such as swans, may have as many as 25.000 feathers. Most feathers have a central shaft (rachis) and a wide region on either side called a vane. Preening restores separated barbules in the feather vane and helps the bird to maintain the feather surface.

Oiling is the feather-maintenance behaviour in which birds squeeze their uropygial (oil) gland to lubricate their feathers. This gland is located on the rump, just above the base of the tail. By squeezing and rubbing the beak sideways over the gland, a bird can use its beak to obtain oil and spread it onto the feathers while preening. This oil lubricates the tiny feather barbules and extends their life by helping to keep them from becoming too brittle. Well-lubricated and preened feathers also help to shed water and give the birds a waterproofed plumage. Water sheds off a duck’s back (and even a sparrow’s back) mainly because the feather barbules are so neatly connected that water does not have a chance to soak into the plumage. In some species the oil contains ergosterol, which converts into vitamin D when exposed to sunlight. When swallowed, the vitamin D helps prevent such diseases as rickets.

Bathing in water helps to clean the plumage. Some seabirds, such as terns, bathe on the surface of the ocean; others, like gulls, often fly to freshwater ponds and lakes for bathing. Robins and grackles bathe in the water that collects on large leaves. Where standing water is not available, cold-climate birds may bathe in snow, while hawks and vultures just spread their wings in the rain.

Regardless of a bird’s size, the bathing behaviour is similar. Birds typically first submerge their head, then quickly raise it and beat their wings in the water. This is usually followed by vigorous shaking, feather fluffing, preening, and oiling. Birdbaths are an excellent way to attract birds into your yard. Many species that do not readily come to feeders, such as catbirds and even screech-owls, will use birdbaths.

Dustingis most common among birds that live in dry, open habitats. House Sparrows, Ruffed Grouse, Wild Turkeys, wrens, kinglets frequently dust bathe. House Sparrows seem to enjoy company as they dust bathe. Sometimes a dozen or more will gather, each scooping out a body-sized patch of dust in which it vigorously flutters its wings and spreads its tail while pressing its breast deep into the dust. While lying in the dust, they frequently peck and scratch with their feet. After dusting, the birds typically give their plumage several vigorous shakes to remove excess dust and then scratch their head and preen their feathers. Dusting probably helps to eliminate such parasites as feather lice and mites. Dusting may also function to remove excess oil, dandruff, and moisture that might otherwise cause feather matting. Most birds that bathe in dust usually do not take water baths.

Summary

- Birds are the only animals with feathers. The bird’s most important feathers are its flight feathers, found on the wings and tail.

- A bird’s skeleton has the same basic plan as a human skeleton, but the details are very different.

- Birds have a special stomach chamber called a gizzard, with powerful muscular walls that squeeze and grind the food.

- Birds can see colours invisible to our eyes or tiny details.

- Flight has allowed birds to colonize almost every environment.

- Birds lay eggs and care for both eggs and chicks. An egg, therefore, serves as an external womb, containing all the nutrients that a chick will need to develop. They are expending up to 25% of their energy just keeping the eggs warm.

- The family lives of birds are much like our own. More than 90 per cent of bird species are “monogamous”.

- Birds’ lungs are far more efficient than ours. In birds, air circulates through the lungs in one direction only, thanks to a complex arrangement of air sacs around the lungs.

- Rich, easily digested food makes up the bulk of most birds’ food.

- Birds construct nests of amazing complexity. A nest may take weeks to build and involve thousands of flights in search of suitable material.

- Birds have similar ways of bathing, oiling, and preening their feathers.

Achievement tests

1. What is a bird?

2. Are birds’ feathers just for flight?

3. How do birds eat food?

4. Do birds have a sense of smell or hearing?

5. How do birds care for eggs and chicks?

6. What provides birds’ “lift” to overcome gravity?

7. How much oxygen do birds need for flight?

8. What are feathers?

9. Where are the bird’s most important feathers?

10. How do birds care of their feathers?

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