Class Aves (Birds) • Birds are some of the most

beautiful and amazing inhabitants on our planet.

• Birds are adapted to move in the air. The body of the bird has aerodynamics shape. The head is small, oval and very mobile. There are no teeth in the jaws, which are covered by a horny substance and form a beak. The shape and the size of the beak depend on the type of food they eat. The front limbs are adapted for flight and they have evolved into wings. On the land they use only their hind limbs.

• The skin is dry and covered with feathers.

morphology of the birds 

aerodynamic shape

head

jawbeak

horny

front limb

featherhind limbs

Sebaceous gland wings

examples of feet and examples of beaks

•The feet of birds are adapted to their lifestyle. •A beak’ s shape is reflected on the lifestyle of the bird species. Its main function is to allow the bird to feed.

• The body is covered in feathers except for the hind limbs, which are covered in scales. Birds change their plumage once or twice a year.

The only skin gland in birds the sebaceous gland, situated at the base of the tail. Water inhabitants use the secretion produced by this gland to lubricate their feathers and to prevent themselves from getting wet.

Internal structure

• Bird bones are hollow – their skeleton is only 18-20% of the body mass. It is typical of flying birds to have an extension of the breastbone, which is called a keel, to which the flight muscles are attached.

• The front limbs have evolved

into wings.

• They have a constant body temperature – about 40-45 °C. Birds are the animals which body have the highest temperature.

• Birds have no teeth. The stomach consists of two part – muscular (gizzard) for the mechanical digestion, and glandular in which the food is digested chemically by digestive juices. The digestive system ends in the cloaca.

• The lungs has a tubular structure . Numerous tubular branches end in thin-wall air sacs situated among the internal organs and in the bone hollows. They make the body lighten and prevent it from overheating.

heart

gizzardcrop

The heart has four chambers (two atria and two ventricles). They are two blood cycles – systemic and pulmonary. The systemic circulation carries oxygenated blood to all the cells in the body and that ensures a good metabolism and a constant body temperature.

• The best developed parts of the brain are the telencephalon and cerebellum. The cerebellum is responsible for coordination and synchronize body movements during flight.

• The birds are heterosexual animals.

• Fertilization is internal.

• Their eggs are rich in nutrients. The shell covers the embryo.

Reproduction and development

Diversity of birds• Class birds comprises about 9 000

living species. According to the way of movement and the specifics in of their structure, they are grouped three in superorders – Swimming, running and flying birds.

• Protected bird species

Birds for  food, meat, decoration

Endangered and protected species of birds

Use the examples of birds in the text, rewrite main characteristics and complete the table

Swimming birds• Penguins are representatives of

swimming birds. They are sea inhabitants. They have lost the ability to fly, but are excellent swimmers and they can dive as deep as 20 m. Their forelimbs have modified into flippers in order to move easily in water.

• Penguins inhabit the southern hemisphere, the coasts of Antarctica, South Australia, Africa, South America and some islands.

• Penguins build their nests in large colonies and incubate 1-2 eggs.

• The largest representative of this species is the Emperor penguin.

lives only in the Atlantic

Superorder Running birds Running birds cannot fly. Their wings are rudimentary, their bones of the hind limbs are massive, the breastbone is small, the keel is absent. Some of the representatives of group are the African ostrich, Rhea, Emu and Kiwi. The African ostrich is the largest living bird. Males can grow to a height reaching of 2,75 m, and a weight of 90 kg.

Superorder Flying birds

• Flying birds are the most numerous superorder. On land, they walk, run, jump, or swim bit their main way of movement is flying. This is reflected in their structure – their wings are strong, they have a strong and large breastbone and very well – developed pectoral muscles. This superorder are grouped in 23 orders.

Order Passerines• Passerines is the biggest group in

class Aves it comprises more than 5,200 species with is about 65% of all birds. About 4000 species of this order have a well-developed vocal organ are included in the group of songbirds. Here belong swallows, larks, wagtails, crows, tit, starlings etc.

• Order Falcons

comprises diurnal

birds of prey –

falcons, hawks,

eagles and vultures.

Features that are specific for them

are the strong, long and sharp

claws, and the hook- like beak,

which help them grasp and tear

their prey.

great horned owl Nocturnal raptor found in the forests of North America, with a tuft of feathers on each side of its head.

eagle raptor with piercing eyes, a hooked beak and sharp talons allowing it to catch live prey.

condor - scavenger of the Americas, with a bald head and neck;

falcon bird of prey with piercing eyes and powerful talons and beak; it is sometimes trained to hunt.

vulture raptor of the Americas and Eurasia, mainly a scavenger, with a bald head and neck, powerful beak and hooked talons.

Order owls

• Order Owls comprises large nocturnal birds of prey Barn Owl, Eagle Owl, Pygmy Owl, Tawny Owl, Screech-owl, etc. They have soft and thick feather covering and fly almost silently in the dark. They are only birds whose eyes are situated frontally on the head.

Snowy owl

• Screech owl

Barn Owl

Pygmy Owl

Order Pelicaniformes

• Pelicans includes fish-eating birds with webbed hind limbs. In most species the lower jaw has a sub-bill pouch, which has given the name of this order. Pelicans and cormorants belong within this order .

• pelican Bird with a

lower jaw featuring an extensible pouch for catching

fish.

• In Bulgarian Red Data Book as well as The World Red Book includes The Pygmy Cormorant, Dalmatian Pelican, Crested Pelican.

Dalmatian Pelican

Pygmy cormorant,

Order Ducks

• Ducks includes water-dwelling birds with have short, story body, long neck, long and pointed wings and a short tail. The beak is flat, wide and covered with a sensitive membrane.

duck - aquatic bird spending most of its time on water; the domestic duck is raised for its meat and for the production of foie gras

Common Crane

swan

Order Ducks comprises swans, ducks, goose, etc. Most of Ducks are protective Mute Swan, Great Crested Grebe, Ferruginous duck and etc.

• Ducks, goose, swans have a short, stocky body, a long neck and

short tail.

goose Bird of the Northern hemisphere are better adapted to land than water; certain species are raised mainly for the production of foie gras.

swans

nightingale

Raven

woodpecker

goldfinch Brightly plumed songbird feeding mainly with seeds of the thistle.

nightingale Bird with a melodious song that feeds with insects and fruit; it is found in the bushes of forests and parks.

kingfisher Colorful fish-eating bird

Flying birdsstarling omnivorous bird with dark plumage; it lives in the cities and in the countryside.

Flying BIRDS swallow Widespread in the Northern hemisphere and found in highly diverse habitats; it usually feeds with insects caught in flight.

.

Hummingbird Tiny brightly colored bird with a long thin beak found on the North and SouthAmerican continent; it can fly backward.

finch Widespread bird with a melodious song.

Flying birdsMagpie Noisy omnivore found in trees and bushes in temperate regions of the Northern hemisphere.

Bullfinch Red-breasted bird found in the woods and parks of Eurasia and the Americas; it feeds mainly on seeds and insects.

Sparrow Bird that feeds mainly on seeds and insects; it is widespread in cities and in the countryside

European robin Bird found in woods and gardens characterized by a bright red throat and chest and emitting a loud, lively melodious song

PartridgeLand-based bird that flies with difficulty

WoodpeckerWidespread insectivore that pecks at the bark of trees to find food and to nest.

RavenStrong-beak scavenger with usually black plumage; it sometimes damages crops.

Tern Aquatic bird with long wings and a forked tail; it dives for the fish it feeds on.

.

Heron Widespread bird found in shallow waters and marshes.

Stork Bird found in marshes and fields; two species are threatened with extinction.

.

Albatross Aquatic bird of the south seas; its wingspan can reach 10 m, allowing it to glide for hours.

Turkey Bird originating in the Americas with a bald head and neck covered with outgrowths; it is raised in captivity for its meat.

Pheasant Bird originally from Asia and characterized by its long tail; its meat is highly prized. Certain pheasants are raised solely for hunting.

Pigeon corn-eating bird prized for its meat and its keen sense of direction (carrier pigeon).

Peacock

Omnivorous bird originally from Asia; during the mating season, the male lifts and spreads its colorful tail feathers to attract females.

Amazing and beautiful birds of

paradise

Cockatoo Noisy perching bird with drab plumage and a tuft of upright feathers on its head, found mainly in Australia; it can mimic human speech.

Macaw Noisy brightly colored perching bird found in the tropical forests of the Americas; it feeds mainly on seeds and fruit

Flamingo, hoatzin, southern hill birds , the beautiful birds of Norfolk

Flamingo Toucan Large, gentle bird found in the forests of the Americas; its dentate beak allows it to feed especially on fruits and insects.

Protected bird species• The Bulgarian RED Book as well

as The World Red Book includes the Eagle Owl, Lesser Kestrel, Imperial Eagle, Egyptian Vulture, Marsh Harrier, Great Bustard, Black Stork, Common Crane, Pygmy cormorant, Dalmatian Pelican, Glossy Ibis, Mute Swan, Ferruginous Duck , Gallo etc.

Glossy Ibis

Mute Swan

Eagle OwlLesser Kestrel

Imperial Eagle,

Egyptian Vulture

Marsh Harrier