The aves are also known as birds. They are bipedal and feathered. They are warm blooded. Their fore limbs are changed into wings. The heart is 4 chambered in the birds with 2 auricles and 2 ventricles. The renal system is not fully developed. The process of excretion and respiration occurs by a pair of kidneys which are metanephric and by the use of lungs respectively. They have the internal mode of fertilization. The development is direct without the formation of larva. They also show sexual dimorphism. The embryonic membranes do occur. They have 24 cranial nerves. They have the hind limbs which serve the purpose of walking and swimming. They are 4 in number. They have no skin glands except the oil gland which is present on the tail. They are absent in the ostrich and parrot. The upper and lower jaws form beak which does not have a teeth. The beaks are used for feeding, crushing, tearing and sipping. There are epidermal scales present on the legs. The crop and gizzard are present in an alimentary canal. The food is stored and softens by crop. The food is crushed by gizzard. They have a cloaca. They have no gall bladder. They have red blood cells which are convex and are nucleated and oval in shape. They have no urinary bladder and have uric acid as their main excretory product. The lungs do not have elasticity and the air sacs are connected to it. The syrinx helps in the production of voice. They are oviparous. Their brain is developed and has a good sense of sight. They have a poor sense of smell. The ear is divided into three parts which are known as external, middle and internal parts. The bones have air cavities which reduce the weight. Such bones are known as pneumatic. They have no bone marrow. They occur in land as well as water. There are nearly 10000 species of birds. These are the most beautiful creations of the God. They have many characteristics that resemble the humans like building nest, migration and parental care. Their skull has one condyle. They have a large sternum and a medium keel. It helps to attach the flight muscles. The vertebra extends from 11 to 25. There is a well developed ovary and oviduct in the females. These are present on the left side. The non functional parts are present on the right hand side.
The class aves are divided into aracheornithes and neornithes. The former types are extinct and have a long tail. They have a tooth beak. The later types are extinct as well as modern. They have a short tail and have no teeth.
There are many birds which are present in groups. They occur in the Galapagos Island and coco’s island. These species are discovered by Charles Darwin as he was the one who visited this island. He went on the beagle ship. They helped in the theory of evolution. The body of bird is divided into head, neck and trunk. They have a high sense of sight and hearing. They have a poor sense of taste and smell. The trunk is divided into thorax and abdomen. The fore limbs form the wings. The hind limbs form 4 or 3 toes. They have claws. The hind limbs are long. They have cloacae in the abdomen. They have a short tail which has an oil gland on the dorsal surface.
There are some flightless birds which include ostrich, rhea, kiwi, penguins, penguins and Island rail.
The ostrich are also known as struthio. It is a large flightless bird. They show sexual dimorphism and the males are bigger than the females. They swallow stone which help in the digestion. They run at sixty kilometer per second. The male has a penis which helps in the process of copulation. A male is surrounded by number of females. They have unequal toes. They help to run fast and are also aided by pads. They produce the largest egg and it is used as a diet for human beings. It occurs in the Africa and Arabia. The penguins occur in groups and also in the cold areas. They occur in the south pole of Antarctica. They eat fishes and have a webbed leg with 4 toes. They have a thick layer of fat. It helps to prevent the loss of body heat. The male penguin incubates the egg. It does not feed for 4 months. They have modified wings which help in the swimming.
The Great Indian Bastard is an Indian bird. It is large in size and has long neck and legs. It occurs in the semi arid areas. It includes Rajasthan, Gujarat and Maharashtra. Its population has declined in the recent years. There is a great demand for its flesh. It is in the bracket of endangered species. The koel is an Indian bird. The male sounds kuoo kuoo kuoo and the female sounds kik kik kik. This type of sound is produced by female during the breeding period. The rest of time it does not speaks. It does not make any nests and its eggs are laid in the crow’s nest. The male is black in color and the female is brown in color. They are parasitic. The koel is also known as the Indian Nightingale. It has a pleasant call. The crow is an Indian bird and is also known as Corvus. The crows which occur in jungle are black in color. The crows which occur in house are grey in color. They are omnivorous. They show sexual dimorphism and the males are bigger than the females. The sticks are used to make nests. It is made at the top of tree or on the branch of tree. The eggs are laid in the crow’s nest in some cases. They help in the incubation. They are parasitic and are useful as well as harmful to the human being. They eat insects as well as the ripe fruit and crops.
The anas are also known as the duck. Its feet are used to swim and they are omnivorous. They eat fishes, grains and vegetables. The male duck is also known as the drake. It has a unique copulatory organ. They show sexual dimorphism and the males are bigger than the females. They have a broad and flat beak. It helps to stain the food material. They have webbed toes which help in the swimming. They have a great economic importance. It destroys the mosquito larvae and has a nice set of eggs and flesh. The parrot is an Indian bird. It has feet to grasp with a large and pointed tail. They have an upper as well as lower beak. The upper beak is moveable and the lower beak is fixed. Their feet help in climbing and holding. They destroy the agriculture products and also have a great impact on fruits. It occurs in the cage and has a unique feature in which they mimic humans. It causes psittacosis. This disease is very fatal.
The pigeon is also known as Columbia. It is also referred as a blue rock pigeon. Its distribution is generalized as it occurs in the grain markets, railway stations etc. It makes nest and occur in the groups. They are omnivorous and their gizzard has a small stones and bricks. These help to grind the food. It is monogamous. The offspring’s get their feed from the pigeons milk. They can be male or female offspring’s. The pigeon milk is composed of the creamy fluid during the breeding season. It destroys the crop and creates a trouble in the house. They are also a source of manure.
The red jungle fowl is also known as Gallus gallus. A cock is surrounded by the group of hens. They show sexual dimorphism. The cock is multi colored. They have a comb and wattles. They have a crimson color. They are large in size. The hen is small in size. It is not attractive. It has small comb and wattles. They are a good source of food and their eggs are of very important use. The white backed vulture is a high flying animal. It is a scavenger and makes the nests on the tress. They show sexual dimorphism. The tyto is also known as barn owl. It is nocturnal and is active during the day. They make a loud hiss noise. Their noise resembles a voice of cobra. They have a very good hearing power and an eye sight. They have a soft and silky feather. They kill the insects so they are very useful to the farmers. The kite is also known as milvus. It is a scavenger which feeds on the flesh. It has a sharp beak which tore the flesh into small parts. They have an upper as well as lower beak. The upper beak is longer and the lower beak is short. They kill many animals and have a positive role to play in the life of human beings. The Bogla is also known as the cattle egret. It moves along with the cattle. It flies in the morning and returns in the evening. They make nests in the tall trees. The beak helps in the feeding. It plays a positive role to play in the life of farmers as it destroys the organisms which have negative effect on the growth of plant. The pea cock is also known as pavo cristatus. They are polygamous. It is the national bird of our country. They play a good role in the sexual display. The male has a blue neck and a long tail which is very beautiful.
