Aves (Birds) are warm-blooded animal belongs to phylum Chordata and kingdom animal.
General Characteristics of Aves
- The members of Class-Aves are commonly known as birds.
- They are warm-blooded vertebrates with an exoskeleton of feathers.
- The forelimbs are modified into wings for flight.
- The hindlimbs are adapted for walking, perching or swimming.
- Skin glands are absent except the oil glands on tail.
- The bones are spongy and light due to the air cavities.
- The skull is monocondylic.
- The lower jaw is made up of five or six bones.
- Teeth are absent. A horny beak is present.
- The vertebrae are heterocoelous, procoelous or amphicoelous.
- The sacral vertebrae are fused with lumbar to form synsacrum.
- The caudal vertebrae from pygostyle in most of the members.
- The sternum is broad with boat-shaped keel.
- The clavicle and interclavicles form “V shaped furcula.
- The gullet is dilated into crop and a muscular gizzard for grinding purposes. Cloaca is three chambered
- Lungs are spongy and non-distensible. Air sacs are present.
- Syrinx produces the voice.
- Heart is perfectly 4-chambered and only right aortic arch is present.
- Red blood corpuscles are oval, biconvex and nucleated.
- Renal portal system is vestigial.
- Kidneys are metanephric. Urinary bladder is absent.
- Cerebral hemispheres and cerebellum are large.
- Sexes are separate. Sexual dimorphism is well marked.
- Only left ovary is present. The right ovary is vestigial and the right oviduct is atrophied.
- Internal fertilization, oviparous.
- The embryo is surrounded by amnion, allantois and a large yolk sac.
- Parental care is well-developed.
Classification of Aves
Examples of Aves
Classification of Columba
It is widely distributed in Asia, Europe, North Africa and is plentiful in Palestine.
Habit and Habitat
- Columbia levia is the common pigeon found all over India.
- In its wild state it lives in fissures and holes in rocks, but never nest on trees. It also nests in sheds, warehouse, old buildings, railway stations etc.
- They roost together and fly in flocks.
Characteristics of Columba
- Columba is commonly known as Blue rock-pigeon.
- It is a familiar slaty-grey bird with glistening, metallic, green-purple and magenta green on the neck and upper breast.
- There are two dark bars on wings and a band across the end of tail.
- Both the sexes are alike and measure about 35 cm. or more in length.
- Food chiefly comprises cereals, pulses and groundnuts.
- Head contains large eyes and slit-like nostrils.
- The forelimbs are modified as wings.
- The hindlimbs are modified for bipedal locomotion.
- Tail is short.
- Breeding season lasts all the year round.
- Fertilization is internal.
- Oviparous, eggs are incubated by parents.
- Parental care is present and nestlings are fed on pigeon’s milk prepared in the crop of parents by certain glands.
- It is wild as well as a domesticated bird.
Classification of Anas
Characteristics of Anas
- Anas is commonly known as ‘Duck’.
- It lives in fresh-water ponds, lakes and streams.
- The body is compact and short with ‘S’ shaped neck.
- The beak is broad and blunt. Transverse lamellae are present on jaws. Teeth are absent. It acts as sieve to filter out water and trap small fish.
- The beak is covered by soft skin. The plumage is made waterproof by the secretions of uropygial glands in the skin.
- Feet are adapted for swimming in the water. The hallux is elevated and the rest three toes are joined by web.
- It has desmognathous palate.
- Anas is diurnal and feeds on fishes.
- It does not build a nest.
Classification of Corvus
Corvus splendens is abundantly found throughout India.
Habit and Habitat
- It prefers to live in close association with man. It is cunning, bold an omnivorous bird.
Characteristics of Corvus
- Corvus is commonly known as ‘House crow’ in English .
- It measures about 40 cm. in length.
- The body is more or less black in color while the neck and breast are covered with grey plumage.
- Beak is stout and elongated, eyes are large.
- Each leg bears 4 clawed toes, three directed forwards and one backwards.
- It is omnivorous, eats almost anything like the dead rat, kitchen refuge, eggs, locusts, fruits and grains.
- Nest is a platform of twigs with a cup-like depression, lined without coir fibres etc.
- It is useful as an efficient municipal scavenger and unfailing commensal.
- Causes damage to fruit crops.
- It is an intelligent and cunning bird and avoids dangers.
4. Psittacula Krameri
Classification of Psittacula Krameri
- It is found in India, Myanmar, Sri Lanka, Pakistan and the United States.
Habits and Habitat
- Commonly found on the fruit trees in the countryside and in forests.
- Gregarious with loud voice, feeds exclusively on fruits and grains.
Characteristics of Psittacula Krameri
- It is commonly known as ‘Parrot‘.
- It is a beautiful bird with bright green plumage.
- Beak is generally bright red in color. It is short, stout, sharp edged and curved.
- Male birds with a rose colored collar round the neck.
- Tail is long and the limbs are modified for grasping.
- Parrot lays its eggs in trees or buildings.
- It can imitate sound if trained.
- Causes much damage to the crops.
- It is a popular domestic cage bird.