Birds Endothermic Vertebrate Social Animals Used For Communication Via Visual Signals Calls Songs

Birds belong to the class Aves and are bipedal, endothermic, vertebrate animals, which are capable of laying eggs. They are found all across the globe right from the Arctic to the Antarctic and are nearly 10,000 living species.

They vary in size and are from 5 cm (2 in) Bee Hummingbird to the Ostrich measuring 2.7 m (9 ft). As per the fossil record they have originated from theropod dinosaurs around 150–200 Ma (million years ago) in the Jurassic period. The bird that was first one to be known to the world was the Late Jurassic Archaeopteryx. The birds of recent times display a beak with the absence of teeth, a high metabolic rate, feathers, laying of eggs in hard shells, a heart with four chambers as well as a light and strong skeleton.

The modification of their forelimbs is done into wings to facilitate flight and they have a different kind of digestive and respiratory systems for this purpose as well. The birds like parrots and corvids are regarded as the species possessed with too much of intelligence. They are also social animals and opts for communication through visual signals and by calls and songs. They also take active part in social behaviors as mobbing of predators, flocking, cooperative breeding as well as hunting.

Birds are also a source of food that are achieved by hunting or farming and the songbirds are used in the form of pets as well. The development of the initial classification of birds was done by Francis Willughby and John Ray in their volume namely Ornithologiae in the year 1676. The bird diversity is the maximum in tropical regions. The skull bones of the birds are fused and do not display cranial sutures while the orbits are bigger in size and are divided by a bony septum.

Birds are similar to reptiles as they are mostly uricotelic, in the way that their kidneys comes up with the extraction of nitrogenous wastes from their blood stream and the excretion is carried out in the form of uric acid in place of urea or ammonia. The feathers of the birds helps in flight, gives insulation which provides for thermoregulation and also finds application in camouflage, display as giving out signals. Birds