Saturday, March 7, 2009

Pelicans : Feeding with unity.
This is Rosy or White Pelican (Pelecanus onocrotalus) out of eight species of pelican found in the world. They are found throughout the tropical and warm temperature zones, on both fresh and salt water. They are powerful, graceful flyers, using the air currents for soaring, although their huge size makes the task of getting airborne a difficult one. When they sight food, they dive perpendicularly into the water, sometimes from a great height. Their diet primarily consists of surface dwelling fish but may include crustaceans. Their enormous pouches, which are modification of the lower part of the bill, are their most obvious distinguishing features contrary to popular belief the pouch is used as sort of fishing net rather than as a place for storing food.
The pelican feeds by scooping up fish with its enormous bill, which may hold 20 ltrs. water at a time. When an individual scoops water, many fishes escape by swimming away from the bill. The pelicans frequently feed in small groups, which swim in a horseshoe pattern, and then all moves forward and scoop the water at the same time. Small fish, which dart away from one pelican's bill are likely to be caught by another, thus all the birds benefit from feeding together. The fishes swallowed immediately and never carried in the pouch.
The nesting season is from November to April. Nest is build with large stick platform in tall trees and often far from water. There are several nests in the same tree and this colony covers a large area.
Among the adaptation of birds, which have contributed to their success, is flight, and the possession of feathers contributed to this adaptation. All birds have feathers but no other animal has them. The feather is formed from the cells of the skin just similar to the formation of scales on the legs of birds or on the bodies of reptiles. The feather grows from the base inside a sheath. Bird's flight feathers have sufficient strength and firmness to remain quite rigid when moved through the air despite being anchored only at the base. Birds spend a significant proportion of their lives engaging in feather maintenance activities. Dirt on the wings is removed by bathing in water or in dust and any water or dust is subsequently removed by flapping the wings, ruffling the feathers and by preening movements. For preening they apply oil from preen or oil gland. This gland is found in most birds and is situated on the rump above the base of the tail. It produces an oily secretion and is most active in aquatic birds. The secretion helps to keep feathers supple so that they do not break and increase their water proofing qualities. Despite their resistance to wear, feather must be renewed at intervals. The moulting process, during which old feathers fall out and are replaced by new ones growing in the same place, also allows birds to change from juvenile to adult plumage or from non-breeding to breeding plumage.
Yuwaraj Gurjar.