Bird feathers first evolved 150 million years ago. They may have originally provided an insulating layer to keep early birds warm but they now play a very important role in flight. They carry out a triple function in modern birds as they still also prevent loss of heat and they also offer waterproofing.
Feathers are made of a substance called keratin, which is a kind of protein. Keratin is also present in the scales of reptiles. Asnbirds are thought to have descended from reptiles this is not unexpected. The central part of the feather is called the shaft or quill and this supports two opposite rows of barbs that together form of vane of the feather. Two sets of barbules branch off from each barb and interlocked by means of tinier barbicels to give the feather great strength and smoothness.
Birds have many different types of feathers that fulfil different functions. For example the external feathers give the bird its outline and streamlining. The feathers of the wing and tail give the bird lift, balance and manoeuvrability during flight. The under feathers are down feathers, and the keep bird warm. (These are the kind of feathers used in high tog-rated duvets.) In some birds, feathers are modified into bristles to provide protection around the bills and nostrils and eyes.
Feathers are made of a substance called keratin, which is a kind of protein. Keratin is also present in the scales of reptiles. Asnbirds are thought to have descended from reptiles this is not unexpected. The central part of the feather is called the shaft or quill and this supports two opposite rows of barbs that together form of vane of the feather. Two sets of barbules branch off from each barb and interlocked by means of tinier barbicels to give the feather great strength and smoothness.
Birds have many different types of feathers that fulfil different functions. For example the external feathers give the bird its outline and streamlining. The feathers of the wing and tail give the bird lift, balance and manoeuvrability during flight. The under feathers are down feathers, and the keep bird warm. (These are the kind of feathers used in high tog-rated duvets.) In some birds, feathers are modified into bristles to provide protection around the bills and nostrils and eyes.