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You will likely have seen bird feathers on the ground when walking, but you may have wondered what this means. Losing and replacing feathers is a normal part of a birds life.

Birds use a process called moulting to replace old or damaged feathers with new, shiny feathers. Some birds moult annually, twice annually or every second year. Feathers will fall out, and new feathers will be replaced in the same follicle.

While mammals lose hair, birds lose feathers that are damaged or old. Bird feathers do not continually grow, and they don’t repair themselves. In this article, we look at why birds lose feathers.

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Why do birds lose their feathers?

Because feathers get old and damaged, they must be able to replace them. Replacing damaged or worn out feathers allows them to maintain their effectiveness. Some birds grow new colourful feathers for the breeding season before losing them again. These new, shiny, colourful feathers can help them attract a mate. Birds also moult when moving into adulthood. Although not all birds moult every year, most do. Some will moult twice a year, while others moult every second year.

There are four stages of plumage.

  • Worn – Old and damaged feathers. Just before moulting
  • Fresh – New, shiny feathers after moulting
  • Breeding – Plumage to attract a mate through displays
  • Non-breeding – Used in non-breeding seasons and is used as camouflage

New feathers are called pin feathers as they are shaped like pins. The sheath is long and sharp with a sheath made of keratin. Keratin, which makes up our skin and nails, protects the feathers as they are growing. Feathers can get damaged quickly while growing, resulting in permanent damage.

The pin feathers on young birds are noticeable, making them look a little like a porcupine when young. As they grow, the feathers open. This stage is known as ‘in pin’ and can be used to deter predators.

While developed feathers are not connected to the nerve and circulatory supply, pin feathers are. Once the feathers have fully developed, they sever the connection to the nerves meaning that they can be broken or cut without any pain.

Moulting can be a little painful for birds. As the new feathers come in, the areas are very tender. Because their skin is exposed, this can cause problems from the elements or insects.

Is it normal for birds to lose feathers?

Birds lose their feathers naturally in a process called moulting. While mammals lose hair, birds lose feathers that are damaged or old. Bird feathers do not continually grow, and they don’t repair themselves. Birds replace the feathers in the same spot as those they have lost over one year.

Moulting occurs for different reasons. Some birds grow new colourful feathers for the breeding season before losing them again. Birds also moult when moving into adulthood. Although not all birds moult every year, most do. Some will moult twice a year, while others moult every second year.

Although birds will lose feathers throughout the year, most birds moult in spring or fall. Moulting is gradual so that the bird cannot fly or is left unprotected.

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How many feathers do birds have?

Birds are covered with feathers on most of their bodies. The size, age, where it lives, and species depends on the number of feathers they have. Birds can have between 3,000-20,000 feathers on their bodies, weighing up to 3 times as much as the skeleton.

The same species living in different temperatures may have more or fewer feathers. Birds in colder temperatures need more feathers to keep them warm, while birds in warmer temperatures need less.

Birds that live in colder temperatures are often bigger than the same species that live in warmer climates. Smaller birds require fewer feathers than larger birds.

Older birds have different types of feathers for various functions and will have more feathers than immature birds.

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Feathers

Why do birds have feathers?

Feathers are needed to provide waterproofing, protection, insulation, streamlining, attracting mates, breeding and camouflage. Feathers are light and make efficient flight possible.

There are seven types of feathers with different functions.

  • Wing feathers – Wing feathers are used for flight and have windproof vanes on either side of the shaft. They are interlocking and asymmetric to stop twisting while flying.
  • Tail feathers – Tail feathers have an interlocking structure and are used to support steering while flying. Birds normally have six pairs of tail feathers.
  • Down feathers – Down feathers provide insulation and warmth for the skin. Down feathers protect young birds
  • Contour feathers – Contour feathers provide insulation and are used for streamlining and protection.
  • Bristles – Bristles can be found around the eyes, nostrils and beak. The bristles stop debris entering and protect them from injury.
  • Filoplumes – Filoplumes are found distributed throughout the body. They tell the bird when they are out of place and need to preen
  • Semiplume feathers – Semiplume feathers can be found between the down and contour feathers.

What are feathers made of?

Feathers are made of keratin that grows from within skin follicles. The keratin found in the feathers, claws, and beaks is stronger than keratins found in the hooves and horns of deer and rhinos.

Feathers have a central shaft that is hollow at the base. The shaft is called the rachi. From the sides of the shaft project parallel branches called barbs. The barbs are the main part of the feather. The barbs have smaller branches called barbules, some of which have small hooks on them. The hooks, called barbicels, allow the feathers to be zipped up by the bird.

Not all feathers have barbicels, but these allow the feathers to be put in the quill, the bare shaft, in place after ruffling.

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