Bird feathers: moult, features & feather types

Where does the splendour of bird feathers come from? Why are there different types of feathers and why do some birds change their plumage with the seasons? We would like to answer these and other exciting questions here.

The plumage of birds is a unique feature in the animal kingdom. Feathers allow bird flight, they keep warm and dry, and they also send visual signals to conspecifics and other animals. Many bird species are characterised by magnificent, colourful plumage, which not only impress potential partners but also inspire us humans. What this splendour is all about, why birds have different feathers and why some birds are coloured differently at different times of the year, you can find out here in our article.

Bird feathers: characteristics

Feathers – just like the hair on our head, the fur of a lion, the scales of a crocodile or the spines of a hedgehog – are made of keratin. They are characterised by an elongated, firm quill from which fine feather branches extend, interlocking to form the soft but dimensionally stable plume. The incorporation of pigments and a special surface structure create the splendid and often iridescent colour impression of the feathers.

Types of bird feathers

A basic distinction is made between two types of feathers: the underfeathers, also called down or down, and the contour feathers. Down has only a short quill and usually unhooked feather branches, resulting in a tangled, soft tuft of feathers rather than a true plume. The down forms the undergarment of birds and protects them from the cold. Contour feathers, on the other hand, are further subdivided and have different functions depending on the spring type:

• Cover feathers cover the bird’s body and shield the fine down from moisture and dirt.
• Vibrating feathers form the wings’ airfoils and enable flight.
• Control feathers form the birds’ tails and also enable flight as well as steering during flight.

Feather identification

To reliably identify feathers, a reference book is usually essential. This is because only a few feathers are so characteristic that they can be directly assigned to a bird species on the basis of special patterns or colours. For example, if you come across a blue-patterned wing coverlet feather of a jay, identification is still simple. but it becomes more difficult if you find a more inconspicuous belly feather of the same bird.

At Featherbase, for example, you can view pictures of the different feather types of pretty much every native bird species and use them to identify feathers you find yourself.

Moulting

During moulting, old feathers are shed and replaced with new ones. This is important because feathers wear out over time and can then no longer perform their respective functions. Many birds moult once a year and do not change their plumage – it looks the same as before and is merely renewed. This can involve renewing only individual plumage sections at a time (partial moult) or changing the entire plumage (full moult). Thus, during the full moult, all feathers are changed regularly and the plumage remains in good overall condition. The disadvantage of the full moult, however, is that the simultaneous absence of many feathers severely limits the ability to fly and the birds are very vulnerable during this period. This form of moulting occurs, for example, in ducklings.

Some birds also moult twice a year, switching between two different plumages: The mating plumage or also breeding plumage is put on in spring and has the task of attracting a mate and intimidating possible rivals during the breeding season.

It is therefore often more conspicuous and colourful than the plain plumage, which covers the bird in winter and provides a better camouflage in their habitat.

Another form of moulting is juvenile moulting. This usually occurs after the first winter and marks the entry of young birds into adulthood. Most young birds initially form a juvenile plumage, which differs from the plumage of their parents, sometimes very strongly. Only after juvenile moulting do these young birds distinguish themselves by the specific plumage characteristics of their species.