Tracks and Signs of the Animals and Birds of Britain and Europe

Feather of a Mute Swan. LG.

Instead of having fur, birds have feathers. They contribute to a bird’s appearance and protect its body from cold, sun, rain, and wind. The feathers grow from a kind of pouch (an umbrella-like sheath) and come in two forms, contour and down feathers. Contour feathers are body feathers and the stiffer wing and tail feathers. The wing feathers allow the bird to move, while the tail feathers allow it to brake and steer. The contour feathers often have characteristic colours and patterns, and underneath they can be like down. Down is often dappled, whitish, grey, or brownish.

A young Teal

Wing feathers

The feather consists of a shaft and two vanes. The feather is hollow at the root. Each vane has very closely placed barbs, which in turn have two rows of smaller barbules. In the case of contour feathers, the barbules have tiny microscopic hooks, the barbicels, on the side of the tip, and they interlock, forming a coherent surface, the vane. In the down feathers, the barbules have no barbicels.

Some birds have special, somewhat unusual feathers. Nightjars have evolved bristle feathers in the area around the beak that make it easier to detect and catch insects. Herons, bitterns, and raptors have special ‘powder’ down that grows continuously; it is not lost during moult but instead crumbles into a fine powder at the tip of the feather, which the birds then use when preening. Woodpeckers possess tail feathers with a strengthened shaft that can carry a large part of the bird’s weight and support it on tree trunks. The tail feathers lack the tip on the shaft.

Wood Pigeon

Since feathers wear out and bleach, they occasionally have to be replaced, normally once a year. During moult, old feathers are lost and replaced by new ones. In most species this occurs between the end of summer and the beginning of autumn as they change from summer to winter plumage. Numerous aquatic birds—ducks, geese, swans, grebes, and loons—lose all their feathers at once and cannot fly for several weeks, so they stay on the water to avoid predators; as a consequence you can often find large quantities of washed-up feathers on shorelines or river banks.

Some male birds with colourful breeding plumage moult their body feathers in the spring but keep their old wing and tail feathers. In Scandinavia, Willow Ptarmigan moult their feathers three times a year. Male Mallards also go through three yearly moults, while male Long-tailed Ducks moult their feathers four times a year.

Great Spotted Woodpecker. LG.

Male Mallard. LG.

Contour feather with down

Curled upper tail covert feather

Secondary with speculum feather

Scapular feather

Undertail covert feather

Tail feather with reinforced shaft for support on trees

Primary feather

Many male passerines lose (abrade) the tips of their body feathers in spring. At this time of year, male Chaffinches have a mixture of red, green, and blue feathers, but in winter, males and females look almost identical. Starlings lose their yellow spots in the spring and become blue-black in breeding plumage.

Some bird species lose their down during the breeding season, and you can easily see this, especially among terrestrial breeders, for example in colonies of gulls and terns. The down is used to cushion the nest, so the warmth from the parent’s body is transmitted directly to the eggs and young chicks. In Eider nests you can find copious amounts of down, the traditional source of stuffing for pillows and duvets.

Raptors and owls moult individual feathers over the course of the year, so they are able to hunt without interruption. Female Sparrowhawks and Peregrine Falcons moult their plumage during the breeding season, while the males, who bring the food, will moult later. This is why the female’s feathers can be found in large quantities near the nest.

Bullfinch. JL.