Types of Feathers
A bird has many different sorts of feathers which perform different jobs.
Contour feathers: The largest feathers are contour feathers. These give the bird its shape and colour and include both the flight feathers, called remiges, and the tail feathers called retrices. Remiges and retrices are the long strong feathers you most commonly found. These two here came from a British Magpie and as you can see they have different shapes. One is a wing flight feather a remige and it is asymmetrical i.e. the vane is much smaller on one side than the other. This is because the pressures on the 'leading edge' of the feather (the part that faces forward) are far greater than those on the trailing edge. If the leading edge vane was as large as the trailing edge it would soon become very ragged and not work properly. The rest of the feathers you see when looking at a bird are the ordinary body 'contour feathers'. These give the bird its characteristic smooth round shape. They also give the bird its visual colouring and provide a first level of defence against physical objects, sunlight, wind and rain. They are very important.
Down Feathers: The next most important feathers on a bird are the down feathers. These are smaller and lack the barbules and their accompanying hooklets so they are not zipped together and do not look so neat. In fact hey are soft and fluffy. They provide most of the insulation and are so good at this that mankind for many years used to collect the 'down' from various birds to put into sleeping bags and eiderdowns to help keep us warm at night. The term eiderdown arose because the softest and best insulating down was collected from Eider ducks (Somateria mollissima). In down feathers the side branches are longer than the rachis.
Semiplumes: are half-way between a contour feather and a down feather. These occur between the contour feathers and help to supply insulation and a certain amount of form as well.
Filoplumes: are much smaller, have only a very few barbs at their tips and are believed to have a sensory function, helping birds keep their feathers in order.
Bristles: are much smaller, have practically no barbs at all and are stiff. They occur around the eyes and mouths of some birds and are protective in function. They are particularly evident in the honey buzzard (Pernis apivorus) for instance, which feeds on the nests and young of social bees and wasps and needs protection around its beak from the stings of the adult bees and wasps.
The fourth main types of feathers are Powder Feathers. These are unusual in that they grow continuously and that they disintegrate at the tip. The barbs breaking down into a fine powder that in Herons at least us useful in mopping up the slime and dust that gets on their fronts during feeding. Thus they help keep the plumage clean. Powder feathers occur scattered throughout the plumage of most birds, but their function is not well understood.
Brood patches are areas where the feathers fall out during or immediately prior to incubation of the eggs. These areas of bare skin on the birds abdomen are heavily infused with blood vessels and allow the incubating adult bird to transfer heat to the eggs thus speeding up development of the embryo. Brood patches are either one large patch or several smaller patches equating with the number of eggs e.g. Herring gulls which normally lay 2-3 eggs have 3 brood patches. Brood patches are necessary because feathers are such good insulators that none of the adult's body heat would reach the eggs without them.
Most information on this page was contributed by EarthLife.
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