Barb A fine projection branching out form the main stem of a feather. Each barb is lined with small hooks called barbules that zip separate barbs together.

Bill The hard, outer part of a bird’s mouth, also known as its beak. It is made of light, hollow bone, covered in a horn-like layer. Birds use their bills to feed, preen, fight and build nests. Bill shape depends on the bird’s lifestyle and diet.

Bird call The sounds that birds use to communicate with each other. Calls are short, simple sounds, used to alert other birds to danger or food. Longer, more complicated calls are called birdsong. They are used to establish territories and warn off intruders, or to attract a mate.

Brooding The process by which birds hatch their eggs, sitting on them to incubate them (keep them warm). However, not all species of bird brood.

Clutch A set of eggs laid by a bird. Clutch size varies between species. Some, such as albatrosses, lay one egg, but others, such as partridges, lay up to 30.

Contour feathers The outermost feathers on the body, wings and tail of a bird. In most species, they give the bird a smooth, streamlined shape for flight, but in some flightless birds they are just for show.

Covert feathers Small contour feathers that overlap flight feathers on the tail and wing of a bird to give a streamlined finish.

Crest The tuft of feathers on the head of some birds. Some species, such as the cockatoo, can raise and lower their crest as a form of communication or to make themselves seem larger to predators.

Down feathers The soft, fluffy feathers close to a bird’s skin. These trap air to keep them warm. They are often a newborn bird’s first feathers.

Feathers Feathers enable birds to fly, and keep them warm and waterproof. They are made of a substance called keratin, similar to that found in our fingernails. Each feather has a central shaft, lined with barbs. The shaft is attached to the bird’s body at one end, called the quill.

Fledge To grow adult or flight feathers. A fledgling is a young bird that has just fledged and is ready to leave its nest for the first time.

Flight feathers The long, stiff feathers on the wings and tail of a bird, used to gain height, steer and control speed when flying. They are divided into large, outer primary feathers and smaller secondary feathers, on the inside of the wing.

Flock A number of birds moving or resting together. Many species of bird flock when migrating. The flock offers them some protection, as a large group is more likely to spot predators.

Nest A structure built by a bird or other animal in which to lay eggs and take care of its young. Bird nests can be cup-like and made of mud, grass and twigs; holes in trees; or burrows underground. They are usually sited out of the reach of predators.

Plumage All of the feathers on a bird’s body. Birds moult their plumage at least once a year, usually in a gradual process. The colour of plumage often varies between males and females of a species. Males are often brightly coloured to attract a mate, while females have more muted colours, for camouflage when they are brooding.

Preening The process by which birds clean their plumage to remove dirt or parasites and keep feathers in good condition. Birds use their bill or toes to smooth the barbs of their feathers. Many species have a preen gland on their tail, which secretes a conditioning, waterproofing oil. This is rubbed into the feathers when preening.

Roost A place where birds (and bats) rest and sleep, often in a tree, cave or other sheltered place. Roosting usually takes place in groups.

Spur A spike on the leg of some male birds, such as pheasants and chickens, used when fighting other males.

Talons The sharp claw of an animal such as a bird of prey. Talons are suited to plucking animals from the ground and carrying them away.

Webbed feet Feet shaped like paddles with a flap of skin between each toe. Webbed feet help aquatic mammals and birds to swim more efficiently.

Wings The feathered front limbs of a bird, controlled by muscles in its chest. Fast flyers, such as ducks, have short, pointed wings which require constant movement in flight. Larger birds, such as eagles, have long wings, that enable them to glide on air currents. Some smaller birds can rapidly flap their wings to hover in the air.

Vane The flat surface of a feather formed of barbs and barbules linked together.

Consultant: Chris Jarvis