Not all birds are able to fly, but they all have feathers.
Feathers are light, but they are linked by hooks called barbs to make them strong enough for flight.
Wrens have 1,000 feathers, while swans have 20,000.
Birds have four kinds of wing feather — large primaries, smaller secondaries, coverts and contours.
Every kind of bird has its own formation pattern and colour of feathers, called its plumage.
Instead of a teeth, birds have a hard beak or bill.
Unlike humans, birds do not give birth to babies. Instead they lay eggs, usually sitting on them to keep them warm until they hatch (see birds’ nests and eggs).
Birds fly in two ways — by gliding with their wings held still, or by flapping their wings up and down.
Gliding is less effort than flapping, and birds that stay in the air a long time tend to be superb gliders — including birds of prey, swifts, gulls and gannets.
Albatrosses and petrels have long narrow wings that help them sail upwards on rising air currents.
Most birds flap their wings to fly. Even birds that spend much of their time gliding have to flap their wings to take off and land.
Birds may be descended from dinosaurs and took to the air 150 million years ago.
Birds make two sorts of sounds — simple calls, giving a warning or a threat, and the more complicated songs sung by some males at breeding time.
Birds’ songs have a definite dialect. The songs of a group of chaffinches in one area, will sound slightly different from those of a group somewhere else.
A songbird reared in captivity away from its family produces a weak version of its parents’ song, but cannot perform the whole repertoire.
Gulls and parrots do not sing, but they do make various calls to attract mates or warn off enemies.
A bird sings by vibrating the thin muscles in its syrinx — a special organ located in its throat. Birds ******
Skylarks make special, fluttering flights accompanied by a distinctive song.
Male and female boubou shrikes sing a duet together, performing alternate parts of the song.
Songbirds may make as many as 20 calls; gulls make only about 10.
Birds make other sounds, too. During courtship flights, male weodpigeons make a loud clapping with their wings.
A sedge warbler may use at least 50 different sounds in its songs.
The chaffinch is the commonest of Europe’s finches and has a cheerful, attractive song. :31.11=1
A baby songbird starts to learn to sing about 10 days after it hatches, and continues to learn for about 40 days.
No bird has more than four toes, but some have three and the ostrich has only two.
Four-toed birds have different arrangements of toes: in swifts, all four toes point forwards; in most perching birds, three point forwards and one backwards; and in parrots, two point forwards and two backwards.
A beak is made up of a bird’s projecting jaw bones, which are covered in a hard horny material.
The hyacinth macaw has one of the most powerful beaks of any bird, strong enough to crack brazil nuts.
Webbed feet make all waterbirds very efficient paddlers.
The Australian pelican has the largest beak of any bird, at up to 50 cm long.
Nightjars have the shortest beaks, at 8-10 mm long.
A bird stands on the tips of its toes – the backward bending joint halfway down its leg is the ankle joint.
A bird’s beak is extremely sensitive to touch. Birds that probe in the ground for food have extra sensory organs at the beak tip.
A baby bird has a spike called an `egg-tooth’ on its beak for breaking its way out of its egg.
After they lay their eggs, most birds sit on them to keep them warm until they are ready to hatch. This is called incubating the eggs.
All birds begin life as eggs. Each species’ egg is a slightly different colour.
The plover’s egg is pearshaped. The owl’s is round.
Hornbills lay just one egg a year. Partridges lay up to 20 eggs. Hens and some ducks can lay around 350 a year.
Most birds build nests to lay their eggs in – usually bowl-shaped and made from twigs, grasses and leaves.
The biggest nest is that of the Australian mallee fowl, which builds a mound of soil 5 m across, with egg-chambers filled with rotting vegetation to keep it warm.
The weaverbirds of Africa and Asia are very sociable. Some work together to weave huge, hanging nests out of straw, with scores of chambers. Each chamber is for a pair of birds and has its own entrance.
Ovenbirds of Central and South America get their name because their nests look like the clay ovens made by local people. Some ovenbirds’ nests can be as much as 3 m high.
Flamingos nest on lakes, building mud nests that look like upturned sandcastles poking out of the water. They lay one or two eggs on top.
The great treeswift lays its single egg in a nest the size of an eggcup.
The bittern, famous for its bull-like booming call, feeds on animals living in reed beds. This is where it makes its nest.
Great auks’ eggs are pointed at one end to stop them rolling off their cliff-edge nests.
The earliest known bird is Archaeopteryx, which lived 155-150 million years ago. It had feathers like a modern bird but teeth like a reptile.
Ichthyornis was a seabird with long, toothed jaws. It lived alongside dinosaurs in the Late Cretaceous period.
Although it could fly, Archaeopteryx could not take off from the ground, and probably had to climb a tree before launching itself into the air.
Scientists believe that birds evolved from lightly built dinosaurs such as Compsognathus, which ran on two legs.
The dodo stood 1 m tall and lived on the island of Mauritius in the Indian Ocean. It became extinct in the 17th century.
Aepyornis (also known as the ‘elephant bird’), a 3-m tall ostrich ancestor from Madagascar, probably became extinct in the 17th century.
The eggs of Aepyornis may have weighed as much as 10 kg – more than 9 times the weight of an ostrich egg today.
The tallest bird ever was the moa (Dinornis) of New Zealand. It was a towering 3.5 m tall.
The great auk first lived 2 million years ago. It became extinct in the mid 19th century after being over-hunted for its fat, which was burned in oil lamps.
An early member of the vulture family, Argentavix of South America had an amazing 7.3 m wingspan.