Birds are the only animals with feathers. Most of them can fly, some can swim, while others can run as fast as a racehorse. There are more than 100,000 million birds - around 16 for each person on Earth - and 9,000 different species, which come in a great variety of shapes and sizes.
The tiniest is the Cuban bee hummingbird, weighing less than 2g and measuring about 65mm from bill to tail, while the biggest is the African ostrich, which is as heavy as two adult people and stands higher than two metres. You can find birds in deserts, rainforests, grasslands, rivers and out at sea. Only those that have adapted to their habitat can survive in these different conditions.
Dinosaurs in your garden
Do you have dinosaurs in your garden? In 1861, scientists discovered a fossil unlike any they had seen before. They named it archaeopteryx, ("ancient wing"); it lived more than 140 million years ago. It was a feathered creature, and is believed to have been the first bird. It is thought that today's birds are related to dinosaurs. By comparing fossils to living animals, scientists extend our knowledge of evolution. Some characteristics change a lot, but some stay the same. Look at a chicken's foot - it looks almost the same shape as that of Tyrannosaurus Rex.
A feather in your cap
Birds' plumage can have from 1,000 to 25,000 feathers. Pluma is Latin for "soft feather". Feathers protect the bird from heat and cold, keep it dry, give it shape and make a smooth surface which makes it more aerodynamic.
The plumage can act as a signal to other birds or as camouflage to protect against predators. The rock ptarmigan, which lives in the Arctic, moults its brown feathers in the autumn and replaces them with winter white plumage to blend in with the snow. There are three main types of feather: * Down is light, fluffy and close to the body, ideal for keeping the bird warm. Duvets are often filled with down feathers.
* Contour feathers are short, rounded and tough. They give birds their sleek shape.
* Flight feathers are found on the wings and the tail. The bird spreads them out to slow down or land. Swimming birds, like penguins, use these feathers to move through the water.
Birds grow new feathers once or twice each year. New feathers push out the old in a process called moulting. Feathers are essential for flight and warmth and it is essential for birds to keep them clean. You may have seen birds bathing or preening (cleaning and lubricating their feathers with their beaks). If the feathers were not kept in good condition, the bird would be unable to fly.
Imagine yourself covered in oil - a thick, black, sticky liquid that you can't get off. Although oil is very important for us (we use it to make petrol for cars), oil-spills from supertankers such as the Exxon Valdez in 1989 or the Prestige last year are disastrous for birds. Birds that live in coastal areas can be covered in spilt oil, which clogs up their feathers so that they cannot fly, and destroys the waterproofing so that they could die from cold and exhaustion. Feathers appear smooth on the surface, but are in fact lots of little hooked threads, interlaced together. When a bird is coated with oil, these hooks become unravelled and the feather is ruined.
Sometimes the oil is broken down and washed away, but birds often need people to help them survive. Volunteers wash them with water and detergent to clean the oil from their feathers. It can take almost two hours to clean just one bird.
Many feathers are highly coloured and attractive to people. Some tribes in the rainforests of Papua New Guinea prize the fantastic, colourful plumes of the bird of paradise; Native Americans used eagle feathers to decorate their headdresses. In the 19th century, it was fashionable for western women to wear hats and clothes decorated with exotic feathers, and millions of birds were killed for the fashion trade; organisations such as the Royal Society for the Protection of Birds were established to campaign against the feather trade.
Feet on the ground
Not all birds can fly. Many flightless birds live on isolated islands with few predators, such as the kiwi, kakapo and takahe in New Zealand. Large flightless birds live in open grasslands - ostriches in Africa, emus in Australia and rheas in South America. They have incredibly powerful legs and can run very fast - ostriches can reach up to 70 kph (43mph).
None of the 18 species of penguin can fly, but they are expert swimmers, using their wings like flippers underwater. The largest, the Emperor penguin, can dive to a depth of 260m and stay underwater for nearly 20 minutes.
Best foot forward
Birds' feet have evolved into a variety of shapes, for swimming, for holding on to branches and for killing and carrying off prey, as well as for taking off and landing.
* Ducks, geese, swans and gulls all have webbed feet, which can act as paddles in water.
* Toucans have two toes pointing forwards and two backwards, giving them a good grip on branches.
* Many wading birds, such as the curlew, have long legs and long, outspread toes to stop them sinking into the soft mud at the mouth of a river.
* Ostriches have extra flesh on their feet to absorb the impact when they run, and tough skin to protect them from thorns.
* Birds of prey, such as the sparrowhawk, have long, sharp talons for grasping their quarry.
Common or garden bird life
You can learn a lot about birds by watching how they behave. In gardens or parks, you might see blackbirds, sparrows, tits, magpies, woodpigeons, wrens and robins. In woodland, you might be lucky enough to spot a woodpecker or an owl. Look out for water birds such as ducks, coots and herons by a river or lake, and for gulls and other seabirds near the coast.
Keep a record of the shape and colour of the birds you see, and where you saw them. Look in a guidebook to find any mystery birds. Soon you'll be able to identify lots of different species. The Royal Society for the Protection of Birds website has lots of information at www.rspb.org.uk.
Some garden birds have difficulty finding enough food during winter. You can make a bird cafe. If you have a bird-table, make sure it is safe from cats and squirrels, which will try to kill the birds or steal the food.
Insect-eaters, such as robins and thrushes, will love a plate of mealworms (you can buy these in fishing shops) or even a little tinned dog or cat food.
Half a fresh coconut is a treat for blue tits and peanuts are popular, too - but remember not to given them salted nuts. Fat is an important source of energy for birds in winter - suet, meat fat or bacon rind. Cut open apples and pears for fruit-eating birds or give them raisins or sultanas that have been soaked in water. Bread will do if there is nothing else. Feed birds only in winter - in summer they can find enough to eat.
BEAKS AND FEET
Birds eat all sorts of things - seeds, fruits, plants, worms, insects and other mini beasts. Some eat fish and raptors - birds of prey such as eagles and hawks - eat small animals and birds. They use their feet and claws as tools in the same way people use knives, forks and spoons. The size and shape of the beaks and feet can indicate what a bird usually eats - looking closely at these details can tell you a lot about its lifestyle.
* The curlew uses its long beak like a pair of chopsticks to pick up worms and small shellfish buried in the soft mud along the shore and river mouth.
* The peregrine falcon has a hooked beak to pull the meat off small prey.
* Flycatchers have thin, delicate tweezer-like beaks for catching insects.
* The flat beak of a dabbling duck acts like a sieve. The duck skims its open beak across the water surface, draining the water away and retaining any food that is collected.
* Most seed-eating birds have short, cone-shaped beaks. The chaffinch is a master nutcracker, cracking open a shell to reach the nut or seed inside.
Topping the bills: below from the left:
The hyacinth macaw uses its beak, tongue and claws to chop up fruit and even break open nuts
* A pelican can store fish in its beak,to eatlater or to feed to its young
* The black-browed albatross, common around the Falkland Islands, feeds on fish, lobster, krill and squid and regurgitates food for its young
* The bird's beak is used to break through the egg shell. l The keel-billed toucan uses its bill to feed on forest fruits, insects, reptiles and the eggs of smaller birds
* A puffin can hold several fish in its colourful beak, which has backward-sloping saw-like serrations
Falconry, the keeping and flying of eagles and hawks as pets, has a long tradition in the British Isles, as this poem shows: An Eagle for an Emperor, a Gyrfalcon for a King: A Peregrine for a Prince and a Saker for a Knight, A Merlin for a Lady, a Goshawk for a Yeoman, A Sparrowhawk for a Priest and a Kestrel for a Knave.
From the Boke of St. Albans, 1486 The British Falconer's Club (www.britishfalconersclub.co.uk) will provide addresses of falconers who present displays.
This feature supports the Qualifications and Curriculum Authority schemes of work for Science KS1 Unit 2B Plants and Animals in the Local Environment, Unit 2C Adaptation, and KS2 Unit 4B Habitats.
Are you 'as wise as an owl?' Do you 'eat like a bird' or have 'sparrow legs'? Birds proliferate in proverbs and sayings. How many can pupils collect?
Many of our summer-visiting birds migrate south for the winter months.
Track migratory paths on an atlas or globe to link in with work on climate and location.
Counting how many and often different species of birds visit a bird table provides data for bar graphs or data manipulation.
Throughout the ages, birds have played an important role in ceremony and religion. While studying Ancient Egypt, you might come across the impressive statuary representing the god Horus as a falcon. Birds abound in Egyptian hieroglyphs and tomb paintings, particularly vultures, ibis, herons, doves, geese and other waterfowl. In Ancient Greece, the owl was the symbol for Athena, patron of the city of Athens and goddess of wisdom and warfare. In Tudor times, birds were more often eaten than worshipped.
Dishes included stuffed peacock and roast swan - brought to table decorated with its own feathers.
Charles Darwin investigated the different types of animals and plants in different regions. He visited the Galapagos Islands off the coast of South America and studied finches. He thought that all finches had evolved from one species and that important differences had gradually developed. Beaks had evolved in relation to the available food supply. The birds used their beaks as tools. In areas where there were plenty of hard nuts, they developed short, strong beaks that could crack the shells open. There are around 13 species of 'Darwin's finches' on the Galapagos; each has a beak with a particular shape, suitable for feeding on the food most abundant in the region they inhabit - insects, leaves, seeds and, in the case of the vampire finch, the blood of other birds. Beaks must be suited to the available food. Only those species with the most appropriate features can survive in a given environment. Darwin called this "natural selection".