Lapwing in flight

Adapted for flight

Flight is birds' most important adaptation. It takes them into an environment that most other animals can't reach: the air.

Their lives depend upon this special skill. It allows them to catch food, avoid enemies, find each other and travel huge distances in super-quick time.

How animals have adapted

Gliders

Some animals are gliders. Flying squirrels, for instance, can glide more than 100 metres between one tree and another by jumping off and stretching out special flaps of skin between their limbs. But gliding is not the same as flight, since there is no power behind it. It’s like a paper aeroplane which soon falls to the ground.

Other flyers

Only some animals can fly properly. Most winged insects can do it, such as flies, moths and dragonflies. Bats are the only true flying mammals. Their wings are made of skin stretched out between special long finger bones.

Flying machines

Birds are the champion flying machines of the animal world. Their bodies are designed for it. Their arms have transformed into wings to power them along. Instead of heavy jaws and teeth, they have lightweight beaks. And instead of fur, they have feathers. These are light, streamlined and cleverly adjustable for flight control. Their bones are also hollow (pneumatised) making them lighter for flight.

Egg weight

Laying eggs gives birds another advantage for flight. Unlike mammals, such as humans, a young bird develops outside its mother’s body – in the egg. So the mother has less weight to carry. 

This may be why the largest egg of any bird relative to its size is actually laid by the flightless kiwi. This huge egg takes up one third of the mother’s body before it is laid. There’s no way she could fly and carry the egg, even if her wings worked.

Hen harrier Circus cyaneus, adult female in flight, hunting, Loch Gruinart RSPB reserve, Islay
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