How birds developed the ability to fly

By: PHILIPPA SUMNER


posted on: July 9th, 2018

Have you ever jumped off a step and pretended to fly? Many of us want to be able to fly! Birds are the best flyers in the animal kingdom. How do they do it?

Birds can fly because of many special characteristics they have. These are called adaptations. Some birds can fly better than others. Chickens are bad flyers- they can only fly for a few metres. However, swallows migrate (fly from one home to another each year) for many miles from England to Ghana. Some birds such as penguins cannot fly. Instead they use their wings to swim long distances.

ENERGY

Firstly, birds need a lot of energy to start the flight. This energy comes from chemical reactions in cells in the bird. The bird breathes in oxygen. The bird also eats seeds and other foods that contain a substance called glucose. This glucose and oxygen react with each other in the cells to release energy. This energy fuels the lift off and flight.

TAKE OFF

Birds take off facing the wind. This gives them more control. If they were to start flying with the winds behind them, they could be pushed in any direction.

There are 2 different types of take off.

Leaping. Some birds such as swallows leap (jump) off a high cliff. Gravity pulls the bird down. During this time, the swallow spreads its wings. When its wings are spread out, the bird is lifted into the air and is stable.

Flapping. The more common lift off way is by flapping the wings. These birds rise from the water or ground by pushing their wings down very fast and hard a few times. Many birds run a long way across land or water to get enough force to fly. The force that pushes the bird upwards is called lift.

FLIGHT

Birds make flying look easy. However they have lots of adaptations to flying such as wings, a tail, feathers and different bones.

Tail. The tail helps the bird slow down, speed up, turn right and turn left. If the bird wants to slow down, then it will lower its tail. This creates a wind ‘block’ called wind resistance. To keep a constant speed, the bird will keep its tail level. This lessens the wind resistance. With less wind resistance, the bird can save energy flying.

Bones. Birds have ‘pneumatic’ bones. ‘Pneumatic’ bones have air spaces in them making them lighter than normal bones. It also makes birds very delicate and can break easily. There are also less bones in a bird than in other animals. All of these reasons make the bird lighter. A lighter bird uses less energy to fly and will not get so tired.

LANDING

Different birds have different ways of landing. All birds must raise their heads or body to slow down. Many birds also spread out their wings to increase wind resistance, to slow down. The bird cannot slow down too much as it will just fall from the sky! When they are flying at the correct speed, the bird will stick its feet out and land either in a tree or on water.

Birds are very good flyers. The arctic swift can fly for 200 days in a row and not touch land. Humans have learnt how to build planes by learning how birds fly.

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