Why can't kiwi birds fly?

Why can't kiwi birds fly?

CPI Ramón y Cajal Ayerbe

What are kiwis?

Kiwi birds

Birds

Birds

Most birds can fly

Why can birds fly?

Birds are light

Birds are strong

Birds are aerodynamic

Their body is designed for flying

Their arms have transformed into wings to power them along.

Their body is designed for flying

Instead of heavy jaws and teeth, they have lightweight beaks.

Their body is designed for flying

Instead of fur, they have feathers.

Their body is designed for flying

They have special bones. They are filled with air sacks.

Which forces affect the flying of birds?

The four forces of flight are weight, lift, drag and propulsion.

Weight

Weight is affected by gravity.Gravity is the force that keeps us to the ground and makes objects fall.The heavier a body is, the faster it falls down.

Lift

Lift is the force that is opposite of weight. For anything to fly, it must have more lift than weight.The air travels faster above the bird's wing than it does below, and this makes the pressure lower above the wing.

Drag

Drag is the resistance offered by a fluid (gas or liquid) when an object moves through it.

Propulsion

Propulsion or thrust is the force that pushes something forward. Birds need this force to take off (start flying) and to face drag.

Types of flying

Flapping: Birds’ wings flap with an up-and-down motion. Flapping flight is basically rowing in the air. It generates lift and thrust.

Gliding or soaring: When a bird is gliding, it doesn't have to do any work. The wings are held out to the side of the body and do not flap.

The importance of wings

Wings produce lift and propulsion. A flying bird changes direction by altering the angle or shape of its wings. When a bird isn’t flying, it folds its wings neatly and tucks them against its body, out of the way. Wings also allow birds to regulate their body temperature.

What about kiwis?

Kiwis are vertebrate animals

Kiwis lay eggs

Kiwis are heavy

Unlike other birds, their bones are filled with marrow and don't have air sacks.

Kiwis have wings

Kiwis have small wings

Their wings are so small they can't hold their weight, lift its body or thrust it.

Why are their wings so small?

What science says: EVOLUTION

Kiwi birds have been evolving in New Zealand for millions of years, and during that time, they have made some adaptations to living on the ground that do not include the presence of wings or the ability of flying. This is because they had no land-based predators in their environment until people arrived in the islands. Now, kiwi birds may be extinct in 50 years.

What Maori people say

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