What are three reasons birds can fly?

1. Strong flight muscles. Birds have powerful flight muscles that are attached to their wings. These muscles allow birds to flap their wings and generate lift, which is the force that keeps them in the air.

2. Light bones. Birds have hollow bones that are filled with air, which makes them very light. This reduces the amount of weight that the bird has to lift off the ground, making it easier for them to fly.

3. Feathers. Birds have feathers that are made of keratin, the same material that makes up human hair and nails. Feathers are very lightweight and flexible, and they help to create drag, which is the force that opposes the bird's motion through the air. This drag helps birds to slow down and land safely.