When we think of birds it’s often with them taking flight in a flock. We envy them the freedom to take to the skies whenever they want to. However not all birds can fly. There are a number of flightless birds such as the emu, ostrich, rhea, kiwi, cassowary and the penguin, to name a few.

Why can’t these birds fly? The first problem is the wing span. A herring gull has a wing span of about 1.4 m where as the fairy penguin has a wing span of merely 32 cm. So even though the two birds weight nearly the same, it is impossible for the fairy penguin to support flight on it’s short wings.

The second problem in the larger birds like the ostrich is weight. They have a decent enough wing span, but the corresponding weight of the bird is too much for the wings to support. Also their bones are filled with heavy bone marrow. Most birds which are blessed with the ability to fly don’t have bone marrow, their bones are filled with air.

Also the flightless birds have other adaptations which help them survive better in their chosen home environment. For instance any science project would agree that it is more helpful for the penguin to be able to swim than to be able to fly in order to procure food.