Question

Why did the Dodo bird never learn how to fly?

Answer 1

Ancestors of dodo was a flying bird. When reached island it has lost flight.

Explanation:

Flight is adaptation against predation. Dodo when reached island it was without predators. After many generations the flight muscles became weak.
When island was inhabited by sailors, the dodo was easy target. The bird was bulked. It was killed for meat.
Dodo has not regained flight once again because change is a slow process. For adaptation sufficient time span should be provided.