Why are flightless birds flightless?

Answer 1

There are 7 families of truly Flightless Birds in total. They include the Kiwi, Cassowaries, Rheas, Ostriches, Tinamous, Emus and Penguins.

Some of these belong to the family of birds known as ratites. Ratites include the Southern cassowary of Australia and New Guinea, the emu of Australia, the kiwi from New Zealand, the ostrich from Africa and the rhea from South America.

Ratites have wings but the bones in their chests do not have the capacity for flight muscles, which is what a bird needs to fly. Also, their wings are also too small by comparison to lift them.

Like ratites, penguins are flightless because they have wings which are too small to support their body weight. Unlike the majority of other birds, penguins do not have hollow bones, so are much heavier and harder to support with their small wings. The solid, as opposed to hollow, bones act as ballast to help them dive. Also, being solid, they are less prone to breakage from the stresses of swimming. Penguins eat fish. The fish they eat swim fairly deep under water, so flying is not an advantage in getting the fish, but swimming is. Therefore, penguins swim rather than fly. Quite simply, they don't fly because they don't need to.

Answer 2

This is a phenomenon known as ecological naivete. It mainly occurs in animals that live on small islands, where there are no large predators. Birds and other animals in such situations loose their fear as there are no predators from which they would need to flee. This is also why they lose the ability to fly, since flight is largely an escape mechanism.

Answer 3

Flightless birds like penguins, ostriches, and emus have evolved to become flightless due to factors such as lack of predators, abundant food sources on the ground, and the need for energy conservation. Over time, these birds have adapted to their environments by developing strong legs for running and finding alternative ways to survive without the need for flight.