Why don't birds like penguins, ostriches and kiwis, take to the skies ???
Birds are often associated with flight.
But fewer than 1% of bird species are flightless.
These birds evolved from flying ancestors but lost their ability to fly, instead adopting to the life on land or water.
The ability to fly is useful especially for escaping from predators and travelling long distances in search of food.
However flight requires a lot of energy.
If flight isn't necessary, birds can divert this energetic investment somewhere else.
Island dwelling birds facing few or no predators and less competition for food and habitat tend to evolve towards flightlessness.
Many od these birds thrived on islands but disappeared shortly after humans arrived due to direct hunting or introducing predators on the island.
