Why don't all birds fly?
When you buy through links on our internet site , we may earn an affiliate military commission . Here ’s how it work . Birds are often associated with flight , but not all of them take to the skies . Around60 species — fewer than 1 % of all wench species — are flightless , including ostriches , penguin and kiwis . These birds evolve from flying ancestors but lose their ability to take flight , instead adjust to lifespan on land or in the water ....