Why can’t some birds fly? The science behind flightless birds

Many birds fly, but some, like penguins and ostriches, don’t, revealing an evolutionary twist. Flightless birds adapted to land or water when survival didn’t require flying. Lacking a keel, crucial for flight muscles, is a key reason. Island birds, predator-free and without migration needs, often evolved flightlessness, saving energy. This led to muscle and skeletal changes, with flight feathers disappearing.