Flightless birds are species that have lost the ability to fly over time, often due to their unique environments. Examples include the ostrich, emu, and kiwi. These birds have adapted to life on the ground, developing strong legs for running and foraging instead of wings for flying. Many flightless birds are found on islands, where they evolved without natural predators. This allowed them to thrive without the need for flight. However, their inability to fly makes them vulnerable to threats like habitat loss and introduced species, highlighting the importance of conservation efforts to protect these fascinating creatures.