Which bird is adapted to running rather than flying?

The story behind the answer

Ostriches are built to run, not fly. As the world’s largest bird, they’re flightless with a flat breastbone lacking the keel needed for powerful flight muscles. Their energy goes into long, muscular legs with springy tendons and two-toed feet (one toe forms a big claw), acting like natural running blades. They can sprint up to about 70 km/h (43 mph), using their wings as rudders for balance.

Context check: Penguins are swimmers, albatrosses are master gliders, and flamingos both fly and wade—only the ostrich is a true sprinter. Memory tip: “Ostrich out-sprints,” the savanna’s two-legged runner.