Book 31, Question 19
Why do flying birds have a tall ridge on their chest bone?
Flying takes strong muscles, and strong muscles need something firm to hold on to.
A bird’s breastbone has a tall ridge called the keel that sticks out like the keel of a boat. The big muscles that flap the wings are attached to the keel. In strong fliers, those muscles make up a big part of the bird’s body weight.