How does a baby bird learn to fly? One anecdote is to push them out of the nest and hope they do not hit the ground. It is also similar o how a human baby learns to walk. The muscles have to grow strong enough to do the job. It can take months for their partially developed wings and flight muscles to become airworthy, and by then the youngsters are almost fully grown. However, long before their maiden flight, chicks probably put their developing wings to use, flapping as they run up steep branches. Brandon Jackson from the University of Montana, USA, explains that Ken Dial and his son first noticed this strange behavior when filming chukar chicks negotiating obstacles: instead of flying over, the birds ran up over the object flapping their wings. When Dial discussed this behavior with local ranchers and hunters, some described adult chukars flapping to run up cliffs. So why do adult birds flap and run up steep objects when they are perfectly capable of flying? Jackson, Dial and their colleague Bret Tobalske wondered whether pigeons might use ‘flap running’ to save energy, so they measured the amount of power generated by the flight muscles of flap running and flying birds and found that flap running birds use less than 10% of the energy of birds flying at the same angle.