Earlier this year in National Geographic, I wrote about how feathers evolved long before flight. This timing naturally raises the question, how did feathered dinosaurs take to the air?  My article was accompanied by a picture from the University of Montana lab of Ken Dial, who argues that before dinosaurs flew, they flapped their wings to help them travel up and down inclines. While not all experts accept Dial’s hypothesis, it has the undeniable strength that he can gather evidence for it in living birds, rather than just inferring behavior from fossils alone.

This video shows some of the astonishing climbs birds can make with the help of some wing flapping. It’s a mix of lab climbs and footage