Researchers studying bird behavior found these jumps with a little flapping are the best way to get from perch to perch, at least for distances of a few feet. Parrots that pushed against a branch with their feet used less energy than when they pushed against the air with their wings.
Those energy needs could also be why we don't see evidence of more flying dinosaurs. They were probably too heavy to make flapping over long distances practical, but the short hops still would have been useful.
Researchers in this new study proposed that as flight evolved, early birds got smaller than their dinosaur precursors because lighter bodies are easier to lift.