Never stopping for breath

Birds warble without taking breath. They need lots of oxygen to fly--how do they manage?

SciTech Daily has an article which shows how air gets pushed through their looped lungs. ("Rectification" in this case means making things flow in one direction.) "back-and-forth motions generated by breathing were transformed into one-way flows around the loops." This lets them use the whole lung loop efficiently, with no dead air areas.

Eat your heart out, Frank Sinatra...