They can glide past eddies that would slow them down and then gain extra thrust by "pushing off" the eddies.
它们可以滑过使它们减速的涡流,然后通过“推开”涡流获得额外的推力。
2
I have this theory that, to us the world is a flat thing we stand on, but to birds it is a cliff they cling to, a huge ball and they cling to the side and then fall off and fly and glide.