Swifts lay 2-3 eggs and breed and hatch the chicks together. In these days they fly late until dark, while the non breeders of a colony assemble and fly high in the sky to sleep there on the wing. At the end of July the young will fly out, mostly right after sunset and will never come back to the nest. They need no exercises in flying and after a few moments they practice as well as the adults. Just in time around the 1st of August the parents will leave Central Europe for Africa .
Swifts breed in holes of caves or hollows of trees.
Nowadays they mostly use holes in walls or a free space under the eves of houses. They accept nest boxes too and don't fear humans. It is easy to place a nest box in a window. The hole must be directed to the open air, of which the bird needs some in front of the nesting place. When leaving the box, the Swifts don't fly up into the air, but just jump down, and while falling a couple of meters, they get the necessary speed to fly.