Swifts

A lightweight sensor attached to alpine swifts reveals that the small migratory birds can remain aloft for more than 200 days without touching down.

Breeding swifts will sleep in the nest, and what a relief that must be. Otherwise they sleep on the wing - the only bird known to do this.

Except when nesting, swifts spend their lives in the air, living on the insects caught in flight; they drink, feed, mate and sleep on the wing.

Swifts are the most aerial of birds and some, like the Common Swift, even sleep and mate on the wing. No other bird spends as much of its life in flight.

The swifts and the swallows told their feathered friends all about it, and they told others, both birds and animals, until at last it began to be rumored through all the animal world that on one day in the year the children of men were made wonderfully happy by means of some sort of a festival which they held about a fir-tree from the forest.