Agreed, wonderful creatures.
Some years ago, each Wednesday I regularly ate my lunch at the Hanningfield Reservoir Visitors' Centre, where there is a book for anyone who goes there to log their "Latest Sightings" on the nature reserve, showing species, location and number.
One day I went there and it seemed that there was a hatch of something especially tasty from the water and wherever you looked there were swifts zooming around gorging themselves.
Some twitcher who had been there shortly before me had solemnly logged his sightings, which included "Swift, everywhere on the Reservoir, c. 180000".