Swifts are becoming an increasingly rare sight in the skies of the UK.
Concerned about the declining numbers, specialists from around the world have met in Cambridge to discuss ways to save them.
The small birds are said to herald the arrival of the British summer when they arrive on these shores on their annual migration from Africa.
Swifts spend nearly all their lives in flight. They eat, mate, even sleep on the wing. Only when it's time to have their young do they settle down for a while.
But after flying 3,000 miles from Africa, in just five days, many are struggling to find a place to stay here.
Dick Newell from Action for Swifts said: "The reason is thought to be mainly loss of nest sites, because roofs and houses and walls get repaired. New buidings are impervious to any living creature and so it's just a one-way street of decline and we have to do something about that."
Click below to watch a report by ITV News Anglia's Claire McGlasson