15-Year Study: 94% of Swifts Reuse Same Nests

The findings carry particular weight because the swift is one of Britain's most threatened birds, on the national "red list" of conservation concern. Its numbers have fallen by about 70% since 1995, largely because traditional nest sites are destroyed when old buildings are re-roofed or fitted with modern insulation. Conservationists argue that this loyalty makes the loss of any single site especially damaging, since displaced swifts cannot easily relocate. They are campaigning for "swift bricks" — simple hollow bricks costing around £35 — to be built into new homes. Scotland has made their installation a legal requirement, but the government in England has repeatedly declined to oblige builders to fit them, despite a four-year public campaign.

Malcolm Burgess, the RSPB's principal conservation scientist, said the research confirmed long-held suspicions. "For the first time, we've documented just how strongly faithful they are to their nest sites, which highlights just how important it is to protect their nesting sites in our neighbourhoods," he said, warning of "further declines" without new and replacement sites. The study was published ahead of UK Swift Awareness Week, when more than 150 local groups from Aberdeen to Devon hold events to help the public protect the birds. Organisers fear a current heatwave could kill chicks in overheated nests, but say community enthusiasm is growing rapidly, with volunteers increasingly stepping in to rescue grounded young swifts.