15-Year Study: Swifts Return to the Same Nests

The findings matter because the swift is one of Britain's most threatened birds and sits on the national "red list" of conservation concern. Its numbers have dropped by about 70% since 1995, mainly because old nesting sites are destroyed when buildings are re-roofed or given modern insulation. Because swifts are so loyal, losing a single site is especially harmful, as displaced birds cannot easily find a new home. Conservationists are campaigning for "swift bricks" — simple hollow bricks costing around £35 — to be built into new houses. Scotland now requires them by law, but England has repeatedly refused to make builders fit them.

Malcolm Burgess, the RSPB's principal conservation scientist, said the study confirmed what experts had long suspected, and warned of "further declines" without new nesting sites. The research appeared just before UK Swift Awareness Week, when more than 150 local groups hold events to help people protect the birds. Organisers fear a current heatwave could kill chicks in overheated nests, but say public interest is growing fast, with volunteers increasingly rescuing young swifts found on the ground.