Common swifts spend almost their entire lives in the air, only landing to nest, making the availability of suitable nesting sites critical to their survival and welfare.
Swifts nest exclusively in cavities in old buildings, under roof tiles, and in rock crevices. Modern building practices including insulation retrofits, reroofing, and demolition routinely destroy active nest sites. Swifts show high nest site fidelity, returning to the same site year after year. Loss of their specific nest site causes breeding failure and population decline. Building regulations in several countries now require swift bricks or boxes to be incorporated into new builds or renovations. Swifts face a narrow welfare window during the breeding season from May to August when any disturbance during chick-rearing is critical.