The common swift (Apus apus) spends more of its life airborne than any other bird — landing only to breed. UK populations have declined by over 50% since 1995, primarily because building renovation seals the roof eaves and wall cavities where swifts have nested for centuries.
Swifts returning to nest sites that have been sealed during building renovation face the immediate welfare consequence of having no available nest site. Pairs that have nested at a site for years — forming strong site fidelity — are left without breeding opportunities. Their inability to walk or take off from flat ground means loss of access to aerial launch points is immediately welfare-critical. Young swifts that become grounded cannot take off and die without human assistance. Conservation welfare requires legal protection for active nests during renovation, provision of swift bricks in new developments, and re-opening sealed sites.