Modern building design and renovation practices are eliminating swift nesting sites at a rate that is driving population decline across Europe.
Swifts that lose established nest sites to building renovation face a welfare cost through failed breeding attempts at a site they have returned to for years. Long-lived birds with strong site fidelity invest years in establishing a successful nest site, and renovation that eliminates that site without replacement undermines decades of reproductive investment. Young swifts searching for their first nest site in areas where building renovation has eliminated cavities must extend their search, expending energy and facing risk in what may be a futile search for diminishing resources. The welfare solution is straightforward: embed nest bricks during renovation or construction to replace lost habitat.