House martins return from Africa each year to breed in colonies under the eaves of buildings. Building renovation that removes nests or blocks access is a significant welfare and legal threat.
House martin nests destroyed during renovation kill eggs and chicks directly, and prevent returning adults from breeding for years. The legal protection of occupied nests is not widely known by homeowners or builders. Artificial nest cups installed under eaves adjacent to original nest sites have high adoption rates. Building regulations and planning conditions can mandate retention of existing nests and installation of artificial cups as mitigation for renovation work.