Common swifts (Apus apus) have declined by over 50% in parts of Europe over recent decades. Understanding the causes and supporting recovery efforts helps protect these remarkable birds.
Swifts face welfare challenges across their lifecycle. Chicks in nest cavities are vulnerable to heat stress during hot summers as modern buildings lack the thermal buffering of old eaves. Aerial insectivores like swifts face increasing food stress during prolonged cold spells when insects disappear — chicks can starve and adults lose weight rapidly. Migratory birds face risks from habitat degradation and climate-driven mismatches between insect emergence and breeding timing. Adults that cannot find nest cavities cannot breed, causing population-level welfare consequences. Swift boxes and bricks installed in buildings provide critical substitute nest sites, and swift-friendly building design is increasingly recognized as essential infrastructure for urban biodiversity.