Common swifts are declining across Europe due to loss of nesting sites in modern buildings and reduction of aerial insect prey from pesticide use and climate change.
Swifts returning after wintering in Africa to find their traditional nest site blocked by renovation face a genuine welfare crisis. Pairs that cannot find a nest site after years of preparation may not reproduce that year despite being in breeding condition. The combined loss of nesting sites and insect prey means swifts must work harder to provision chicks in increasingly degraded environments. Chicks in food-poor years are slow-growing and may not develop sufficient body condition to survive the arduous migration to Africa. Individual and population welfare are both compromised by the modernization of the built environment swifts depend on.