Nature Table: The Swift

The swift is a summer bird. One of the last migrants to arrive, usually in May, they fly swiftly, catching insects on the wing and screaming as they do so.

They are also an urban bird, because almost all Irish swifts nest in crevices in buildings. Their flight silhouette is similar to a swallow or martin but this is a result of convergent evolution - they are quite unrelated but have independently evolved the most efficient shape for a life spent almost entirely in flight.

They only land to breed and are unable to take off from a horizontal surface. The rest of the year they’re on the wing, engaging a kind of ‘cruise control’ that allows them to sleep in flight.

Swifts are declining in Ireland because the use of uPVC and strict building regulations are reducing the number of nesting sites.

Other countries, such as the UK and the Netherlands have more enlightened regulations that insist that suitable nesting sites are retained in old buildings and incorporated into new ones.