Credit: Phil Savoie / Naturepl.com
How do swifts breed?
Swifts mate for life and will return to the same nest site each year. Historically, swifts would have nested in holes in large trees, cliffs and crevices. However, today's UK population depends almost entirely on buildings for nest sites.
The nest is built under the eaves of old buildings and is made from any materials the swift can catch in flight. The birds then use their own saliva to hold the nest together.
Two to three eggs are normally laid, hatching after three to four weeks. The chicks will spend up to eight weeks in the nest before fledging.