Swifts mate for life, usually returning each year to use the same building and the same nest location they have used in previous years.
These locations are nearly always in buildings built before the 1950s and about a half of all nest sites are in private dwelling houses.
Unfortunately over the last few years their numbers have shown a marked decline for reasons not fully understood, but a significant impact is likely to be the loss of their traditional nesting sites.
Changes to buildings, re-roofing, repairs and building improvements which result in swifts being excluded from their previously used nest sites may be a major cause of their decline.
Swifts are very faithful to their previous nesting locations and are reluctant to move quickly to an alternative, so preserving the facility for birds to use their traditional nest sites is an important aspect of their conservation.
The trend to modernise and improve older properties, even if not currently used by nesting swifts, gradually depletes the potential stock of possible nesting places.
New swift nest locations can be created by installing external nest boxes.
New swift nest locations can also be created by incorporating appropriate facilities into new buildings and old buildings undergoing significant redevelopment.