Swifts also tend to return to favoured sites, with more than half (52%) of those locations surveyed being known swift nesting sites for more than 10 years.
However, the RSPB is concerned that almost one-fifth (16%) of the sites preferred by swifts for nesting are considered threatened. The charity believes that declining swift numbers could be due to such buildings being improved or even demolished.
A significant proportion (5%) of the chosen nest sites were churches, and the RSPB worries that church preservation work could be causing a loss of nesting sites.
Sarah Niemann, RSPB species recovery officer, said: ‘The scream of the swift marks the start of summer for many people. To think that we’re losing them at such a fast rate is devastating.
‘It’s imperative that we find out where they nest, so that efforts can help them can be effectively targeted.’
The RSPB is asking people to keep swift nests intact and to think about providing further nesting sites in new buildings. Swift nests are protected by law when they’re in use.
Emma Teuten, RSPB data management officer, added: ‘These are birds that don’t touch down for two years or more after they first leave the nest—we need to ensure they have a safe, secure nest site to settle in when they come to breed themselves.
‘Swifts are very site faithful, so once they move in, then the same site may be used for many, man years.’
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