The numbers of swifts visiting the UK in decline
Demolition works and repairs to properties are affecting the swift population, conservationists say.
The RSPB said numbers of the bird, which visits from Africa and nests almost exclusively in buildings, have declined by 47% in the past decade.
The charity wants the public to report sightings so it can build up a picture of where the birds are found and target conservation work in those areas.
The RSPB said swifts were "perfect, quiet neighbours".
The wildlife charity is also offering advice to the building industry and homeowners on how to do renovation work without stopping swifts, which nest in colonies, from successfully rearing their young.
Sarah Niemann, species recovery officer for the RSPB, said the reasons for the decline in numbers of migrant bird were not entirely clear.
She added: "We do know there appears to be a problem with nest sites in this country.
"There may be a variety of stresses on these birds, but certainly there has been a big trend in this country in making houses look smart."
She said efforts to prevent rot and decay and make houses more airtight was good for maintaining properties "but can unwittingly make it difficult for swifts that cause no bother at all".
She also said swifts were "perfect, quiet neighbours", which build nests next to the entrance hole of the nest site, meaning they do not get into the roof space.
The RSPB is urging any householders who need repair work carried out on roofs or faschias to make new nest access holes to match the old ones at the same spot.