Home & Garden
‘Give birds more space’
RSPB shares how to help ground-nesting birds this spring and summer.
26 May 2026
Main image: Common swift group in flight, Cambridgeshire. © RSPB / Ben Andrew
New research by the RSPB has revealed the true loyalty of the iconic swift – the fastest bird in the world in level flight, which sleeps, eats, bathes and even mates on the wing and has a scream that heralds the start of summer.
The 15-year study showed that when looking for a place to breed, most swifts seek to return to the same nesting site each spring, with many pairing up with previous partners.
But when push comes to shove, it turns out that swifts have greater loyalty to their nest site than a previous partner; nine out of 10 (94%) birds used the same nesting site as a previous year, while only six out of 10 (59%) paired with the same partner.
Over 15 years, researchers collected data from swifts breeding in nest boxes in and around a Dartmoor village. Breeding swifts were identified by uniquely numbered leg rings which enabled scientists to track which birds bred together and which nest box each swift nested in every year. Data were collected from 243 nests during this period.
Where the team were able to identify both birds from a pair for two years in a row, they found only 5.5% (three out of 55) known to have returned had ‘divorced’ and paired up with a new partner.
Over the course of the study, 59% of pairings were between previous partners. Across the 15-year period, the majority (95%) of swifts returned to the same nesting site to breed. For swift pairs which stayed together for two or more years, 89% reused the same nest site.
‘We’ve anecdotally thought for a long time that Swifts are loyal, returning to the same nesting sites and partners each spring. But for the first time we’ve documented just how strongly faithful they are to their nest sites, which highlights just how important it is to protect their nesting sites in our neighbourhoods. The decline in Swift numbers is a great cause for concern and without increasing the availability of nest sites, and replacing those that are being lost, we will see further declines of this extraordinary bird in our towns and cities.’
MALCOLM BURGESS
RSPB’s principal conservation scientist
Swifts are a familiar sight in many of our villages, towns and cities, nesting in the eaves of buildings and identifiable by their scream-like calls. Their scythe shaped wings mean they are capable of incredibly efficient flight, spending their whole lives eating, sleeping and mating on the wing.
Each spring, after wintering in Africa, these birds migrate 3,400 miles to the UK. It has been widely believed they returned to the same nest sites. Using the same nest site year after year means birds become familiar with the local area and find food more efficiently, and they attract other swifts to nest within the same colonies.
Historically, swifts have made use of small crevices and holes in buildings to raise their chicks, but new building methods have left them increasingly few spaces for nesting. Changes in building practices mean the nooks and crannies in the roofs and stonework of our houses are disappearing, reducing the availability of nest sites. Where swift nest sites were lost during the study, scientists observed that the swifts were forced to move colony.
The species has declined by 70% (1995-2024) in the UK, likely due to loss of nest sites and availability of insects.
Providing specially designed nest boxes or swift bricks is becoming increasingly important, but the fitting of swift boxes to new buildings is still not compulsory and is only encouraged by planning policy rather than required by law. All too many new houses and other buildings still fail to provide them.
This must change, alongside stronger controls and penalties to prevent the demolition of buildings while swifts are nesting in them, if swifts are to be guaranteed the much-needed supply of alternative new homes that they increasingly need.
‘Recent changes to planning policy made by the Westminster Government to more strongly encourage developers to fit Swift bricks to new buildings are a small step in the right direction. However, they fall far short of what is needed if we are to halt and reverse the decline in our Swifts.
‘The fitting of Swift bricks in accordance with the relevant British Standard wherever possible should be a legal requirement. Tighter controls are also needed on the demolition of buildings where Swifts are, or may be, nesting, alongside more resources for the stronger enforcement of the Wildlife and Countryside Act 1981 where nests are illegally disturbed or destroyed. Swifts need us to act, and now.’
CARL BUNNAGE
Head of Nature Policy at RSPB England
This year Scotland became the first UK country to make installation of swift bricks, bricks designed to provide an ideal space for swifts to nest in, a legal requirement for new buildings, to help safeguard the future of this threatened species.
Despite much campaigning, the rest of the UK still falls short of this simple measure. It is clear from this new research that if swifts continue to lose the nest sites they return to each year and not enough suitable new nest sites are made available, they will eventually be lost from our skies.
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