Sensational Swifts

Swift © Stefan Johansson

The sight of swifts soaring overhead and their unmistakable screaming is the ultimate sign of summer. Andy Broadhurst from Hampshire Swifts tells us more about these beautiful birds, their drastic decline in numbers and the simple steps we can take to ensure their survival.

In early May our hitherto quiet villages, towns and cities are enlivened by the return of one of the UK’s most iconic bird species, the swift. These dark, crescent-shaped birds are masters of the air, spending the majority of their lives airborne, feeding, sleeping and mating in the air, landing only to breed.

They are only short-term visitors to the UK, capitalising on an abundance of insects and airborne spiders during a short summer season, returning to the skies above the equatorial rainforests of Congo and Mozambique as soon as their young have fledged in July (please click the map to view a larger version). 

Originally nesting in mature trees they have adapted to breed almost entirely on human habitations, relying on small gaps and holes through which they can access a safe space in which to lay their eggs. Swifts are social birds and on summer evenings groups of feeding swifts will spontaneously coalesce into a tight formation of screaming birds flying at breakneck speed between buildings before just as suddenly dispersing, often returning to their nesting sites. The sight and sound of this behaviour marks the summer and makes the swift one of our best loved summer migrants.

swift map

Why are swifts in decline?

The swift is undergoing a drastic decline and if we are not to be consigned to summers of silence then urgent action is needed to reverse this trend. A major factor impacting swift numbers is thought to be reduced availability of nest sites. The push to seal and make buildings more energy efficient and presentable by replacing wooden soffits and fascias with plastic, blocking holes and gaps around guttering and indiscriminate reroofing of council properties is slowly strangling the overall supply of the gaps and holes swifts require to breed.

swift graph

This is made worse by the very evolutionary adaptation that allows swifts to breed successfully within the constraints of a very tight breeding timetable. Swifts exhibit a high degree of fidelity to their nest sites and breeding swifts will always return to the nest site they used the year previously, allowing them to mate and lay eggs much quicker than other species. If returning swifts cannot access these sites they probably won’t breed that season, so impacting on the overall productivity of the population.

For these reasons, the swift nest site is the primary factor to consider when planning swift conservation. If we can protect existing swift nest sites and simultaneously provide new sites by installing nest boxes onto existing buildings and integrating swift bricks into new developments then we can start to reverse this drastic decline.

Conserving swifts in Hampshire

Hampshire Swifts was formed in 2016 to raise awareness of the plight of swifts and to promote activities supporting their conservation. Nest sites can only be protected if we know their precise location and this is best done by contributing to the Hampshire Swift survey via an online survey form. Nest site records are shared with the Hampshire Biodiversity Information Centre, which makes them available to planners and developers allowing renovation and repair work to be done with swift nest site conservation in mind. There is still much to do as our knowledge of swift breeding sites is incomplete and renovation works are often scheduled at the worst time for swifts simply because of a lack of awareness of the conservation issues involved. Planning submissions need to be monitored on a regular basis to ensure known colonies of swifts are not impacted.

Our second objective is to increase the number of nesting sites across the county. We do this by encouraging householders, businesses, churches and public bodies to install nest boxes on their buildings, especially if swifts are known to breed nearby. The biggest challenge is lobbying for the inclusion of swift bricks in the thousands of new houses being planned across the county as well as in hotel chains, residential homes for the elderly and other developments. 

How you can help

There are so many ways you can help swifts in your local area from recording nesting sites, monitoring planning applications or adding a nest box to your house. If you'd like to install a nest box, Hampshire Swifts can provide advice on the nest box type and where to place them. You can purchase a box from them directly and a local volunteer can even install the box for you! Please contact:

If you're keen to find out more or would like to get involved in local swift conservation, come and see us at the Hampshire Swift Day being held in Romsey on the Saturday 30th June. 

Hampshire Swift Day

With special thanks to Andy Broadhurst from Hampshire Swifts.

Migration map and swift decline graph © British Trust for Ornithology