Swift mitigation safeguards colony of migrating birds Jamie Fletcher 15 June 2023

Swift mitigation safeguards colony of migrating birds

How working in partnership on swift mitigation is helping to tackle the UK’s decline in cavity-nesting birds.

Swift mitigation

The issue: reversing the decline of an endangered species

It’s estimated that swift numbers in the UK have plummeted by nearly 60% over the past 25 years, which is why adequate swift mitigation was critical when house-builder Countryside Partnerships set out to regenerate the New Avenue estate in Southgate, London.

Surveys by the local swift group suggest that historically the location was home for 29 nesting pairs of swifts.

In 2021, the species was added to the UK’s list of most endangered birds, the red list of Birds of Conservation Concern. This is an official register delivered by a coalition of government and charitable wildlife bodies, including the RSPB.

These days, swifts are almost entirely dependent on man-made structures such as tower blocks to find nesting sites where they can breed. They are also loyal to their chosen locations, which means adults return to the same nesting site year-on-year throughout their 20-year lifespans.

When older buildings are replaced, modern construction materials such as unplasticised polyvinyl chloride (uPVC), are less likely to create the cavities through wear and tear that swifts prefer for their nests.

Our approach: working in partnership with local people

Jamie Fletcher, Principal Ecological Consultant with Middlemarch, was appointed by Countryside Partnerships in 2018 to support the regeneration scheme with ecology services including a swift-mitigation strategy.

With the population nationally under such severe pressure, the loss of a local colony estimated at 29 nesting pairs could have a significant impact on the national fortunes of the species – not to mention denying local people the chance to see this popular bird in flight and get closer to nature.

At the time, New Avenue was a former council estate with a high-rise block of flats that was due to be demolished to make way for new residential properties. The tower block in particular was home to a colony of swifts nesting in cavities within the fabric of the building.

Working in partnership with Countryside Partnerships and the local swift group, Jamie put together a swift mitigation strategy for the site. He decided that more than 60 swift bricks and boxes of various types would be needed to maintain the population at historic levels.

The birds usually arrive from West Africa during the first week in May each year. To attract them to the boxes, audio lures are put out shortly before they arrive so they are greeted with the sound of swifts calling to each other.

Over time, the swifts will get used to the boxes and more of them will decide to use them for nesting and breeding.

“Ecology projects like swift mitigation are usually more successful when local people and organisations work together towards a common goal.”
Jamie Fletcher
Principal Consultant, Middlemarch

More than 60 swift bricks and boxes (pictured) were installed at the New Avenue estate in Southgate, London. Will Rees, Senior Ecological Consultant, created the audio lures used on site.

The result: swift population back on the rise

Swift mitigation on the housing estate is now in its second full year. Population numbers are still recovering, but the fact that so many birds at least visited the nesting sites last year means that Jamie is confident the colony will return to its former size.

At least 12 swift bricks were seen to have birds enter or exit at some point during last year’s breeding season.

Jamie said: “The birds returning to the site this year will know that there is an existing colony, even if it’s not as big as before. This will encourage them to stay and make more nests. It might take a few years, but I’m confident and hopeful that the numbers will return to a healthy level.

“Ecology projects like swift mitigation are usually more successful when local people and organisations work together towards a common goal. For example, Michael Priaulx and his colleagues from Islington Swift Group monitor the site informally every year, as well as during periods of high swift activity. This regular monitoring has proven invaluable in feeding back any notable observations to our team.”

FOOTNOTE: Jamie fully supports Hannah Bourne-Taylor’s ongoing campaign to make the inclusion of swift bricks and boxes mandatory in new developments. Jamie’s contribution to the provision of integrated and retrofitted swift bricks and boxes in new buildings to date is likely to be in the several hundreds, on projects throughout south-east England.

Find out more


Need some advice and support about protecting species, including swift mitigation? Simply fill in our form here and we will get in touch.


Our qualified environment consultants are happy to discuss your requirements over the phone prior to instruction. We’ll provide you with clear and concise advice in an understandable, no-nonsense way. Please contact us on 01676 525 880.