A quiet conservation project at Wells Cathedral is aiming to bring back one of Britain's most extraordinary birds.

After months of preparation, 16 new sound-enhanced swift boxes hidden in the North West tower of the Cathedral have been officially switched on, just in time for the birds' return from Africa.

Tim Norriss, founder of conservation charity Hampshire Swifts, made the climb up the tower to activate the speakers, which will now broadcast swift calls three times a day until the end of July. The idea is to attract the birds to nest in the specially built boxes.

He was joined by local environmental consultant Simon Nash, who helped lead the installation of the boxes last summer. After the switch-on, they gave a talk to Cathedral volunteers about the challenges facing swifts and why projects like this are urgently needed.

Swifts are among Britain's most remarkable birds, able to sleep and mate in flight, and spend almost their entire lives on the wing. But despite their strength in the air, swift numbers have plummeted by around 70% over the past 30 years, largely because of modern building designs that block access to traditional nesting sites.

The new swift boxes, high in the North West tower of the Cathedral's iconic West Front.

In Wells, the decline has been particularly stark — from around 25 nesting sites 40 years ago, just three remain today.

Nash said: "Wells Cathedral has stepped up as a model for other communities. With swifts now on the Red List of highest conservation concern, every nesting site counts. This is a small act with the potential for huge ecological impact."

The new boxes could have a major impact if successful. A similar scheme at Winchester Cathedral grew from one nesting pair to more than a dozen in just a few years.

The speakers will run daily through the summer and then be switched off to allow any new residents to settle quietly. Conservationists hope that before long, the skies above Wells Cathedral will once again echo with the screeching calls and acrobatic flights of these much-loved birds.

Residents and visitors are being encouraged to keep an eye — and ear — out over the next few weeks.