Our urban lives are wrapped up in the swift’s fate. To survive, they need our help

Given it only weighs the equivalent of 40 paper clips, the swift certainly makes a racket. As I write, five of them are circling the house like aerial lunatics, screeching as they zoom past the window. The increasing and decreasing volume of their calls tracks the rapidity of their movements; given they’re the fastest bird in level flight in the world, it makes for a heady soundscape.

Soon, all will be quiet. The adults, who pair for life, arrive from Africa in the first two weeks of May and seek out the same nest cavity they’ve used all their lives. By mid-August, when the last chick has left, the adults take to the skies and fly, in silence, back to their home in central Africa. No time is wasted making this trip – they can cover up to 830km a day.

I’m fortunate that, like others across urban Ireland, I’ve long had a close entanglement with swifts. For years, they’ve kept a nest under the eaves of the house. But such is the sheer speed at which they enter and exit the gap under the gutters that I often wonder if I’m losing my mind to think they’re up there at all. Swifts give no indication they’re about to fly into their nest until the last millisecond, so they’re easily missed. They slip and dip out of the eaves in a haze; by the time my eyes have tried to follow their path into the sky, they’ve disappeared as if in some kind of David Blaine magic trick.

One year, I got a close look. After a few days away, I returned to find a swift sitting on a windowsill upstairs. It must have mistakenly flown through an open window under the eaves while returning to its nest. Because they’ve evolved into creatures of the air, their legs are short and stubby – barely useful at all – and this one sat still and stared outside. But it was panting with dehydration, so I took a ball of cotton wool soaked in water and pushed it in its beak. It drank the ball dry and, within about 40 seconds, lifted its head upwards. I opened the window from below and it flew out in a flash.

I’ve written before about swifts and their mind-boggling aerial existence. They sleep, eat and mate in the air, and for their first three years, before they start to breed, they never once land. The closest they come to Earth is when they hurtle down towards a lake, their beak open to increase drag and slow them down as they skim the water’s surface and fill themselves up before taking off again into the air, their forked silhouette dark against the sky.

Like salmon, swifts are faithful to their breeding site and return to the same nest year after year. But a lot can happen in the nine months they’re in Africa. Buildings are renovated, and nesting sites are inevitably – if inadvertently – blocked. It’s one of the reasons why their numbers are plummeting – a 50 per cent drop in 25 years – and they’re now listed as in danger of extinction. In 1936, a written record was made of “hundreds of swifts” circling over a house in Powerscourt, Co Wicklow, before heading towards Greystones. Today, you’d be fortunate to see 10 at any one time.

Our urban lives are wrapped up in their fate, and for them to survive, birds need cavities in buildings to breed. Leaving these gaps isn’t always compatible with insulation projects, but there are alternatives that don’t cost a huge amount. “Swift nest bricks” – hollow bricks with a small hole as an entrance – can be integrated into new builds and are permanent nesting sites for birds.

Nest boxes can also be attached to walls. A few years ago, I put swift boxes, made by Stephan de Beer in Kerry, on my house and on the outer wall of my kids’ primary school. Because swifts are madly sociable and love being around each other, playing a looped recording of their call through a small speaker beside the box can attract the attention of young swifts who’ll repeatedly bounce off the cavity, mapping the site as a potential nest for future years.

There’s potential for boxes and bricks on public buildings such as sports clubs, churches, libraries and county council offices. This summer, Patrick Earls, a volunteer with Swift Conservation Ireland, installed 34 swift boxes on the walls of four primary schools in Dublin – St Mark’s Tallaght, St Louise’s Ballyfermot, the Harold School Glasthule and Scoil Íosagáin Crumlin. The project was trialled last year in schools in Cork and has funding from Gas Networks Ireland and the civil engineering firm Murphy. It is, says Patrick, “remarkable to witness the agile swifts on a summer evening along Dublin’s South Circular Road … and to think that only a month or so before they were gliding above the Serengeti or the river Congo in equatorial Africa”.

Soon, pairs of swifts will take a break from each other and fly back to Africa before reuniting next spring. I’m slightly dreading the silence in the air, not least because it reminds me autumn is on the way, but as we face the cold months ahead, it’s endearing to think of the swifts flying above the headwaters of the river Congo, chasing swarms of termites in the air.