agerly anticipated by many, it is a thrilling moment when you first hear the distinctive screech or catch sight of the long, tapered wings of the first swifts arriving for the summer. For thousands of years they have looped to the British Isles from Africa to raise the next generation, taking advantage of the long daylight hours in the north and the opportunity to scour the skies for insects from dawn to dusk. Since they left Britain’s shores in August last year, these remarkable birds will have flown some 14,000 miles without stopping; feeding, sleeping, drinking and preening themselves on the wing. The birds returning now are likely to be at least four years old – the breeders. They head straight back to their nesting holes under eaves or gaps in stone and brickwork that they claimed and defended last summer. Within a few days their mate will arrive and, having spent nine months living independently, they will start to preen each other’s feathers within the nesting hole, crooning softly and bonding once again. Unfortunately, each year many of these site-faithful birds return to find access to their nest holes blocked by renovation works that have not taken account of their needs. Plastic soffits, fresh mortar or expanding foam may have sealed the entrance – and the fate of these swifts’ nesting opportunities. Modern construction materials virtually exclude them from new buildings. Common swifts are in perilous decline in the UK. For 23 years the British Trust for Ornithology has recorded a relentless, downward trajectory, with numbers falling by 57% in 22 years. Insect decline is almost certainly a factor, but so too is the loss of nesting sites. Buildings, once permeable to a range of wildlife, from bats to bees, sparrows to swifts, are increasingly closed off to the natural world. Champions of the swift have sprung to the rescue around the country, installing nest boxes on houses, schools, libraries and hospitals, and inside church belfries. But replacing nest holes that have been blocked over a period of decades requires a strategic approach. This is where nest bricks come in. These are hollow, rectangular boxes made of a breathable material called woodcrete or stonecrete – a mixture of concrete and wood or stone. Integrating them into walls does not compromise insulation and the only part visible from the exterior of the house is the small entry hole. While they are referred to as swift bricks, they have been found to attract a range of wildlife, making them qualify as a “universal” bird brick. House sparrows, house martins, blue tits, great tits, starlings and nuthatches have all been recorded nesting in them, while hibernating tortoiseshell butterflies and bees can also use them. Sparrows actually prefer them to the heavily marketed sparrow terrace, a compartmented box that provides accommodation for several pairs of the birds. Sparrows like to have space between themselves and their neighbours, just as swifts do, nesting in loose colonies, not living cheek by jowl. This summer, the British Standards Institution will, for the first time, issue guidance on bird bricks, making it simple for architects to incorporate them within their designs. Specifications for brick and entry hole size will be given, and illustrations will show where to install them – and where they are best avoided. It will become a simple matter for planners to place conditions on a development for “bird bricks” instead of navigating the confusing array of options currently available. While the reality is that compliance with conditions is frequently ignored by developers, the government’s biodiversity net gain policy, combined with the low cost of these bricks and their simplicity of use, is likely to drive uptake. Stephen Fitt, a retired financial consultant who has worked as a volunteer for the RSPB for many years from his home near Exeter, has acted as an unpaid adviser to numerous architects across the country, including many in south-west England. Fitt gently persuades them to adopt the swift brick in new developments, ideally at a ratio of one per dwelling. He says: “House sparrows, starlings and swifts are all at risk because they nest in buildings and the holes they once used are disappearing. Nest bricks are inexpensive and need minimal maintenance.” Exeter city council is installing the bricks in new schools, hotels, social housing, care homes and residential buildings, while the university has integrated them into student flats and educational structures. The Duchy of Cornwall is committed to integrating one into each dwelling in all its housing projects and associated buildings. Monitoring of nest bricks installed in the first phase of the Duchy’s Nansledan development at Newquay clearly demonstrated their effectiveness. A survey conducted last summer found that of 628 nest bricks, almost half – 294 – showed signs of use. There were 64 confirmed house sparrow nests, 31 house martin nests and 22 starling nests. And where sparrows go, swifts will follow. Swift bricks have been around for several years, but the designs have improved and prices have dropped massively. Paul Sears, sales manager at Vivara Pro, which sells biodiversity nest bricks around Europe, says: “The market for swift bricks in the UK has expanded by 30-40% per annum over the last five years.” In response to rising demand, the company has just launched a new nest brick constructed in accordance with the dimensions of British bricks, along with its existing range that suits the size of bricks in Germany and the Netherlands. Now that national planning guidance on swift bricks has been updated, and with local councils, including Cornwall and Ribble Valley in Lancashire, recommending the installation of at least one box per dwelling, there are hopes that the swift brick will one day be as common a sight as the swifts themselves. Sarah Gibson’s Swifts and Us, The Life of the Bird that Sleeps in the Sky, published by William Collins, is available at the Guardian bookshop.