Save our swifts
They’ve screamed us into summer for millennia – but now they’re vanishing from our skies. Author Nicola Chester looks at the decline in swifts and how we can make a difference.
A thrilling return
I recall one late pre-pandemic spring, when I was the first to know the swifts had returned to our little town. I was working in the secondary school library, with my back to the fields and the south, and the windows flung open. Thrillingly, I heard the screams of a party of swifts, screeching over the three-storey English block and on down Hungerford High Street. I fired off a whole-school celebratory email: ‘the swifts are baaaack!’
I share generations of these swifts and other birding haunts with celebrated landscape and wildlife artist Jonathan Pomroy, who attended this school. I like to think spirits of these very birds are in his beautifully illustrated book On Crescent Wings, and his illustrations of Charles Foster’s swift monograph The Screaming Sky. And that’s how these birds get us: through their connections. Their high-octane, vertiginous fairground rides, rollercoastering through our summer towns, are hard to ignore. They make us look up, and are the perfect conduit for connection to the wider world. They are the world’s birds: global travellers come to touch down momentarily on the fabric of our own urban lives.
Swifts are a truly ancient, almost entirely aerial-living species, that separated taxonomically from other birds 65–70 million years ago. Back then, they would have nested in gaps in rocks or trees alongside the last of the Tyrannosaurs. They’ve thrived for so many millennia – but now things are changing.
Swift populations have plummeted. More than halved, freefalling 58% in 23 years. In 2021, they were added to the UK’s list of most endangered birds, the Red List of Birds of Conservation Concern, an official register delivered by a coalition of government and charitable wildlife bodies including the RSPB, because they are at risk of vanishing from our skies. And like so many things, we are both the cause and the solution.
For a bird so evolutionarily honed over millennia, it’s a shocker. These dark brown, almost matt black birds seem all one scimitar-curve of wing, torpedoed by a body and a short forked tail (as if the bow had flown off with the arrow, as poet Edward Thomas put it) and a small mouse-like, almost reptilian head. The tiny bill opens to a wide gape and the crescent of narrow wings, longer than the bird itself, are whetted scythes through the air. No other bird can fly faster in level flight.
Life on the wing
Everything except nesting is done on the wing: eating, drinking (scooping raindrops or making low passes over still, open water) mating, sleeping (dolphin-like in part torpor, up near Earth’s stratosphere) and preening and bathing (cruising slowly through rain). When they arrive at their nest, it will usually be the first time they’ve touched anything solid in 10 months. In the case of young birds (which begin breeding at four years old) it could be three years or more. UK swifts winter in Africa, and in an average swift’s lifetime (5.5 years) it might fly 4 million miles. Some individuals survive much longer; 21 years has been recorded, and because of their aerial mastery they have few predators.
Why the decline?
Swifts seem to be declining at similar rates across much of the UK, without regional variation. Loss and lack of nesting sites certainly plays a part in this decline, at least in some areas. Changes in insect food might have also had an effect but currently, evidence for this is lacking. Research into this possibility is ongoing.
Homes and nest sites
Swifts nest in our buildings, flying fast and straight to post themselves through small slots, into cavities in old buildings, behind roof tiles, eaves, fascia boards and soffits. Renovations and improved insulation measures (no bad things in themselves) can, often unwittingly, mean that nest sites are blocked or lost. Swifts pair for life, and are ‘site-faithful’, so if a building has been demolished, renovated, or the gap obstructed or repaired, they must find somewhere new, quickly. Swifts are only here for around three months, two of which are spent raising chicks. So if an alternative site can’t be found fast, a whole breeding season must be skipped.
Food, habitat loss and climate change
Swifts feed on aerial plankton; flying insects and high-ballooning spiders. These are collected in a pouch at the back of the throat and compressed. A pair of swifts may gather 20,000 aphids, midges and other insects a day! But it is well-documented that a combination of pesticide use and habitat loss have led to crashes in some insect populations.
Climate change could also have potential impacts on swifts, if disrupted weather patterns and predicted increased frequency of extreme weather events affects either swifts directly, or their insect food.
Dr Guy Anderson, UK Migrants Recovery Programme Manager on the RSPB’s Global Species Recovery Team is a man enthralled by swifts. He emphasises that, although we’ve discovered much in recent years, we still have a lot to learn about these birds; and the key is a combination of continued scientific research and community involvement. “And these globe-trotting avian marvels are the perfect bird for that!” he adds.
He describes the amazing experience of ringing swifts (to monitor their survival rates); the privilege of holding such an astonishing piece of evolution in your hand: “They are a very old species, very weird, with huge eyes surround by bristles that act as sun visors and tiny, incredibly strong, needle-sharp feet! “Ringing can help us estimate how many swifts survive from one year to the next, but to understand swift movements, we need some higher-tech kit,” he continues.
A data-gathering project with the BTO in Northern Ireland has tracked movements during the breeding season, and on migration. “With data loggers (tiny backpacks weighing one gram) we’ve learnt the routes swifts take. We know UK-bred swifts can spend the winter over south-east Africa, returning via the Congo Basin, West Africa, crossing the western edge of the Sahara, and up through Spanish and French airspace. We know they can have extended stop-offs on the way back, probably taking advantage of seasonal insect peaks. We also know Belfast swifts make 40-mile daily round trips to feed over Lough Neagh – what we don’t yet know, is if this is ‘normal’ for them, or indicative of the distances they must now travel to find food.”
Guy explains community is key. “We can’t easily save swifts by creating nature reserves in the traditional sense; they are too widespread, they can travel large distances to feed, and many nest in urban areas. But, swifts are a tremendously powerful conduit for engaging people and communities.” Swifts are in your face, in your buildings, hooning round your cities like dizzy avian hooligans. Their arrival is an event. This makes them ‘gateway birds’ to community, urban involvement and relevance. They’re poster birds for our towns.”
There’s a growing number (100+) of swift community groups across the UK, co-ordinating interest, engagement and focus. Laurinda Luffman, Head of Trusts & Foundations for the RSPB, is another Swift Champion – she introduced me to Bob Hook of Bedfordshire Swifts, who said, “Swifts are a brilliant way to bring people together. In one road in Leighton Buzzard (which has at least six pairs nesting along the rooflines) residents came together for a street party in 2019 to celebrate their swifts.” And in Bedford last summer, 90-year-old engineer Henry, handled the carpentry for 12 swift nest boxes for his church tower of St. Andrews, to provide sites for a colony of swifts threatened by the renovations of Victorian houses nearby.
Communities coming together
Alongside ‘Swift Cities’ such as Bristol, Cardiff, Exeter, Oxford, Belfast, Lancaster and Edinburgh; Harleston in Norfolk has declared itself as “reviving a whole town with swifts”. It lists the birds as “economic drivers, social melders, educational, biodiversity indicators, unique selling points and activity generators”. Swift flags made in its primary school are put up to welcome the birds.
Swifts are clearly in peril, but with a powerful combination of research, practical advice to empower and guide, support from RSPB members and community actions, we are determined to understand and halt the decline – and hopefully, reverse it. We already know more than we ever have about these remarkable birds. With everyone playing a part, our summer rooftops could reverberate to their excitable pelotons for centuries to come, and more generations of these ‘international aviators’ will be freewheeling away, two months out of those nests, to take our hearts over Mozambique, Malawi, Tanzania, all the way to the Congo. And back.
Three ways you can help swifts
Put up a nest box
Swift chicks make very little mess or noise, and you can either buy or make your own box. Swifts need an unobstructed flyway, at least 5m above the ground, to which they zoom in at high speeds! Find out more at www.rspb.org.uk/makeswiftswelcome or buy a swift box from the RSPB shop.
Encourage more insects
Swifts and many other birds rely on healthy insect populations. You can help by planting wildlife-friendly flowers and not using any kinds of garden chemicals. You’ll find lots of practical tips on our Nature on Your Doorstep pages.
Share what you see
Help locate breeding hotspots for swifts and so help target efforts to protect their homes. If you see groups of screaming swifts or swift nest sites anywhere in the UK, please tell us on Swift Mapper.