Swifts – our aerial summertime visitors

Common Swift Apus apus Norfolk summer - David Tipling/2020VISION

It’s around this time of year you may be lucky enough to spot a common swift; they’re in the UK from April to August for their breeding season.

They’re not the quietest of birds; you may hear them screeching as they dart about above you, recognisable by their crescent, pointed wings and forked tail. The rest of the year they’re considered an African bird. Regardless of which land they’re residing in, it’s unlikely that they’ll touch the ground in either. Except for during the breeding season, swifts spend their life in the air, not even landing for a second. Their maximum lifespan is believed to be eighteen years, and in that time they can fly over four million miles. That’s the equivalent of flying to the moon and back eight times! 

Swifts are insectivores (feed mainly on insects) - they catch aphids, spiders, beetles, dragonflies and any other bug that’s flown or been blown up into the air. They mate in the air and are the only birds to do so in the UK. They drink by gliding over smooth water and taking a sip. They’re even thought to bathe in the air, flying at low heights through a rain shower. Once a young bird leaves its nest, it won’t land until it reaches sexual maturity which means they spend the first four years of their life without stopping once! Mature adults land only during the breeding season, and spend the other ten months on wing.

To us this aerial lifestyle sounds exhausting, but swifts are perfectly adapted to flying and gliding – they have long wings and slender bodies without a large tail or long legs weighing them down. Their tiny legs mean they’re not the best at walking anyway and if they’re seen on the floor it’s likely they need help. Swifts even sleep in the sky – flying up to 10,000 ft, roughly the same altitude as some small planes. In fact, in the past they’ve been spotted by pilots at this height, mysteriously gliding almost motionlessly in their sleep state.

Swifts build their nests in crevices in walls, under roof eaves or inside S-shaped roof tiles. Gathering nest-building materials can take a while as they do this whilst flying too, collecting feathers, grasses, tree seeds and flower parts that are blowing around.

Because of their ability to fly at great heights, as well as their speedy flight (speeds of 70mph have been recorded!) common swifts are generally good at avoiding predators. Despite this, their numbers are sadly in decline. The renovation of old houses has destroyed many current and potential nesting sites, whilst newly built houses are often fairly sealed up. Because of the use of pesticides in agriculture and gardens, our insect numbers have dropped dramatically in recent years too, stripping the air of the swifts’ food source.

Across the UK, small groups have been working hard locally to conserve swifts. They’ve been conducting surveys to locate nesting sites, installing nestboxes and preventing nests from being filled in. Several Wildlife Trusts are working with local authorities and planners to get the installation of swift nesting bricks (a brick with hole behind which a nest box is fitted) written into local planning policies. North Wales Wildlife Trust’s People and Wildlife Officer, Ben Stammers, has worked hard to get over 300 nestboxes installed onto houses, university buildings, schools, the local pub and a doctor’s surgery and has engaged over 1000 people through walks and talks.

Individually, you can help too, by: 

  1. Putting up a swift box on your house (must be at least 5m high)
  2. Cutting out any chemicals in your garden to allow insect populations to recover. You can sing up to take #ActionForInsects here wildlifetrusts.org/take-action-insects and receive a free guide with insect-friendly gardening advice
  3. Ensure nesting holes are kept open during renovations and insulation installation
  4. Record any swifts you see entering or exiting a nest site on a building. Swifts are completely brown except a small patch of white on their throat.

See wildlifetrusts.org/swifts for further resources on nestboxes and ways that we can all help.