The swift is one of the last summer migrants to arrive in the UK and one of the first to leave. 'Screaming' calls reveal the presence of parties of swifts flying above towns.
A life on the wing
Studies of swifts have revealed some startling facts – particularly their ability to fly long distances.
Swifts can fly up to 800km (500 miles) a day on migration. Swifts spend their life almost entirely on the wing and even feed, sleep and mate in flight. They feed exclusively on insects and only come to land when nesting.
They hunt for insects over a range of habitats from meadows, open water and over woods, to the skies above towns and cities.
An abundant supply of insects is critical for their survival. Parent swifts collect lots of insects to take back to their chicks – up to 1,000 at once, which make a big bulge in their throat. When they have chicks to feed, swifts can gather up to tens of thousands of insects a day.
'Our' swifts fly across the Sahara desert in autumn and some even go as far south as South Africa. Others don't go quite as far and stay around central Africa. It's a long journey but they don't hang around: one young bird left its nest in Oxford and flew all the way to Madrid in just three days.
As a group, swifts are the fastest birds in level flight. The peregrine is officially the fastest bird but only in a steep dive called a stoop. Our swift holds the record for the fastest proven flight, recording an impressive top speed of 69.3mph in a recent study. A large Asian species of swift, the white-throated needletail, has been reported to reach over 100mph, but this is yet to be officially proven.
Sharing your house with swifts is a great privilege. They are unobtrusive when nesting and make perfect, quiet neighbours.
Previously more commonly found nesting in cliffs and caves, swifts make use of roof spaces in buildings where they construct a simple nest. These can be hard to locate because swifts enter and leave quietly through a narrow opening (usually measuring 25–35mm by 60–70mm) and leave few, if any, droppings below the entrance.
Swifts incubate their eggs for between 19 and 25 days. To prepare themselves for an aerial life, swift chicks build up their flight muscles in the nest by performing 'press-ups' with their wings. For a bird that's used to flying all the time, it must be difficult for them to keep still for so long. So, to keep in shape, they perform 'press-ups' using their wings.
Why swifts are amazing
Here are our top reasons why they're so fantastic:
- After leaving the nest where they hatched, they'll keep flying non-stop for three years!
- They even eat, mate and sleep in the air - they can 'snooze' with one side of their brain at once, and then switch to the other side
- Some of 'our' swifts migrate as far as South Africa for winter
- Parent swifts gather insect snacks for their chicks, carrying as many as 1,000 at once. Gulp!
- Swifts nest in houses, churches, old factories and many other types of building - they squeeze through small gaps to nest in cavities inside roofs and walls.
- At dusk, groups of swifts fly at high speeds around the areas where they are nesting, screaming.
Swifts can be confused with three similar but unrelated species: the swallow, house martin and sand martin.
In built-up areas, the house martin is the species commonly confused with swifts.
Here's a handy Nature's Home guide to help you spot the difference.