Understanding Swift Migration Routes Across Europe

The long haul from Africa to Britain

Every May, a thrilling scream returns to our skies. The common swift, Apus apus, has just completed one of the most extraordinary migrations in the natural world. These masters of the air spend only a few short months with us, arriving from sub-Saharan Africa to breed, before vanishing south again in August. Understanding where they go and how they get here is vital if we are to reverse their worrying decline. In the UK, swifts are now red-listed, meaning they are of highest conservation concern. The more we know about their routes, the better we can protect them.

Two main flyways across Europe

British swifts do not all follow the same path. Research using tiny geolocators has revealed two broad migration routes. The majority of birds that breed in the UK travel up through the western flyway. They cross the Sahara into West Africa, then move north through Morocco, Spain, and France. Many pause to feed over wetlands and farmland before making the final hop across the Channel. A smaller number use a more central route, passing through Italy, the Balkans, and eastern Europe. Weather patterns and insect abundance heavily influence these choices. In spring, a swift may drift east or west depending on prevailing winds, but they are remarkably faithful to their chosen corridors year after year. Some even cross the Bay of Biscay directly, a risky shortcut that saves time but offers no chance to rest.

Crossing the Sahara and the Mediterranean

The Sahara is the greatest obstacle. Swifts cannot land to rest, so they must cross the desert in one long, non-stop flight. They climb to high altitudes where the air is cooler, often flying through the night to avoid the worst heat. The Mediterranean presents a different challenge: a wide sea with few places to refuel. Swifts feed entirely on flying insects, so they need to find swarms of aphids, flies, and beetles. Bad weather can ground them for days, and a cold snap can be deadly. Once they reach Europe, they still face unpredictable springs. A late frost or heavy rain can wipe out insect prey just when the birds need it most.

When they arrive: birdwatching tips

For British birdwatchers, the return of the swift is a highlight of the year. Look for them from late April in southern England, with numbers building through May. They are easiest to spot in the evening, when they perform 'screaming parties' – low, fast chases around rooftops. Listen for the piercing, high-pitched call. Here are some practical steps to get the most from your swift watching:

• Scan old buildings – churches, terraced houses, and barns are favourites. Check under eaves for dark, narrow crevices.
• Use binoculars to watch for birds entering a gap. A swift squeezing into a tiny hole is a sure sign of a nest.
• Record your sightings – note the date, location, and number of birds. Share with your county bird recorder or a local swift group.
• Go at dawn or dusk on warm, calm days when insects are plentiful. Midday can be quiet, especially in cool weather.

Patience pays off. A single screaming party can reveal several nest sites in a row of houses.

Threats on the wing and at the nest

Swifts face dangers at every stage. During migration, extreme weather, drought, and storms take a toll. Climate change is shifting the timing of spring, so swifts may arrive before their insect food is available. In Britain, the biggest problem is loss of nesting sites. Renovation, roof repairs, and new builds often seal up the eaves and crevices swifts rely on. Pesticides reduce insect numbers, meaning adults struggle to find enough food for their chicks. Starvation is common in cold, wet summers. Collisions with cars and windows also kill some birds, especially when they fly low in search of insects.

How you can help swifts

Conservation starts at home. If you have a suitable building, install a swift brick or a nest box with a small entrance hole. Place it high under the eaves, facing north or east to avoid overheating. Do not block existing nests – if you spot swifts entering a gap, leave it alone. Here are more ways to make a difference:

• Plant native wildflowers to boost insect numbers. Avoid pesticides and herbicides in your garden.
• Join a local swift group to monitor nests, survey buildings, and raise awareness.
• Spread the word – tell neighbours and local councillors why swifts matter. Swift bricks are cheap and easy to include in renovations.
• Record your sightings with your county bird recorder. This data helps target conservation efforts.

Small actions add up. By making our towns and villages swift-friendly, we can help these incredible travellers return for generations to come. Every scream overhead is a reminder of the journey they have made – and a call to action.