Distribution and migration
Swifts (Common swift Apus apus)breed throughout Europe as far north as Lapland and the Arctic Circle, reaching east across Asia to China.
Remarkably little is known about swift foraging preferences. They feed on flying insects (and ‘ballooning’ spiders) over a wide variety of ground-level habitats. They usually feed above 50m although can feed lower, especially over fresh-water bodies, where they can congregate during colder weather. Recent tracking studies have shown us that swifts can routinely fly tens of miles from their nest each day to find food.
Swifts traditionally nested in crags, sea-cliffs, caves, hollow trees and nest holes made by other birds. These sites have largely been replaced by nesting in buildings, which has allowed the swift to colonise many new areas, including cities, throughout its world range.
In more recent decades the application of pesticides and habitat destruction may have had adverse effects on swifts by affecting their food supply. The modernisation of many buildings has resulted in loss of nesting sites.
Swifts are migratory throughout their range. They arrive in the UK in the last week of April or early May and stay only long enough to breed. Autumn migration begins in late July or early August. The onset of the migration is believed to be triggered by the lack of insects high in the air. Few swifts are left in September.
Swifts that breed in the UK migrate through France and Spain to spend their winter in Africa, south of the Sahara, where they follow the rains to take advantage of rapid changes in insect populations. While many immature birds return to the breeding grounds in the spring - some will remain in Africa.
The European population is estimated at between 19-32 million pairs.