European swallows spend the winter in Africa south of the Sahara, in Arabia and in the Indian sub-continent.
British swallows spend their winter in South Africa: they travel through western France, across the Pyrenees, down eastern Spain into Morocco, and across the Sahara. Some birds follow the west coast of Africa avoiding the Sahara, and other European swallows travel further east and down the Nile Valley. Swallows put on little weight before migrating.
They migrate by day at low altitudes and find food on the way. Despite accumulating some fat reserves before crossing large areas such as the Sahara Desert, they are vulnerable to starvation during these crossings. Migration is a hazardous time and many birds die from starvation, exhaustion and in storms.
Migrating swallows cover 200 miles a day, mainly during daylight, at speeds of 17-22 miles per hour. The maximum flight speed is 35 mph.
In their wintering areas swallows feed in small flocks, which join together to form roosting flocks of thousands of birds. Swallows arrive in the UK in April and May, returning to their wintering grounds in September and October.