Compared with other migratory birds, the common swift follows a very unusual pattern when it migrates from the breeding areas in Europe to its wintering locations south of the Sahara. This is what researchers have observed in a major eleven-year international study of the birds.
“Our study is very significant for understanding how organisms, in this case the common swift, can migrate from one part of the world to another, where access to food is much better at a given time”, says Susanne Åkesson, professor at Lund University and principal investigator of the study.
Common swifts that nest in Sweden and northern Europe arrive in sub-Saharan Africa four to six weeks later than the swifts that nest in southern Europe. By that time, the southern European swifts have already migrated even further south on the African continent. Hence the term chain migration, as opposed to the much more common pattern known as leap-frog migration, in which the populations that arrive first in a location claim the territory and occupy it, forcing populations that arrive later to leap-frog over the occupied area and fly further. MORE
Header image: Aron Hejdström.