The aquatic warbler is a long-distance migrant able to cover more than 6,000 km from Eastern Europe to sub-Saharan Africa.
The aquatic warbler is a long-distance migrant able to cover more than 6,000 km from Eastern Europe to sub-Saharan Africa on its seasonal migrations. Its presence has been noted regularly in Germany, Holland, Belgium, France, United Kingdom, Spain and Portugal on its passage to and from its breeding and wintering grounds. This trans-Saharan migrant follows a loop migration pattern, rendering the species more abundant in Western Europe during the autumn migration whereas on the spring migration the eastern route is dominant.
The autumn migration commences with adult birds leaving the breeding areas in the month of July. This takes place in two waves: adult males, juveniles from early nests and some adult females on an initial migratory drive; and later juveniles and the remainder of adult females in a second, less numerous, migration.
The analysis of the array of data on arrivals at resting areas during the autumn passage, a single migration front can be observed passing first over the Baltic coast and then over the coasts of the North Sea, on a bearing for Africa over the Atlantic coast and the Iberian Peninsula.
The spring migration route is less well known, but seems to be a more direct route further east than the autumn migration judging by the fewer sightings registered in western European countries during the spring months. Adult birds return to the breeding grounds at the end of April, gradually increasing their numbers up to the end of May.
The winter quarters are located in sub-Saharan Western Africa. The aquatic warbler’s presence has been noted in several countries such as Mauritania, Senegal, Mali and Ghana, but the extension and nature of the wintering grounds are as yet little known. Only two regular winter grounds are certain, one in the National Park of Djoudj located in the delta of the river Senegal, and the other on the inner delta of the river Niger in Mali.
There are records of the aquatic warbler’s presence in nine African countries, but sightings have only been reported in five countries since 1980 (Egypt, Ghana, Mauritania, Morocco and Senegal), and just in the months of November and January in four countries (Mauritania, Senegal, Mali and Ghana). All the data examined so far seem to indicate that the aquatic warbler migrates across the northwest of Africa in autumn and in spring, spending the winter in the wetlands of the Sahel region located between the Sahara desert and the African tropical belt. Recent data in areas further south from the Sahara, however, point to possible overwintering locations in countries such as Gambia, Guinea, Sierra Leone, Ivory Coast, Togo or Benin.