In the first or second week of April, something happens in the barn: the first barn swallows return from their winter quarters. The little birds have covered a distance of up to 6000 km and immediately start to repair last year's nests. The next few months will be busy and they will breed normally twice. At the end of August, the birds start to gather in large groups before they fly to their wintering grounds in Africa by the end of September. The following year they all find their way back to the barn where they were born.