Studies of Swedish ospreys showed that females tend to migrate to Africa earlier than males. More stopovers are made during their autumn migration. The variation of timing and duration in autumn was more variable than in spring. Although migrating predominantly during the day, they sometimes fly in the dark hours, particularly in crossings over water and cover on average 260–280 km (160–170 mi) per day with a maximum of 431 km (268 mi) per day