Pre-migratory and migratory movements of SwallowsHirundo rusticain Britain and Ireland

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Abstract
Previous published information on the migratory and pre-migratory movements of Swallows Hirundo rustica in Britain and Ireland was based on 191 birds ringed up to 1965 and found within the same autumn. By 1988, this number had increased to 3337. In view of recent interest in the migratory strategies and conservation of Swallows in Britain, this expanded data base has now been analysed. Particular attention is paid to the speed, distance, direction and timing of movements shown by 468 ringed birds which were found between July and November within 10 days of ringing at least 5 km from the ringing site. First-year birds showed pronouned non-directional wandering during August, but became increasingly oriented to the south-east from September onwards. Movements to the north and west were, on average, 25–38 km within 10 days, but some were up to 270 km. Eight out of 20 adult movements were also westward or northwards for up to 43 km. Data from all birds combined showed evidence that birds from easterly regions used easterly routes through Britain, and those from westerly regions used westerly routes. The speeds and distances of movements within Britain and within 10 days changed significantly with month of ringing and direction of movement. Flights to the south-east were longest and fastest at averages up to 71 km in one day (maximum 194 km per day). However, there was evidence that movements were not uniform on a day-to-day basis, since apparent speeds declined with time after ringing to averages of 2–26 km per d over 10 days. Increased speeds during September and October to the south-east probably reflected both longer flights per day, and a decreased tendency to loiter from day-to-day. These aspects of the migratory strategy are discussed in relation to the moderate pre-migratory fattening shown by British Swallows from September onwards. Movements between roost sites showed a stronger south-east orientation than unspecified movements, reflecting the use of roosts during migration. Movements between roosts in one day averaged 27 km, though overall roost to roost journeys of 1–10 days were made at an average of 10 km per day. These features are discussed in relation to the conservation value of an appropriate network of Swallow roosts.