Sedentary throughout range.
Most populations show little evidence of movement other than post-breeding dispersal. In Belgium, of 165 recoveries up to 1969, none more than 10 km distant; in July 1970, bird recovered 16 km north-east of site where ringed in May 1969; at Knokke on Belgian coast, 21 of 28 captures 1952-70 were in September-October, suggesting slight tendency to move, but birds probably of local origin. On Polish coast, small numbers recorded each year are likely to be local birds; at Bukowo, 1965, 11 of 19 ringed were retrapped at same site. In southern West Germany, exceptional record of bird ringed as nestling in Württemberg recovered 40 km WNW in November. At Col de Bretolet in western Switzerland (regular passage route for many migrants), only 1 record (juvenile) over many years. In Channel Islands, autumn movement of c. 35 km recorded from Jersey to Sark. In Strait of Gibraltar area, increase in numbers from September suggests possible small-scale passage, but no evidence of immigration into northern Morocco. In Sweden, 5 records up to 1988, all in south, presumably linked to range expansion in Denmark: 1 at Ottenby, October, and 4 at Falsterbo, March-June; bird ringed Laesö island (eastern Denmark), 16 May, had moved south-east to Falsterbo by 7 June. Records in Britain are perhaps also attributable to potential range expansion; 8 up to 1988, of which 5 autumn (September-October) and 3 spring (April-May); one (October) was in Yorkshire in north-east, the rest in south-east: Kent (6) and Essex (1). In view of sedentary nature, 2 long-distance records claimed from northern Czechoslovakia to northern Poland (c. 400 km), and from Belgium to Portugal probably result from incorrect data.
Thanks to BWP on CD-ROM