Nocturnal autumn bird migration at Falsterbo, South Sweden

We investigated the patterns of nocturnal bird migration in autumn 1998 at a coastal site on the Falsterbo peninsula in south-western Sweden, by means of a passive infrared device. In total 17411 flight paths, including track direction and altitude, of migrating birds were recorded for 68 nights fro m August to October. Mean migratory traffic rate per night varied between 6 and 6618 birds km(-1) h(-1), with an average of 1319 birds km(-1) h(-1). M igration at Falsterbo showed a similar seasonal pattern to that reported fo r central Europe, with pronounced peaks of migration and intermittent perio ds with relatively low migratory intensities. Weather factors explained two thirds of the variance in the intensity of bird migration. During nights w ith intense migration, associated with weak winds, the mean track direction was close to that in central western Europe (225 degrees). Birds usually m aintained a constant heading independent of wind directions and, in consequ ence, were drifted by the wind. The mean orientation clearly differed from that of the nearest coastline, suggesting that the birds did not use the to pography below to compensate for wind drift.