ORDEN C VAN (1962) Short announcements: Day-migration with Sylvia communis. LIMOSA 35 (1): 168-168.

Common Whitethroat Sylvia communis On April 23d, 1961 at least 30 Whitethroats were seen between 8.30 and 10.00 a.m., which rose from the shrubs, while circling like homing-pigeons, to a height of about 40-50 metres and disappeared in N.E.-direction

[free pdf] [dutch summary]