Massale roofvogeltrek over Telpost Kinderdijk op 13 september 2008

On 13 and 14 September 2008 higher numbers of migrating raptors than usual were recorded in The Netherlands and Belgium, coinciding with the passage of a cold front from Scandinavia to the Low Countries. Raptor migration counted at Kinderdijk, in the western part of the Netherlands, on 13 September revealed relatively large numbers of Marsh Harriers Circus aeruginosus (N=164, mostly females and/or juveniles), with smaller numbers of twelve other raptor species (among which a radiotagged Montagu’s Harrier C. pygargus). Species with a relative low wing-loading started migration in the (early) morning, whereas soaring raptor species mostly passed in the (late) afternoon. Migration came to a halt during noon, when the local weather temporarily deteriorated; as soon as the weather improved, migration continued unabated and even increased in intensity. The numbers observed are exceptional for a site this far west in The Netherlands.