Dutch Birding volume 28 (2006) no 5

Northern Hawk Owl at Westerbork in October 2005

On 30-31 October 2005, a Northern Hawk Owl Surnia ulula was observed in a coniferous forest near Westerbork, Drenthe, the Netherlands. It was identified as a first-winter on basis of the pointed, broad white tips to the longest tail-feathers, poorly marked tertials and the fact that all visible primaries and secondaries appeared of the same age. On the basis of the pale-coloured crown and upperparts, the Nearctic subspecies S u caparoch (which has been recorded in Britain and the Canary Islands) and the Central Asian S u tianschanica can be excluded. The bird therefore belongs to the nominate subspecies S u ulula, which breeds in the northern parts of Scandinavia and Russia. The European population is estimated at a minimum of 9200 pairs. The species is renowned for its pronounced invasions into southern parts of its breeding range, and sometimes beyond. These movements are induced by a lack of prey (and/or a good previous breeding season). One of the largest invasions was in the winter of 1983-84 when many 100s were found in southern Denmark, Norway and Sweden, and even in Germany and in Shetland, Scotland. The bird at Westerbork was also part of a (smaller) invasion, which was most apparent in Finland (171 birds up to 31 December 2005), Sweden (at least 65), Estonia (14) and Denmark (at least three). The southernmost (and latest) record during the 2005-06 invasion concerned a bird in Brandenburg, Germany, from 19 February until 23 March 2006. The bird at Westerbork was accepted as the third for the Netherlands and the first to be seen by numerous observers. Previous records concern one collected in Utrecht on 5 October 1920 and one photographed by a single observer in Limburg on 2 April 1995.

Peter van Wetter, Brandgans 11, 7827 LD Emmen, Nederland
(p.wetterwxs.nl)
Eric Jan Alblas, Beukenlaan 8, 9603 DA Hoogezand, Nederland
(ej.alblaskpnplanet.nl)
Gert Ottens, Ganzebloem 14, 3984 CG Odijk, Netherlands
(glanskraaihotmail.com)