Doorschieten van kraaiennesten in relatie tot Ransuilen Asio otus

In The Netherlands, one of the methods to destroy Carrion Crows Corvus corone is to organise systematic shoot-outs of crow’s nests in April and May. In peak vole-years, Long-eared Owls are commonly using old crow’s nests for breeding. During a survey of raptors and owls in western Drenthe in 1990-96, it was tested whether or not breeding Long-eared Owls leave their nest after the observer repeatedly kicked the nesting tree (i.e. the normal procedure for testing occupancy of raptor nests). This method has been advised by the Royal Dutch Hunters Organisation to their members to make sure that no other bird species is using the nest. However, among 36 occupied Long-eared Owl nests, none of the breeding birds left the nest after the nesting tree had been kicked (Table 1). Only four birds raised their head to watch the observer on the ground; all other birds remained invisible. Occupied nests could be often recognised by some down on the nest rim, although down was exceedingly difficult to detect in rainy periods. Not surprisingly, several Long-eared Owls breeding on old crow’s nests were killed by hunters in 1996, a peak vole-year with high numbers of Long-eared Owls. Shoot-outs of old crow’s nests are useless when crows are being targeted, because Carrion Crows rarely re-use old nests (lx in 53 nests in 1970-78 on the Veluwe, Ox in 36 nests in 1992-96 in Drenthe). Shoot-outs of crow’s nests should be banned, because several other species depend on these nests (Kestrel, Hobby, Long-eared Owl) and because killing protected bird species during shoot-outs of crows can not be avoided.