Het Korhoen, de Havik en Staatsbosbeheer

The recent capture and translocation of at least two Goshawks in the National Park De Sallandse Heuvelrug in the eastern Netherlands, apparently to remove Goshawks “specialised in capturing Black Grouse”, and the many unresolved questions, was sufficient cause to ask for further information from the governmental body responsible for these management actions, i.e. the State Forestry Service. The lack of reply, and after some prodding, the sparse and confusing answers led us to further investigate the role of the State Forestry Service in the management of the last surviving pocket of Black Grouse in The Netherlands, especially in regard of predator control. In both 2009 and 2010, a female Goshawk was captured in the National Park and removed from the De Sallandse Heuvelrug to areas unknown or inadequately specified. Despite claims of having captured non-breeding. Black Grouse-eating specialists, data was not forthcoming or inadequate to substantiate these claims. In fact, even the observed predation (plucks of three male Black Grouse found) and the observations of failed attempts at capturing a Black Grouse by a – allegedly the same – Goshawk were insufficiently documented to be able to test their validity. For example, because Goshawks normally pluck a single prey in several locations, it is mandatory to count primaries and rectrices in order to avoid counting the same prey twice or thrice. Furthermore, how the observer was able to individually recognise this particular Goshawk (in flight?), apparently based on the fact that the bird was ringed, is beyond our grasp. Even more puzzling is the claim that these specific birds were captured with a non-selective catching device, i.e. a crow trap, within a few days of its employment. No information was available on by-catches, nor on biometrics, status (if the second bird was already ringed, where was it bom and what were its age, biometrics and condition) and date and site of release, and the people involved (catching, ringing, transportation). The arguments put forward in the application for a permit to capture said Goshawks were based on poorly documented observations (and hence biased conclusions) and a disregard of science-based information. Despite several decades of habitat management and predator control (foxes and crows) targeted to favour Black Grouse, the local population remained more or less stable at very low numbers (15-35 displaying cocks annually) between 1976-99, to further dwindle to 7-23 cocks per annum in 2000-10. This trend is not surprising given the isolated position of this population (nearest breeding sites, also with exceedingly low numbers, are at a distance of 200 km in northern Germany and in Belgium), genetic drift (inversely correlated to population size) and the negative impact of agri-farming and urbanisation increasingly affecting the landscape surrounding the National Park. The focus on recreation in the National Park is likely to add another stress factor. This setting may explain why the local managers increasingly resort to desperate ad hoc conservation measures, irrespective of their chances of success, meanwhile disregarding the scientific literature and failing to promote scientific research, experiments and long-term monitoring of basic life-history parameters (except for some short-term projects). Goshawk control is one such measure, the efficacy of which has never been validated for prey populations stressed by deterioration and fragmentation of habitats. In the case of the Sallandse Heuvelrug, where Goshawks were translocated after capture, the managers failed to take note of the extensive literature on return rates of translocated Goshawks, but rather used uninformed hearsay to determine the removal distance. Recent suggestions of translocating Black Grouse from Sweden to Sallandse Heuvelrug, in order to boost the local population, also completely ignore the extensive literature on reintroductions and translocations elswehere in Europe since the late 19th century: none of these projects resulted in the establishment of a viable, selfsupporting population.