The 1979 EU Birds Directive requires that each Member State of the European Union classify suitable areas as Special Protection Areas (SPAs) for the protection of endangered species of bird, including the Hen Harrier. Under Article 6 of the Habitats Directive, which applies to SPAs, Ireland is obliged to prevent the deterioration of these SPAs as suitable areas for the species and only to consent to projects, including afforestation, where there is clear scientific evidence that such projects will not lead to an adverse impact on the integrity of the SPA. It is now well established that afforestation interacts with the ecology of Hen Harriers. During the early growth stages, these areas are selected by breeding Hen Harriers for nesting and foraging. Depending on the location and scale, afforestation can lead to an increase in breeding populations. However, as plantations mature, their value as a feeding and nesting resource is significantly diminished. Therefore, if particular areas are dominated by plantations of a similar age, then the overall availability of suitable breeding habitat for the Hen Harrier declines as a result of the maturing trees. The availability of suitable habitat is a fundamental requirement for the conservation of breeding birds in the wild. The results of the latest national survey recorded a significant decline in the numbers of breeding Hen Harriers in those SPAs that were designated for the conservation of this species.
A report based on a recent Irish scientific study observed that the breeding productivity rate of Hen Harriers in their study sites was low and that a negative relationship existed between second rotation pre-thicket forests and Hen Harrier breeding success. The potential impact of such a negative association is of concern, due to the fact that a large proportion of Hen Harrier nests in Ireland are situated in second rotation pre-thicket forestry.
The following published scientific reports and papers have informed this understanding:
- Irwin, S., Wilson, W., O'Donoghue, B., O'Mahony, B., Kelly, T., O'Halloran, J. (2012) Optimum scenarios for Hen Harrier Conservation in Ireland; Final Report 2012. Prepared for the Department of Agriculture, Food and the Marine by the School of Biological, Earth and Environmental Sciences, University College Cork;
- O’Donoghue, B.G. (2010) The Ecology and Conservation of Hen Harriers (Circus cyaneus) in Ireland. PhD Thesis. University College Cork;
- O'Flynn, W. J. (1983) Population changes of the Hen Harrier in Ireland. Irish Birds, 2: 337–342;
- Ruddock, M., Dunlop, B. J., O’ Toole, L., Mee, A. and Nagle, T. (2012) Republic of Ireland National Hen Harrier survey 2010. Irish Wildlife Manual, No. 59. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland;
- Wilson, M.W., Irwin, S., Norriss, D.W., Newton, S.F., Collins, K., Kelly, T.C. & O’Halloran, J. (2009) The importance of pre thicket conifer plantations for nesting Hen;
Harriers Circus cyaneus in Ireland. Ibis 151: 332 343.
- Wilson, M. W., Gittings, T., Pithon, J., Kelly, T. C., Irwin, S. and O’Halloran, J. (2012) Bird diversity of afforestation habitats in Ireland: current trends and likely impacts. Biology and Environment: Proceedings of the Royal Irish Academy. 112B;
- Wilson, M. W., O’Donoghue, B., O’Mahony, B., Cullen, C., O’Donoghue, T., Oliver, G., Ryan, B., Troake, P., Irwin, S., Kelly, T. C., Rotella, J. J. and O’Halloran, J. (2012) Mismatches between breeding success and habitat preferences in Hen Harriers Circus cyaneus breeding in forested landscapes. Ibis, 154: 578–589.
