What Are Hen Harriers?

The Hen harrier (Circus cyaneus) is a medium-sized ground-nesting bird of prey that breeds between April and July in upland areas of Ireland, typically between 100m and 400m above sea level (Wilson et al., 2015). They spend winter at communal roost sites distributed throughout a broader range, including low-lying agricultural areas, blanket bog and coastal reedbeds. They traditionally breed in open moorland, but will also use recently established, open canopy conifer plantations for hunting and nesting (Irwin et al., 2012).

What Do Hen Harriers Look Like?

Mature male and female hen harriers differ in both size and colour. Females are brown with a white rump and white tail bars and are much larger than the males, grey and white with black-tipped wings. Juveniles of both sexes are similarly coloured to adult females until they moult into their adult plumage at the end of their first year (Wilson et al., 2015).

What Are Their Population Levels In Ireland?

Circus cyaneus (a scientific name for the species) are a protected raptor species listed in Annex I of the EU Birds Directive. Six Special Protection Areas, covering a total land area of 1,671km², have been designated for conserving the Hen Harrier in Ireland (Moran and Wilson-Parr, 2015). The most recent national survey estimated 108 – 157 breeding pairs during 2015, a decline of 8.7% from the 2010 survey. They face main pressures and threats: forestry, predation, loss of habitat, non-intensive grazing, recreation and roads (Ruddock et al., 2016). They are widely distributed within Ireland. However, they are particularly concentrated in Cork, Kerry and Limerick (Irwin et al., 2011).

For information about how we can assist you with Hen harrier surveys or ecological monitoring, please contact us here.

References:

Irwin, S., Wilson, M. W., Kelly, T. C., O’Mahony, B., Oliver, G., Troake, P. and O’Halloran, J. (2011). The breeding biology of Hen Harriers Circus cyaneus in Ireland over a five year period. Irish Birds, 9(2), 165-172.

Irwin, S., Wilson, M., O’Donoghue, B., O’Mahony, B., Kelly, T. and O’Halloran, J. (2012). Optimum scenarios for Hen Harrier conservation in Ireland. HENHARRIER, School of Biological, Earth & Environmental Sciences, University College Cork.

Moran, P. and Wilson-Parr, R. (2015). Hen Harrier Special Protection Area (SPA) Habitat Mapping Project 2014. Irish Wildlife Manuals, No. 83. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Ireland.

Ruddock, M., Mee, A., Lusby, J., Nagle, A., O’Neill, S. and O’Toole, L. (2016). The 2015 National Survey of Breeding Hen Harrier in Ireland. Irish Wildlife Manuals, No. 93. National Parks and Wildlife Service, Department of the Arts, Heritage and the Gaeltacht, Ireland.

Wilson, M., Fernández-Bellon, D., Irwin, S. and O’Halloran, J. (2015). The interactions between Hen Harriers and wind turbines. WINDHARRIER, School of Biological, Earth & Environmental Sciences, University College Cork, Ireland.