Circus cyaneus (L.)
Family: Accipitridae

The hen harrier, recently renamed as the northern harrier, is most at home in open moorland, where it quarters low over the ground in search of small birds and mammals. Its spectacular sky dance display can be seen in upland areas in the spring, when the male and female chase and tumble high over the moors and forests in a frenetic ‘sky-dance’. The uplands of Counties Antrim and Fermanagh support the majority of Northern Ireland’s breeding pairs.

In brief

• Can be seen on the uplands of Counties Antrim, Tyrone and Fermanagh.

• Most easily observed in spring when birds are displaying

• In summer, it can be found on upland moorland and young conifer plantation: in winter on open ground around the coast and larger lakes

• Vulnerable to habitat change and egg/nest predation and persecution

• Major UK and All-Ireland decline

• Northern Ireland supports the only tree nesting population of Hen Harriers in the world.

Species description
The males and females are very different in appearance, but both sexes have the long wings and tail which characterise harriers. The larger female is brown above and streaked below with a distinctive white rump and black bands on its tail. Immatures resemble females and they are collectively referred to as "ring-tails". The male is blue-grey above, with black tips to its wings. Its head and breast are grey, but its belly and rest of its underparts are whitish. Like the female it also has a white rump. Harriers have a distinctive low flight interspersed with frequent glides when they raise their wings into a V shape.

Life cycle
Hen harriers begin the breeding season with their dramatic ‘sky-dancing’ displays over their territories in early spring. Eggs (usually 4 to 6) are laid by late April or early May, generally in a nest on the ground among tall heather or in young forestry plantations. The nest is made from whatever material is available, such as heather stems and rushes, and is lined with finer grasses. In recent years a new development was discovered in Northern Ireland – tree nesting in the tops of conifers within plantation forests. This is apparently unique among European hen harriers, and seems to be spreading to other forests in Northern Ireland. All eggs have hatched by between 29 and 39 days and after a further five or six weeks the young will have fledged and left the nest. By the autumn, many birds have left their upland breeding areas and moved to the lowlands or coast where finding food in winter is easier. In winter, harriers can be found in a variety of habitats including wetlands, estuaries and sea coast and farmland. Favoured sites such as reed beds or forestry plantations can be used as winter roosts.

The hen harrier is a bird of prey which favours small birds (such as skylarks and meadow pipits) and mammals. However, it also takes larger prey and has come into conflict with grouse moor managers who blame it for reducing the numbers of grouse on commercial moors. There has been extensive recent research into the effects of harrier predation on grouse numbers.

Similar species
The male is unmistakable; the female and immatures are difficult to separate from both Montague’s and pallid harriers, but these are only vagrants or potential vagrants to Ireland.

How to see this species
In Northern Ireland, the hen harrier is most likely to be encountered in the Antrim Hills and Fermanagh uplands. The best time to look is in March/April when birds are displaying over potential nesting sites.

Current status
The population in the Republic of Ireland was estimated at 102-131 pairs in 2000, while in Northern Ireland there were 50 to 60 pairs in 2004. Although small, this population is of both Irish and UK significance and shows an increase from 38 pairs in 1998.

Why is this species a priority in Northern Ireland?

• UK and All-Ireland Priority Species (Red-listed)

• Listed as Endangered in the Irish Red Data Book

• Major UK decline.

Threats/Causes of decline
Hen harriers suffered a large decline in numbers across Europe between 1970 and 1990. While the rate of decline has slowed, and populations in many European countries are now stable, their numbers are much lower than before the decline began. In northern Britain, harrier numbers are suppressed by illegal persecution, particularly where they occur on grouse moors. They were persecuted almost to extinction in the nineteenth century, but spread due to the planting of forestry plantations which offered suitable habitat and safety while the trees were still young. In 1998, 570 pairs were found in the UK and Isle of Man, and there is continuing concerns over its absence from many areas. Apart from persecution, overgrazing of uplands and the loss of semi-natural habitats are threats to the hen harrier across its European range. In Ireland, while there is less anxiety about persecution, the condition of the harriers’ upland breeding grounds is the main concern, including some proposed wind farm developments.

Conservation of this species

Current action

• Hen harriers are specially protected under the Wildlife (NI) Order 1985

• There are proposals to designate SPAs for Hen Harriers in Northern Ireland

• Some important breeding sites are designated as ASSI and/or cSAC. Forest Service, in conjunction with the Northern Ireland Raptor Study Group and RSPB, are developing procedures designed to prevent disturbance and destruction of nests in forests under their control

Proposed objectives/actions
The following targets are taken from the Northern Ireland Action Plan (see links below)

• Maintain the current population of 57 nesting females.

• Maintain the range of breeding birds at 20 10km²

• By 2010, increase the population to 68 nesting females

• Increase the range of breeding birds to 25 10km² by 2010

• By 2020, increase the population to 90 nesting females

• Increase the range of breeding birds to 30 10km² by 2020.

What you can do

• Report any sighting of a hen harrier to the Northern Ireland Birdwatchers' Association via Flightline (Tel: 028 9146 7408)

• Participate in any forthcoming survey of Hen Harriers where volunteer participation is required

• Report any suspected persecution of Hen Harriers to the Police Service Northern Ireland

• If you are a landowner in an upland area, contact DARD to find out about participating in the Countryside Management Scheme or Environmentally Sensitive Area Scheme.

Further information

Links
A simple identification page provided by RSPB.

Background to concerns about illegal persecution.

Scientific research into conflicts between Harriers and Grouse and management solutions.

http://www.forestry.auburn.edu/hepp/raptors%20and%20grouse.pdf

http://www.gct.org.uk/text03.asp?PageId=53

The NI Species Action

Literature
Norriss, D.W., Marsh, J., McMahon, D. and Oliver, G.A. (2002). A national survey of breeding Hen Harriers (Circus cyaneus) in Ireland 1998-2000 Irish Birds 7: 11-12.

Redpath, S.M. and Thirgood, S.J. (1997). Birds of Prey and Red Grouse. London: Stationery Office.

Scott, D. (1998). The ecology of a Hen Harrier winter roost in Northern Ireland Northern Ireland Bird Report 1998.

Scott, D. (2000). Marking a decade of tree nesting by hen harriers in Northern Ireland, 1991-2000. Irish Birds 6: 4 BirdWatch Ireland.

Scott, D., Clarke, R. and Shawyer, C.R. (1991). Hen harriers breeding in a tree nest. Irish Birds 4: 413-417.

Scott, D., Clarke, R. and McHaffie, P. (1992). Hen harriers successfully breeding in a tree nest of their own construction. Irish Birds 4: 566-570.

Watson, D., (1977). The Hen Harrier. Poyser, Berkhampstead.

Whilde, T. (1993). The Irish Red Data Book. Vol 2: Vertebrates. HMSO, Belfast.

Text written by:
Allen & Mellon Environmental Ltd.