Hen Harrier (Circus cyaneus)

	Hen Harriers (illustration courtesy of Dan Powell)

A pale, ghostly shape floats over a New Forest heath, skimming the top of winter-dark heather in a hungry, determined search for the few small birds and mammals concealed below.

It is a Hen Harrier, a subtly marked, light-grey male, a large bird of prey and one of the New Forest’s most striking winter visitors. William Turner, writing 460 years, or so, ago, said: ‘It gets this name amongst our countrymen from butchering their fowls’, although that now is somewhat difficult to imagine.

The Hen Harrier’s breeding grounds are in Britain’s uplands - on the moorlands and mountains of northern England, Scotland, Wales, Northern Ireland and the Isle of Man. Hen Harriers are specially protected by legislation, but in these remote places, gamekeepers even now sometimes illegally trap and kill numbers of these magnificent creatures.   

As autumnal weather closes in, food supplies dwindle and the Hen Harriers move in search of more hospitable winter quarters, seeking out places that offer both safety and the prospect of easier, more productive hunting.

Hen Harriers usually start to arrive in the New Forest in late-September, but more usually they are seen from October. Most depart by mid-April.

Slim and noticeably long-winged, female Hen Harriers have a wingspan of up to 118 centimeters (almost 4 feet), and a body length of 55 centimeters (almost 2 feet), whilst males are slightly smaller.

	Hen Harrier female (illustration courtesy of Dan Powell)

Females and first year Hen Harrier males have somewhat nondescript, dark brown plumage with a distinctive pale rump that gives them the often used name ‘ring-tail’. Mature males, once fittingly known as blue hawks, are primarily pale, blue-grey in colour, neatly rounded off with blackened wing tips.

In the New Forest, even at a distance, it’s hard to confuse Hen Harriers with any other bird, except maybe in April when the extremely rare Montagu’s harrier may also occasionally be present.

Hunting behaviour is distinctive. Using flapping, buoyant flight they quarter the ground, keen-eyed, alert, looking for signs of life below, and in the worst of weather, flying into the wind, cleverly using the currents to help keep aloft. Determined to let nothing escape their attention, Hen Harriers often repeatedly over-fly the same patch of ground before moving on to try again elsewhere.

Success rates are probably quite low, but by hunting over extensive areas, Hen Harriers generally seem to find enough food upon which to eke out at least a meagre living.  

Somewhat incongruously for such fierce, seemingly independent creatures, Hen Harrier night-time roosts are communal affairs down on the ground amongst rank vegetation. At dusk, New Forest Hen Harriers and also some that spend the day hunting further afield, gather in a small number of traditionally used roost sites, flapping in over the heaths before plunging down out of sight to rest in the company of others.

In recent years, Hen Harrier roost site disturbance has been something of a problem, caused at times by careless dog walkers, but more often, sad to say, the fault of over-enthusiastic bird watchers anxious to view these stunning birds.

References:
Collins Bird Guide: Killian Mullarney, Lars Svensson, Dan Zetterstrom and Peter J.Grant
The Shell Guide to the Birds of Britain and Ireland: James Ferguson-Lees, Ian Willis and J.T.R. Sharrock
The New Atlas of Breeding Birds in Britain and Ireland (1988-91): D.W. Gibbons, J.B. Reid and R.A. Chapman
Hampshire Bird Reports: Hampshire Ornithological Society
The New Forest – A Natural History: Colin R. Tubbs
All the Birds of the Air: Francesca Greenoak