Map: Distribution of Circus cyaneus Light green - nesting area Dark green - resident all year Blue - wintering area
https://commons.wikimedia.org/wiki/File:Circus_cyaneus_distribution_map.png The Engineer [CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0/)]
Rare and Declining
Did you know that the Hen Harrier (Circus cyaneus) population in Ireland has been declining for the last 40 years? And that in 2015 there was only an estimated 108-157 pairs remaining – a decrease of 8.7% since 2010 (National Survey 2015)?
A rare, ground-nesting bird-of-prey, the Hen Harrier needs an open habitat for hunting its prey, such as Meadow Pipit and Skylark and small mammals. Its decline is linked with the fact that the semi-natural habitat which it needs to hunt and breed in, is rapidly disappearing in Ireland, due to changes in land use.
For the Hen Harrier to survive, it needs very specific habitat requirements – it needs cut-over bog, heathland and newly planted forestry (ideally 6 to 11 years old) for foraging and nesting.
Why is the Hen Harrier known as the Skydancer? Because of a very distinctive part of it’s mating ritual. Around about March and April, the male bird flies up high in the sky and then free falls down, twisting and ‘dancing’ in the air to attract the female.
Another acrobatic performance occurs when the male, carrying prey in its talons, passes it to the female in mid-air as she somersaults upside down to grab it.
Nesting and Roosting
Individual Hen Harriers may occupy different habitats during the breeding and non-breeding seasons. While rearing young they occupy ground nests, usually in heather dominated areas or young, pre-thicket, forestry plantation. During the non-breeding season, Hen Harriers regularly form communal roosts, with multiple numbers of birds interacting with one another and settling in the one habitat each evening.
The EU Birds Directive was adopted in 2009 to protect wild birds and their habitat. Under the Directive, various species of birds are listed in order of their endangered status. The list is divided into Annexes, with those listed under Annex I being the most endangered birds. The Hen Harrier is listed under Annex I.
Each member state established Special Protection Areas (SPAs) to protect the habitats of listed birds. Special Protection Areas (SPAs) for the Hen Harrier are designated under the European Birds Directive (Directive, 2009/147 /EC).
The Hen Harrier in my local area
Hen Harriers have been recorded on Mount Callan in County Clare. This area of upland is covered by forestry plantations and re-vegetating cutover bog. There are small, shallow pools and hummocks of numerous grasses, bog mosses, rushes and lichens to be found in the bog areas.
A roughly one square kilometre on the highest part of the mountain has been designated as a Natural Heritage Area (Slieve Callan Mountain Bog NHA Site Code 002397) under Irish Legislation. The designated area is important because it contains one of the few intact areas of blanket bog in this part of the country and bogs are a globally scarce resource! The remaining bogland of Mount Callan is particularly vulnerable owing to erosion caused by overgrazing and afforestation. Because of this, its long-term survival needs sensitive management!
This is a very small amount of protected area on Mount Callan and it begs the question why can it not be extended to be more effective – is it because of pressure from local farmers/landowners (wind-farm/forestry)? And why is it not a designated SPA for the protection of the Hen Harrier?
Areas dominated by forestry may remain as suitable habitat for the Hen Harrier, provided that a mosaic of age classes is maintained within the forest, such that areas of young, pre-thicket forest are always available. These are the preferred hunting grounds for these birds.
So, these requirements mean a strict regime of management of the habitat, which, I feel is somewhat lacking in this case. Take for example, permission being given – at the highest level – for the development of a 29 turbine -windfarm on the mountain very close to the NHA and directly on the Hen Harrier foraging and nesting area!