Circus aeruginosus – BOD Y GWERNI – Winter visitor.
The Hen Harrier is widely distributed across northern Eurasia. In Britain it breeds primarily over 450m on heather-covered uplands, including in north Wales. In most areas it is migratory, heading south for the winter, although in some areas (including the UK) the migrations may be short – eg from the Welsh uplands to lowland heaths and mires, and to coastal areas – depending on the food supply.
More information in Hen Harrier 1994
When can they be seen?
Hen harriers are seen from the beginning of September (week 36) with the peak number of observations in October and November. It remains throughout the winter, with observations tailing off during April. Occasionally a straggler is seen during May.
Where can they be seen?
The best areas for observing hen harriers are the St Davids Peninsula, Mynydd Preseli, Dudwell/Plumstone Mountains, the Marloes Peninsula, and the Castlemartin area.