BTO - Breeding Birds of the Wider Countryside: Hen Harrier

HEN HARRIER
Circus cyaneus

Hen Harrier © John Marchant

• Population
changes

• Productivity
trends

• Additional
information

Conservation listings

Europe: SPEC category 3, vulnerable
UK: red (historical decline)

Long-term trend

UK: stable (between 1988–89 and 1998)

UK population size

570 (500–640) territorial pairs in 1998 (Sim et al. 2001: BiE04, APEP06)

Status summary

Listed because of substantial declines over the last two centuries, this species has suffered from persecution on grouse moors (Etheridge et al. 1997) and recently also from loss of habitat as forestry plantations have matured (Bibby & Etheridge 1993). The UK population was unchanged between surveys in 1988–89 and 1998, with declines in Orkney and England but increases in Northern Ireland and the Isle of Man (Sim et al. 2001). A decrease of 70% in the Orkney population over the last 20 years has been linked to reductions in the area of unmanaged grassland (Amar & Redpath 2005); the demographic drivers of this decline have been a decrease in polygyny and reduced nesting success among secondary females (Amar et al. 2005). Although average clutch size has declined substantially since the mid 1980s, further investigation has shown that this trend is due to the increased proportions in recent years of records from Orkney, where clutch sizes tend to be smaller than on the mainland (Summers 1998, Crick 1998).

Population changes

Annual breeding population changes for this species are not currently monitored by BTO

Productivity trends

Insufficient data on laying date
available for this species

Insufficient data on CES
available for this species

Additional information

Distribution maps for this species are not currently available online (see Atlases species help)
BirdFacts page on species biology
BirdTrack results


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This report should be cited as: Baillie, S.R., Marchant, J.H., Crick, H.Q.P., Noble, D.G., Balmer, D.E., Coombes, R.H., Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. and Thewlis, R.M. (2006) Breeding Birds in the Wider Countryside: their conservation status 2005. BTO Research Report No. 435. BTO, Thetford. (http://www.bto.org/birdtrends) Pages maintained by Susan Waghorn and Iain Downie: Last updated 28 April, 2006