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Breeding Bird Survey
Common Birds Census
Constant Effort Sites
Nest Record Scheme
Waterways Bird Survey
What the categories mean
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HEN HARRIER Circus cyaneus
Conservation Listings Long term trend

Table 2/Red (Historical decline)
Biodiversity Steering Group
Conservation Concern List

UK: Stable since 1988-89

Status Summary
Listed because of substantial declines over the last 200 years, this species has suffered from persecution on grouse moors (Etheridge et al. 1997) and more recently from loss of habitat as forestry plantations have matured (Bibby & Etheridge 1993). The UK population was unchanged between surveys in 1988-89 and 1998, although there were declines in Orkney and England but increases in Northern Ireland and Isle of Man (DETR 2000). Although average clutch size has declined substantially since the mid 1980s, further investigation has shown that this trend is due to increased proportions of records from Orkney in recent years, where clutch sizes tend to be smaller than on the mainland (Summers 1998, Crick 1998).
Annual breeding population changes for this species
are not currently monitored by BTO
Table of productivity information for Hen Harrier
Variable Period
Years Mean
Trend Predicted
in first year
in last year
Change Comment
Clutch size 30 1968-1998 13 Linear decline 5.09 eggs 4.44 eggs -0.65 eggs Small sample
Brood size 30 1968-1998 19 None       Small sample
Daily failure rate (eggs) 30 1968-1998 11 None       Small sample
Daily failure rate (chicks) 30 1968-1998 13 None       Small sample


Insufficient data on laying date
available for this species



Insufficient data on CES
available for this species



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Last updated: 7 March, 2001

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