Conservation Science in the RSPB 2006

24
The 2004 hen harrier survey
In common with many other
raptors in the 19th century, hen
harriers were driven close to
extinction in the UK by human
persecution, exacerbated by
habitat change in the lowlands.
Although there has been some
population recovery since, they
remain restricted to upland areas.
There is evidence that illegal
persecution limits the numbers
and range of hen harriers in the
UK, most markedly in areas of
moorland managed for shooting
driven red grouse. The hen harrier
is red-listed as a species of high
conservation concern and a
priority species for the UK
Partnership for Action Against
Wildlife Crime. In order to monitor
recent population trends, a
national survey was conducted
in 2004.
Mature conifer plantations are being
used increasingly by hen harriers.
Philip Newman (rspb-images.com)
The survey produced an estimate of
806 territorial pairs (95% confidence
limits 732–889) in the UK and Isle of
Man in 2004, an increase of 41%
since the previous survey in 1998.
This increase was evident through
the north and west of the UK range,
with estimated numbers more than
doubled in Orkney, the Hebrides and
north Highlands, and lesser
increases in the west Highlands,
Northern Ireland, Wales and the Isle
of Man. However, declines were
detected in the Southern Uplands
and eastern Highlands of Scotland,
and in England. These decreases
were all in areas where grouse
moors are most prevalent and
where the most likely cause is the
continued illegal killing of harriers
Populations of hen harriers by region in 1998 and 2004.
Number of territorial pairs
250
200
150
100
50
0
Orkney
Hebrides
West
Highlands
North
Highlands
East
Highlands
Southern
Uplands
Isle of Man
Northern
Ireland
Wales
1998
2004
England
% change 1998–2004: Orkney 181, Hebrides 100, North Highlands
240, West Highlands 53, East Highlands -21, Southern Uplands -45,
Isle of Man 16, Northern Ireland 66, Wales 54, England -47