Literature review to assess bird species connectivity to Special ...

2.8.5 Habitat use
Likely habitat use
Potential merlin nesting habitat includes: grass and heather moorland, bracken,
young plantation, mature plantation edges and rides (within 100m of plantation),
open areas within afforested blocks, and open birch, pine and alder woods (Rebecca
& Bainbridge, 1998). Of these, the dominant habitat types used for nesting are
heather moorland, grass moorland, trees in grassland, and conifer plantation. Where
merlin nest in trees, old carrion crow (Corvus corone), hooded crow (C. cornix),
magpie (Pica pica) or buzzard (Buteo buteo) nests are used. Carrion crow nests are
used most often. Preferred heather depths vary, with nests having been recorded in
heather ranging in height from 30-70cm (Wright, 1997), 7-50cm (Meek, 1988), and
10-35cm (Ellis & Okill, 1990).
Habitat used for hunting during the breeding season is mainly open country, including
moorland. In winter, merlin favour arable farmland, rough pasture, estuaries, sand
dune systems and low lying heaths (Hardey et al., 2006)
2.8.6 Winter behaviour
Winter dispersal
In the UK, many merlin disperse to lower altitudes and coastal areas after breeding.
Of ringed birds, data show that 71% of first year birds, and 78% of adult birds,
disperse within 100km of breeding sites (Heavisides, 2002). Scottish birds
dispersing further afield move into England and Ireland, with small numbers having
been recovered in Europe, from south-east Spain to northern Germany (Heavisides,
2002). All the birds recovered in Europe were recovered during the winter period
(October-April) and consisted of both first-year and adult birds (Heavisides, 2002). In
Shetland, some birds do over-winter in the islands, although there are very few
sightings of adult males (Ellis & Okill, 1990).
A study of urban merlin during the winter in Saskatchewan, Canada, found mean
hunting ranges of 1960ha (equivalent to a mean foraging distance of 2.5km) for
adults and 1790ha (equivalent to a mean foraging distance of 2.4km) for first year
birds (Warkentin & Oliphant, 1990). A study in west Galloway found a small winter
range for one adult female that was observed occupying a range of just 2km from a
communal roost (Dickson, 1989).
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