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

2.11 Short-eared Owl
2.11.1 Foraging
Foraging range
The foraging range of short-eared owls during the breeding season, and the degree
to which this will overlap with neighbouring pairs, is poorly-known. Information that
does exist suggests ranges vary between areas and years, depending on the
abundance of prey. When prey items, such as voles, are abundant, short-eared owls
will tend to defend exclusive home ranges (Hardey et al., 2006). When food items
are more limited, and when the pair is feeding young, hunting outwith this defended
area will be more frequent (Cramp, 1985).
Several studies have estimated territory size, producing widely-varying means of
between 40ha and 350ha (Table 4). On this basis, mean foraging distances vary
between 0.4km and 1.7km. However, these estimates do not take into account any
foraging that may occur outwith the territory.
Based on these studies, the core foraging range for short-eared owl is likely to be
within 2km of the nest site. However, longer foraging distances will take place. For
example, a bird on North Uist was recorded flying 4 to 5km with food to its nest
(Andrew Stevenson pers. comm.).
Table 4 - Short-eared owl territory estimates
Location
Year of
study
Area per
territory
(ha)
Mean distance to
territory boundary
(km)
Reference
Roxburgh 1934 230 to 300 0.9 to 1.0 Goddard 1935
Stirlingshire 1954 40 0.4 Lockie 1955
Wales
Dumfries
Finland
1971-
1984
1976-
1978
1977-
1987
875 1.7
Roberts & Bowman
1986
62 to 112 0.4 to 0.6 Village 1987
96 0.6
Korpimäki & Nordahl
1991
Galloway 1991 60 0.4 Shaw 1995
Islay
1985-
2004
350 1.1
M. Ogilvie pers
comm., per
Calladine et al. 2005
2.11.2 Nesting
No information on nesting, pertinent to connectivity, was found.
2.11.3 Display flights
During display flight, the male typically climbs quite rapidly in fairly tight circles, with
characteristic ‘wing clapping’, followed by a near-vertical stoop in rocking flight
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