Monitoring and conserving Scotland's birds of prey
Largely nocturnal or crepuscular, the short-eared owl can be one of the most active of British owls during daylight hours (Calladine & Morrison 2013). Despite this, and its charismatic appeal, current breeding numbers are poorly known with any surveys likely to be biased towards the detection of those that have successfully hatched young (Calladine et al. 2010). An estimate of the Scottish population suggested 780 - 2,700 breeding pairs, with an estimate for the U.K. of 1,000 - 3,500 pairs in the early 1990s: although this is acknowledged to be one the most unreliable estimates for any raptor or owl species (Greenwood et al. 2003). A recent population estimate for Britain is 610 - 2140 pairs (Musgrove et al. 2013). A personal opinion is the typical figure will be within the lower half of that estimate and the species is a contender to be amongst the predatory birds showing the most marked declines during the past two decades. However, breeding numbers are known to fluctuate markedly in response to prey availability (e.g. Village 1987, Petty et al. 2000) and the birds are believed to range quite widely. This variation in abundance has no doubt added to the difficulty in assessing the numbers of breeding short-eared owls in Britain and any recent population trends.
In Scotland, most breeding short-eared owls are associated with moorland and the highest densities are reported from rough grasslands adjacent to, or intermixed with, heather moors (marginal hill ground or 'white moor'). A diversity of sward structures within a typical home range (ca. 200 ha) could be important to support short-eared owls through the breeding season (Calladine & Morrison 2013). Young conifer plantations can also be important habitats (Shaw 1995), though second and later rotation plantings are perceived to be less used than initial plantings.
Lowland rough grassland, marshes and coastal sand dunes are also used for breeding though their use of such areas can be erratic, except on some of the western islands and Orkney. Published territory sizes of breeding short-eared owls in Britain range from one territory per 40 hectares to one per 875 hectares (Goddard 1935, Lockie 1955, Village 1987, Shaw 1995, Roberts & Bowman 1986, Calladine & Morrison 2013). Elsewhere in Europe, breeding short-eared owls can be found in relatively intensive agricultural areas including cereal crops, meadows and rye grass fields, though this probably reflects a different prey base to that found in Britain. In Britain, a major prey item is the short-tailed field vole, though other small mammals can be important, notably on islands where voles are absent or where alternative prey is available, for example, common voles in Orkney (Glue 1977).
In winter, when many upland areas are abandoned, the species is mostly found in marshes and coastal grasslands. Ringing recoveries suggest a proportion of the short-eared owls seen on the east coast in autumn originate from Scandinavia (Glue 2002) with some of these birds remaining for the winter. Although British short-eared owls (and those from neighbouring North Sea coasts) tend to migrate lesser distances than those from elsewhere in Europe, ring recoveries have come from as far as Russia, the Mediterranean and North Africa. An analysis of European ringing recoveries suggested that the distances moved between breeding and wintering areas generally increased from the early 20th century through to the 1960s and 1970s and then subsequently declined, those changes possibly reflecting changes in breeding population densities, at least in some areas (Calladine et al. 2012). The degree and nature of connectivity between birds that breed in Britain and elsewhere in Europe remains unclear.
Calladine, J., du Feu, C. & du Feu, R. (2012). Changing migration patterns of the Short-eared Owl Asio flammeus in Europe: an analysis of ringing recoveries. Journal of Ornithology 153: 691-698.
Calladine, J., Garner, G., Wernham, C. & Buxton, N. (2010). Variation in the diurnal activity of breeding Short-eared Owls Asio flammeus: implications for their survey and monitoring.
Bird Study 57: 89-99.
Calladine, J. & Morrison, N. (2013). Diurnal and nocturnal ranging behaviour by moorland breeding Short-eared Owls Asio flammeus in Scotland. Bird Study 60: 44-51.
Glue, D.E. (1977). Feeding ecology of the Short-eared Owl in Britain and Ireland.
Bird Study 24: 70-78.
Glue, D.E. (2002). Short-eared Owl. In Wernham, C.V., Toms, M.P., Marchant, J.H., Clark, J.A., Siriwardena, G.M. & Baillie, S.R. (Eds.). The Migration Atlas: Movements of the Birds of Britain and Ireland. T. & A.D. Poyser, London. Pp. 437-440.
Goddard, T.R. (1935). A census of short-eared owls (Asio f. flammeus) at Newcastleton, Roxburghshire, 1934. Journal of Animal Ecology 4: 113-118.
Greenwood, J.J.D., Crick, H.Q.P. & Bainbridge, I.P. (2003). Numbers and international importance of raptors and owls in Britain and Ireland. In Thompson, D.B.A., Redpath, S.M., Fielding, A.H., Marquiss, M. and Galbraith, C.A. (Eds.). Birds of Prey in a Changing Environment. The Stationery Office, Edinburgh. Pp. 25-49.
Lockie, J.D. (19550. The breeding habits and food of short-eared owls after a vole plague.
Bird Study 2: 53-69.
Musgrove, A., Aebischer, N., Eaton, M., Hearn, R., Newson, S., Noble, D. Parsons, M., Risely, K. and Stroud, D. (2013). Population estimates of birds in Great Britain and the United Kingdom. British Birds 106: 64-100.
Petty, S.J., Lambin, X., Sherratt, T.N., Thomas, C.J., Mackinnon, J.L., Coles, C.F., Davison, M. and Little, B. (2000). Spatial synchrony in field vole Microtus agrestis abundance in a coniferous forest in northern England: the role of vole-eating raptors. Journal of Applied Ecology 37: 136-147.
Roberts , J.L. and Bowman, N. (1986). Diet and ecology of Short-eared Owls Asio flammeus breeding on heather moor. Bird Study 33: 12-17.
Shaw, G. (1995). Habitat selection by Short-eared Owls Asio flammeus in young coniferous forests. Bird Study 42: 158-164.
Village, A. (1987). Numbers, territory size and turnover of Short-eared Owls Asio flammeus in relation to vole abundance. Ornis Scandinavica 18: 198-204.
Hen Harrier• Goshawk• Sparrowhawk• Common Buzzard• Golden Eagle
Osprey• Kestrel• Merlin• Hobby• Peregrine Falcon• Barn Owl
Tawny Owl• Long-eared Owl• Short-eared Owl• Raven