Range extension of Great Grey Owl in Europe.

G Grey Owl Strix nebulosa is a boreal species, occurring in vast areas of the taiga of Eurasia (S n lapponica) and North America (S n nebulosa). Its main range in the Western Palearctic includes Fennoscandia and northern Russia (König et al 2008, Mebs & Scherzinger 2008, Mikkola 2012; figure 1). The poorly known population in Euro pean Russia (west of the Ural mountains) is estimated at 1500-4500 pairs (BirdLife International 2004). In Fennoscandia, the species is relatively abundant in Finland, with slightly smaller populations in Sweden and Norway, where in recent years its range has expanded far to the south (Solheim 2009, Berg et al 2011, Valkama et al 2011; see below). Around 1900, it was known to breed in Fennoscandia’s northernmost forests only, mainly in northern Finland and Sweden and in north-eastern Norway but, probably in the mid1960s, the area expanded southward (Sulkava & Huhtala 1997). In addition to its extensive range in the north there is also an isolated population in northern Ukraine and adjacent Belarus, c 400500 km from the southern boundary of its main range (Snow & Perrins 1998; see below). In this paper, we discuss the southward and westward spread of the Great Grey Owl population in Europe, which in recent years has proceeded very rapidly.