Boreal Owl
Aegolius funereus Linnaeus, 1758
Nyctala tengmalmi (Gm. 1788): Reiser, 1894: 102.
Order Strigiformes
Family Strigidae
Conservation status: in Bulgaria: Vulnerable VU [B1biii + C2ai], BDA-II, III; International: CITES-II, BeC-II, BD.
General distribution. A Siberian-Canadian species. It breeds in the boreal parts of the northern hemisphere. In Europe, apart from the northern parts, it inhabits the Alps, the Carpatians, the Pyrenees, the Balkan peninsula, the Caucasus Mountains and Asia Minor. In the Balkans it is a glacial relict.
Distribution and abundance in Bulgaria. Resident. At the beginning of the 20th century it was widely distributed in the mountains, especially in the Rhodopes [4]. In 1985, it was already considered on the verge of extinction, known only from several habitats, mainly in Rila mountain [1] and the Balkan range [2, 3]. At present, it is widely distributed in most mountains, mainly in the Rila-Rhodope massif, the Central and the Western Balkan range [5, 6, 7, 8, 9, 10, 11]. The total numbers may be estimated at 1 025 – 1 400 pairs. The values of the numbers in the major habitats, according to data from the 1995-2005 period, are, as follows (mountains): Rila – 300-400 pairs, Pirin – 200-220 pairs, Vitosha – 25- 40 pairs, the Rhodopes – 400-600 pairs (?), the Central Balkan range – 50-70 pairs, the Western the Balkan range – 25-35 pairs, Plana – 10-15 pairs, Osogovo – 5-10 pairs, Slavyanka – 10-12 pairs.
Habitats. Coniferous and mixed forests. It breeds mainly in old spruce and pine forests between altitudes of 1 100 and 1 950 m. It also breeds, less often, in pure beech forests [8, unpublished data].
Biology. It courts in the period from March to May and in the autumn: September-October. It breeds most frequently in hollows in trees of the black woodpecker. Between April and the beginning of May, the female lays 4-7 white eggs; it incubates for 25-29 days, the young ones leave the nest at the age of 30-32 days [12]. It feeds on small mammals, less often birds and insects [13].
Similar species. The Little Owl (Athene noctua).
Negative factors. Loss of habitats. Intensive deforestation. Infrastructure development related to ski sports and tourism. Fires.
Conservation measures taken. Protected according to the Biological Diversity Act. Included in the Red Data Book of Bulgaria (1985). In the Vitosha Natural Park, bird houses have been placed. Parts of its population are preserved in the national parks Pirin, Rila, Central Balkans, and the Rila Monastery Natural Park, the Chuprene Nature Reserve.
Conservation measures needed. Declaration of the Western Rhodopes and the Western Balkans National Parks. Declaring a reserve in the regions of peaks Sveshtnik and Mutorog in the Southern Pirin mountain. Ban on the felling of trees in regions where breeding of the species has been registered. Selective management of the forests, leaving old trees with hollows. Discontinuation of building ski tracks.
References. 1. Simeonov, 1980; 2. Spiridonov, Sopasov,1981; 3. Spiridonov et al., 1982; 4. Boetticher, 1927; 5. Kouzmanov et al. 1995; 6. Nankinov, 1997; 7. Nikolov et al., 2001; 8.Nikolov S., 2003; 9. Shurulinkov et al., 2003; 10. Shurulinkov, Stoyanov, 2005; 11. Nankinov, 2002; 12. Simeonov et al.,1990; 13. Simeonov, 1988.
Authors: Petar Shurulinkov, Geko Spiridonov, Tsvetan Zlatanov, Boris Nikolov, Stoyan Ch. Nikolov, Radoslav Stanchev
