Rear-edge populations of montane species are known to be vulnerable to environmental change,which could affect them by habitat reduction and isolation.Habitat requirements of two cold-adapted boreo-alpine owl species—Boreal Owl(Aegolius funereus)and Pygmy Owl(Glaucidium passerinum)—have been studied in refugial montane populations in the western Rhodopes,South Bulgaria.Data on owl presence and forest stand attributes recorded in situ have been used to identify significant predictors for owl occurrence.The results revealed Boreal Owl's preference for comparatively dense forests(high canopy closure values),big trees(diameter at breast height≥50 cm)and large amount of fallen dead wood in penultimate stage of decay.For Pygmy Owl the only significant explanatory variable was the total amount of fallen dead wood.Results suggest preference of both owl species for forests with structural elements typical of old-growth forests(i.e.,veteran trees,deadwood),the Pygmy Owl being less prone to inhabit managed forests.Being at the rear edge of their Palearctic breeding range in Europe both Boreal and Pygmy Owls are of high conservation value on the Balkan Peninsula.Hence,additional efforts are needed for their conservation in the light of climate change and resulting alteration of forest structural param-eters.Current findings can be used for adjusting forest management practices in order to ensure both,sustainable profit from timber and continuous species survival.

Boris P.Nikolov;Tzvetan Zlatanov;Thomas Groen;Stoyan Stoyanov;Iva Hristova-Nikolova;Manfred J.Lexer

Institute of Biodiversity and Ecosystem Research,Bulgarian Academy of Sciences,2 Yuri Gagarin Str.,Sofia,Bulgaria;Faculty of Geo-Information Science and Earth Observation(ITC),University of Twente,Hengelosestraat 99,7514AE,Enschede,the Netherlands;University of Forestry,10 Sv.Kliment Ohridski Blvd.,Sofia,Bulgaria;Biota Films Ltd,51 Prof.Kiril Popov Str.,Sofia,Bulgaria;University of Natural Resources and Life Sciences,Peter-Jordan-Str.82,Vienna,Austria

鸟类学研究（英文版）

[1]Boris P.Nikolov;Tzvetan Zlatanov;Thomas Groen;Stoyan Stoyanov;Iva Hristova-Nikolova;Manfred J.Lexer-.Habitat requirements of Boreal Owl(Aegolius funereus)and Pygmy Owl(Glaucidium passerinum)in rear edge montane populations on the Balkan Peninsula)[J].鸟类学研究（英文版）,2022(02):175-182

Owl,Aegolius,funereus,Pygmy,Glaucidium,passerinum,Balkan,boreo,owl,refugial,Rhodopes,Bulgaria,penultimate,Palearctic,Owls

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