Michele Mendi

Large-sized nocturnal raptor breeding in extensive mature stands of boreal or coniferous forest, favouring areas with openings such as bogs and small fields. Outside breeding season sometimes occurs in other habitats, incl. close to human settlements (Bull, Duncan, 2020).

The species shows variable migration patterns. In can be resident or nomadic depending on prey abundance. Widely distributed across the boreal zone of North America and Eurasia (from Fennoscandia to NE China and E Russia, in Europe S to Poland, Belarus and Ukraine) (Keller et al. 2020).

Its population trend in Europe is increasing. Evaluated as “Least Concern” (BirdLife International 2021).

Season of assessment

B

Population trendStable
Population size
(min-max, best estimate)		12400-19900,15700
Red List categoryLC
Franks, S., Fiedler, W., Arizaga, J., Jiguet, F., Nikolov, B., van der Jeugd, Ambrosini, R, Aizpurua, O., Bairlein, F., Clark, J., Fattorini, N, Hammond, M., Higgins, D, Levering, H., Skellorn, W., Spina, F, Thorup, K. Walker, J., Woodward, I. and Baillie, S.R. (1) (2022) Online Atlas of the movements of European bird populations. https://migrationatlas.org EURING/CMS (1) Principal investigator
Map

Overall Connectivity for Great Grey Owl

The species can be sedentary in some areas in certain years but highly irruptive in others, its movements thought to be influenced by availability of rodent prey (Bull, Duncan, 2020).

Most birds ringed in Finland have been encountered within the country. Almost all encounters during the first autumn and winter have been reported close (< 50km) to the place of ringing; an exceptional record exist from early Nov 197km N of the ringing site (Saurola et al. 2013).

Most encounters of birds ringed in Finland and N Sweden and found in NW Russia have been taken place NE, E and SE from the breeding sites (Noskov et al. 2016). A bird ringed as nestling in E Finland has been subsequently encountered in its 3rd calendar year in Russia, 912km away SE of its breeding place, which is the longest distance known so far in species’ natal dispersal in Europe (Saurola et al. 2013).

Recoveries by Condition for Great Grey Owl

Currently protected species in Europe. Encounters have been recorded after 1961 only, ca. 19% obtained in just two years (2017-2018) only. Most encounters come from the breeding season (May-Jul) – ca. 71%. N Europe holds almost all (ca. 97%) of the encounters.

The encounters based on dead birds considerably decreased over time – from 80% during the period 1961-1980 (15% shot) to 35% after 1991, while those based on alive birds – considerably increased (from 15 to 63% respectively), mostly due to ringing encounters (Finland holding the majority of them). Hitting of wires was more important negative factor in the past (6.1%), its impact is currently lowered to 1.3%.

Quite limited number of distant recoveries (>=50 km), most of them less than 350 km away from the ringing site.

Annual Movements for Great Grey Owl

In Finland, when encountered in two successive breeding seasons both males and females have been found to move < 10km between the two nests; in contrast, the females encountered some years later have moved much longer distances (median 67km, max. 405km) (Saurola et al. 2013).

Post-natal dispersal in juveniles start in Aug-Sep, but it is more evident Oct-Nov (But’ev et al. 2005; Noskov et al. 2016).

The adults are back on their breeding sites in late Feb – early Mar, while non-breeding immatures may roam until mid-May (Noskov et al. 2016).

The newly emerged and increasing population in SE Norway during the last decade is believed to have been founded by birds from Sweden (Sonerud et al. 2021); regular ringing activities showed a short-distance dispersal in W, S, & E directions in S Norway & S Sweden.

Between 1955 and 1981 nine sporadic invasions have taken place S of the breeding range in Europe (Cramp 1985).

Connectivity by Month by Region for Great Grey Owl

All encounters are located within N Europe (N & E regions) – Fennoscandia and Russia (the bulk of ringing data coming largely from Finland): mostly within-country movements and small amount of short-distance movements across neighbouring countries.

Finnish data suggest that part of the populations (particularly the males) remains resident, while the rest is nomadic (Saurola et al. 2013).

The juveniles start their dispersal after the breeding season – in late summer, and it continues until late autumn (But’ev et al. 2005). They disperse only moderate distances from the natal site in their first year (Bull, Duncan, 2020).

Adults occupy their breeding sites in late winter or early spring; in contrast, non-breeding immature birds may look for appropriate territory until late spring (Noskov et al. 2016).

Ringing data are insufficient for outlining connectivity patterns in detail.

Boris Nikolov

References

Statistics Map
N records N individuals N recoveries
Mapped data*
Total available data
*Mapped data include only distant (>= 50 km) recoveries
References Map
2020 . European Breeding Bird Atlas 2: Distribution, Abundance and Change. European Bird Census Council & Lynx Edicions, BarcelonaEditor(s): Keller, V., S. Herrando, P. Voříšek, et al.
BirdLife International 2021 . Species factsheet: Strix nebulosa. Downloaded from http://www.birdlife.org on 01/08/2021.
Bull, E. L., J. R. Duncan 2020 . Great Gray Owl (Strix nebulosa), version 1.0. In Birds of the World Link to Article (DOI: https://doi.org/10.2173/bow.grgowl.01) Cornell Lab of Ornithology, Ithaca, NY, USA
But’ev, V. T., Zubkov, N. I., Ivanchev, V. P., Koblik, E. A., Kovshar, A. F., Kotyukov, Y. V., Lyuleeva, D. S., Nazarov, Y. N., Nechaev, V. A., Priklonskiy, S. G., Pukinskiy, Y. B., Rustamov, A. K., Sorokin, A. G., Fridman, V. S. 2005 . Birds of Russia and adjacent territories: Strigiformes, Caprimulgiformes, Apodiformes, Coraciiformes, Upupiformes, Piciformes. KMK, Moscow
Cramp, S. 1985 . Handbook of the Birds of Europe, the Middle East and North Africa, Volume 4. Terns to Woodpeckers. Oxford University Press, New York, NY, USA
Noskov, G. A., Rymkevich, T. A., Gaginskaya, A. R. 2016 . Migration of Birds on Northwest Russia. Non-Passerines. ANO LA “Professional”, Saint Petersburg
Saurola, P. Valkama, J., Velmala, W. 2013 . The Finnish Bird Ringing Atlas Vol. I. Finnish Museum of Natural History and Ministry of Environment, Helsinki
Sonerud, G.A., Solheim, R. & Berg, T. 2021 . Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls. J Ornithol 162: 109–118

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