Michele Mendi

The species occurs in the forest-tundra and boreal taiga zones, inhabiting moderately dense coniferous or mixed coniferous-deciduous forests near open areas like marshes and meadows. It has circumpolar distribution across the Holarctic – North America (from Alaska to Newfoundland) and Eurasia (Fennoscandia through Siberia) (Duncan, Duncan 2020). In Europe, it is confined exclusively to N & C Fennoscandia and N Russia (Keller et al. 2020).

Mainly resident species; sometimes undertake eruptive long-distance movements in response to feeding requirements (Duncan, Duncan 2020).

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

Season of assessment

B

Population trendIncreasing
Population size
(min-max, best estimate)		20800-92400,36800
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 Northern Hawk-Owl

The species shows a nomadic behaviour, dispersing extensively within its breeding range in response to regional food availability (rodent prey cycles) and climatic conditions (Mikkola 1983). During irruptions the species is prone to occupy more open areas and to overwinter within or close to human habitations (But’ev et al. 2005).

Data for mostly within-region movements are available – from Finland, Sweden, Norway and to a lesser extent Russia. A single bird marked in NW Russia has been encountered in Denmark.

Most encounters of birds ringed in Finland and Sweden and found in NW Russia have been taken place NE, E and SE from the breeding sites (Noskov et al. 2016). The birds from the large influx in 2016 in S Norway are believed to originate from N Fennoscandia (Dale 2017).

Ringing data are insufficient for outlining connectivity patterns in detail.

Recoveries by Condition for Northern Hawk-Owl

Currently protected species in Europe. Just three encounters prior to 1960. About 16% of all encounters were obtained in a single year (1976), during an influx. The bulk of encounters (mostly juveniles) come from May-Jun – 29% (nestbox ringing), and from Sep-Nov (42%, autumn dispersal/ irruptions). N Europe holds the majority of encounters (92%).

Those based on dead birds did not change much over time – from 42% in 1961-1980 (10% shot) to 35% after 1991 (no shot birds, other reasons only), neither those based on alive birds – 54 and 59% respectively (the latter mostly due to ringing encounters and metal ring read in the field). Traffic is among the currently important negative factors (8%).

Quite limited number of distant recoveries (>=50 km).

Annual Movements for Northern Hawk-Owl

Post-natal/ autumn dispersal is particularly evident in juveniles – starting from Sep but encountered until Dec, some tens or hundreds of kilometers away from the breeding sites. Several extreme cases involve encounters of birds in W Siberia, almost 3000km E from their breeding sites.

In prey-rich years many birds stay resident, overwintering in their breeding territories; in prey-poor years they disappear in Oct and in years of rodent population minimum owls migrate even earlier – in Aug. Those birds which had travelled away to overwinter return to their breeding sites in Mar-Apr (Noskov et al. 2016).

Irruptions involve large number of juveniles (85%) (Cramp 1985) or consist entirely of juvenile birds (Duncan, Duncan 2020).

Connectivity by Month by Region for Northern Hawk-Owl

Species density and population trend highly dependent on the geographically asynchronous fluctuations of microtine populations which peak every 3-5 years (Duncan, Duncan 2020).

All encounters are located within N Europe (N & E regions) – Fennoscandia and Russia: mostly within-country movements and small amount of short-distance movements across neighbouring countries.

Post-breeding movements in juveniles are evident from early autumn and last until late autumn or early winter. Depending on the prey availability populations can be resident or partly migratory (the birds leaving their breeding sites in mid-autumn or even in late summer). The breeding territories are occupied back in early- to mid-spring (Noskov et al. 2016).

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: Surnia ulula. Downloaded from http://www.birdlife.org on 03/08/2021.
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
Dale, S. 2017 . Density, numbers and origin of Northern Hawk Owls Surnia ulula in southern Norway during the 2016 irruption. 40Ornis Norvegica : 1–13
Duncan, J. R., Duncan, P. A. 2020 . Northern Hawk Owl (Surnia ulula), version 1.0. In Birds of the World Link to Article (DOI: https://doi.org/10.2173/bow.nohowl.01) Cornell Lab of Ornithology, Ithaca, NY, USA
Mikkola, H. 1983 . Оwls of Europe. Т & A D Poyser, London
Noskov, G. A., Rymkevich, T. A., Gaginskaya, A. R. 2016 . Migration of Birds on Northwest Russia. Non-Passerines. ANO LA “Professional”, Saint Petersburg

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