Gunther Zieger

The species occupies for breeding deep lakes and rivers – often in wooded country, mainly across the Holarctic boreal zone: most of N North America, S Greenland, Iceland, N Europe (with some isolated breeding sites in C and SE Europe), N Asia. Outside breeding season it occurs mainly on coastal waters (Craik et al. 2020).

Intra-Eurasian partial migrant, resident or locally dispersive in much of NW Europe. Its wintering grounds include most of coastal zones in N and NW Europe, but also the Black Sea/ E Mediterranean region, and the S Caspian Sea as well.

Not globally threatened but declining on a European scale (Keller et al., 2020).

Season of assessment

B

Population trendDecreasing
Population size
(min-max, best estimate)		141000-282000,198000
Red List categoryNT
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 Red-breasted Merganser

Most breeding birds from the British Isles and Denmark are considered sedentary or locally dispersive. Birds breeding in Fennoscandia travel S & SW to the W Baltic and North Seas, W Europe, as well as S to the Mediterranean and Black Sea regions. NW Russian breeders have similar routes, the 1st-year birds tend to winter in W Europe while the adults – in the Black Sea region (Noskov et al. 2016). The wintering grounds of birds breeding in Germany are largely matching those of the Fennoscandian birds. S Ukrainian breeders disperse for wintering in Black and Azov Seas, some reaching Aegean Sea. Icelandic breeding population consists of both resident and migratory birds – the latter travel mostly SE (British Isles).

During winter males tend to remain closer to the breeding grounds than females and immatures (Craik et al. 2020).

Recoveries by Condition for Red-breasted Merganser

Game species in Fennoscandia, Denmark, Iceland, Russia; it has been hunted until recently (2016) in Malta. Most encounters obtained during the breeding season in early summer – ca. 65% in Jun-Jul. In total, the share of encounters based on alive birds forms about half (48%) of all cases; however, it fluctuates from 15% pre-1960s, about half (ca. 53%) during 1961-1990 to ca. 47% after 1991. Inversely, dead recoveries largely decreased from about 77% before 1960 to ca. 44-46% during the following periods. Shooting’s share dropped from ca. 37% of all cases pre-1960 to ca. 10% after 1991. Some recoveries are based on drowning in fishing nets – 9% of all dead birds found in Denmark (Bønløkke et al. 2006), 29% in Finland (Saurola et al. 2013).

Most encounters obtained between mid-1960s and mid-1970s, mainly in N & C Europe (ca. 90%).

Annual Movements for Red-breasted Merganser

The species undergoes a flightless wing-moulting period in Aug-Sep (Craik et al. 2020). The largest known moulting area in Europe is in Denmark (Scott, Rose, 1996). Females and immatures start autumn migration earlier than males (Craik et al. 2020). Post-breeding movements of the Fennoscandian birds start in Aug but are more evident in Sep-Oct; the wintering grounds in the Black Sea and W Europe are reached as early as Oct. Spring migration in the Baltic Sea region is active in Mar-Apr (Skov et al. 2011). Breeding sites in Fennoscandia are reached in late Apr and May. British Isles breeders overwinter on local coastal waters, some moving as far as Denmark and Norway; local birds are joined by wintering birds from the Iceland mostly in Dec-Jan. Black Sea population overwinters locally dispersed (Sep-Feb). Single birds remain in their wintering areas until Apr-May.

Connectivity by Month by Region for Red-breasted Merganser

The bulk of birds breeding in Fennoscandia are encountered from early autumn until late spring primarily in the region of Baltic and North Seas (including the straits in between), where they join the local residents from Denmark, Germany and S Sweden. The remainder Fennoscandian breeders take longer routes to spend the winter along the Atlantic Coast of W Europe, Mediterranean Sea, SE Europe and Black Sea. C European breeders (Germany) are found wintering along the coasts of Mediterranean Sea and W Europe from early autumn to early spring. Bird breeding in S Ukraine are found during autumn and winter primarily in the Black Sea basin.

Icelandic breeders are recorded during the winter on the coastal waters of British Isles; stragglers are recorded in E Greenland (Nov) and The Netherlands (Lyngs 2003).

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.
Bønløkke, J., Madsen, J. J., Thorup, K., Pedersen, K. T., Bjerrum, M., Rahbek, C.2006 . Dansk Traefugleatlas. Rhodos, Humblebæk
Craik, S., Pearce, J., Titman, R. D. 2020 . Red-breasted Merganser (Mergus serrator), version 1.0. In Birds of the World Link to Article (DOI: https://doi.org/10.2173/bow.rebmer.01) Cornell Lab of Ornithology, Ithaca, NY, USAEditor(s): S. M. Billerman
Lyngs, P. 2003 . Migration and winter ranges of birds in Greenland. An analysis of ringing recoveries. Danish Ornithological Society/BirdLife Denmark, Copenhagen
Noskov, G. A., Rymkevich, T. A., Gaginskaya, A. R. 2016 . Migration of Birds on Northwest Russia. Non-Passerines. ANO LA “Professional”, Saint Petersburg
Scott, D. A., Rose, P. M. 1996 . Atlas of Anatidae Populations in Africa and Western Eurasia. Wetlands International , Wageningen, The Netherlands

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