Dark-bellied Brent Goose
Branta bernicla bernicla
The Dark-bellied Brent Goose breeds along the Arctic coasts of Russia and winters exclusively along the coasts of Western Europe, the majority concentrated at sites along the Atlantic west coast of France, the south and east coasts of England, southwest Netherlands and the Wadden Sea.
In England, Dark-bellied Brent Geese usually occur in largest numbers at The Wash and the Thames Estuary.
Global status (IUCN Red List of Threatened Species)
African-Eurasian Waterbird Agreement (AEWA)
European status (European Red List of Birds)
The Birds Directive (European Commission)
UK status (Birds of Conservation Concern)
UK quarry species (Wildlife & Countryside Act 1981)
* assessed at species level Branta bernicla
Least Concern (Europe and EU27)*
Annex II (Part B)
† Brent Goose Branta bernicla is listed as ‘Least Concern’ by IUCN. The Red List assessment of sub-species is not routinely undertaken, however, an assessment of Dark-bellied Brent Goose Branta bernicla bernicla was undertaken as part of the UK’s Birds of Conservation Concern 3; the subspecies was evaluated as ‘Vulnerable’.
Flyway population size (CSR 7; Wetlands International 2015)
GB estimate (Frost et al. 2019)
GB trend (SUKB 2017)
Breeding success (GSMP survey)
Long-term trend (1989/90 – 2014/15): 17% increase
Ten-year trend (2004/05 – 2014/15): 42% increase
Marked cyclic fluctuation, varying between 0% and 31%
Annual estimates of the percentage of young (%) and mean brood size (young per successful pair) of Dark Bellied Brent Goose in Britain, 2003/04-2018/19.
Season Percentage of young (%) Mean brood size 2018/19 8.0 1.88 2017/18 1.0 1.91 2016/17 8.6 1.96 2015/16 0.9 1.57 2014/15 23.0 2.77 2013/14 15.4 2.49 2012/13 3.1 1.61 2011/12 16.2 2.26 2010/11 12.7 2.7 2009/10 5.3 1.83 2008/09 1.1 1.74 2007/08 11.0 2.60 2006/07 2.0 1.62 2005/06 28.4 2.76 2004/05 11.9 2.33 2003/04 10.0 2.14
Frost, T., G.E. Austin, R.D. Hearn, S. McAvoy, A. Robinson, D.A. Stroud, I. Woodward & S.R. Wotton. 2019. Population estimates of wintering waterbirds in Great Britain. British Birds 112: 130-145.
The Dark-bellied Brent Goose breeds along the Arctic coasts of the Yamal, Gydan and Taimyr Peninsulas and the islands of the Kara Sea. It winters exclusively along the coasts of Western Europe, the majority concentrated at sites along the Atlantic west coast of France, the south and east coasts of England, southwest Netherlands and the Wadden Sea (Ebbinge et al. 1999). The migration route follows the coastline from northern Russia, through the White Sea and Baltic Sea, and along the North Sea coast, the English Channel and the French Atlantic coast.
Flyway of the Dark-bellied Brent Goose
On arrival in western Europe, some Dark-bellied Brent Geese initially stage on the Danish and Schleswig-Holstein coasts of the Wadden Sea, or at Foulness, Essex. From Foulness, birds disperse to winter in other parts of southern Britain, and to France. Whilst most birds depart wintering sites in March for pre-migration fattening on the Wadden Sea, up to 10,000 now stage on the Wash, eastern England, with much smaller numbers in north Norfolk, north Kent, the Stour Estuary and the Beaulieu Estuary (Ward 2004).
Since 1973, associated with the rapid population growth, Dark-bellied Brent Geese have made increasingly extensive use of inland habitats in the UK for foraging, including grassland, winter cereals and oilseed rape. For most sites, a sequential pattern of habitat use now occurs as birds successively deplete Zostera, Enteromorpha and finally saltmarsh food resources prior to switching to inland habitats. By mid winter, a large proportion of total feeding time is spent inland at most key sites in the UK. Most birds return to saltmarshes to exploit fresh growth of more natural foods at their spring staging sites in western Europe (Ward 2004).
In the UK, conflict with agriculture arises in Norfolk, Suffolk, Essex and the south coast of England when Dark-bellied Brent Geese forage on winter cereals and oilseed rape. To lessen the conflict locally, nature reserves are managed for these birds, providing alternative feeding areas often in combination with scaring operations outside.
The breeding success of Dark-bellied Brent Geese has previously been shown to follow a three-year cycle of ‘good’, ‘poor’ and ‘variable’ success (Dhondt 1987) and is greatly influenced by interactions between lemming abundance, predator pressure and other factors such as weather. Between the mid 1990s and 2005, whilst there was still considerable annual variation in Brent breeding success, the pattern shifted away from a predictable three-yearly cycle, and there were fewer than expected good breeding seasons. This suggests that the connection between rodent abundance and breeding success may no longer function in the same way, or that rodent abundance is no longer following such a predictable pattern.
Dhondt, A.A. 1987. Cycles of lemmings and Brent Geese Branta b. bernicla: a comment on the hypothesis of Roselaar and Summers. Bird Study 34: 151-154.
Ebbinge, B.S., C. Berrevoets, P. Clausen, B. Ganter, K. Gunther, K. Koffijberg, R. Maheo, M. Rowcliffe, A.K.M. St Joseph, P. Sudbeck & E.E. Syroechkovsky Jnr. 1999. Dark-bellied Brent Goose Branta bernicla bernicla. In: Madsen, J., G. Cracknell & A.D. Fox (eds.). 1999. Goose populations of the Western Palearctic. A review of status and distribution. Wetlands International Publication no. 48, Wetlands International, Wageningen,The Netherlands/National Environmental Research Institute, Ronde, Denmark.
Ward, R.M. 2004. Dark-bellied Brent Goose Branta bernicla bernicla in Britain 1960/61 – 1999/2000. Waterbird Review Series, The Wildfowl & Wetlands Trust/Joint Nature Conservation Committee, Slimbridge.
Wetland Bird Survey
The abundance of the Dark-bellied Brent Goose population in the UK is monitored through the Wetland Bird Survey (WeBS). The results from the survey are published in an annual report (see the WeBS website for details).
GSMP age assessments
Age assessments of Dark-bellied Brent Geese are undertaken at various sites in Britain, with counts carried out between September and March. Counters record the number of first winter birds present within a flock and individual brood sizes (i.e. how many young in each family group).
Results of the age assessments can be found on the ‘Latest results’ tab.
Find out more about age assessments
Results for 2018/19 [August 2019]
The winter of 2018/19 marked the 34th consecutive winter that experienced volunteer observers assessed the breeding performance of Dark-bellied Brent Geese (for methods see Hall 2008). Geese were aged at 79 localities within fourteen estuaries or coastal areas along the south and east coast of England from Lindisfarne in Northumberland to the Exe Estuary in Devon (Figure 1 & Table 1). Data were collected between 10 October 2018 and 4 March 2019.
A total of 27,899 geese were aged, a decrease on the previous year when 42,706 were aged. The largest samples came from the North Lincolnshire Coast (5,409), the Humber (3,865), North Norfolk (3,664) and Chichester Harbour (3,457) (Figure 1 & Table 1). At all other sites, fewer than 3,000 birds were aged. Of the 103 flocks assessed, the majority were aged in November (38.2%) and January (24.5%) with 12.7% aged in December, 9.8% in October and February, and 4.9% in March.
The overall percentage of young was 8.0% and of the 382 broods recorded the mean brood size was 1.88 (± 0.05 SE) young per successful pair (Table 1 & Figure 2).
The percentage of young throughout the winter peaked at 9.7% in October and ranged between 5.1% and 9.0% during other months (Table 2). The mean brood size of successful pairs peaked in March at 2.67 (± 0.33 SE) and ranged between 1.71 (± 0.09 SE) and 2.00 (± 0.28 SE) during other months.
Figure 1. Sites in the UK at which Dark-bellied Brent Geese were aged during winter 2018/19. See Table 1 for a key to the sites.
Table 1. Numbers of Dark-bellied Brent Geese aged at UK estuaries and coastal areas in winter 2018/19.
Estuary Sample flocks Number of sites Total aged Percentage of young Mean brood size SE Number of broods First Last Number of flocks 1 Exe Estuaty 11/11/18 17/02/19 8 6 1,492 5.1 3.5 1.5 2 2 The Solent 15/11/18 19/01/19 2 2 1,445 3.7 – – – 3 Langstone Harbour 05/11/18 30/01/19 5 4 1,496 7.4 2.08 0.14 53 4 Chichester Harbour 27/10/18 28/01/19 13 11 3,457 8.4 1.82 0.13 49 5 Thames Estuary 19/10/19 24/10/18 3 2 1,888 11.9 1.82 0.15 44 6 Roach Estuary 20/10/18 20/10/18 1 1 – – 1.65 0.15 34 7 Crouch Estuary 25/12/18 27/02/19 4 2 2,415 8.8 – – – 8 Blackwater Estury 28/11/18 28/11/18 1 1 278 5 – – – 9 Hamford Water 13/11/18 03/02/19 7 2 1,768 12 2.32 0.21 34 10 Stour Estuary 25/11/18 30/11/18 4 4 127 15 – – – 11 North Norfolk Coast 20/10/18 01/03/19 18 16 3,664 9.4 2.58 0.17 50 12 North Lincolnshire Coast 10/10/18 15/01/19 24 23 5,409 6.8 1.47 0.07 116 13 Humber Estuary 05/11/18 04/03/19 9 1 3,865 7.2 – – – 14 Lindisfarne 06/11/18 03/02/19 4 4 595 4 – – – 103 79 27,899 8.0 1.88 0.05 382
Figure 2. The percentage of young (blue columns) and mean brood size (red circles) of Dark-bellied Brent Geese recorded in the UK, 1985/86–2018/19. No brood size data were collected in 1985/86, 1986/87 or 1989/90.
Table 2. Monthly variation in the percentage of young and mean brood size of Dark-bellied Brent Geese in the UK during winter 2018/19.
Month Percentage young Mean brood size % n Mean SE n October 9.7 2,721 1.71 0.09 103 November 8.2 8,590 1.98 0.09 144 December 7.1 4,375 1.92 0.23 26 January 7.5 7,644 1.88 0.10 89 February 9 3,519 2 0.28 17 March 5.1 1,050 2.67 0.33 3 Total 8 27,899 1.88 0.05 382
Results from age assessments made at wintering sites in the UK indicate that the breeding success of Dark-bellied Brent Geese in 2018 was 7% higher than the previous year, although it remained below the previous ten-year mean (8.7% ± 2.45 SE). Mean brood size was also lower than the previous year and below the previous ten-year mean (2.1% ± 0.13 SE).
The results during 2018 follow a poor breeding performance in 2017 (1.0% young), a relatively poor breeding season in 2016 (8.6% young) a poor breeding year in 2015 (0.9% young).
At the time of writing, no data were available on the breeding success of Dark-bellied Brents wintering elsewhere along the flyway, so it is uncertain how representative the estimates from the UK are of the population as a whole.
Reports from monitoring stations in the breeding grounds in Arctic Russia (Soloviev & Tomkovich 2018) suggest that weather conditions were not ideal with snowfall in June and strong winds that adversely affected the nesting attempts of many species of bird. The breeding season was moderately late starting and monitoring stations reported that in some areas Dark-bellied Brent Geese did not attempt to nest at all. There is also some indication that early moult migrations were carried out by Dark-bellied Brent Geese, possibly suggesting an early finish and abandonment to the breeding season as moult got underway. Fox abundance was considered high; it is therefore likely that a mixture of predator pressure and weather conditions resulted in another relatively poor breeding season for Dark-bellied Brent Geese.
As always, our thanks go to the network of dedicated GSMP volunteers for their help with collecting age assessments.
Hall, C. 2008. The breeding success of Dark-bellied Brent Geese Branta bernicla bernicla in 2007, as assessed in the UK. Wildfowl & Wetlands Trust Report, Slimbridge. Download
Soloviev, M. & P.S. Tomkovich (Eds.) 2018. Arctic Birds: an international breeding conditions survey. Online database: http://www.arcticbirds.net/. Accessed 3 April 2019.
Previous annual results will be archived here. Annual age assessment reports for 1985-2007 inclusive can be found on the Reports & newsletter page.
Ebbinge, B.S., J. Blew, P. Clausen, K. Günther, C. Hall, C. Holt, K. Koffijberg, S. Le Dréan-Quénec’hdu, R. Mahéo & S. Pihl. 2013. Population development and breeding success of Dark-bellied Brent Geese Branta. b. bernicla from 1991-2011. Wildfowl Special Issue: 3: 74-98. Download
Ward, R.M. 2004. Dark-bellied Brent Goose Branta bernicla bernicla in Britain 1960/61 – 1999/2000. Waterbird Review Series, The Wildfowl & Wetlands Trust/Joint Nature Conservation Committee, Slimbridge. Download
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