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 Thames Estuary, The Wash and Chichester Harbour.
Global status (IUCN Red List of Threatened Species) Least Concern*† African-Eurasian Waterbird Agreement (AEWA) B2b European status (European Red List of Birds) Least Concern (Europe and EU27)* The Birds Directive (European Commission) Annex II (Part B) UK status (Birds of Conservation Concern) Amber UK quarry species (Wildlife & Countryside Act 1981) not huntable * assessed at species level Brent Goose Branta Bernicla † 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) 211,000 individuals UK estimate (APEP 4) 98,500 individuals GB estimate (Frost et al. 2019) 98,000 individuals UK trend (Frost et al. 2020) 25-year trend (1992/93-2017/18) = 23% decrease
10-year trend (2007/08-2017/18) = 5% increase
Table 1. 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 2019/20 13.1 2.26 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.M., N.A. Calbrade, G.A. Birtles, H.J. Mellan, C. Hall, A.E. Robinson,S.R. Wotton, D.E. Balmer & G.E. Austin. 2020. Waterbirds in the UK 2018/19: The Wetland Bird Survey. BTO, RSPB and JNCC, in association with WWT. British Trust for Ornithology, Thetford.
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.
Dark-bellied Brent Goose data for Britain presented in Table 1 (Percentage of young/Mean brood size) are licensed under the Open Government Licence 3.0 except where otherwise stated.
When you use information from this report under the Open Government Licence you must include the following attribution:
Contains Goose & Swan Monitoring Programme (GSMP) data from “WWT. 2020. Goose & Swan Monitoring Programme: survey results for Dark-bellied Brent Goose Branta bernicla bernicla. WWT/JNCC/NatureScot, Slimbridge” retrieved from https://monitoring.wwt.org.uk/our-work/goose-swan-monitoring-programme/species-accounts/dark-bellied-brent-goose/ © copyright and database right 2020. The GSMP is organised by the Wildfowl & Wetlands Trust (WWT) in partnership with the Joint Nature Conservation Committee (JNCC) and NatureScot with fieldwork conducted by volunteers.
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 2019/20 [October 2020]
The winter of 2019/20 marked the 35th consecutive winter that experienced volunteer observers assessed the breeding performance of Dark-bellied Brent Geese (for methods see Hall 2008).
Geese were aged at 46 sites within ten estuaries or coastal sites along the south and east coasts of England from the Humber Estuary in Yorkshire to the Exe Estuary in Devon (Figure 1 & Table 1). Data were collected between 22 September 2019 and 4 March 2020.
Of the 58 flocks assessed, only one was aged in September (1.7%), 13.8% were aged in October, the majority were aged in November (29.3%), followed by a gradual decrease as the winter progressed: 22.4% in December, 15.5% in January, 12.1% in February and 5.2% in March.
A total of 18,738 geese were aged, a notable decrease on the previous year when 27,899 were aged. The largest samples came from the Blackwater Estuary (4,258 birds aged), North Lincolnshire Coast (4,001), North Norfolk Coast (3,371) and the Crouch Estuary (2,933) (Table 1). At all other sites, fewer than 1,100 birds were aged. Mean brood size data was collected at four of the estuaries/coastal areas
The overall percentage of young was 13.1% and, of the 160 broods recorded, the mean brood size was 2.26 (± 0.10 SE) young per successful pair (Table 1 & Figure 2).
The percentage of young throughout the winter peaked at 26.0% in October and ranged between 6.0% and 17.0% during the other months (Table 2). The very small sample assessed in September did not include any young birds. The mean brood size of successful pairs peaked at 3.43 (± 0.43 SE) in October and ranged between 1.98 (± 0.13 SE) and 2.77 (± 0.41) during other months.
Figure 1. Estuaries / coastal sites in the UK at which Dark-bellied Brent Geese were aged during winter 2019/20. See Table 1 for a key to the estuaries / coastal sites.
Table 1. Numbers of Dark-bellied Brent Geese aged at UK estuaries and coastal areas in winter 2019/20
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 Estuary 22/09/2019 22/12/2019 7 2 648 15.3 — — — 2 Langstone Harbour 19/12/2019 19/12/2019 3 3 1,097 5.9 — — — 3 Chichester Harbour 19/12/2019 07/02/2019 4 4 1,079 17.5 2.40 0.28 27 4 Thames Estuary 04/10/2019 19/10/2019 2 2 637 31.4 — — — 5 Crouch Estuary 30/11/2019 11/01/2019 4 2 2,933 21.0 — — — 6 Blackwater Estuary 01/11/2019 17/12/2019 5 4 4,258 12.2 — — — 7 Hamford Water 04/11/2019 12/02/2020 5 5 264 27.3 3.33 0.80 6 8 North Norfolk Coast 30/10/2019 03/02/2020 14 10 3,371 11.2 2.75 0.19 75 9 North Lincolnshire Coast 12/10/2019 14/02/2020 13 13 4,001 7.2 1.77 0.19 52 10 Humber Estuary 04/03/2020 04/03/2020 1 1 450 5.3 — — — Total 22/09/2019 04/03/2020 58 46 18,738 13.1 2.26 0.10 160
Figure 2. The percentage of young (blue columns) and mean brood size (red circles) of Dark-bellied Brent Geese recorded in the UK, 1985/86–2019/20. No brood size data were collected in 1985/86 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 2019/20.
Month Percentage young Mean brood size % Number of flocks Number aged Mean SE Number of broods September 0 1 10 – – – October 26.0 8 1,004 3.43 0.43 7 November 11.3 17 5,784 1.98 0.13 83 December 11.5 13 6,450 2.62 0.35 13 January 17.0 9 3,515 2.42 0.23 36 February 11.6 7 1,370 2.77 0.41 13 March 6.0 3 605 2.00 0.42 8 Overall 13.1 58 18,738 2.26 0.1 160
Results from age assessments made at wintering sites in the UK suggest 2019 was the most successful breeding year for Dark-bellied Brent Geese wintering in the UK since 2014/15. In 2019, the percentage of young recorded in flocks was higher than the previous year (8.0% in 2018) and the previous ten-year mean (2009/10–2018/19; 9.4% ± 2.30 SE). The mean brood size was also higher than in 2018 (1.88) and the previous ten-year mean (2.1% ± 0.13 SE). This compares with 2014/15 when 23.0% young was recorded, with the percentage of young in 2015/16 to 2018/19 ranging between 0.9% and 8.6%.
At the time of writing, no data were available on the breeding success of Dark-bellied Brent Geese 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 2019) suggests that the breeding season was generally average, although one monitoring station did indicate that they had recorded a significantly high abundance of geese. The abundance of rodents and arctic foxes and other predators varied between monitoring stations, from low to high. All in all, the conditions were favourable for breeding geese in 2019.
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.) 2019. Arctic Birds: an international breeding conditions survey. Online database: http://www.arcticbirds.net/. Accessed 14 July 2020.
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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