Canadian Light-bellied Brent Goose
Branta bernicla hrota
The East Canadian High Arctic (ECHA) population of Light-bellied Brent Goose breeds in Canada and winters almost entirely in Ireland, with smaller numbers in Britain, the Channel Islands and the north coasts of France and Spain.
It undertakes one of the longest migrations of any Western Palearctic goose population, crossing the Greenland ice-cap, staging at sites in Greenland and Iceland before crossing the North Atlantic to Ireland.
Strangford Lough in Northern Ireland hosts over 75% of the population during the late autumn and is by far the most important site for this species outside the breeding season.
Global status (IUCN Red List of Threatened Species) Least Concern* African-Eurasian Waterbird Agreement (AEWA) A3a; International Single Species Action Plan 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
** assessed at race level Light-bellied Brent Goose Branta bernicla hrota
Flyway population size (CSR 8; Wetlands International 2021) 37,000 individuals UK estimate (APEP 4) 31,000 individuals GB estimate (Frost et al. 2019) 1,600 individuals All-Ireland estimate (Burke et al. 2018) 35,150 individuals UK trend (Frost et al. 2021) 25-year trend (1993/94-2018/19) = 85% increase
10-year trend (2008/09-2018/19) = 10% increase
The All-Ireland Light-bellied Brent Goose Census and the age assessments for this population are organised by the Irish Light-bellied Brent Goose Research Group.
Table 1. Annual estimates of the population size, percentage of young (%) and mean brood size (young per successful pair) of East Canadian High Arctic Light-bellied Brent Goose, 2003/04-2017/18; recorded during the All-Ireland Light-bellied Brent Goose Census.
Autumn Estimate of population size Percentage of young (%) Mean brood size 2017 35,042 0.8 2.05 2016 36,811 11.9 2.60 2015 37,192 12.0 2.16 2014 31,985 4.1 2.10 2013 34,734 0.04 0.83 2012 41,465 1.9 2.61 2011 48,002 25.0 2.69 2010 38,708 3.1 3.36 2009 39,399 0.7 2.00 2008 37,996 18.2 3.42 2007 38,993 25.1 3.28 2006 31,882 2.2 2.33 2005 32,088 13.2 3.22 2004 32,923 21.7 3.43 2003 28,714 17.9 2.30
Burke, B., L.J. Lewis, N. Fitzgerald, T. Frost, G.E. Austin & T.D. Tierney. 2018. Estimates of waterbird numbers wintering in Ireland, 20011/12-2015/16. Irish Birds 11: 1-12.
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.
Frost, T.M., N.A. Calbrade, G.A. Birtles, C. Hall, A.E. Robinson, S.R. Wotton, D.E. Balmer & G.E. Austin. 2021. Waterbirds in the UK 2019/20: The Wetland Bird Survey. BTO, RSPB and JNCC, in association with WWT. British Trust for Ornithology, Thetford.
Wetlands International. 2021. Waterbird population estimates. Retrieved from http://wpe.wetlands.org/ September 2021.
The East Canadian High Arctic population of Light-bellied Brent Goose breeds in the eastern Queen Elizabeth Islands from eastern Melville Island to Devon Island and northern Ellesmere Island. Almost all of these geese winter in Ireland, with much smaller numbers reaching the west coast of Britain, the Channel Islands, and the north coasts of France and Spain. It undertakes one of the longest migrations of any Western Palearctic goose population, crossing the Greenland ice-cap, staging at sites in Greenland and Iceland before crossing the North Atlantic to Ireland.
Flyway of the East Canadian High Arctic Light-bellied Brent Goose
Strangford Lough in Northern Ireland hosts over 75% of the population during the late autumn and is now by far the most important site. Lough Foyle, on the north coast, has also become increasingly important in recent years as a landfall site. As winter progresses, these geese disperse around the coast of Ireland, favouring sites in the northwest, east, southeast, southwest and west of the country with notably high numbers at Dublin Bay and Wexford Harbour and Slobs. Over 3,000 also disperse thinly along the rocky coastlines of Ireland in the late winter (Robinson et al. 2004).
It has been suggested that Light-bellied Brent Geese may have relied almost entirely on Zostera during the winter, before a wasting disease caused almost the entire depletion of Zostera in Ireland during the 1930s. Since then, the diet in estuarine and saltmarsh areas has become more cosmopolitan, including algal foods such as Enteromorpha and Ulva, and saltmarsh plants such as Festuca and Puccinella. Inland feeding was first recorded in Ireland and Iceland during the mid 1970s. Feeding on grasslands has increased steadily since then, especially in east and southeast Ireland, with 25% of the population spending a large proportion of its time foraging on managed grasslands. In a few areas, most notably Wexford Slobs, Dungarvan Harbour and Strangford Lough, Light-bellied Brent Geese feed on cereal crops, both waste in autumn stubbles and spring seed, and waste potatoes. Although these food types remain available in early spring, most birds return to the saltmarshes at this time to exploit fresh growth of more natural foods prior to spring migration (Robinson et al. 2004).
Robinson, J.A., K. Colhoun, G.A. Gudmundsson, D. Boertmann, O.J. Merne, M. O’Briain, A.A. Portig, K. Mackie & H. Boyd. 2004. Light-bellied Brent Goose Branta bernicla hrota (East Canadian High Arctic population) in Canada, Ireland, Iceland, France, Greenland, Scotland, Wales, England, the Channel Islands and Spain 1960/61 – 1999/2000. Waterbird Review Series, The Wildfowl & Wetlands Trust/Joint Nature Conservation Committee, Slimbridge.
All-Ireland Light Bellied Brent Goose Census
A complete census of the ECHA Light Bellied Brent Goose population is undertaken twice a year, one in autumn and one in spring. Counters record the number of geese present and the age structure of flocks. The census is organised by the Irish Brent Goose Research Group.
Results from the census are summarised on the ‘Latest results’ tab.
Find out more about the All-Ireland Light Bellied Brent Goose Census
Interim results for 2018-2020 [added September 2021]
The annual census of the East Atlantic High Arctic Light-bellied Goose population is organised by the Irish Brent Goose Research Group. Counts are undertaken in Iceland, Ireland, Britain and France.
This report presents the interim results in advance of official figures from the 2018–2020 censuses being compiled. The estimates of population size and breeding success for 2018–2020 presented below are derived from Strangford Lough counts only and are depicted graphically both as a proportion of the census totals for 1996–2017, as well as being used to predict population totals for 2018–2020.
Numbers of Light-bellied Geese wintering at Strangford lough have contributed between 55% and 83% (average 71.5% ± 1.55 SE) of the total count of the East Canadian High Arctic population since flyway counts began in 1996. Furthermore, weekly counts at Strangford Lough during 1996–2014 showed that in most years there was a lagged peak within a month of the census, with the total count at the site contributing up to 94% (average 79.7% ± 1.8 %) of the census total, as more geese continue to arrive and prior to further dispersal of the birds southwards.
As Strangford Lough numbers have such a bearing on the overall census totals they are used here – tentatively – to estimate population levels (see Figure 1). Although a simple linear model demonstrates that the Strangford Lough and census totals are highly correlated (R² = 0.87), the 95% prediction intervals are still relatively wide at ± 20%. Nevertheless, and until overall flyway figures can be compiled, the population estimates (extrapolated from the Strangford Lough counts) indicate continued stability over the last three years with five-year running means consistent at between 35,000 and 36,000: the extrapolated estimates being c. 37,000 for 2018, c. 30,000 for 2019 and c. 37,500 for 2020.
Figure 1. Annual census-derived estimates of the Canadian Light-bellied Brent Goose population size, 1961–2020 (solid circles; the predicted estimates using an extrapolation of the data from Strangford Loch are shown as open circles, and the open triangle represents a likely undercount in 2014 due to a lack of coverage in Iceland) and the total counts from Strangford Lough, 1996–2020 (solid squares). The five-year running means for the annual census-derived estimates (solid line) and the total counts from Strangford Lough (hashed line) are also presented (e.g. the mean for 2018 is for 2016–2020).
Samples of c. 10,000 Light-bellied Brent Geese were aged annually on Strangford Lough between 2018 and 2020 and the results show a continuation of the “boom and bust” years of recruitment, with 1.7%, 23.5% and 6.4% young recorded among flocks, respectively (Figure 2). A successful breeding year in 2019 has helped stabilise a downward trend in productivity from a peak ten-year running mean of 14% young in 2008 to a current mean of 8% young.
Brood size samples were predictably low in 2018 with mean of 2.1 ± 0.19 SE young per successful pair (for the 36 broods assessed), followed by 3.3 ± 0.10 SE in 2019 (204 broods) and 2.4 ± 0.12 SE in 2020 (140 broods). The breeding success in 2019 marked the end to a 40-year low in the ten-year mean which had dropped steadily from 2.95 (± 0.16 SE) in 2007/2008 to 2.25 (± 0.21 SE) by 2018.
Figure 2. The percentage of young (solid column = census, hashed column = Strangford Lough only) and mean brood size (red solid circles = census, open circles = Strangford Lough only) of East Canadian High Arctic Light-bellied Brent Geese, 1960/61 – 2020/21.
Following an all-time peak in 2011, the East Canadian High Arctic population of Light-bellied Brent Goose has still retained the gains made over the previous two decades and remains at a level equivalent to that believed to predate the eelgrass (Zostra), previously the primary food for the geese, depletion of the early 1930s. The reason for a lower than expected Strangford Lough goose tally in 2019 (and thus a notable drop in the extrapolated population estimate) considering the high level of recruitment that year, may be clarified at a later date when the rest of the flyway data have been compiled.
The frequency of successful breeding years remains a key dynamic to population resiliance with annual censusing, robust productivity estimates and the continuation of a long-term ring resightings program all providing invaluable flyway-level insights. Climatic conditions are highly variable across the population’s breeding range allowing some pockets of successful breeders to return with young even during poor years. However, as can be seen in the productivity chart above (Figure 2), there are regular years when very few young returned at all, either having been lost through regional weather events or through late springs and widespread ice preventing the onset of laying or incubation.
Research continues to probe into migration dynamics and into the “cost prohibitive” arctic breeding grounds, using remote sensing and telemetry, while endevouring to provide conservation direction on staging areas and more recently, the mid-winter urban haunts of down-town Dublin.
Many thanks to the Irish Brent Goose Research Group for providing this report.
Previous annual results will be archived here.
2016/17 Results (including 2015/16 results)
2012/13 Results (including 2011/12 results)
Colour-marking of this population began in 2001 and is overseen by the Irish Brent Goose Research Group. A large number of birds are currently colour-marked with engraved rings on each leg, and this underpins a range of detailed scientific studies also being carried out on this small, but increasing, population. Further details about this work can be found here.
Robinson, J.A., K. Colhoun, G.A. Gudmundsson, D. Boertmann, O.J. Merne, M. O’Briain, A.A. Portig, K. Mackie & H. Boyd. 2004. Light-bellied Brent Goose Branta bernicla hrota (East Canadian High Arctic population) in Canada, Ireland, Iceland, France, Greenland, Scotland, Wales, England, the Channel Islands and Spain 1960/61 – 1999/2000. Waterbird Review Series, The Wildfowl & Wetlands Trust/Joint Nature Conservation Committee, Slimbridge. Download
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