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74
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
Population development and breeding success
of Dark-bellied Brent Geese Branta b. bernicla
from 1991–2011
BARWOLT S. EBBINGE1, JAN BLEW2, PREBEN CLAUSEN3,
KLAUS GÜNTHER4, COLETTE HALL5, CHAS HOLT6,
KEES KOFFIJBERG7, SOPHIE LE DRÉAN-QUÉNEC’HDU8,
ROGER MAHÉO9& STEFAN PIHL3
1Team Animal Ecology, Alterra Wageningen-UR, P.O. Box 47, NL-6700 AA Wageningen,
the Netherlands.
2BioConsult SH GmbH & Co. KG, Schobüller Str. 36, D-25813 Husum, Germany.
3Department of Bioscience, Aarhus University, Grenåvej 14, DK-8410 Rønde, Denmark.
4Schutzstation Wattenmeer, Hafenstrasse 3, D-25813 Husum, Germany.
5Wildfowl & Wetlands Trust, Slimbridge, Gloucestershire GL2 7BT, United Kingdom.
6British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU,
United Kingdom.
7Sovon Vogelonderzoek Nederland, P.O. Box 6521, NL-6503 GA Nijmegen,
the Netherlands.
8Clinique vétérinaire, 10 rue de la Mézière, F-35520 Melesse, France.
9WI French coordinator, 34 rue de Brocéliande, F-56000 Vannes, France.
Abstract
The Dark-bellied Brent Goose Branta bernicla bernicla is the largest of the six Brent
Goose populations, which collectively number around 600,000 birds globally. After a
major decline to 16,500 geese in 1958, numbers recovered during the 1970s and
1980s to a peak of c. 330,000 individuals between 1992 and 1994. From 1994
onwards the population declined again to 200,000–250,000. This decline has been
attributed to poor breeding, associated with faltering cycles of Siberian Brown
Lemming Lemmus sibiricus (predominantly) and Palearctic Collared Lemming
Dicrostonyx torquatus abundance on the breeding grounds on the Taimyr Peninsula,
where lemmings are a main food resource for potential predators of goslings. Dark-
bellied Brent Geese only breed well in peak lemming years (Summers & Underhill
1991), and this usually occurs every three years, but the frequent failure since 1994 of
lemming numbers to peak (except in 2005) has resulted in the absence of very good
breeding years for the geese (Nolet et al. 2013). The mid-winter distribution has
shown a marked shift towards France over the last decade. France currently supports
50% of the population in January, Great Britain 35–40%, the Netherlands 15–20%,
Numbers of Dark-bellied Brent Geese 1991–2011 75
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
and Germany and Denmark 2%. In spring, almost the entire population gathers in
the Wadden Sea, leaving only 4% of the population in Great Britain, and virtually
none in France, with the Dutch part of the Wadden Sea supporting 40–45%, the
German section 45–50% and Denmark 6%.
Key words: breeding success, Dark-bellied Brent Goose, population development.
(IWCs) coordinated by Wetlands
International. Each country has a national
coordinator who communicates with
members of the national count network and
collates the count data. The area covered
includes the Atlantic coast of France, the
south and east coast of Great Britain, the
southwest Delta area in the Netherlands and
the Wadden Sea from the northern part of
the Netherlands, through Lower Saxony
(Germany), Schleswig-Holstein (Germany)
to Denmark. As Brent Geese also forage
inland on grassland and winter wheat near
the sea shore, such areas are also included in
the survey.
In addition to this mid-winter census, a
spring census in late April or early May is
carried out in most years covering the same
area, except for France, which holds hardly
any Dark-bellied Brent Geese (20–50 sick or
injured birds) at this time (R. Maheo & S. Le
Dréan-Quénec’hdu, in litt.). In the Wadden
Sea, this census forms part of the Trilateral
Assessment and Monitoring Programme
which is carried out simultaneously in
the Netherlands, Germany and Denmark
(Laursen et al. 2010). Results from the spring
censuses presented in this paper are for
1995 onwards, as before 1995 not all sites
were necessarily covered in Great Britain.
Both mid-winter and spring counts are
made from the ground, except for Denmark
where some sites in the Baltic archipelago
Salomonsen (1958) first attempted to
estimate the size of the Dark-bellied Goose
Branta bernicla bernicla and Light-bellied
Brent Goose Branta bernicla hrota
populations in Europe, following a dramatic
decline of both sub-species during the
1930s. Salomonsen’s review revealed that no
more than 16,500 Dark-bellied Brent were
left of this once common coastal goose in
1958, estimated at < 8% of the population
that wintered in Europe in the early decades
of the 20th century. He concluded “we
cannot ever expect to see such large flocks
again in Europe, but we can endeavour to
check the decline and let the population
grow to a reasonable height”.
However, the “unexpected” (Salomonsen
1958) recovery of this subspecies in the
1970s (Ogilvie & St. Joseph 1976; Prokosch
1984; Ebbinge 1985, 1991; Ebbinge et al.
1999; Ward 2004) resulted in well over
300,000 Dark-bellied Brent Geese being
recorded during the mid-winter census in
January 1992. In this paper we describe and
assess subsequent population trends over
the period 1991–2011.
Methods
Each January, Dark-bellied Brent Geese are
counted by experienced volunteer bird
counters at all important coastal sites in
western Europe, within the framework of
the International Waterbird Censuses
76 Numbers of Dark-bellied Brent Geese 1991–2011
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
and in the Wadden Sea are surveyed by
aircraft. To a minor extent the national
coordinators have used data imputing
techniques to allow for the few sites where
actual counts were missing (Soldaat et al.
2007). Population estimates were calculated
by summing the country totals resulting
from these counts, and rounding these to
the nearest thousand. Both mid-winter and
spring counts are carried out in the same
week, and there is very little movement of
Brent Geese at the time of these counts.
Mass migration from France and Britain to
the Wadden Sea takes place in March
(Ebbinge et al. 1999), so the risk of missing
birds or counting the same birds twice is
minimal in mid-winter and spring.
Breeding success for the preceding
summer is estimated annually by assessing
the proportion of first-winter birds in
wintering flocks, which can be distinguished
from adults by plumage characteristics.
These age ratio assessments are carried out
from October–February in the Netherlands,
Great Britain and France. In spring, moult
of the wing coverts makes it more difficult
to distinguish first-winter birds from adults.
Family groups, as opposed to failed or non-
breeding birds, usually arrive somewhat later
in Britain and France, because they linger
in the Wadden Sea in autumn, whereas
many adults without young fly straight to
the wintering areas in Britain and France
during October (Lambeck 1990). Thus the
proportion of first-winter birds tends to
increase in Britain and France from October
to January, and to decrease over the same
period in the northernmost part of the
wintering range – i.e. at the Wadden Sea in
the Netherlands (Lambeck 1990), Germany
and Denmark. This pattern is most obvious
in years when the proportion of young birds
is high, which has been linked to an
abundance of lemmings Lemmus sibiricus and
Dicrostonyx torquatus on the breeding
grounds, where lemmings are a main food
resource for potential predators of goslings
(Summers & Underhill 1991; Ebbinge et al.
1999; Nolet et al. 2013). Ideally, one should
only use age ratio assessments made
simultaneously across the wintering range in
January each winter, but as it was difficult to
coordinate such age counts, in this analysis
data from only the three main wintering
countries that were gathered between
October and January were used. To calculate
an overall estimate of the proportion of
young for the entire population we have
therefore used the figures for France, Britain
and the Netherlands and calculated
weighted means. The weighted mean was
calculated using a ratio of 2:2:1 for France,
Britain and the Netherlands, respectively,
roughly in proportion to the total number
of Dark-bellied Brent present in January
in each of these countries (see Nolet
et al. 2013). To detect a trend pair-wise
comparison of Dark-bellied Brent Goose
breeding success recorded in each decade
from the 1970s to the 2000s was made using
logistic regression analysis.
Results
Population estimates
Following two decades of spectacular
recovery, from the early 1970s through
to 1992, the number of Dark-bellied
Brent Geese peaked at 329,000 birds in
January 1992 (Figs. 1 and 2, Appendix 1).
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Subsequently the population declined, with
numbers fluctuating between 200,000–
250,000 birds from 1996 onwards. The only
exception was in January 2006 when the
population increased again to number
280,000 birds following a very good
breeding season in the peak lemming year of
2005 (Figs. 1 and 2).
Breeding success
Breeding success over the last two decades
varied from year to year in a less extreme
Figure 1. Population counts for Dark-bellied Brent Geese from 1960–2011.
Figure 2. Distribution of Dark-bellied Brent Geese over western Europe in January: France (F), Great
Britain (UK), the Netherlands (NL), Niedersachsen, Lower Saxony (NS), Schleswig-Holstein (SH) and
Denmark (DK). Count data for each country are provided in Appendix 1.
78 Numbers of Dark-bellied Brent Geese 1991–2011
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way than it had done in the previous two
decades (Fig. 3, Appendix 2). Before 1990,
between 40–50% of the winter flocks
consisted of first-winter birds following
successful breeding years, coinciding with
lemming peak years on the Taimyr Peninsula
(Fig. 3). At that time, a regular three-year
pattern was present, with many young every
third year when lemming numbers peaked,
e.g. in winters following the summers of
1982, 1985 and 1988 (Summers & Underhill
1991). The last peak followed the summer of
1991 (peak population count in January
1992), but thereafter the three-year pattern
has been less clear. During the last two
decades, even in the very best years (1991
and 2005), the population comprised only
30% of first-winter birds. Extremely poor
years with almost no young, which occurred
in the years after a lemming peak, have also
become less frequent since 2000 (Fig. 3).
A series of expeditions to Taimyr by
Alterra (a research institute of Wageningen
University) from 2002–2008 revealed just
Figure 3. Proportion of first-winter Dark-bellied Brent Geese in January. Annual values and fitted
logistic regression curve (Table 1). Lemming peak years (filled circles); years with no or few lemmings
(open circles).
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one real lemming peak year, in 2005, at
which time the whole tundra was teeming
with life (Nolet et al. 2013). Snowy Owls
Nyctea scandiaca were nesting surrounded by
nesting Brent Geese. Waders were nesting in
much higher densities. Extremely high
densities of Pomarine Skuas Stercorarius
pomarinus made it difficult for Arctic Foxes
Vulpes lagopus to roam freely over the tundra.
Also Snowy Owls that tried to take goslings
just as Brent families were leaving the
nesting sites were so heavily attacked by
Pomarine Skuas that most goslings safely
reached the nursery grounds. To the benefit
of waders and geese, all predators more or
less restricted one another in capturing non-
lemming prey. Even Brent Geese nesting in
gull (notably Taimyr Gull Larus taimyrensis)
colonies were more successful, because
lemmings were also available as alternative
food for the gulls, which reduced the rate of
goose egg predation by gulls.
A weighted average of productivity
recorded for the three main wintering
countries – France, Great Britain and the
Netherlands – was calculated to represent
overall breeding success for the entire
population (Appendix 2). Because the
difference between countries is much smaller
than the difference between years, taking a
straightforward average would have yielded
virtually the same values. Mean values for
breeding success for the four decades
(1969–1979, 1980–1989, 1990–1999, and
2000–2011) were 27.3% juveniles in the
population for the 1970s, 13.6% for the
1980s, 14.1% for the 1990s and 11.7% for the
first decade of the 21st century. Pair-wise
comparison by logistic regression shows that
only the values for the 1970s and the first
decade of the 21st century differed
significantly (P= 0.041) (Table 1). The boom-
and bust-years, characteristic of Dark-bellied
Brent Goose breeding success (Fig. 3) makes
it hard to demonstrate a significant change in
breeding success over time. The difference
found between the 1970s and the first decade
of the 21st century is mainly attributable to
lemming peak years (black dots) becoming
rarer in recent years (Nolet et al. 2013).
Table 1. Pair-wise comparison of Dark-bellied Brent Goose breeding success recorded in
each decade from the 1970s to the 2000s. Results show pair-wise Pvalues from logistic
regression analyses, comparing the percentage of juveniles recorded each winter across the
decades. Breeding success in the 1970s differed significantly (was higher) than in the 2000s
(bold font); all other comparisons were not significant.
Decade 1970s 1980s 1990s 2000s
1970s *
1980s 0.091 *
1990s 0.943 0.943 *
2000s 0.041 0.753 0.698 *
80 Numbers of Dark-bellied Brent Geese 1991–2011
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Mid-winter distribution
In mid-winter, 80% of the population
winters in France and Great Britain, both
countries where peak numbers occur in
mid-winter, and from which many Dark-
bellied Brent Geese depart in March. Some
18% of the population winters in the
Netherlands where, particularly in the
Wadden Sea, numbers peak in spring. The
southwest part of the Netherlands, known
as the Delta area, is similar to France and
Great Britain in having peak numbers in
mid-winter.
Only a small proportion of the
population, about 2%, winters in northern
Germany (Lower Saxony and Schleswig-
Holstein) and in Denmark, mainly in the
Wadden Sea region. These two countries
support much higher numbers in autumn
and particularly in spring.
When the mid-winter distribution over
the five countries is expressed as a
percentage of the entire population, it is
evident that there has been a shift in
distribution from Great Britain towards
France during the last decade, with France
receiving more than half of the Dark-
bellied Brent Goose population in recent
years (Fig. 5). Of particular note is the
decline of 9% in the number of Brent
Geese wintering in Great Britain from
January 2005 to January 2006 (Table 2);
following the very good breeding season in
2005, total numbers might have been
expected to increase as they did in France,
the Netherlands and Lower Saxony where
numbers rose by 40–50%. Only in the
northernmost parts of the Brent Goose’s
wintering area was there also no increase
(in Schleswig-Holstein) or a similarly
marked decrease (Denmark) in mid-winter
Figure 4. Proportional distribution over the five countries of Dark-bellied Brent Geese in January:
France (F), Great Britain (UK), the Netherlands (NL), Niedersachsen, Lower Saxony (NS), Schleswig-
Holstein (SH) and Denmark (DK).
Numbers of Dark-bellied Brent Geese 1991–2011 81
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
in a year with a high proportion of juveniles
in the wintering flocks. The first major shift
to France (+43%) occurred in January 2002,
coinciding with a decline in numbers in both
Great Britain (–25%) and the Netherlands
(–11%). In that winter there were about
10% young, and given an annual mortality of
15% (Ebbinge et al. 2002), no major change
in overall population size would have been
expected.
Spring distribution
In late February and particularly in March
Dark-bellied Brent Geese shift from their
southern winter quarters to stage in the
Wadden Sea, where they remain until the
end of May (Ebbinge et al. 1999; Fig. 5).
The spring counts (Appendix 3) yielded
on average 85% of the total number
counted in mid-winter. Since annual
mortality is 15% (Ebbinge 1992; Ebbinge et
al. 2002), and it is very unlikely that all
mortality takes place only in the short time
span between January and early May, the
difference between January and May cannot
be explained solely by mortality. A survival
analysis for Light-bellied Brent Geese Branta
bernicla hrota staging in spring in Denmark
also shows that mortality is very low in that
period (Clausen et al. 2001). The difference
is more likely the result of some birds that
are missed during the spring counts. In
some years, flocks of Dark-bellied Brent
Geese remain at sea in the western part of
the Dutch Wadden Sea even during high tide
and are then missed (C. Swennen, pers.
comm.). Additionally, birds staging in the
Baltic (Germany and Denmark) are not
always well covered, but in years when the
Baltic islands of Denmark were monitored
Figure 5. Distribution over the five countries of Dark-bellied Brent Geese in spring (late April/early
May): France (F), Great Britain (UK), the Netherlands (NL), Niedersachsen, Lower Saxony (NS),
Schleswig-Holstein (SH) and Denmark (DK).
82 Numbers of Dark-bellied Brent Geese 1991–2011
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
more effectively by aerial surveys, usually
c. 5,000 and never > 10,000 Dark-bellied
Brent Geese were counted there during the
period when the total population exceeded
300,000 individuals. Moreover there could
also be some birds staging then in France,
though these numbers are very small.
In late April–early May, 6% of the
population were recorded in Denmark,
39% in Schleswig-Holstein, 8% in
Niedersachsen, 43% in the Netherlands
(mainly in the Wadden Sea, but also in the
Delta area), and 4% in Great Britain, with
almost all of the Dark-bellied Brent Geese
wintering in France having departed by then
(Fig. 5).
Discussion
Density dependence or climate change
It is tempting to explain the overall decrease
in numbers since 1992 as an effect of
density-dependence on Brent Goose
survival and breeding success, but Summers
and Underhill (1991) failed to detect any
significant density-dependent effect in
breeding success in their analysis. A more
recent analysis by Nolet et al. (2013),
covering a longer time series, indicates that
faltering lemming cycles resulting in a
marked reduction in overall breeding
success is the most likely explanation for the
observed decline. The reason why lemmings
have failed to reach the previous high peak
levels during the last two decades (except in
2005) is thought to be related to changes in
winter climate, which have resulted in short
periods of snow-melt or even rain in late
spring followed by re-freezing. Such
conditions can cause lemming tunnels to
collapse or to fill with water under the
protective snow cover, which then becomes
solid with ice, all highly detrimental to
lemming overwinter survival (Kausrud et al.
2008; Nolet et al. 2013).
Nolet et al. (2013) also found a significant,
Table 2. Number of Dark-bellied Brent Geese recorded during the January censuses (i.e. total
population size estimates), before and after the peak lemming year of 2005.
Country No. geese No. geese % change % young
counted in counted in in total birds
2005 2006 numbers
France 104,301 147,708 +42% 24%
Great Britain 85,664 78,194 –9% 28%
Netherlands 32,946 49,753 +51% 42%
Lower Saxony, Germany 1,870 2,713 +45% ?
Schleswig-Holstein, Germany 703 720 +2% ?
Denmark 1,774 1,387 –22% ?
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©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
albeit weak, effect of density-dependence. If
lemmings had continued to the cyclical
abundance patterns evident in the 1970s and
1980s, the models developed by Nolet et al.
(2013) indicated that there would have been
a further increase in population size to
450,000 geese.
Shift in mid-winter distribution
A southward shift in the mid-winter
distribution of Dark-bellied Brent Geese in
the early 21st century, mainly from Great
Britain to France, differs from observations
made for many other migratory waterbird
species which found that the birds
tend to winter further north, closer to the
breeding grounds, due to the milder
weather associated with climate change (e.g.
Lehikoinen et al. 2013). The changes
recorded for the geese could be caused by
Brent Geese preferring to feed on eelgrass
Zostera sp. in autumn and winter, a plant
species that is more abundant along the
French coast. Even as far south as Morocco,
small numbers of up to 30 Dark-bellied
Brent Geese have been reported feeding on
Dwarf Eelgrass Zostera noltii in Kniffiss
Lagoon (Radi et al. 2009; Imad Cherkaoui,
pers. comm.)
Another striking aspect is the effect of
cold winters on the proportion staging in
the Netherlands. The cold spells in January
in 1997, and in 2009–2011 inclusive, are
reflected in a reduced proportion of Dark-
bellied Brent Geese wintering in the
Netherlands, resulting in a higher
proportion of birds either in Great Britain
or in France. In 1997 an increase was
noticeable in both Great Britain and France,
whereas in 2009 and 2011 there was an
increase in France, but not in Great Britain,
and in 2010 the reverse happened and
numbers increased in Great Britain but not
in France.
The marked decline between January
2005 and January 2006 in the proportion of
the Brent Geese population recorded in
Great Britain in mid-winter (Table 2) is of
note, as it follows the very good breeding
season in 2005. The similar lack of an
increase in the more northern parts of the
Brent Goose’s wintering area (in Schleswig-
Holstein and in Denmark) in a year with
many young is in line with Lambeck’s (1990)
conclusion that families winter further south
than non- or failed breeders. It is unlikely
that large numbers would have been
overlooked in Great Britain during the
January 2006 census, and later in the same
winter, numbers in Great Britain did
increase from 78,200 in January to reach a
peak of 84,700 in February, but even that
peak number was 1% lower than the peak
number in January 2005. If the low mid-
winter numbers in Great Britain in 2006 was
due to birds remaining longer in the
Netherlands, then one would also have
expected to see lower numbers in France.
The overall population increase was
reflected in the spring counts for Great
Britain, however, which increased by 30%
between 2005 and 2006.
The unexpectedly low number in Great
Britain in January 2006 could perhaps be a
result of scaring, which may have driven
Brent Geese from Great Britain to both the
Netherlands and France. In the autumn of
2005, 86 licences to shoot Brent Geese in
order to prevent crop damage were issued in
Great Britain, and 833 Brent Geese were
84 Numbers of Dark-bellied Brent Geese 1991–2011
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
reported shot under these licences. In the
previous year the number of licences issued
was similar (88), but then 527 birds were
reported shot (D. Stroud, pers. comm.).
Great Britain is the only country issuing
such licences in western Europe in order to
protect crops of winter wheat from serious
damage. It is known that particularly in years
with many young, Dark-bellied Brent Geese
move much earlier in the season inland from
their coastal habitat to feed on farmland
(Ebbinge et al. 1999). Because scaring takes
place only on farmland, the impact of
scaring activities on the geese may be much
greater in a year with many young. A
thorough analysis of the effects of British
scaring activities is required, however, to
determine whether this hypothesis is
correct.
Comparison with other Brent Goose
populations
It is interesting to compare the change in
abundance of the Dark-bellied Brent Goose
population with those of the other five
Brent Goose populations in the world.
During the 15th Conference of the
Wetlands International/IUCN-Species
Survival Commission Goose Specialist
Group, held in Arcachon, France, in January
2013 latest information on all Brent Goose
populations was compiled (Fig. 6), and it
became evident that following its
remarkable recovery during the 1970s, the
Figure 6. Trends in population size on a log scale from 1960–2012 of all six Brent/Brant populations
world-wide, Pac = population of Pacific Black Brant Branta b. nigricans including small numbers that
winter in East Asia that winters on the West Coast of North America, WHA = population of Western
High Arctic Brant, also known as Gray-bellied Brant an admixture population resulting of interbreeding
of Branta b. hrota and Branta b. nigricans that winters on the West Coast of North America,
Atl= population of Atlantic Brant Branta b. hrota, that winters on the East Coast of North America,
EHA= population of Eastern High Arctic Brent Branta b. hrota, that winters mainly in Ireland,
Dbel = population of Dark-bellied Brent Geese Branta b. bernicla, that winters in western Europe, and
EA = population of East Atlantic Light-bellied Brent Branta b. hrota, that breeds on Svalbard and
NE-Greenland and winters in Denmark and NE-Britain.
Numbers of Dark-bellied Brent Geese 1991–2011 85
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Dark-bellied Brent Goose population is
now the most numerous population of all.
Altogether there are currently about
600,000 Brent Geese globally, divided
between six different populations. The
second and third largest are two of North
America’s populations, namely the Pacific
Black Brant (including the small numbers
wintering in East Asia), and the Atlantic
Light-bellied Brant (Fig. 6). The two large
North American populations are still hunted
and have been quite stable in numbers over
the last fifty years. Only the Atlantic Light-
bellied Brant has shown two major crashes
in numbers, but quickly recovered following
a temporary hunting ban. The numbers in
Fig. 6 are plotted on a log scale, so the rate
of increase is directly comparable for each
population. The exceptional high rate of
increase of the Dark-bellied Brent Goose in
the 1970s is matched only by that of the
Atlantic Light-bellied Brant, when hunting
was banned to allow this population to
recover after major crashes due to hard
winters and over-hunting. The Dark-bellied
Brent Goose has been fully protected over
almost its entire range since Schleswig-
Holstein finally introduced legislation to
protect this sub-species in 1976. Prior to
this, the population had been protected
from hunting in the Netherlands since 1950,
in Great Britain since 1954, in France since
1966, and in Denmark since 1972. Only in
Russia is there still some hunting of these
birds both in autumn and in spring.
The other three populations are much less
numerous. The western High Arctic Light-
bellied Brant (also known as Grey-bellied
Brant, considered to be the result of inter-
breeding by Branta b. nigricans and Branta b.
hrota) winters along the west coast of North
America, where it is hunted to a moderate
extent. The remaining two populations, both
of the race Branta b. hrota, are the Eastern
High Arctic Light-bellied Brent, which
winters in Ireland, and the East Atlantic
Light-bellied Brent Goose population which
winters in Denmark and Great Britain. Both
are protected from hunting. Of these three
Grey- and Light-bellied Brent Goose
populations, the Eastern High Arctic Light-
bellied Brent in particular has increased
rapidly in numbers over the last decade.
Acknowledgements
We would like to thank all bird counters and
those assessing age ratio estimates in western
Europe for their time and willingness to
collect this important information. For the
information about other Brent Goose
populations presented in Fig. 6 we would like
to thank David Ward, Kathy Dickson, Kevin
Clausen, and Kerry Mackie. We also thank
David Stroud for providing information on
shooting of Brent Geese under licence in
order to prevent serious crop damage in
Great Britain.
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Numbers of Dark-bellied Brent Geese 1991–2011 87
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Appendix 1. Mid-winter counts of Dark-bellied Brent Geese from 1991–2011 inclusive.
F = France, UK = Great Britain, NL = the Netherlands, NS = Niedersachsen, Lower Saxony,
Germany, SH = Schleswig-Holstein, Germany, and DK = Denmark.
Year F UK NL NS SH DK Total
1991 85,000 96,201 64,564 2,651 2,684 2,789 254,000
1992 115,229 137,943 70,224 2,341 1,562 2,047 329,000
1993 103,121 92,146 65,644 1,446 1,373 4,402 268,000
1994 108,416 125,304 79,379 2,747 3,864 2,470 322,000
1995 102,336 91,946 53,609 2,064 1,086 2,914 254,000
1996 91,422 87,252 38,227 1,431 475 476 219,000
1997 99,563 92,368 23,173 1,446 316 235 217,000
1998 97,870 96,482 44,862 2,415 813 1,876 244,000
1999 87,019 74,510 33,987 2,229 555 1,639 200,000
2000 97,000 87,668 47,044 5,989 1,050 1,662 240,000
2001 81,000 93,713 39,739 2,543 978 1,083 219,000
2002 115,621 70,745 35,820 1,928 383 1,239 226,000
2003 95,146 68,874 30,352 1,990 288 84 198,000
2004 90,485 64,453 35,197 2,088 682 479 193,000
2005 104,301 85,664 32,946 1,870 703 1,774 227,000
2006 147,708 78,194 49,753 2,713 720 1,387 280,000
2007 87,156 77,379 43,515 3,210 1,734 6,951 220,000
2008 118,223 83,135 40,921 2,377 716 1,275 247,000
2009 134,016 69,294 31,230 1,823 593 1,780 239,000
2010 102,840 78,944 28,982 998 1,179 828 214,000
2011 116,275 69,747 22,637 1,272 359 370 211,000
88 Numbers of Dark-bellied Brent Geese 1991–2011
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
Appendix 2. Age ratio assessments of Dark-bellied Brent Geese in France (F), Great Britain
(UK) and the Netherlands (NL), expressed as the percentage of first-winter birds recorded
in the wintering flocks.
Winter F UK NL Weighted mean
1990/91 34.0 21.4 21.1 26.4
1991/92 31.2 31.1 30.0 30.9
1992/93 0.1 0.0 0.1 0.1
1993/94 33.0 18.0 25.6 25.5
1994/95 5.8 5.8 8.6 6.4
1995/96 0.5 0.3 0.9 0.5
1996/97 15.4 8.3 20.8 13.6
1997/98 11.8 9.0 12.7 10.9
1998/99 1.3 0.9 0.9 1.1
1999/00 27.7 23.6 23.2 25.2
2000/01 0.5 0.6 5.7 1.6
2001/02 10.4 6.2 14.5 9.5
2002/03 9.3 6.8 9.6 8.4
2003/04 9.7 10.0 18.1 11.5
2004/05 13.8 11.9 21.3 14.5
2005/06 23.6 28.4 42.0 29.2
2006/07 2.2 2.0 3.0 2.3
2007/08 10.7 11.0 16.5 12.0
2008/09 0.9 1.1 2.3 1.3
2009/10 6.2 5.3 11.9 7.0
2010/11 12.2 12.7 17.8 13.5
2011/12 21.4 16.2 23.6 19.8
Numbers of Dark-bellied Brent Geese 1991–2011 89
©Wildfowl & Wetlands Trust Wildfowl (2013) Special Issue 3: 74–89
Appendix 3. Spring counts of Dark-bellied Brent Geese in France (F), Great Britain (UK),
the Netherlands (NL), Niedersachsen, Lower Saxony (NS), Germany, Schleswig-Holstein
(SH), Germany and Denmark (DK)
Year F UK NL NS SH DK Total
1995 – 588 116,443 16,701 105,048 19,190 258,000
1996 – 7,993 81,310 15,731 84,487 3,291 193,000
1997 – 2,016 92,435 17,550 82,720 6,985 202,000
1998 – 13,045 63,055 15,615 86,416 11,686 190,000
1999 – 9,563 60,730 11,628 77,237 11,339 170,000
2000 – 10,234 83,301 7,641 84,287 9,030 194,000
2001 – 1,100 72,336 10,000 70,639 10,000 164,000
2002 – 486 79,108 19,072 54,471 No data >153,000
2003 – 5,903 76,988 19,260 61,406 14,251 178,000
2004 – 7,636 79,110 17,219 59,642 13,244 177,000
2005 – 9,532 69,854 21,061 67,599 8,454 177,000
2006 – 12,495 104,373 27,689 74,568 18,595 238,000
2007 – 5,335 105,000 19,330 61,098 10,657 201,000
2008 – 5,330 106,973 24,673 77,494 17,163 232,000
2009 – 5,136 81,000 16,460 54,883 12,295 170,000
2010 – 8,185 78,000 11,729 58,048 13,909 170,000
2011 – 4,688 80,713 10,251 66,577 19,445 182,000
