Common Gull Larus canus
Status; International importance;
Population estimates; Distribution; Annual abundance/
productivity; Phenology/diet/survival
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Description

The following has been adapted from original text by
Mark L. Tasker in
Seabird Populations of Britain and Ireland (with
permission from A&C Black, London).
The common gull breeds across the Palaearctic and
in North America. They breed on coasts and at inland sites, and
spend the winter inland, on estuaries and at sea. Terrestrial foods
include earthworms, beetles and other insects, while discarded
fishery wastes supplements natural food at sea. In the UK their
breeding distribution is virtually confined to Scotland and
Northern Ireland. It is a colonial breeder, but will also nest
solitarily. During Seabird 2000, over half of the total
population in the UK was breeding inland. Despite the inland bias
in the distribution, this was the first time that all
inland-breeding mew gulls had been censused. There is no
reason to suggest that the coastal and inland
nesting populations are in anyway separate. Therefore, it is
essential that inland colonies are surveyed as thoroughly as those
on the coast if an accurate assessment of the current status of the
species is to be made.
Conservation status
Common gull is currently identified as a conservation priority
in the following:
EC Birds Directive -
migratory species
Amber listed in Birds
of Conservation Concern 4 (2015 update)
(further information on Conservation Designations for UK Taxa)
Amber listed in
Birds of Conservation Concern in Ireland 2014-2019 (2014
update)
International importance
*AON = Apparently Occupied Nests
The UK population figure (rounded to the nearest hundred) was
derived from data in Mitchell, P.I., Newton, S.F., Ratcliffe, N. and Dunn, T.E.
(eds.) 2004. Seabird Populations of Britain and Ireland. Poyser, London. This was also the
source of figures for the Biogeographic and World populations.
Note: The UK population figure above includes data from both
inland and coastal colonies hence differs from that tabled
below.
UK population estimates and change 1969-2002 (census
data)
Only coastal-nesting common gulls were counted fully during both
Operation Seafarer (1969-70) and the SCR Census (1985-88), so
comparison between Seabird 2000 population estimates and the
previous censuses are based only on coastal colonies. During the
SCR Census (1985-88) the total inland population was estimated to
be 60,000 pairs. This was based largely on the fact that in 1988-89
some 40,000 pairs were nesting at just a few colonies in the
Mortlach Hills (Moray) and Correen Hills
(Gordon). Common gulls nest in many inland areas of
Scotland and in more remote areas of England and Northern Ireland.
Given the relatively small number of observers involved, coverage
of such areas during Seabird 2000 is difficult to assess but it is
likely that all areas were covered at least once during the period
of the census. If, however, the species is mobile between sites
within this count period, some breeding sites could have been
missed and other groups of birds double-counted. There has never
been a census of this species over one year that would enable this
possibility to be assessed.
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
UK Population estimate (AON*)
Inland
Total
|
12,295 |
15,357 |
20,883
27,831
48,714
|
% change since previous census |
N/a |
+25 |
+36 |
*AON = Apparently Occupied Nests
Note: Inland colonies were not counted during the first
two national censuses, so, to enable direct comparison,
the percentage change refers to coastal colonies
only.
For census results for individual countries and Ireland, the
Channel Islands and the Isle of Man see under relevant
sections below.
Distribution/abundance
The Seabird
2000 census provides the most comprehensive recent
assessment of the distribution and abundance of breeding seabirds.
Numbers of mew gull found in different regions, and a map
showing the locations and size of colonies, is provided in the
Seabird 2000 common
gull results page (PDF, 1.1 mb).
An
interactive map is available on the NBN Gateway, where you can
filter to display only the Seabird 2000 data. For more
recent, but less comprehensive, coverage view the distribution on
the NBN with all available contributing datasets.
The locations sampled during the annual
Seabird Monitoring Programme provide some information on
distribution and are accessible via the Seabird Monitoring Programme
online database.
Annual abundance and productivity by geographical area
With reference to the regional
accounts below please note the following.
Breeding abundance:
graphs of abundance index with 95% CLs are only shown for a region
where the trend produced has been deemed accurate (see
methods of analysis). Where a trend was thought to be
inaccurate, graphs of abundance at major colonies in a
region may be shown instead, particularly if such colonies
hold greater than 10% of the regional population,
are monitored frequently and may thus help illustrate regional
population fluctuations outwith national censuses.
Occasionally, too few data have been collected regionally to
produce either of these.
Productivity: graphs
of productivity are only shown if analysis of breeding
success data produced a significant result for regional and/or
year effects (again see
methods of analysis). If results were not significant,
then a regional mean productivity value is given.
However, on some occasions too few data are
available from which to provide a meaningful average.
Furthermore, for 11 species where the quality of monitoring data
available was considered high, population viability analysis
was undertaken at the UK level and the results of this are
also reported.
Breeding abundance
The annual sample of common gull colonies is insufficient
to produce reliable trend information for the UK as a
whole. Note that the only comparable data from national
censuses relate to coastal-nesting common gulls. Coastal nesting
birds increased by 24% between 1969-70 and 1985-88, with
another increase of 36% up to Seabird 2000. The reason for
the increase in abundance of coastal nesters is not known; it is
possible that it may have been an artefact due to less complete
survey coverage during the earlier censuses. With Scotland holding
about 98% of the UK population, the trend there can be used as a
proxy for the UK situation post Seabird 2000, and suggests that
numbers have declined since the last census. American
mink Neovison vison are known to have severe negative
effects at a local level, taking both eggs, chicks and adults, and
causing colony abandonment1,2, but it is
unknown whether this is the main reason for the
apparent decline nationally.
During Seabird 2000 over half (57%) of the total population in
Britain and Ireland bred inland. Due to colonies being surveyed
infrequently no trend can be generated from data submitted to
the SMP. However, some large inland common gull colonies
in Scotland are known to have declined severely, although the
reasons are unknown.
Productivity

Figure 1: Trend in
UK productivity (no. of chicks fledged per pair)
of common gull 1986-2015. Based on SMP data; view
the methods
of analysis (PDF 158 kb).
The sample of colonies for
which productivity was studied may not be representative of
the UK. Most information comes from a study of the effects of
American mink control on productivity of gulls and terns in western
Scotland2, which shows
significant negative effects of mink, although results in some
years may be partially clouded by predation of common gull eggs by
larger gulls. Common gull breeding success data collected from this
study area between 1996 and 2013 found colonies with
successful mink control fledged an average of 0.71 chicks per pair
per year, compared to 0.30 at colonies with no, or
unsuccessful, mink control; on average breeding success was
57% (range 27-77%) lower at colonies in the latter group. In 2014,
success at these two groups of colonies was 0.68
and 0.19 chicks fledged per pair, respectively - a difference
of 72%3.
Population estimates and change 1969-2002 (census data)
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
Population estimate (AON*)
Inland
Total
|
12,229 |
15,134 |
20,467
27,646
48,113
|
% change since previous
census |
N/a |
+24 |
+35 |
* AON = Apparently Occupied Nests
Note: Inland colonies were not counted during
the first two national censuses, so, to enable direct
comparison, the percentage change refers to coastal
colonies only.
Breeding Abundance

Figure 1: Trend in abundance index
(solid line) of coastal-nesting common gulls in Scotland,
1986-2015 with 95% confidence limits (dotted lines). Based
on SMP data; view the methods
of analysis (PDF 158 kb).
Coastal nesting common gulls in Scotland have been increasing
since 1969-70 according to national census data. Numbers recorded
during Seabird 2000 were 35% higher than during the Seabird
Colony Register, and 67% higher than during Operation Seafarer. The
abundance trend using the SMP sample agrees with the
national census data over the same period, although suggests a
slightly higher abundance at the time of Seabird 2000.
Since 2005, the trend has been downward, with the index
in 2015 at 22% below that of 1986.
Numbers at some large inland common gull colonies, not part of
the analysis above, are known to have declined severely, for
unknown reasons. For example, the first systematic survey of
colonies at the Correen Hills and Mortlach Hills in
1988-89 found 24,500 and 16,200 AON, respectively. By 1995, the
Correen Hills colony had declined to 6,400 AON, and by 1998, had
become extinct. The Mortlach Hills colonies have also declined
since 1998 when they held 18,136 AON; 6,565 AON were recorded in
2003 and 6,240 AON in 2007/08. It is doubtful whether decreases at
both these areas have been compensated for by increases at existing
colonies or by the establishment of others. Few large colonies are
routinely surveyed as part of the SMP. Two major colonies
(Tom Mor and Tips of Corsemaul both Moray) held just 4,156 and
2,084 in 2007 and 2008 respectively. No additional data has been
collected at any inland colony holding at least 2,000 AON since
then.
Productivity

Figure 2: Trend
in productivity (no. of chicks fledged per pair)
of common gull in Scotland, 1986-2016. Based on SMP
data; view the methods
of analysis (PDF 158 kb).
The productivity of common gulls in Scotland shows no clear
trend across the entire recording period but does appear to have
declined since the late 1990s with poor breeding seasons in
2008, 2011, 2013 and 2015. Most information collected is from
a study of the effects of American mink control on productivity of
gulls and terns on west coast islands2, so may not be
representative of Scotland as a whole. This mammal can have
a significant depressive effect on breeding success. Common
gull breeding success data collected from this study area between
1996 and 2013 found colonies with successful mink control
fledged an average of 0.71 chicks per pair per year, compared to
0.30 at colonies with no, or unsuccessful, mink control; on
average breeding success was 57% (range 27-77%) lower at
colonies in the latter group. In 2014, success at these two
groups of colonies was 0.68 and 0.19 chicks fledged per
pair respectively - a difference of 72%3. Trapping in recent
years, specifically targeting colonies where the American mink are
most active, has helped to raise the number of young fledged.
However, trapping effort increased in the late 1990s but may
have decreased since, possibly explaining the decline in
overall productivity over the last decade shown in Figure 2.
Population estimates and change 1969-2002 (census data)
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
Population estimate (AON*)
Inland
Total
|
8 |
31 |
33
11
44
|
% change since previous
census |
N/a |
+287 |
+6 |
* AON = Apparently Occupied Nests
Note: Inland colonies were not counted during
the first two national censuses, so, to enable direct
comparison, the percentage change refers to coastal
colonies only.
Breeding Abundance
Few common gulls nest in England: eight pairs were recorded
during Operation Seafarer rising to 31 pairs by the Seabird Colony
Register. During Seabird 2000, 15 colonies were known with
total numbers close to that recorded by the SCR. Since
Seabird 2000, numbers of common gulls in England have
probably remained at least stable and may even have increased.
For example, between 2003 and 2014 reports were received from a
sample of between five and nine colonies
annually and numbers ranged from 20 AON (2004 and 2005)
to 64 AON (2008). However, only 21 pairs were reported from six
colonies in 2015; Havergate Island (Suffolk) and Holkham
NNR (Norfolk) are the main colonies holding 6 and 7 AON
respectively.
Productivity
With only a handful of pairs nesting in
England, few meaningful data on productivity are received.
Monitored pairs tend to be in colonies containing terns which
receive most of the targeted effort toward recording breeding
performance. Complete failure is usually noticed and recorded,
but successful years may not be recorded. Hence, productivity data
for this species may be biased toward collecting zeros so the
estimated average productivity of 0.23 chicks fledged per nest
per year (there was no significant difference over time) may
be low due to this potential bias.
Population estimates and change 1969-2002 (census data)
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
Population estimate (AON*)
Inland
Total
|
2 |
0 |
0
0
0
|
% change since previous
census |
N/a |
-100 |
N/a |
* AON = Apparently Occupied Nests
Note: Inland colonies were not counted during
the first two national censuses, so, to enable direct
comparison, the percentage change refers to coastal
colonies only.
Breeding Abundance
Common gull no longer breeds in Wales.
Two pairs were recorded during Operation Seafarer but none were
found during the later censuses.
Productivity
This species ceased to breed
in Wales before the SMP started so no data on
productivity are available.
Population estimates and change 1969-2002 (census data)
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
Population estimate (AON*)
Inland
Total
|
56 |
192 |
383
174
557
|
% change since previous
census |
N/a |
+243 |
+99 |
* AON = Apparently Occupied Nests
Note: Inland colonies were not counted during
the first two national censuses, so, to enable direct
comparison, the percentage change refers to coastal
colonies only.
Breeding Abundance

Figure 1: Abundance of common gull at
Strangford Lough (Co. Down), 1986-2015.
National census data show the number of common gulls nesting
along the coast of Northern Ireland increased
between Operation Seafarer and Seabird 2000, and this increase
appears to have continued. Common gull numbers at Strangford Lough
(Co. Down, Figure 1), one of the largest and most frequently
counted colonies in the region, increased steadily from the
late 1980s to 1999. A sharp decline occurred between 1999 and
2002 (access restrictions due to foot and mouth disease prevented
counting in 2001) as numbers fell from 138 to 28 AON. Numbers then
increased rapidly to a peak of 532 AON in 2010 but have
declined since with only 229 AON recorded in
2015. A further 93 pairs were estimated at three other
colonies in 2014. The Copeland Islands (Co. Down), another major
colony which held 452 AON in 2012, were not counted since then,
although numbers there have decreased since 2009 when 850 AON were
estimated to be nesting. Thus, coastal
colonies visited in 2015 hold a minimum of 350 AON, with
unsurveyed colonies likely to hold a few hundred more, so the
total population will be above that recorded by Seabird 2000.
Inland colonies, which held 174 AON during Seabird 2000, have
not been surveyed to any great extent in recent years although 164
AON were recorded at the largest one on Lower Lough Erne (Co.
Fermanagh) in 2015.
Productivity
Data submitted to the SMP on
the productivity of common gulls
in Northern Ireland are sparse; thus, no meaningful
average productivity value can be given.
Population estimates and change 1969-2002 (census data)
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
Population estimate (AON*)
Inland
Total
|
688 |
109 |
586
474
1,060
|
% change since previous
census |
N/a |
-531 |
+438 |
* AON = Apparently Occupied Nests
Note: Inland colonies were not counted during
the first two national censuses, so, to enable direct
comparison, the percentage change refers to coastal
colonies only.
Breeding Abundance
During Seabird 2000, 586 pairs of common gull were recorded in
the Republic of Ireland, five times as many as had been recorded by
the Seabird Colony Register, but still 100 pairs fewer than were
found by Operation Seafarer. Few data have been collected since,
with no regular monitoring at all but the smallest colonies, and so
the current status of the population is unknown.
Productivity
Data submitted to the SMP on
the productivity of common gulls in the Republic
of Ireland are sparse; thus, no meaningful average
productivity value can be given.
Population estimates and change 1969-2002 (census data)
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
Population estimate (AON*)
Inland
Total
|
744 |
301 |
969
648
1,617
|
% change since previous
census |
N/a |
-60 |
+222 |
* AON = Apparently Occupied Nests
Note: Inland colonies were not counted during
the first two national censuses, so, to enable direct
comparison, the percentage change refers to coastal
colonies only.
Breeding Abundance
National census data show numbers increased greatly
between the Seabird Colony Register and Seabird 2000,
after a large decline from that recorded by Operation Seafarer.
Large increases have been recorded at some colonies in
Northern Ireland over the past decade but the trend in the Republic
of Ireland is unknown due to few colonies of any size being
surveyed. However, the total Irish
population probably now lies slightly above that recorded
by Seabird 2000. The small sample of colonies counted between 2012
and 2015 (12 of about 100 known colonies during the last census,
both coastal and inland) were entirely in Northern Ireland
(which held c.35% of the Irish population during Seabird
2000) with a composite figure suggesting they hold around
1,000 nesting pairs; the total coastal and inland population during
Seabird 2000 was just over 1,600 pairs.
Productivity
Data submitted to the SMP on
the productivity of mew gulls from colonies throughout
Ireland are sparse; thus, no meaningful average productivity
value can be given.
Population estimates and change 1969-2002 (census data)
|
Operation Seafarer
(1969-70)
|
Seabird Colony Register
(1985-88)
|
Seabird 2000
(1998-2002)
|
Population estimate (AON*)
Inland
Total
|
N/a |
5 |
6
0
6
|
% change since previous
census |
N/a |
N/a |
+20 |
* AON = Apparently Occupied Nests
Note: Inland colonies were not counted during
the first two national censuses, so, to enable direct
comparison, the percentage change refers to coastal
colonies only.
Breeding Abundance
Only a few pairs of common gull nest on the Isle of Man. Five
pairs were found during the Seabird Colony Register and six pairs
during Seabird 2000. No data have been received recently
although the one colony is surveyed near-annually for other
species; it is possible that common gulls no longer breed on the
Isle of Man.
Productivity
No systematic data on the productivity of common gulls on the
Isle of Man have been submitted to the SMP.
Common gull does not breed on the Channel
Islands.
UK phenology, diet, survival rates
No data have been collected as part of the Seabird Monitoring
Programme.
References
1 Craik, J.C.A. 1997. Long-term effects of
North American Mink Mustela vison on seabirds in western
Scotland. Bird Study 44: 303-9.
2 Craik, J.C.A. 1995. Effects of North
American Mink Mustela vison on the breeding success of
terns and smaller gulls in west Scotland. Seabird 17:
3-11.
3 Craik, J.C.A. 2015. Results of the
mink-seabird project in 2014. Unpublished Report, Scottish
Association for Marine Science, Oban.
Partners
Data have been provided to the SMP by the generous contributions
of its partners, other organisations and volunteers throughout
Britain and Ireland. Partners to the SMP are: BirdWatch Ireland;
The British Trust for Ornithology; Centre for Ecology and
Hydrology; Natural Resources Wales; Department of Environment,
Food and Agriculture (Isle of Man); Department of Environment,
Heritage and Local Government (Republic of Ireland); States of
Guernsey Government; JNCC; Manx Birdlife; Manx National Heritage;
The National Trust; National Trust for Scotland; Natural England;
Northern Ireland Environment Agency; The Royal Society for the
Protection of Birds; Scottish Natural Heritage; Seabird Group;
Shetland Oil Terminal Environmental Advisory Group; Scottish
Wildlife Trust. More about the SMP partners >>
Image of mew gull appears courtesy of Ian Rendall
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not be reproduced in any form whatsoever.