Herring Gull Larus argentatus

Status;  International importance;  Population estimates;  Distribution;  Annual abundance/ productivity; Phenology/diet/survival

 

Description

Larus argentatus vignette

The following has been adapted from original text by Brian Madden and Stephen F. Newton in Seabird Populations of Britain and Ireland (with permission from A&C Black, London).

 

The herring gull breeds mainly in north and west Europe. It is widely distributed around the coasts of the British Isles, and prefers to nest on rocky coastline, with cliffs, islets and offshore islands, though a range of other habitats are used including sand dunes, shingle banks and, increasingly, buildings in urban areas. A small proportion of the population nests inland, mainly on lake islands and moorland. The herring gull is an opportunist feeder, being both predator and scavenger. While primarily a coastal feeder, it readily takes advantage of the often abundant food supplies available indirectly from man, especially waste from the fishing industry and landfill sites. Outside of the breeding season, herring gulls are common along coastlines and inshore waters but also occur inland.

 


Conservation status

 

Herring gull is currently identified as a conservation priority in the following:

EC Birds Directive - migratory species

Red listed in Birds of Conservation Concern 3 (2009 update)

UK BAP - priority species

(further information on Conservation Designations for UK Taxa)

Red listed in Birds of Conservation Concern in Ireland 2008-2013 (2013 update)

 


International importance

 

UK Population % Biogeographic Population % World Population
 139,200 AON* 18.5 12.1
 
*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 and hence differs from that tabled below.

 


UK population estimates and change 1969-2002 (census data)

 

Seabird 2000 represents the first attempt to census all inland breeding colonies of herring gulls. However, only 1% of herring gulls in the UK breed away from the coast. Coverage in Seabird 2000, although not complete, was comprehensive across the different colony types and all major colonies and breeding areas were censused. Inland Durham was not surveyed and some large roof-nesting colonies in Dumfries (Dumfries and Galloway), Jarrow (Northumberland), Sunderland (Tyne and Wear) and in Dover & Folkestone (Kent) were also missed. Elsewhere, coverage of roof-nesting gulls was good, abetted by aerial surveys in places like south Wales, Gloucester, Glasgow and Inverness. At most colonies, apparently occupied nests (AON) were counted. However, at some colonies, flush counts of individuals attending the colony were made and then divided by two to provide a rough measure of the number of AON. This is the least accurate method for censusing breeding gulls, as such counts will include an unknown percentage of non-breeders and attendance at the colony by both members of a pair is highly variable throughout the day and throughout the breeding season. During Seabird 2000, only 4% of the population estimate for the UK was obtained from counts of individuals, compared to 6% during the SCR Census (1985-88). Hence the estimates from the two censuses are comparable in terms of the methods used. In mixed colonies, more often than not shared with lesser black-backed gulls, the determination of the proportion of a count to assign to a particular species provides a further potential source of error, as the eggs of the two species can not be readily distinguished. In all but the smallest colonies it was recommended that the proportion of herring gulls is determined from sample head counts representative of the colony as a whole.

 

 

Operation Seafarer

(1969-70)

Seabird Colony Register

(1985-88)

Seabird 2000

(1998-2002)

UK Population estimate (AON*) 285,929 149,197 130,230
% change since previous census N/a -48 -13

 

*AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses so to enable direct comparison the Seabird 2000 figure refers to the coastal population 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 herring gull found in different regions, and a map showing where colonies are found and how large they are, is provided in the Seabird 2000 herring gull results page (PDF, 2.1 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

 

UK HG abundance 2012

Figure 1: Trend in UK abundance index (solid line) of herring gull 1986-2012 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

 

Between 1969/70 and 1985-88, the UK herring gull population decreased by 48%. This decline continued between 1987 and 1990, with a subsequent recovery to 1994 (Figure 1). A further drop in abundance is apparent after 2000; although rapid at the start, this decline levelled off for a few years but now appears to be continuing again. At the time of the Seabird 2000 census, around 14% of the population nested on buildings, as compared with natural habitats; a proportion and total number that increased from 1976 (when just 63 pairs nested on roofs) to 1993-951 (10,900) and 1998-2002 (20,000). The abundant food supply in urban areas provided by street litter and insecure refuse bags/bins, combined with abundant safe nesting sites, has probably encouraged this increase1. We do not know the current number of urban nesting gulls.

 

Despite the increases in urban-nesters, the total herring gull population is now at its lowest level since monitoring began in 1969/70. The reason for the decline is not well understood. Botulism is thought to have been a major factor in the decline between the first two censuses and possibly thereafter; refuse tips may be the source of the Clostridium botulinum bacterium that causes the disease, which also is widespread in wetland sediments2. Decreases in the availability of food scavenged from refuse tips (associated with changes in refuse management in recent years)2 and reductions in discards from fisheries3 have also likely played a role in decreasing herring gull populations. Ground predators have also had an affect at some colonies.

 

Productivity

 

UK herring gull breeding success 2012

Figure 2: Trend in UK productivity (no. of chicks fledged per pair) of herring gull 1986-2012. Based on SMP data; view the methods of analysis (PDF 158 kb).

 

Although there are big fluctuations in UK herring gull productivity between 1989 and 1999 there does appear to be an underlying declining trend during this period. From 2000 onwards productivity improved and has been relatively stable over the last decade although has never been high. Most information comes from a study of the effects of mink control on productivity of gulls and terns in western Scotland, which shows significant depressive effects of mink, for example mink lowered breeding success by an estimated 19% in 20124.

 

Analysis by Cook and Robinson5 found the mean breeding success of herring gulls at monitored nests was 0.75 and declined at a rate of 0.016 chicks per nest per year. This equated to a decline of 31% over the study period 1986-2008. The quality of the existing dataset meant a change in breeding success greater than 10% could be detected with confidence. Population viability analysis (using available life history information such as population size, clutch size, age at first breeding and survival rates of different age classes) predicted that, were this rate of success to be maintained, herring gull populations would decline by 60% over 25 years. For the population to stabilize, breeding success would have to increase to 1.30-1.50 chicks per nest per year.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (AON*) 159,237 92,950 71,659
% change since previous census    N/a -42 -23

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

Scot Herring Gull index 2012

Figure 1: Trend in abundance index (solid line) of herring gull in Scotland,1986-2012 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

 

The trend for Scotland shown above shows a decreasing index during the late 1980s, followed by a period of relative stability before another decline from 2000 onward. The abundance index has fluctuated recently but was at its lowest points in 2009 and 2011. This comes on top of a longer term decline; numbers had already fallen by 42% between Operation Seafarer and the Seabird Colony Register. In summary, herring gull numbers are probably now far lower than at any time since 1969/70.

Numbers nesting on buildings in towns and cities increased from 1976 (55 pairs) to 1993-951 (3,568) and 1998-2002 (5,843). The current size of the population in towns is unknown. The increases in urban-nesters do not make up for the overall declines recorded at coastal colonies.

 

Productivity

 

UK herring gull breeding success 2012

Figure 2: Trend in productivity (no. of chicks fledged per pair) of herring gulls in Scotland, 1986-2012. Based on SMP data; view the methods of analysis  (PDF 158 kb).

 

In combination with the mew gull, most information on the productivity of herring gull in Scotland comes from a study of the effects of mink control on the breeding success of gulls and terns on west coast islands. This introduced mammal can have a significant depressive effect on breeding success, although usually not to the same extent as that seen for mew gull. Herring gull breeding success data collected from this study area between 1996 and 2010 found colonies with successful mink control fledged an average of 0.92 chicks per pair per year, compared to 0.59 at colonies with no, or unsuccessful, mink control; so, on average, mink lowered breeding success by 35% (range 0-71%). In 2012, success at these two groups of colonies was 0.77 and 0.62 chicks fledged per pair respectively - a reduction of 19% due to the effects of mink4. Trapping in recent years, specifically targeting colonies where the mink are most active, has helped to raise the number of young fledged over at least the last decade and thus may be the cause of the upward trend in productivity visible in Figure 2 since the late 1990s.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (AON*) 62,114 27,597 43,932
% change since previous census    N/a -56 +59

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

Eng HG abundance 2012

Figure 1: Abundance of herring gull at South Walney, 1986-2012.

 

In common with herring gull populations in Scotland and Wales, numbers in England declined greatly between the censuses in 1969/70 and 1985-88. By Seabird 2000, although the population had increased, numbers were still some 18,000 pairs lower than during Operation Seafarer. The trend in abundance, calculated from colonies sampled for the SMP, over-estimates this increase, rendering it unrepresentative. However, numbers at South Walney, the largest colony in England holding about one-fifth of the national population, had fallen considerably since surveyed for Seabird 2000; only 1,734 AON were counted in 2012 compared to 10,129 in 1999. Of other large colonies (>1,000 pairs) monitored regularly over the last decade, Rockcliffe, Orfordness and Outer Trial Bank have all declined with only Steep Holm increasing. In contrast, the number of roof-nesters increased greatly, from 1,960 pairs in 1976 to 6,383 pairs in 1993-951 and to 12,284 pairs by Seabird 2000. The current size of the urban population is unknown, though recent increases have occurred in towns in south-west and north-west England6.

 

Productivity

 

Relatively few data are available on the productivity of herring gulls at English colonies. There was no statistically significant variation over time; on average approximately 0.55 chicks fledged per pair per year between 1990 and 2012.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (AON*) 48,576 11,089 13,930
% change since previous census    N/a -77 +26

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

Herring gull numbers fell by 77% in Wales between Operation Seafarer and the Seabird Colony Register and although an increase (of 26%) was detected by Seabird 2000, numbers recorded were still 25,000 pairs lower than in 1969/70. Further losses may have occurred over the last decade; 24 colonies counted in 2012 held 4,471 pairs compared with 5,483 pairs in 2000, representing a fall of 18%, assuming any other sources of error e.g. observer differences, timing of survey relative to timing of nesting are minimal.

 

Roof-nesters increased from 772 pairs in 1993-951 to 1,826 pairs in Seabird 2000. In 2011, a survey of Cardiff urban gulls alone recorded 640 AON. This represents a remarkable turn around in fortunes as supposedly no roof-nesting herring gulls were recorded in Cardiff during Seabird 2000. Previous estimates indicated 425 pairs there in 1975 falling to 4 pairs by 1993.

 

Productivity

 

Wales herring gull breeding success 2012

Figure 1: Trend in productivity (no. of chicks fledged per pair) of herring gulls in Wales, 1986-2012. Based on SMP data; view the methods of analysis  (PDF 158 kb).

 

The number of herring gull chicks fledged at colonies in Wales has been declining since 1994. Birds were very successful in that year, productivity reaching two chicks per pair, but between 1998 and 2012 herring gulls have usually fledged less than one chick per pair. Unfortunately, the reasons for the continued decline in productivity are largely unknown.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (AON*) 16,002 17,561 709
% change since previous census    N/a +10 -96

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

NI Herring Gull index 2012

Figure 1: Trend in abundance index (solid line) of herring gull in Northern Ireland,1986-2012 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

 

Seabird 2000 found that herring gull numbers in Northern Ireland had declined severely since the previous census. Between Operation Seafarer and the Seabird Colony Register, numbers were buoyant when populations in other UK countries, and in the Republic of Ireland, were falling. The subsequent massive decline of 96% left just 709 pairs by Seabird 2000. Botulism has been suspected as the main cause for large losses at some colonies e.g. Rathlin Island, the Copeland Islands and Strangford Lough. Figure 1 reveals that there has been only a very limited recovery in the population during the last decade, mostly in the last few years. In 2012, 1,389 pairs were recorded at six colonies sampled (almost double that recorded during Seabird 2000 although still far less than that recorded by the SCR census) although some counts were of individuals converted to pairs. Few herring gulls have been recorded nesting on roofs in Northern Ireland.

 

Productivity

 

Data submitted to the SMP on the productivity of herring gulls in Northern Ireland are sparse; thus, no meaningful average productivity value is 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*) 43,710 15,255 5,411
% change since previous census    N/a -65 -64

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

National census data show the herring gull population of the Republic of Ireland has declined steadily since Operation Seafarer; the Seabird Colony Register recorded a 65% fall with a further decline of 64% by the time of Seabird 2000. Few colonies are monitored frequently, or in any one year (e.g. just five small colonies in 2011, two in 2012, with most holding fewer than 40 pairs), but available data suggest that the decline has continued over the last decade; six colonies surveyed in 2010 held 1,098 pairs compared with 2,556 pairs during Seabird 2000, a fall of close to 60%. Relatively few herring gulls have been recorded nesting on roofs in the Republic of Ireland.

 

Productivity

 

Data submitted to the SMP on the productivity of herring gulls in the Republic of Ireland are sparse; thus, no meaningful average productivity value is 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*) 59,712 32,816 6,120
% change since previous census    N/a -45 -81

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses, so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

All Ire Herring Gull index 2012

Figure 1: Trend in abundance index (solid line) of herring gull throughout Ireland, 1986-2012 with 95% confidence limits (dotted lines; drawing of upper limit restricted to preserve detail in the abundance index). Based on SMP data; view the methods of analysis (PDF 158 kb).

 

The trend in abundance of herring gull for the whole of Ireland using the SMP sample (Figure 1) closely matches that shown for Northern Ireland, where the majority of data were collected. National census data showed that herring gull numbers had declined severely between Operation Seafarer and Seabird 2000, although numbers in Northern Ireland were actually stable between the first two censuses. The abundance trend using the SMP sample suggests only a very limited recovery in the total population during the last decade. This is certainly the case in Northern Ireland but the few data collected in the Republic of Ireland indicate numbers may still be on the wane. Relatively few herring gulls have been recorded nesting on roofs in Ireland.

 

Productivity

 

Data submitted to the SMP on the productivity of herring gulls from colonies throughout Ireland are sparse; thus, no meaningful productivity value is 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*) 9,977 9,062 7,126
% change since previous census    N/a -9 -21

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses, so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

IOM herring gull abundance 2012

Figure 1: Abundance of herring gull on the Calf of Man, 1986-2012.

 

Between Operation Seafarer and the Seabird Colony Register there was a decline of 9% in the number of herring gulls nesting on the Isle of Man. A larger decline then occurred so that by Seabird 2000 numbers had fallen a further 21% to 7,126 pairs. The current status of herring gull on the Isle of Man is unknown as only one colony, on the Calf of Man, has been surveyed since Seabird 2000. In the late 1980s and early 1990s this colony regularly held over 10% of the Isle of Man population. The most recent count available is from 2010 when 447 pairs were recorded, compared to 670 pairs in 1999. Relatively few herring gulls on the Isle of Man have been recorded nesting on roofs. 

 

Productivity

 

No systematic data on the productivity of herring gulls on the Isle of Man have been submitted to the SMP.

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (AON*) 3,970 3,551 4,347
% change since previous census    N/a -11 +22

 

* AON = Apparently Occupied Nests

Note: Inland colonies were not counted during the two earlier national censuses, so to enable direct comparison the Seabird 2000 figure refers to the coastal population only.

 

Breeding abundance

 

In common with other areas of the British Isles, the number of herring gulls breeding in the Channel Islands also declined between Operation Seafarer and the Seabird Colony Register, although the size of this fall, a decline of 11%, was less severe than elsewhere. Numbers increased by 22% between the Seabird Colony Register and Seabird 2000. The only recent data from the Channel Islands comes from the island of Burhou, where 125 pairs (less than 3% of national population) were found during Seabird 2000. Survey work on Burhou in 2005 recorded 202 pairs but successive declines were recorded in 2006 (109) and 2010 (85), with an increase in 2011 (99). Very low numbers were recorded in 2012 (22 pairs). It is not known whether this fall in numbers is similarly occurring at other colonies in the island group. 

 

Productivity

 

No systematic productivity data have been collected for herring gull in the Channel Islands as part of the SMP.

 

 


UK phenology, diet, survival rates

 

Phenology

 

No systematic data on phenology (timing of life-cycle events) have been collected as part of the SMP.

 

Diet

 

No systematic data on diet have been collected as part of the SMP.

 

Survival rate

 

Survival data submitted to the SMP comes from only one colony in the UK, Skomer in south-west Wales. Figure 2 shows there has been a slight decline in adult survival over most of the study period. Overall survival rate averages 0.82 and has been particularly low in the last two years. The extent to which this trend is representative of the UK as a whole is not known.

 

Skomer herring gull survival 2012

Figure 3: Estimated adult survival rate of herring gull on Skomer (SW Wales), Pembrokeshire, 1987-2011.

 


References

1 Raven, S.J. and Coulson, J.C. 1997. The distribution and abundance of Larus gulls nesting on buildings in Britain and Ireland. Bird Study 44: 13-34. 

2 Madden, B. and Newton, S.F.  2004. Herring Gull Larus argentatus. In: Mitchell, P.I., Newton, S.F., Ratcliffe, N. and Dunn, T.E. (eds.) 2004. Seabird Populations of Britain and Ireland: 242-262. Poyser, London.

3 Furness, R.W., Ensor, K. and Hudson, A.V. 1992. The use of fishery waste by gull populations around the British Isles. Ardea 80: 105-113.

4 Craik, J.C.A. 2012. Results of the mink-seabird project in 2012. Unpublished Report, Scottish Association for Marine Science, Oban.

5 Cook, A.S.C.P. and Robinson, R.A. 2010. How representative is the current monitoring of breeding success in the UK? BTO Research Report No. 573, BTO, Thetford.

6 Sellers, R.M. and Shackleton, D. 2011. Numbers, distribution and population trends of large gulls breeding in Cumbria, northwest England. Seabird 24:90-102.

 


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; Countryside Council for Wales; Department of Agriculture, Fisheries and Forestry (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 herring gull appears courtesy of Ian Rendall ©, is subject to international copyright law and may not be reproduced in any form whatsoever.