Herring Gull Larus argentatus

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

 

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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, rooftops of 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 4  (2015 update)

UK BAP - priority species

(further information on Conservation Designations for UK Taxa)

Red listed in Birds of Conservation Concern in Ireland 2014-2019 (2014 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 counted. 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 and 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, generally 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 cannot 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*)

Inland

Total

285,929 149,197

130,230

     1,960

132,190

% change since previous census N/a -48 -13

 

*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 herring gull found in different regions, and a map showing the locations and size of colonies, 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 gull abundance trend

Figure 1: Trend in abundance index (solid line) of natural-nesting Herring gulls in the UK, 1986-2015 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

 

UK census data, where each census is a complete count of all known colonies at that time, indicate coastal nesting herring gulls decreased by 48% from 1969-70 (285,900 pairs) to 1985-88 (149,200 pairs), with a continuing decline, albeit at a slower rate (-13%), between the 1985-88 and 1998-2002 censuses (130,230 pairs). The derived SMP sample trend (which possibly under-represents roof-nesting birds) indicates a further decline of 40% between 1999 and 2014. The 2014 population estimate of 80,743 pairs is extrapolated from the population size at the time of the last census (Seabird 2000). This gives an estimated long term trend of coastal-nesting Herring gulls (which includes a proportion of roof-nesters), of -72% between 1969 and 2014. 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.

At a first glance, there seem to be two pieces of evidence that suggest the SMP sample is representative of the actual population. Firstly, since 2000 the confidence intervals have been relatively close to the abundance index, indicating confidence in the underlying data of a real downward trend in population size. Secondly, if we compare the SMP sample trend between two periods where we have certainty about the true population size (i.e. between the 1985-88 and 1998-2002 censuses) we find that there is reasonable accordance: the change between the two censuses is known to be -13% whereas the change estimated from the SMP sample over the same period is -2.0%, thus falling within our criteria for accuracy (<15%)). This gives a discrepancy of 11% over a 13 year period, which would suggest that the SMP sample tracks the true trend in herring gull population size reasonably well.

There are, however, uncertainties as to how representative the SMP derived trend is of the true urban nesting Herring gull population, as only a relatively low number of the urban population (6% average per-annum over SMP 1999 to 2014 sampling range) contribute to the sample. This coupled with the likelihood that methods used during the 1998-2002 census under-estimated the roof-nesting population means the SMP UK annual trend for herring gull should be viewed with caution. We, consequently, have low confidence in the ability of SMP sample data to predict trends in UK Herring gull population and, therefore, now advise that census data should solely be used for this purpose. These indicate a 1969-70 to 1998-2002 population decrease of 55%. This also indicates a need for more urban sampling.

The SMP sample breeding abundance trend may not be representative of the UK Herring gull population but the sample from the natural nesting population is based on a sufficient amount of data and, therefore, is presented here. Natural nesting abundance decreased until 1992, after which it increased close to the 1986 baseline value until 2000. The index then fell to its lowest ever value in 2011, 52% below the baseline. In 2015, the index was based at 31% below the 1986 baseline (Figure 1).

 

Despite increases apparent in the urban nesting population, the total herring gull population is now thought to be at its lowest level since first counted in 1969-70. However, this will not be confirmed until a new census has been undertaken, as the SMP sample is our only guide. The reasons for the apparent decline are 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 botulinumbacterium 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 effect at some colonies.

 

Productivity

 

UK Herring gull productivity trend

Figure 2: Trend in UK productivity (no. of chicks fledged per pair) of natural-nesting Herring gull 1986-2015. This productivity trend excludes urban nesting gulls from the sample and therefore, may not be representative of trends in the entire UK population. Based on SMP data; view the methods of analysis (PDF 158 kb).

 

Although there are big fluctuations in UK natural-nesting Herring gull productivity between 1989 and 1999 there does appear to be an underlying declining trend during this period. Between 2000 and 2014, productivity improved and was relatively stable, although never high. In 2015 productivity declined to its lowest level since sampling began (0.31). Declines in productivity are often due to the depredation of eggs and young. A study on the effects of American mink Neovison vison on gull and tern productivity in western Scotland has shown the significant negative effects mammalian predators can cause; for example, the presence of mink reduced breeding success by an estimated 41% in 2014 and by an average of 33% between 1996-20134.

 

Analysis of the SMP dataset found the mean productivity of herring gulls at monitored nests was 0.75 and declined at a rate of 0.016 chicks per nest per year5. 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 stabilise, 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*)

Inland

Total

159,237 92,950

71,659

      471

72,130

% change since previous census    N/a -42 -23

 

* 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

 

Scotland HG gull abundance trend

Figure 1: Trend in abundance index (solid line) of natural-nesting Herring gull in Scotland, 1986-2015 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

 

The number of Herring gulls nesting in coastal areas of Scotland declined severely between 1969-70 and 1998-2002. National census data show 55% of the population disappeared between Operation Seafarer and the Seabird Colony Register with a further decline of 23% by the time of Seabird 2000. Due to colonies being surveyed infrequently no trend can be generated from data submitted to the SMP. However, counts at two of the largest and most frequently counted coastal colonies, the Isle of May (North-east Fife) and Canna and Sandy SPA (Lochaber), show the different fait in abundance. At the Isle of May, numbers decreased between 1986 and 1992 and then steeply increased until 1996. Since 1999 the number of AON have decreased until 2005 and increased ever since with 4,200 AON counted in 2014. No data was submitted in 2015. In contrast, Canna and Sanday SPA increased between 1986 and 1989 and has been decreasing slowly until 2001 after which it declined steeply and has held less than 100 AON ever since. In 2015, only 85 AON were recorded. 

 

At the last census, Scotland held the second largest proportion of urban roof-nesting gulls within the UK (33.0%). Numbers nesting on buildings in towns and cities increased from 1976 (55 pairs) to 1993-951 (3,568 pairs) and 1998-2002 (5,843 pairs). The current number of urban nesting gulls in Scotland is unknown but may have increased in some areas. However, any increase in the numbers of urban-nesters is unlikely to compensate for declines recorded at coastal colonies.

 

In Scotland, natural nesters have declined ever since monitoring started in 1986. Since 2008, the abundance index has fluctuated, although has remained well below the 1986 baseline. In 2015, the index was 37%, the lowest value recorded since herring gull monitoring began.

 

Productivity

 

Scotland Herring gull productivity trend

Figure 2: Trend in productivity (no. of chicks fledged per pair) of natural-nesting Herring gulls in Scotland, 1986-2015. This productivity trend excludes urban nesting gulls from the sample and, therefore, may not be representative of trends in the entire UK population. Based on SMP data; view the methods of analysis  (PDF 158 kb).

 

The trend in productivity for natural-nesting Herring gull in Scotland closely matches that of the UK because 84% of the data have been collected at Scottish colonies. Most information on productivity of natural-nesting herring gull in Scotland comes from a study of the effects of American 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 common gull. Herring gull breeding success data collected from this study area between 1996 and 2013 found colonies with successful mink control fledged an average of 0.91 chicks per pair per year, compared to 0.61 at colonies with no, or unsuccessful, mink control; so, on average, mink lowered breeding success by 33% (range 0-71%). In 2014, success at these two groups of colonies was 0.99 and 0.58 chicks fledged per pair, respectively - a reduction of 41% due to the effects of American mink4. Trapping in recent years, specifically targeting colonies where the American mink are most active, has helped to raise the number of young fledged over at least the last decade and thus may be one of  the causes 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*)

Inland

Total

62,114 27,597

43,932

   1,433

45,365

% change since previous census    N/a -56 +59

 

* 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

 

Herring gull England abundance graph 1986-2015

Figure 1: Trend in abundance index (solid line) of natural-nesting Herring gull in England, 1986-2015 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

In common with Scotland and Wales, the coastal herring gull population in England declined greatly between the censuses of 1969-70 and 1985-88. By Seabird 2000 (1998-2002), although the population had increased, numbers were still some 18,000 pairs lower than recorded during the 1969-70 census.

 

The SMP sample abundance trend for natural nesters (Figure 1) indicates that numbers declined until the early 90s but then recovered to a maximum of 17% above the 1986 baseline in 1994. Herring gulls maintained positive index values until 2001, then plummeted to 62% of the 1986 baseline in 2001. Index values have improved since 2012 and in 2015 were 78% of those when monitoring began.

 

At the last census, England held the largest proportion of urban roof-nesting gulls within the UK (59.7%).The number of roof-nesters has increased greatly, from 1,960 pairs in 1976 to 6,383 pairs in 1993-951 and to 12,284 pairs by Seabird 2000. However, 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 natural-nesting Herring gulls at English colonies. There was no statistically significant variation over time; on average approximately 0.54 chicks fledged per nest per year between 1990 and 2015.

 

 

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

48,576 11,089

13,930

        44

13,974

% change since previous census    N/a -77 +26

 

* 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

 

Herring gull Wales abundance graph 1986-2015

Figure 1: Trend in abundance index (solid line) of natural-nesting Herring gull in Wales, 1986-2015 with 95% confidence limits (dotted lines). Based on SMP data; view the methods of analysis (PDF 158 kb).

Herring gull numbers fell by 77% in Wales between Operation Seafarer and the Seabird Colony Register and, although a subsequent increase (of 26%) was detected by Seabird 2000, numbers recorded were still 25,000 pairs lower than in 1969-70. Twenty-five coastal-nesting colonies counted in 2015 held 4,059 AON compared with 5,712 AON in 2000, representing a slight decline. Natural nesters decreased in the late 1980s but began increasing again in the early 1990’s until 2002. Since then the trend has fluctuated above the 1986 baseline, only dropping below in 2015 (94%, Figure 1).

 

Roof-nesters increased from 772 pairs in 1993-951 to 1,826 pairs in Seabird 2000. In 2011, a survey of urban gulls in Cardiff (South Glamorgan) alone recorded 640 AON. This represents a remarkable turnaround 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 four pairs by 1993.

 

Productivity

 

Wales Herring gull productivity trend

Figure 1: Trend in productivity (no. of chicks fledged per pair) of natural-nesting Herring gulls in Wales, 1989-2015. This productivity trend excludes urban nesting gulls from the sample and, therefore, may not be representative of trends in the entire UK population. Based on SMP data; view the methods of analysis  (PDF 158 kb).

 

Productivity of natural-nesting herring gulls at colonies in Wales has been declining since 1994. Birds were very successful in that year, with productivity at 1.46 chicks per pair, but between 1998 and 2015 herring gulls have typically 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*)

Inland

Total

16,002 17,561

709

  12

721

% change since previous census    N/a +10 -96

 

* 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

 

NI HG gull abundance trend

Figure 1: Trend in abundance index (solid line) of natural-nesting Herring gull in Northern Ireland, 1986-2015 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 (Co. Antrim), the Copeland Islands and Strangford Lough (both Co. Down). 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 2014 and 2015, the only sizeable colony surveyed was at Strangford Lough SPA where 720 and 679 AON nested respectively, figures which are close to that recorded for the country as a whole during Seabird 2000. In 2012, more extensive surveys recorded 1,389 pairs at six colonies sampled, near double that recorded during Seabird 2000. However, this was still far less than that recorded by the SCR census.

 

In Northern Ireland, natural nesters decreased for most years of the monitoring period which started in 1986. They reached a low point in 2000 at 8% of the the baseline. Since then it has been slowly increasing has never been above 36% of the 1986 baseline (Figure 1).

 

Few Herring gulls have been recorded nesting on roofs in Northern Ireland; only eight were found during Seabird 2000. It is not known if this situation has changed.

 

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*)

Inland

Total

43,710 15,255

5,411

   103

5,514

% change since previous census    N/a -65 -64

 

* 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 that 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, none in 2013, four in 2014) however, a census of four cliff‐nesting seabirds at 28 colonies was carried out in 2015 when 22 herring gull colonies were also counted7. At these a total of 1,660 AON were recorded compared to 2,284 AON during Seabird 2000. The majority of AON (55%) were recorded on Lambay Island (Co. Dublin), one of the largest colonies in the country where the population has declined by 50% since Seabird 2000 (1,806 AON). More colonies need to be counted to understand what is happening to the national population.

 

Relatively few Herring gulls have been recorded nesting on roofs in the Republic of Ireland. The status of these is unknown as no counts have been carried out at urban colonies since Seabird 2000 when they held 209 AON.

 

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*)

Inland

Total

59,712 32,816

6,120

   115

6,235

% change since previous census    N/a -45 -81

 

* 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

 

All-Ireland HG abundance trend

Figure 1: Trend in abundance index (solid line) of natural-nesting Herring gull in All-Ireland, 1986-2015 with 95% confidence limits (dotted lines). 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 declined severely between Operation Seafarer and Seabird 2000, although numbers in Northern Ireland were actually stable between the first two censuses.  Twenty-two Herring gull colonies were counted in 20157, indicating a 33% decline in the national population since Seabird 2000. However, more colonies need to be counted to understand what is really happening to the herring gull population in the Republic of Ireland.  

 

Across Ireland, natural nesters increased at the beginning of the monitoring period but have been declining and reached a low point in 2000 at 17% of the baseline. Since then, the abundance index has been increasing slowly but has never been higher than 60% of the 1986 baseline (Figure 1).

 

Relatively few Herring gulls have been recorded nesting on roofs in Ireland. The status of these is unknown as no counts have been carried out at urban colonies since Seabird 2000 when roofs held 217 AON.

 

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*)

Inland

Total

9,977 9,062

7,126

        0

7,126

% change since previous census    N/a -9 -21

 

* 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

 

Herring gull Calf of Man abundance 2015

Figure 1: Abundance of Herring gull on the Calf of Man (Isle of Man), 1986-2015.

 

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 the Calf of Man regularly held over 10% of the Manx population, with land-based estimates ranging from 1,000 to 1,450 AON between 1986 and 1994. By Seabird 2000, a land-based count found only 670 AON in 1999, a decline of 44% since the SCR count in 1987 (1,200 AON). This decline has continued; only 272 AON were recorded in 2015. 

 

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*)

Inland

Total

3,970 3,551

4,347

        0

4,347

% change since previous census    N/a -11 +22

 

* 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

 

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 come from the island of Burhou, where 125 pairs (less than 3% of the population) were found during Seabird 2000. Annual survey work on Burhou in recent years has recorded declining numbers from 202 AON in 2005 to 32 AON in 2014 (with a low of five AON in 2012). No data was submitted to the SMP in 2015. It is not known whether this fall in numbers is similarly occurring at other colonies in the island group but, given declines recorded at other countries in the UK and Ireland, this would seem a likely scenario. 

 

Productivity

 

Data submitted to the SMP on the productivity of Herring gulls in the Channel Islands are sparse; thus, no meaningful average productivity value is given.

 

 


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 come from only one colony in the UK, namely Skomer (Dyfed). Figure 2 shows there has been a slight decline in adult survival over most of the study period. Overall survival rate averages 0.83 and has been particularly low in the last four years before 2015 due to unknown reasons. 2015 was a particularly good year of birds returning to the colonies, showing the highest ever recorded survival rate at 97.1%. The extent to which this trend is representative of the UK as a whole is not known.

Herring gull Skomer survival 2015

Figure 3: Estimated adult survival rate of Herring gull on Skomer (Dyfed), 1986-2014.


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. 2015. Results of the mink-seabird project in 2014. 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.

7 Newton, S.  Lewis, L. and  Trewby, M. 2015. Results of a Breeding Survey of Important Cliff‐Nesting Seabird Colonies in Ireland 2015. National Parks and Wildlife Service Ireland.

 


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 herring gull appears courtesy of Ian Rendall ©, is subject to international copyright law and may not be reproduced in any form whatsoever.