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Lesser black-backed gull (Larus fuscus)

The following has been adapted from original text by John Calladine in Seabird Populations of Britain and Ireland (with permission from A&C Black, London).

 

The lesser black-backed gull breeds in north and west Europe and has increased in numbers throughout its range during much of the 20th century. During this time, they have become less migratory and can now be found within much of their breeding range throughout the year. The species nests colonially, often with other gulls, especially the herring gull. Colonies are found on islands offshore and within inland freshwater bodies, coastal cliffs, sand dunes, salt marshes, moorland and on the rooftops of buildings. Seemingly, many sites that are either inaccessible to ground predators (e.g. islands and urban rooftops) or where ground predators are particularly scarce (e.g. narrow peninsulas or on moorland managed as sporting estate) can prove attractive for nesting. Though often sharing breeding areas with herring gulls, their nest sites and feeding strategies generally differ; lesser black-backed gulls can forage over larger distances and they tend to nest within more vegetated areas.

Conservation status

Lesser black-backed gull is currently identified as a conservation priority in the following:

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International importance

UK Population

Biogeographic Population

% World Population

112,000 AON*

62.6 (ssp. graellsii)

38.4

*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.

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

Prior to Seabird 2000, the population of lesser black-backed gulls in the UK has only ever been surveyed incompletely. During Operation Seafarer (1969-70), complete coverage of coastal colonies was achieved but no inland colonies were counted. Both coastal and inland colonies were surveyed during the SCR Census (1985-88), but coverage inland was incomplete and so only provided a minimum estimate of the number nesting away from the coast. Seabird 2000 thus represented the first attempt to census all coastal and inland breeding colonies. While coverage was good in most areas, the following urban areas were not surveyed: inland Durham (although this probably had little overall impact since only two nests were recorded there in 1987); West and East Lothian; Dumfries; Dover and Folkestone; Cheriton; and Sunderland and South Shields. Furthermore, the several hundred pairs that were believed to be nesting on the rooftops of Edinburgh proved practically impossible to survey. Elsewhere, coverage of roof-nesting gulls was good, and was aided by aerial surveys in places like south Wales, Gloucester, Glasgow and Inverness. Apparently occupied nests (AON) were counted at the majority of colonies. However, at some colonies flush counts of individuals attending the colony were made and then divided by two to provide a rough approximation of the number of AON. This is the least accurate method for counting 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, 91% of counts were of nests; the rest were derived from counts of birds, apparently occupied sites or territories. In colonies mixed with herring gulls, the determination of the proportion of a count to assign to a particular species was 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*)

48,217

62,321

87,413

Inland numbers

-

-

24,547

Total Figures

-

-

111,960

% change since previous census   

n/a

+29

+40

*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.

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Distribution/abundance

The Seabird 2000 census provides the most comprehensive recent assessment of the distribution and abundance of breeding seabirds. Numbers of lesser black-backed gull found in different regions, and a map showing the location and size of colonies, is provided in the Seabird 2000 lesser black-backed gull results page.

The locations sampled during the annual Seabird Monitoring Programme provide some information on distribution and are accessible via the Seabird Monitoring Programme online database.

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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% confidence limits 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.

 

United Kingdom

Breeding abundance

lbb-gull-uk-ab.jpg

Figure 1. Trend in abundance index (solid line) of natural-nesting lesser black-backed gulls in the UK, 1986–2018 with 95% confidence limits (dotted lines). This abundance 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.

Note: 'Natural-nesting' is defined as moors, cliffs, marshes, beaches and other areas of semi-natural habitat, while 'urban-nesting' is defined as human-built structures.

 

National census data indicate lesser black-backed gulls nesting in coastal colonies increased by 29% from 1969-70 (48,000 pairs) to 1985-88 (62,000 pairs). Increases from 1969 onward were probably a result of increased food availability from fishery discards1 and from landfill sites. A further 40% increase (87,413 pairs) occurred between the 1985-88 census and the next one in 1998–2002.

There are uncertainties as to how representative the SMP sample is of the lesser black-backed gull UK population trend since the last seabird census (1998–2002). Uncertainties relate to the relatively small number of urban nesting sites contributing to the annual SMP sample for lesser black-backed gulls (annual average 5% of sites 1999–2014).

The trend in Figure 1 is, therefore, based only on the natural-nesting component of the SMP sample and may not reflect the UK population trend i.e. that of both natural and urban nesting lesser black-backed gulls. Between 2002 and 2018, confidence intervals derived from the natural-nesting lesser black-backed gull sample have run parallel to the abundance index and have become increasingly narrow, giving confidence that the underlying data indicate a real downward trend of their population over the last 15–20 years.

Although a real downward trend at UK level is likely given large scale declines at key colonies, representativeness of the magnitude of the SMP trend is still somewhat unclear when compared to census data. We, consequently, have low confidence in the ability of SMP sample data to predict trends in the UK lesser black-backed gull population and, therefore, advise that census data should solely be used for this purpose.

Several major colonies surveyed since Seabird 2000 in Scotland, England and Wales appear to be in decline while increases have been recorded in the smaller population in Northern Ireland. For example, in 2017 two of the largest colonies in Wales (Skomer and Skokholm) had declined, since Seabird 2000, by 49% and 46% respectively. Similar has been observed in England where the major colony at Orford Ness declined by 98% from 5,500 AON in 2001 to 335 AON in 2013 and 97 AON in 2018. However, the neighbouring colony at Havergate Island increased from 290 AON during Seabird 2000 to 1,327 AON in 2018. The colony at Walney Island has decreased by 91% (19,487 AON during Seabird 2000 to 1,981 in 2018) and Bowland Fells by 21% (18,518 AON during Seabird 2000 to 14,627 AON in 2018). In contrast the Ribble and Alt Estuary colony increased by 69% from 4,150 AON in 1998 to 7,022 in 2016. Ailsa Craig, the largest colony in Scotland during Seabird 2000, now only holds 146 AON a decline of 64%. The causes of these declines may be due to a decrease in the availability of domestic refuse, reduced discards from fisheries2, predation, cannibalism3 and human disturbance. A major driver of recent population decline in Wales may have been a reduction in adult survival rate; estimates of survival on Skomer, the only UK colony where this parameter is monitored for lesser black-backed gull, declined between 1993 and 2002 although have been higher since. Natural nesters increased until 1997, after which a slow decline is evident until 2000 when the index drops more steeply but recovers the year after. Since then the index has decreased further and in 2018 was 59% below the 1986 baseline when monitoring began (Figure 1).

Three censuses of roof-nesting gulls were undertaken: in 19764, in 1993-955 and during the 1998–2002 Seabird 2000 census6, which aimed to count all gulls regardless of habitat. The number of roof-nesting lesser black-backed gulls increased dramatically between these surveys with their populations increasing by 7.7 and 4.3 times respectively since the 1976 census. These censuses counted all inland and coastal gulls nesting on buildings from vantage points and were seen as absolute counts at the time. However, the first two censuses (1976 and 1993-95) stated that, because of difficulties in locating all nests at colonies, population sizes were likely to be underestimates. The Seabird 2000 census suffered similar methodological issues and did not attain complete coverage so will have also underestimated the size of the roof-nesting population. The degree of under-estimation is, however, likely to be modest, particularly for Operation Seafarer, as inland/roof-nesting only became commonplace from the mid-1970s onwards4. The UK trend in roof-nesters since Seabird 2000 is unknown due to insufficient survey coverage, though colonies in south-west and north-west England have expanded in range (comparing Seabird 2000 with the 2007-11 Breeding Bird Atlas)7.

The causes of the population increase in urban areas may have been facilitated by an abundance of locally available food (e.g. from fast-food street litter and domestic/commercial rubbish bins), and safe (predator-free) nesting sites in the form of flat roofed buildings.



Productivity

lbb-gull-uk-prod.jpg

Figure 2. Trend in UK productivity (no. of chicks fledged per pair) of natural-nesting lesser black-backed gull 1989–2018. 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.

 

Productivity measured at UK natural-nesting colonies has fluctuated widely over the recording period, though has often been low. Local productivity rates have been linked to nesting habitat8,9, parental condition10 and fishery discards11. American mink Neovison vison are known to lower productivity in Scotland but factors influencing this parameter in other parts of the UK are largely unknown or poorly reported.

There have been three years with productivity above 0.60 chicks fledged per nest (2010, 2012 and 2014). In 2018, productivity was just 0.38 (Figure 2), very much below the national average of 0.52 chicks fledged per pair between 1989 and 2018.

 

Scotland

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

12,031

19,524

21,565

Inland numbers

-

-

3,492

Total Figures

-

-

25,057

% change since previous census   

n/a

+62

+10

*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

lbb-gull-scotland-ab.jpg

Figure 3. Trend in abundance index (solid line) of natural-nesting lesser black-backed gull in Scotland, 1986–2018 with 95% confidence limits (dotted lines). This abundance 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.

 

Between the Seabird Colony Register and Seabird 2000 censuses, coastal-nesting lesser black-backed gull numbers increased by 10%. Prior to this, a large increase was recorded by the SCR census, 62% higher than Operation Seafarer. Reasons for the increase are unknown but, for example, on the Isle of May (the largest colony in Scotland that is counted frequently), numbers increased from the late 1980s to the mid-1990s, with a particularly steep increase between 1992 and 1993, associated with the cessation of gull control measures undertaken in 1984-88 to reduce gull predation on other seabirds12.

In Scotland, the natural-nesting lesser black-backed gull population declined during the late 1980s but increased between 1992 and 1996. Since then it has fluctuated between 30% below and 90% above the 1986 baseline (Figure 3). In 2018, the index was 9% above the 1986 baseline. The trend in abundance obtained from analysing natural-nesting colony data held by SMP (Figure 3) does, however, overestimate the change known to have occurred between the SCR and Seabird 2000.

Urban-nesting lesser black-backed gulls increased considerably between surveys in 1993-955 (1,356 AON) and Seabird 2000 (3,846 AON), although little information on their status is available since then. At the last census, Scotland held the second largest proportion of urban-nesting lesser black-backed gulls in the UK (33%).

 

Productivity

LB Scotland productivity.jpg

Figure 4. Trend in productivity (no. of chicks fledged per pair) of natural-nesting lesser black-backed gull in Scotland, 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.

 

Productivity of natural-nesting lesser black-backed gulls in Scotland has been variable over the recording period, with no clear trend. Predation by American mink at colonies in south-west Scotland is the main cause of low productivity in some, but not all, years. Higher productivity in recent years may be a result of efforts to remove this destructive species from affected colonies. However, productivity from 2011 to 2015 was lower than the period until 2007, probably due to a combination of factors such as predation, poor weather and poor feeding conditions. In 2015, 0.26 chicks were fledged per pair, the second lowest value recorded since the beginning of the SMP data collection in 1986. No additional productivity data have been submitted to the SMP since 2015.

 

England

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

24,434

22,306

44,133

Inland numbers

-

-

20,075

Total Figures

-

-

64,208

% change since previous census   

n/a

-9

+98

*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

lbb-gull-england-ab.jpg

Figure 5. Abundance of lesser black-backed gull at South Walney (Cumbria), 1986–2018.

 

National census data show numbers of coastal-nesting lesser black-backed gulls in England changed little between Operation Seafarer and the Seabird Colony Register but had doubled by the time of Seabird 2000 to just over 44,000 pairs.

The SMP sample trend for natural-nesting lesser black-backed gulls is not provided as it has extremely wide confidence intervals, although since Seabird 2000 numbers at several natural nesting sites have decreased. For example, at South Walney (Figure 5) numbers have decreased by 91% since a peak of 22,200 AON in 1997. Declines have also occurred at other large colonies since Seabird 2000 such as Bowland Fells by 21% and Orford Ness (-98%) However, Orford Ness’ neighbouring colony at Havergate Island increased from 290 AON during Seabird 2000 to 1,327 AON in 2018, an increase of 357%. The causes of the declines may be linked to past control measures at Bowland Fells SPA due to extensive culling of lesser black-backed gulls (to protect breeding red grouse and wading birds) and predation of their chicks and eggs by foxes Vulpus vulpus at Orford Ness13.

Urban-nesters increased greatly between surveys in 19764 (127 AON), 1993-955 (954 AON) and Seabird 2000 (6,550 AON)6. Since then, comprehensive information is unavailable, although large increases have been recorded in some cities and towns in south-west and north-west England14. However, the number of gulls nesting in some urban areas may have been underestimated during Seabird 2000, or not counted at all. At the last census, England held the largest proportion of urban roof-nesting gulls within the UK (59.7%).

 

Productivity

Few data on the productivity of natural-nesting lesser black-backed gulls at English colonies have been collected as part of the SMP. On average, lesser black-backed gulls fledged 0.42 chicks per nest per year between 2007 and 2018; there was no statistically significant variation over time.

Wales

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

11,529

20,043

20,682

Inland numbers

-

-

40

Total Figure

-

-

20,722

% change since previous census   

n/a

+74

+3

*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

lbb-gull-wales-ab.jpg

Figure 6. Trend in abundance index (solid line) of natural-nesting lesser black-backed gulls in Wales, 1986–2018 with 95% confidence limits (dotted lines; drawing of upper limit restricted to preserve detail in the abundance index). This abundance 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.

 

In Wales, the number of coastal-nesting lesser black-backed gulls increased by 74% between Operation Seafarer and the Seabird Colony Register with similar numbers recorded during Seabird 2000. Counts at two of the largest Welsh colonies, Skomer and Skokholm do, however, suggest that the natural nesting lesser black-backed gull population in Wales may have declined considerably since the last census. These colonies held a total of 12,426 AON in 2000 and only 6,499 in 2018, a decline of 48%. Decreases in adult survival rate and productivity are likely to be the main drivers of this long-term breeding population decline, although it is also possible that some birds may have relocated. Other causes may be a reversal of the factors responsible for earlier population increases, namely a decrease in the availability of domestic refuse and reduced discards from fisheries1,15.

In Wales, natural nesters increased during the late 1980s and early 1990s. Since then, the abundance index shows a sustained decline (Figure 6), with the lowest ever value being recorded in 2017. In 2018, the index was 49% lower than the 1986 baseline, only a slight improvement on 2017 (54% below).

Urban-nesters increased between surveys in 19764 (198 AON), 1993-955 (201 AON) and Seabird 2000 (394 AON)6. No nationwide census has been undertaken since, but 2,696 AON were reported from Cardiff alone in 2011, suggesting a large increase may have occurred in urban areas.

 

Productivity

lbb-gull-wales-prod.jpg

Figure 7. Trend in productivity (no. of chicks fledged per pair) of natural-nesting lesser black-backed gull in Wales, 1990–2018. This productivity trend excludes urban nesting gulls from the sample and, therefore, may not be representative of trends in the entire Welsh population. Based on SMP data; view the methods of analysis.

 

The trend in natural-nesting lesser black-backed gull productivity for Wales fluctuates widely and is heavily influenced by data from the very large Skomer colony where success has often been low, averaging 0.33 chicks fledged per pair between 1990 and 2018. Years with poor productivity have been linked with a reduction in food availability during the chick rearing period, largely due to changes in the fishing industry and chicks being fed on earthworms16. In 2010, lesser black-backed gulls on Skomer had their most successful breeding season in the period of the SMP, fledging 0.89 chicks per pair. Only on five other occasions in 28 years of monitoring has success at this colony been above 0.50: 1991 (0.54), 1997 (0.71), 2005 (0.66), 2011, (0.89), 2015 (0.53) and 2018 (0.50).

 

Northern Ireland

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

223

448

1,033

Inland numbers

-

-

940

Total Figure

-

-

1,973

% change since previous census   

n/a

+101

+131

*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

lbb-gull-ni-ab.jpg

Figure 8. Abundance of lesser black-backed gull at Strangford Lough, 1986–2018.

 

Lesser black-backed gulls breed at approximately 30 colonies in Northern Ireland, although few are monitored in any one year, so a representative annual trend is not available. Numbers doubled between Operation Seafarer and the Seabird Colony Register, and then more than doubled again by Seabird 2000. Recent counts of both natural and urban nesting lesser black-backed gulls suggest that the Northern Ireland population has increased overall since Seabird 2000.

At Strangford Lough (Figure 8), one of the more frequently monitored colonies, natural nesting lesser black-backed gull numbers increased from 50 AON in 2003 to a peak of 438 AON in 2015, although held only 310 AON in 2018. In 2018, Lighthouse Island (Copeland Islands) held 365 natural nesting lesser black-backed gull AON, a decline of 34% since 2012. Inland, 1,316 AOT were recorded at Lower Lough Erne in 2018 where just over 100 AOT were found during Seabird 2000 and a total of 2,052 individuals were recorded at colonies on Lough Neagh in 201817.

The number of urban-nesting lesser black-backed gulls in Northern Ireland increased from eight AON in 1993-954 to 63 AON in Seabird 20006. The urban nesting population has increased since Seabird 2000, with at least 101 AON being recorded in Belfast city centre and harbour in 2018, and an additional 12 AON recorded in the wider Belfast area. However, due to the complexity of the roof-scape and the limited number of vantage points, this is likely to be an underestimate. In addition, 77 urban-nesting adults were recorded at a colony in Carrickfergus17.

 

Productivity

Data submitted to the SMP on the productivity of lesser black-backed gulls in Northern Ireland are sparse; thus, no meaningful average productivity value can be given.

 

Republic of Ireland

Population estimates and change 1969–2018 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Republic of Ireland Census

(2015-18)

Population estimate (AON*)

1,460

1,219

2,062

7,112**

Inland numbers

-

-

814

-

Total Figure

-

-

2,876

-

% change since previous census   

n/a

-20

+69

+148

*AON = Apparently Occupied Nests

** This population estimate figure is a combination of inland and coastal as information on the split were not available18.

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

Seabird 2000 recorded just over 2,000 pairs of coastal-nesting lesser black-backed gulls in the Republic of Ireland. This was an increase of 69% since the Seabird Colony Register and 41% higher than that recorded by Operation Seafarer. The recent Irish Seabird Census (2015–2018) recorded a total of 7,112 AON, an increase of 148% since Seabird 2000, of which approximately 20% were from islands on inland lakes18. One of the most important inland colonies (Inishgoosk on Lough Derg) during Seabird 2000, no longer holds a breeding lesser black-backed gull population. This extirpation coincided with strong recorded growth at other inland sites, including Loughs Conn and Mask. The colonies at Roaringwater Bay and Incharmadermot Island (Lough Ree) now hold almost a third of the Republic of Ireland lesser black-backed gulls breeding population, with 1,288 AON and >1,000 AON recorded respectively during the recent census.

During Seabird 2000, 21 pairs nested on roofs in urban areas of the Republic of Ireland but there has been no update on this figure.

There were insufficient data from the Republic of Ireland to allow an abundance trend to be generated.

 

Productivity

Data submitted to the SMP on the productivity of lesser black-backed gulls in the Republic of Ireland are sparse; thus, no meaningful average productivity value can be given.

 

All Ireland

Population estimates and change 1969–2002 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Population estimate (AON*)

1,683

1,667

3,095

Inland numbers

-

-

1,754

Total Figure

-

-

4,849

% change since previous census   

n/a

-1

+86

*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

The lesser black-backed gull coastal-nesting population for the whole of Ireland was stable between the first two national censuses but increased by 86% between the Seabird Colony Register and Seabird 2000. In Northern Ireland, total numbers at the few inland and coastal colonies (1,991 AON) surveyed recently now exceed that recorded for the whole country during Seabird 2000 (1,973 AON). These, combined with data from the recent census of the Republic of Ireland, suggest that the total breeding population in the whole of Ireland is at least 9,103 AON.

Roof-nesters increased from eight AON in 1993-953 to 63 in during Seabird 2000, although a more recent update is not available.

 

Productivity

Data submitted to the SMP on the productivity of lesser black-backed gulls from colonies throughout Ireland are sparse; thus, no meaningful average productivity value can be given.

 

Isle of Man

Population estimates and change 1969–2018 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Isle of Man Census

(2017-18)

Population estimate (AON*)

54

99

114

36

Inland numbers

-

-

0

-

Total Figure

-

-

114

-

% change since previous census   

n/a

+83

+15

-68

*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

lbb-gull-iom-ab.jpg

Figure 9. Abundance of lesser black-backed gull on the Calf of Man, 1986–2017.

 

The population of lesser black-backed gulls on the Isle of Man more than doubled between Operation Seafarer and Seabird 2000 from 54 to 114 AON, although in 2017 a breeding seabird census recorded just 36 AON. The most comprehensive time series of breeding lesser black-backed gull data comes from the Calf of Man which held c.25% of the lesser black-backed gull population during Seabird 2000 (28 AON in 1999) and 27 AON during the 2017 census (Figure 9)19.

 

Productivity

No systematic data on the productivity of lesser black-backed gulls on the Isle of Man have been submitted to the SMP.

 

Channel Islands

Population estimates and change 1969–2016 (census data)

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998–2002)

Channel Islands Census

(2015-16)

Population estimate (AON*)

304

778

1,734

1,796

Inland numbers

-

-

0

0

Total Figure

-

-

1,734

1,796

% change since previous census   

n/a

+156

+123

+4

*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 population of breeding lesser black-backed gulls in the Channel Islands increased between Operation Seafarer and Seabird 2000 (1998–2002), when numbers were nearly six times those recorded in 1969/70. A breeding seabird census of the Channel Islands in 2015 and 2016 recorded a total of 1,796 lesser black-backed gull AON representing an increase of 4% since Seabird 200020.

 

Productivity

No systematic data on the productivity of lesser black-backed gulls on the Channel Islands have been submitted to the SMP.

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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

LB adult survival rate Skomer.jpg

Figure 10. Estimated adult survival rate of lesser black-backed gull on Skomer, 1986–2017.

 

The single estimate of adult survival rate provided to the SMP comes from the large population breeding on Skomer (Figure 10) where it has averaged 0.88, although there has been a decline over time21. Survival rate declined between 1994 and 2003, then recovered until 2009. Survival rate then fluctuated, although since 2014 has again been in decline. The decline in survival rate between 1994 and 2003 coincided with a rapid decrease in the number of lesser black-backed gulls breeding on Skomer, presumably caused by very low breeding success, lowering recruitment to the breeding population, although unsuccessful adults may have been deserting Skomer in favour of other breeding locations. Survival of breeding adult birds between 2016 and 2017 dropped to 0.79, the lowest level since 2003. Poor adult survival may be one of the drivers behind long-term decline in breeding numbers on Skomer but it is not known how many of the 'missing' birds die over the winter and how many move elsewhere21.

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References

1 Furness, R.W., Ensor, K. and Hudson, A.V. 1992. The use of fishery waste by gull populations around the Britain and Ireland. Ardea, 80, 105–113.

2 Bicknell, A.W. J., Oro, D., Camphuysen, J.C. and Votier, S.C. 2013. Potential consequences of discard reform for seabird communities. Journal of Applied Ecology, 50, 649–658.

3 Parsons, J. 1971. Cannibalism in Herring Gulls. British Birds, 64, 528–537.

4 Monaghan, P. and Coulson, J.C. 1977. Status of Large Gulls Nesting on Buildings. Bird Study, 24(2), 89–104.

5 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.

6 Mitchell, P.I., Newton, S.F., Ratcliffe, N., and Dunn, T.E. eds. 2004. Seabird populations of Britain and Ireland. T. and A.D. Poyser, London, UK.

7 Balmer, D.E., Gillings, S., Caffrey, B., Swann, R. L., Downie, I. S., and Fuller, R. J. 2013. Bird Atlas 2007–11: the breeding and wintering birds of Britain and Ireland. British Trust for Ornithology, Thetford.

8 Calladine, J. 1997. A comparison of Herring Gull Larus argentatus and Lesser Black-backed Gull Larus fuscus nest sites: their characteristics and relationships with breeding success. Bird Study, 44(3), 318–326.

9 Kim, S.Y. and Monaghan, P. 2006. Interspecific differences in foraging preferences, breeding performance and demography in herring (Larus argentatus) and lesser black-backed gulls (Larus fuscus) at a mixed colony. Journal of Zoology, 270, 664–671.

10 Nager, R.G., Monaghan, P., Houston, D.C. and Genovart, M. 2000. Parent condition, brood sex ratio and differential young survival: an experiement study in gull (Larus fuscus). Behaviour Ecology and Sociobiology, 48, 452–457.

11 Oro, D. 1996. Effects of trawler discard availability on egg laying and breeding success in the lesser black-backed gull Larus fuscus in the western Mediterranean. Marine Ecology Progress Series, 132, 43–46.

12 Wanless, S., Harris, M.P., Calladine, J. and Rothery, P. 1996. Modelling responses of Herring Gull and Lesser Black-backed Gull populations to reduction of reproductive output: implications for control measures. Journal of Applied Ecology, 33, 1420–32.

13 Coulson, J.C. 2019. Gulls. New Naturalist 139. Harper Collins, London.

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

15 Calladine, J. 2004. Lesser Black-backed Gull Larus fuscus. In: Mitchell, P.I., Newton, S.F., Ratcliffe, N. and Dunn, T.E. eds. 2004. Seabird Populations of Britain and Ireland: 226-241. Poyser, London.

16 Thompson, G.V.F. 2007. The natural history of Skokholm Island. Trafford Publishing.

17 Booth Jones, K.A. and Wolsey, S. 2019. The Northern Ireland Seabird Report 2018. British Trust for Ornithology, Thetford.

18 Cummins, S., Lewis, L.J. and Egan, S. 2016. Life on the Edge – Seabird and Fisheries in Irish Waters. A BirdWatch Ireland Report.

19 Hill, R.W., Morris, N.G., Bowman, K.A. and Wright, D. 2019. The Isle of Man Seabird Census: Report on the census of breeding seabirds in the Isle of Man 2017-18. Manx BirdLife. Laxey, Isle of Man.

20 Veron, M. and Veron, C. 2016. Seabird Count 2015; monitoring the status of Guernsey’s Seabirds. La Société Transactions, Channel Islands.

21 Stubbings, E.M., Büche, B.I., Riordan, J.A., Baker, B. and Wood, M.J. 2018. Seabird monitoring on Skomer Island in 2018. Unpublished JNCC Report. Joint Nature Conservation Committee, Peterborough.

 

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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; UK 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 Department of Agriculture, Environment and Rural Affairs; 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 lesser black-backed gull appears courtesy of Ian Rendall ©, is subject to international copyright law and may not be reproduced in any form whatsoever.

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