Lesser Black-backed Gull Larus fuscus

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

 

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Description

Lesser Black-baked gull vignette

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:

EC Birds Directive - migratory species

Amber listed in Birds of Conservation Concern 4 (2015 update)

(further information on Conservation Designations for UK Taxa)

Amber listed in Birds of Conservation Concern in Ireland 2014-2019 (2014 update)


International importance

 

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.

 


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*)

Inland

Total

48,217 62,321

  87,413

  24,547

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.

 


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 (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% 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.   

 



 

Breeding abundance

 

Lesser black-backed gull abundance index 2015

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

 

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. During this period, culls of lesser-blacked backed gulls (and herring gulls) were introduced on some nature reserves where gulls were predating upon and competing with other seabirds, especially terns, though such culling ceased in the 1990s2. Other culls have been locally instigated to reduce the risk of contaminating water sources. However, culls did not substantially affect UK populations.

There are uncertainties as to how representative the SMP sample is of lesser black-backed gull trends since the last seabird census (1998-2002). These are based on the relatively low number (5% average per-annum over 1999 to 2014 SMP sampling range) of the lesser black-backed gull urban population in the SMP coastal sample and/or high count variability. Between 2000 and 2012, confidence intervals derived from the SMP sample, although wide, have run parallel to the abundance index), giving confidence that the underlying data indicate a real downward population trend. However, these have widened markedly in recent years (2012–14) and, if we compare the SMP trend between the two previous censuses periods with the more accurate trend based on the actual census data (i.e. between the 1985-88 and 1998-2002 censuses), we find that although the direction of trend is accurately reflected in the SMP sample, the magnitude of change appears to be over-estimated. The population change between the two censuses using census data is +40% whereas the change estimated from the SMP sample over the same period is +71% (if just coastal colonies are included in the SMP sample). This falls outside our criteria for accuracy; a Thomas trend index (based on Thomas 1993 and developed in 2009 by Biomathematics & Statistics Scotland) is rejected as inaccurate when a discrepancy of more than 15% has occurred between the Thomas estimate and the census figure.  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 1969-70 and 1998-2002 census data should solely be used for this purpose. These indicate a 1969-70 to 1998-2002 population increase of 81%.

 

The calculated trends may not reflect the true picture across both habitats (urban and natural colonies), however since trends have been steeply declining in recent years, abundance trends on natural nesting gulls - where sufficient data was available - are presented. This also indicates a need for more urban sampling.

 

However, 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 2015 two of the largest colonies in Wales (Skomer and Skokholm) had declined, since Seabird 2000, by 24% and 39% respectively. Similar has been observed in England where the major colony at Ordford Ness declined by 98% from 5,500 AOT in 2001 to 640 AOT in 2012. Ailsa Craig, the largest colony in Scotland during Seabird 2000, now only holds 166 AON a decline of 58%. The causes of these declines may be due to a decrease in the availability of domestic refuse, reduced discards from fisheries2, predation and human disturbance. A major driver of recent population decline in Wales is likely to have been a reduction in adult survival rate; estimates of survival on Skomer (Dyfed), the only UK colony where this parameter is collected 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. Since then it fluctuated just below the 1986 baseline (Figure 1). In 2015, the index was based at 100%, equal to 1986 when monitoring started.

 

Three censuses of roof-nesting gulls were undertaken: in 1976 (Monaghan & Coulson 1977), in 1993-95 (Raven & Coulson 1997) and during the 1998-2002 seabird census, when all gulls - regardless of habitat - were surveyed (Mitchell et al 2004). The number of roof-nesting lesser black-backed gulls increased dramatically between these surveys with their populations doubling 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 (see above) 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 onwards (Monaghan & Coulson, 1977).

 

The UK trend in roof-nesters since Seabird 2000 is unknown due to insufficient coverage, though colonies in south-west and north-west England have increased. 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

 

UK lesser black-backed gull productivity trend

Figure 2: Trend in UK productivity (no. of chicks fledged per pair) of natural-nesting lesser black-backed gull 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 measured at UK natural-nesting colonies has fluctuated widely over the recording period, though has often been low, for unknown reasons. There have been few successful years with productivity generally below 0.60 chicks fledged per nest in most years. American mink Neovison vison are known to lower breeding success in Scotland but factors influencing this parameter in other parts of the UK are largely unknown or poorly reported. In 2015, productivity was very low with 0.14 chicks fledged per pair. 

 

 

Population estimates and change 1969-2002 (census data)

 

 

Operation Seafarer    

(1969-70)

Seabird Colony Register    

(1985-88)

Seabird 2000    

(1998-2002)

Population estimate (AON*)

Inland

Total

12,031 19,524

21,565

  3,492

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

 

Lesser black-backed gull Scotland abundanace index 2015

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

Between the Seabird Colony Register and Seabird 2000, coastal-nesting lesser black-backed gull numbers increased by 10%. Prior to this, a large increase was recorded with numbers during the SCR 62% higher than during 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 seabirds4. The trend in abundance obtained from analysing colony data held by SMP is unrepresentative as it overestimates the change known to have occurred between the SCR and Seabird 2000. However, a suite of 11 colonies counted in 2015 held 2,348 AON compared to 3,249 AON during Seabird 2000 - a decline of 27%. 

 

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 been fluctuating between 70% below and 180% above the 1986 baseline (Figure 1). In 2015, the index was based at 11% below the 1986 baseline.

 

Roof-nesters increased considerably between surveys in 1993-953 (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 roof-nesting gulls within the UK (33%).

 

Productivity

 

Scotland lesser black-backed gull productivity trend

Figure 1: 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 (PDF 158 kb).

 

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 at affected colonies. However, productivity from 2011 to 2015 was much less than prior to 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.

 

 

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

24,434 22,306

44,133

20,075

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

 

Lesser black-backed gull South Walney abundance 2015

Figure 1: Abundance of lesser black-backed gull at South Walney (Cumbria), 1987-2015.

 

National census data show numbers of coastal-nesting lesser black-backed gulls in England had 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 trend in abundance, calculated from colonies sampled for the SMP, over-estimates the increase between the SCR and Seabird 2000, rendering it unrepresentative. 

 

The SMP sample trend for natural nesting lesser black-backed gulls is not provided as it has extremely wide confidence intervals, although numbers at natural nesting sites are thought to be decreasing. For example, at South Walney (Figure 1), numbers have decreased by 88% since a peak of 2,200 AON in 1997).

 

Roof-nesters increased greatly between surveys in 19765 (127 AON), 1993-953 (954 AON) and Seabird 2000 (6,550 AON). Since then, comprehensive information is unavailable, though large increases have been recorded in some cities and towns in south-west and north-west England6. 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 0.62 chicks per nest per year between 2007 and 2015; there was no statistically significant variation over time.

 

 

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

11,529 20,043

20,682

        40

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

 

Lesser black-backed gull Wales abundance index 2015

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

 

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. The trend in abundance obtained from analysing colony data held by SMP is unrepresentative, as it overestimates the change known to have occurred between the SCR and Seabird 2000, thus is no longer presented and so the current trend in the Welsh coastal population (post Seabird 2000) is unknown. However, it appears, from data collected by the SMP that numbers may be in decline; for example, two important colonies, Skomer and Skokholm (also Dyfed), combined held 9,997 AON in 2014 and 9,116 AON in 2015 compared to 12,426 AON in 2000. The causes of these declines are unknown, though may essentially be a reversal of the factors responsible for earlier population increases, namely a decrease in the availability of domestic refuse and reduced discards from fisheries2. A major driver of recent population decline in Wales may also be a reduction in adult survival rate; estimates of survival on Skomer, the only UK colony where this parameter is collected for lesser black-backed gull, declined between 1993 and 2002 although have improved recently.

 

In Wales, natural nesters increased during the late 1980s and early 1990’s. Since then the abundance index shows a gradual decline (Figure 1), with the lowest ever value being reached in 2015. In 2015, the index was based at 38% lower than the 1986 baseline.

 

Roof-nesters increased between surveys in 19765 (198 AON), 1993-953 (201 AON) and Seabird 2000 (394 AON). No nationwide census has been undertaken since, but 2,696 AON were reported from Cardiff (South Glamorgan) alone in 2011, suggesting a huge increase may have occurred in urban areas.

 

Productivity

 

Wales lesser black-backed gull productivity trend

Figure 2: Trend in productivity (no. of chicks fledged per pair) of lesser black-backed gull in Wales, 1986-2015. Based on SMP data; view the methods of analysis (PDF 158 kb).

 

The trend in natural-nesting lesser black-backed gull productivity for Wales fluctuates widely with no real pattern. The trend 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 2015, largely due to inclement weather and/or a lack of food. 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 four other occasions in 24 years of monitoring has success at this colony been above 0.50: 1997 (0.63), 2005 (0.56), 2014 (0.57) and 2015 (0.68).

 

 

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

223 448

1,033

   940

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

 

Lesser black-backed gull Strangford abundance 2015

Figure 1: Abundance of lesser black-backed gull at Strangford Lough (Co. Down), 1986-2015.

 

The lesser black-backed gull breeds 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. At Strangford Lough (Co. Down), one of the more frequently monitored colonies, lesser black-backed gull numbers increased between 2003 and 2014 from 50 AON to a peak of 438 AON. In 2015, Strangford Lough held 433 AON, similar to 2014. Although not surveyed in 2013 or 2014, the Copeland Islands (Co. Down) held a minimum of 1,000 AOT (based on a count of individuals) in 2012. Inland, a further 1,211 AON were counted at Lower Lough Erne (Co. Fermanagh) in 2015 where just over 100 were found during Seabird 2000. Thus, total numbers at these three colonies now exceeds that recorded during Seabird 2000 for the whole of Northern Ireland. Colonies not surveyed since Seabird 2000 (about 15) probably hold a further several hundred pairs.

 

The relatively small number of roof-nesters in Northern Ireland increased from eight AON in 1993-953 to 63 AON in Seabird 2000. No further updates on this figure are available.

 

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.

 

 

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

1,460 1,219

2,062

   814

2,876

% change since previous census    N/a -20 +69

 

* 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

 

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. In 2015, a census of four cliff‐nesting seabirds at 28 colonies was carried out during which eight lesser black-backed gull colonies were counted6. At these a total of 461 AON were recorded compared to 610 AON during Seabird 2000. The majority of AON (75%) were recorded on Lambay Island (Co. Dublin), one of the largest colonies in the country where the population had increased by 12% since Seabird 2000 (309 AON). However, numbers have fallen at Loop Head and Cape Clear Island from 240 AON during Seabird 2000 to 31 AON in 2015.   

 

During Seabird 2000, 21 pairs nested on roofs in urban areas, but there is no update on this figure.

 

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.

 

 

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

1,683 1,667

3,095

1,754

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. Since then, counts from the more frequently monitored colonies suggested there had been little change up to 2009, although large increases have recently been detected at Strangford Lough, Lambay and Puffin Island. In Northern Ireland at least, total numbers at the few inland and coastal colonies surveyed recently now exceed that recorded for the whole country during Seabird 2000 but too few colonies have been monitored in the Republic of Ireland from which to draw any firm conclusion, although those monitored appear to be increasing, as to the trend for the whole of Ireland.

 

Roof-nesters increased from eight pairs in 1993-953 to 84 in Seabird 2000 with no further update on this figure 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.

 

 

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

54 99

114

     0

114

% change since previous census    N/a +83 +15

 

* 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

 

Lesser black-backed gull Calf of Man abundance 2015

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

 

The small population of lesser black-backed gulls on the Isle of Man more than doubled between Operation Seafarer and Seabird 2000 from 54 to 114 pairs. Only one colony has been surveyed since then, on the Calf of Man, which held c.25% of the lesser black-backed gull population during Seabird 2000 (28 AON in 1999). Numbers had initially increased, from 40 AON (in 1985) during the SCR to a peak count of 65 pairs in 1993, before falling to a low figure of 28 AON recorded for the census in 1999. The decline has continued post Seabird 2000, although numbers nesting vary considerably between years; only 19 AON were recorded in 2006 and 22 AON in 2014 although 46, 5 and 50 AON were recorded in 2009, 2010 and 2015 respectively. 

 

Productivity

 

No systematic data on the productivity of lesser black-backed 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

304 778

1,734

        0

1,734

% change since previous census    N/a +156 +123

 

* 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 lesser black-backed gulls in the Channel Islands had been increasing over the long-term up until 1998-2002 at least, when numbers were nearly six times those recorded in 1969/70. Since Seabird 2000, data have only been received from Burhou, one of the largest colonies, which held 313 pairs (18% of Channel Islands population) during the last census. Several counts at this colony between 2005 and 2014 range from 936 to 1,392 AON, indicating a sizeable increase in the region of 66-78% has occurred. 

 

Productivity

 

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

 

 

The single estimate of adult survival rate provided to the SMP comes from the large population breeding on Skomer. Survival rate there declined between 1994 and 2003 and 2011 and 2013, but increased in 2014. This decline in survival rate coincided with a rapid decline in the number breeding on Skomer, presumably caused by very low breeding success lowering recruitment to the breeding population although unsuccessful adults may be deserting Skomer in favour of other breeding locations. Overall survival has averaged 0.88, but there has been considerable variation over time. The steady decline in survival from the late 1970s to the early 2000s appears to have recovered somewhat in recent years, perhaps recovering to the high levels of the 1970s and 80s. Survival of breeding adult birds in 2013-2014 was 0.93. It is not known if changes in survival have affected the population in Wales (declining) or adjacent areas (e.g. Northern Ireland; increasing).

Lesser black-backed gull Skomer survival 2015

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

 


References

1 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.

2 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.

3 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.

4 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.

5 Monaghan, P. 1977. The status of large gulls nesting on buildings. Bird Study 24: 89-104.

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