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The Lesser Black-backed Gull Larus fuscus in England: how to resolve a conservation conundrum
Abstract and Figures
Lesser Black-backed Gull Larus fuscus numbers in England have fluctuated in recent decades. Both breeding and wintering populations rose sharply in the latter half of the twentieth century, mostly due to increases at a small number of colonies and changes in migratory behaviour. However, there was a decline in breeding birds between 2000 and 2013 (largely because of losses at the same key colonies) and this species is on the Birds of Conservation Concern Amber List. Although protected at various sites in the breeding season, the Lesser Black-backed Gull can be taken under three General Licences issued under the Wildlife and Countryside Act 1981, allowing population control in certain circumstances without specific permission or reporting. There are no sites where the Lesser Black-backed Gull is a protected feature outside the breeding season, although numbers surpass the relevant thresholds at certain roosts. This review paper synthesises available information on the Lesser Black-backed Gull in England to help policy makers resolve this apparent legislative contradiction and formulate a clearer conservation policy to guide future practice.
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... Over the last decades, several populations of large gulls belonging to the genus Larus have increased in size and expanded their range, including the Yellow-legged Gull Larus michahellis (Belant 1997, Morais et al. 1998, Vidal et al. 1998, Ross-Smith et al. 2014, Huig et al. 2016, Winton and River 2017. The fast increase in food availability originating from human related activities is considered one of the main reasons for the current trend of large gulls (Duhem et al. 2008). ...
Over the last decades, the population size and breeding range of several gull species have increased worldwide. The unlimited amount of food of anthropogenic origin is thought to be the main vector for such increase. In Portugal, the Yellow-legged Gull Larus michahellis is the most abundant breeding gull species. There is some evidence of an expansion of this species in mainland Portugal since the 1990s, but no up-to-date data is available. During the breeding season of 2021-2022, a national census was performed. Data on potential anthropogenic food sources was gathered in order to assess the effect of commercial fishing, urban residues and landfills on the numbers of Yellow-legged Gulls. It is estimated that 7,350 to 8,000 pairs breed in Portugal along all mainland coast and nearly on all islands and islets. Despite the sharp decline in the population on Berlenga Island, the largest breeding colony in the country, due to long-term population control, the remaining mainland population is experiencing an increase in both size and breeding distribution. Approximately 30% of the mainland population was found to breed in urban areas. Conversely, the gull population in Madeira has decreased approximately 98% compared to the last census, in 2002. In the Azores, the
population appears to be decreasing, which should be confirmed in future monitoring. Decrease in Madeira and Azores are likely mainly explained by a reduction in food availability following the closure of several landfills. At a national scale, higher numbers of gulls were found near fishing harbours and in municipalities where the amount of urban waste is higher. Our results suggest that an improvement on both the management of fish discards/offal and waste treatment in order to reduce food subsidiaries for Yellow-legged Gulls will affect the size of the breeding population.
... Nevertheless, if spatially correlated environmental conditions influence vital rates, then vital rates among closely situated colonies may be more similar to each other than distant sites (O'Hanlon & Nager 2018). Therefore, to understand population trends on regional, national or biogeographical scales, it would be best to evaluate vital rates and trajectories of multiple colonies or populations simultaneously (Holt 1997, Frederiksen et al. 2005, Ross-Smith et al. 2014. However, it takes large samples of marked birds and many years of data to provide reliable estimates of annual apparent survival for long-lived species (Lebreton et al. 1992). ...
Demographic rates such as recruitment and survival probability can vary considerably among populations of the same species due to variation in underlying environmental processes. If environmental processes are spatially correlated, nearby populations are expected to have more similar demographic rates than those further apart. Breeding populations and foraging ranges are spatially segregated in colonial seabirds, making them ideal to study spatial patterns in demographic rates and their effects on local population dynamics. Here we explored variation in age‐dependent survival probabilities across 14 colonies of Herring Gulls Larus argentatus breeding along the Dutch North Sea coast. We used long‐term mark‐recapture data of marked fledglings to estimate survival, and estimated spatial autocorrelation of survival probabilities. We assessed whether survival until recruitment age or until ten years old (close to their expected lifespan) explained variation in population trajectories of each colony. Juvenile and adult survival showed a strong, but different, north‐to‐south gradient in survival probability with lower juvenile but higher adult survival in northern colonies compared to southern colonies, while the spatial pattern of immature survival was less distinct. Neither recruitment nor the proportion of 10‐year‐old adults alive predicted whether a colony collapsed, declined, remained stable or increased. The distinct spatial pattern in survival suggests variation in regional food availability, which do not seem to drive local population dynamics. The absence of a link between survival and colony trajectories implies that connectivity between populations plays an important role affecting population dynamics.
... Populations in the southernmost region of the Netherlands also first appeared in the 1980s and strongly increased during the 1990s (Strucker, Hoekstein, and Wolf 2016). The expansion of this species in Northwestern Europe has been attributed to the bans on hunting and egging, combined with their efficient use of anthropogenic food subsidies (see Ross-Smith et al. 2014 and references therein), two factors that were up to now difficult to disentangle. In the Zeebrugge colony, which hosts the largest number of nests in Belgium, numbers peaked in 2011 with 4760 breeding pairs (Adriaens et al. 2012). ...
Human activities benefit a range of animal species, the resulting presence of which in cities can have negative societal consequences. One example are food subsidies, which buffer natural variation in food availability and allow these species to maintain larger populations. These buffers will likely gain importance under future environmental change whereby natural food sources become decreasingly available. To inform on the current importance of different habitats for a bird reliant on human-made food subsidies (Lesser Black-backed Gull Larus fuscus), and its possible population response toward changes in climate and the availability of these subsidies, we characterized population-level short-term responses to variation in drivers of local food availability, both natural (weather related) and anthropogenic (fisheries activity). We expected foraging effort to vary in relation to local wind speed and soil moisture, as well as to the alternation of fisheries activity between weekdays and weekends. Individuals were predicted to adjust their foraging habitat use in response to these environmentally driven variations in effort. To this end, we analyzed GPS tracking data of 45 breeding individuals, between 2013 and 2018, nesting in the Port of Zeebrugge, Belgium. Effort was approximated as the energy expenditure rate per trip, the daily time spent away from the colony and the trip frequency, which were analyzed by means of linear mixed effects models. Habitat use per trip was compared between marine, agricultural fields and built-up areas (cities, industry and cattle farms), in a multinomial logistic model. Marine areas and agricultural fields were most frequently exploited, but all considered stressors (wind, dry conditions and inactivity of fisheries) resulted in a higher use of built-up areas. Stronger winds increased the energetic cost of foraging at sea, and thus diminished the use of marine areas, as also did the inactivity of fisheries in weekends. Dry conditions diminished the use of fields and decreased trip frequency. Built-up areas thus constitute a buffer for the variation in food availability at sea and in agricultural fields. The expected increase in frequency and severity of extreme weather events (storms and drought) under global change, combined with the disappearance of discards, may therefore result in a longterm increase in the use of urban habitats by opportunistic large Gull species.
... Populations in the southernmost region of the Netherlands also first appeared in the 1980s and strongly increased during the 1990s (Strucker, Hoekstein, and Wolf 2016). The expansion of this species in Northwestern Europe has been attributed to the bans on hunting and egging, combined with their efficient use of anthropogenic food subsidies (see Ross-Smith et al. 2014 and references therein), two factors that were up to now difficult to disentangle. In the Zeebrugge colony, which hosts the largest number of nests in Belgium, numbers peaked in 2011 with 4760 breeding pairs (Adriaens et al. 2012). ...
Human activities benefit a range of animal species, the resulting presence of which in cities can have negative societal consequences. One example are food subsidies, which buffer natural variation in food availability and allow these species to maintain larger populations. These buffers will likely gain importance under future environmental change whereby natural food sources become decreasingly available. To inform on the current importance of different habitats for a bird reliant on human-made food subsidies (Lesser Black-backed Gull Larus fuscus), and its possible population response toward changes in climate and the availability of these subsidies, we characterized population-level short-term responses to variation in drivers of local food availability, both natural (weather related) and anthropogenic (fisheries activity). We expected foraging effort to vary in relation to local wind speed and soil moisture, as well as to the alternation of fisheries activity between weekdays and weekends. Individuals were predicted to adjust their foraging habitat use in response to these environmentally driven variations in effort. To this end, we analyzed GPS tracking data of 45 breeding individuals, between 2013 and 2018, nesting in the Port of Zeebrugge, Belgium. Effort was approximated as the energy expenditure rate per trip, the daily time spent away from the colony and the trip frequency, which were analyzed by means of linear mixed effects models. Habitat use per trip was compared between marine, agricultural fields and built-up areas (cities, industry and cattle farms), in a multinomial logistic model. Marine areas and agricultural fields were most frequently exploited, but all considered stressors (wind, dry conditions and inactivity of fisheries) resulted in a higher use of built-up areas. Stronger winds increased the energetic cost of foraging at sea, and thus diminished the use of marine areas, as also did the inactivity of fisheries in weekends. Dry conditions diminished the use of fields and decreased trip frequency. Built-up areas thus constitute a buffer for the variation in food availability at sea and in agricultural fields. The expected increase in frequency and severity of extreme weather events (storms and drought) under global change, combined with the disappearance of discards, may therefore result in a long-term increase in the use of urban habitats by opportunistic large Gull species.
... Gulls may have a lower level of accumulated debris due to their feeding at human-altered sites and their ability to regurgitate, but the rate of debris that is ingested may be significantly higher than most other species. As members of a diverse and populous group of seabirds that rely on, exploit, and link both terrestrial and marine food webs, and for which carcasses should be available from a variety of control programs (e.g., Skarphedinsson, 1996;Ross-Smith et al., 2014;Nisbet et al., 2017), we suggest that Laridae should be given more research attention for studying spatiotemporal trends in plastic ingestion, and perhaps for considering species-specific EcoQO targets. ...
Ingestion of plastic pollution by pelagic seabirds is well-documented globally, but increasingly, researchers are investigating plastic ingestion in generalist predators and scavengers like gulls. We studied the gut contents of two sympatric gull species, American herring gulls (Larus smithsoniansus) and great black-backed gulls (L. marinus), collected year-round as part of “kill-to-scare” measures at the regional sanitary landfill in St. John's, Newfoundland and Labrador, Canada, to compare ingested anthropogenic debris, trophic position and diet breadth through the year. Although great black-backed gulls fed at a higher trophic level, frequency of occurrence of plastic ingestion was similar to American herring gulls, and varied little through the year. Diet breadth (isotopic niche size) was similar between species, but American herring gulls fed at a lower trophic level during winter, perhaps indicating a change in their reliance on anthropogenic food subsidies throughout their annual cycle.
... Several gull species are generalist and have the ability to adapt and exploit novel food (Carmona et al. 2021;Lopes et al. 2020Lopes et al. , 2021 and nesting site opportunities provided by human-modified environments, leading to the worldwide increase of their populations over the past decades (Belant 1997;Vidal et al. 1998;Rock 2005;Ross-Smith et al. 2014;Huig et al. 2016;Winton and River 2017). Such increase of opportunistic gull species in urban areas has caused human-gull interactions and conflicts worldwide. ...
The effects of growing urbanization have caused an increase in human-wildlife interactions in urban areas. Human-gull conflicts have been particularly studied during the breeding season when gulls cause an obvious nuisance in urban areas. However, with many gulls being present in urban areas throughout the year, stakeholders need knowledge of seasonal effects on local human-gull interaction dynamics. Here we present a comprehensive study on spatial and temporal variation of urban habitat use and human interactions with urban gulls, Larus spp., in Porto, Portugal. The work combined: (1) a large-scale study, using year-round monthly surveys to quantify gulls' behaviour and their use of multiple urban habitats, with (2) a small-scale study, using 10-h daily urban surveys to capture gulls' daily routines and interactions with humans during the winter and breeding seasons. We found a strong temporal effect in the number of gulls and human-gull interactions occurring in urban areas, with both highly increasing during winter. Habitats with higher urbanization intensity were mainly used by adult gulls, and the number of breeding-related conflicts reported by the human population peaked during the chick-rearing period. Still, during winter, several adult gulls kept occupying their rooftop nesting grounds, and the number of individuals foraging and interacting with humans in city-squares increased. This was mostly triggered by humans feeding birds. Therefore, when designing urban management landscape measures, seasonal variations of the urban gulls' behaviour and habitat-use should be considered, as well as anthro-pogenic activities and human behaviour.
Despite urbanisation’s general erosion of biodiversity, towns and cities provide novel opportunities for some species. During the 20th century, gulls (Laridae) colonised urban areas around the world where they flourished. At the same time, some coastal populations declined. Reasons for this difference are not fully understood, partly because little is known about any ecological differences between urban and non‐urban gulls such as their foraging ecology. Here we compare the movement ecology and habitat selection of Lesser Black‐backed Gulls (Larus fuscus graellsii) breeding at two neighbouring colonies – one urban and one coastal in northwest England. We used bird‐borne GPS loggers to first compare colony‐level movement behaviour and habitat selection and then investigated individual‐level habitat use. We observed clear colony‐level habitat segregation: urban breeders preferentially foraged in urban areas while coastal breeders foraged primarily in coastal habitats and avoided urban areas. Coastal breeders also had larger foraging and home ranges than urban breeders, possibly due to differences in colony size. However, we also found inter‐individual differences in habitat use which may have important management implications. These findings suggest a link between nesting and foraging ecology and thus management or environmental change altering food availability will impact gulls at the coastal and urban sites differently.
Vagrancy is critical in facilitating range expansion and colonization through exploration and occupation of potentially suitable habitat. Uncovering origins of vagrants will help us better understand not only species-specific vagrant movements, but how the dynamics of a naturally growing population influence vagrancy, and potentially lead to range expansion. Under the premise that occurrence of vagrants is linked to increasing population growth in the core of the breeding range, we assessed the utility of breeding population survey data to predict source populations of vagrants. Lesser Black-backed Gulls (LBBG) (Larus fuscus) served as our focal species due to their dramatic and well-documented history of vagrancy to North America in the last 30 years. We related annual occurrence of vagrants to indices of breeding population size and growth rate of breeding populations. We propose that the fastest growing population is the most likely source of recent vagrants to North America. Our study shows that it is possible to predict potential source populations of vagrants with breeding population data, but breeding surveys require increased standardization across years to improve models. For the Lesser Black-backed Gull, Iceland’s breeding population likely influenced vagrancy during the early years of colonization, but the major increase in vagrants occurred during a period of growth of Greenland’s population, suggesting that Greenland is the source population of the most recent pulse of vagrant LBBG to North America.
Renewable energy continues to grow globally, and the number of offshore wind farms is set to increase. Whilst wind energy developments provide energy security and reduced carbon budgets, they may impact bird populations through collision mortality, habitat modification and avoidance. To date, avian collision mortality has received the most attention and collision risk models have been developed to estimate the potential mortality caused by wind turbines. The utility of these models relies not only on their underlying assumptions but also on the data available to ensure the predictions are informative. Using a stochastic collision risk model (sCRM; based on the Band collision risk model) as an example, we explore the importance of bird flight speed and consider how the assumptions of the model influence the sensitivity to flight speed. Furthermore we explore the consequences of using site-specific GPS-derived flight speed rather than a standard generic value, with Lesser Black-backed Gulls Larus fuscus as an example, and consider how this generic value is currently used. We found that the model was most sensitive to the parameters of bird density, non-avoidance rate and percentage of birds at collision risk height, as well as bird flight speed. Using site-specific flight speed data derived from GPS tags rather than a standard value reduced the predicted number of collisions. We highlight that within the model, both the estimation of the probability of collision (PColl) and the flux of birds are sensitive to the bird flight speed; this sensitivity acts in opposite directions but the two do not necessarily balance out. Therefore, when the sCRM is used as generally done, there is little difference in collision estimates if airspeeds (bird flight speed relative to air through which it is moving) are used rather than groundspeeds (bird flight speed relative to ground). Estimates of seabird collision rates in relation to offshore wind farms are impacting future offshore wind development. By using site specific flight speed estimates and, accounting for different speeds in relation to wind direction, we demonstrate that cumulative collision estimates can be affected, highlighting the need for more representative flight speed data and where possible site-specific data.
Research on the space use and behaviour of waterbirds yields important insights on human‐wildlife interactions of ecological and societal importance under global change. The extent to which dynamic (within‐season) changes in anthropogenic landscapes affect these interactions is poorly understood. Lesser Black‐backed Gulls (Larus fuscus) are prominent bio‐vectors of biological, synthetic and inorganic materials, and have exhibited large increases in abundance in parts of southern Europe in recent decades. We combined GPS tracking, earth observation, accelerometry and field observations to study the space use of overwintering gulls in a mixed rice field landscape in Andalusia, Southern Spain. We used Manly selectivity metrics, a common quantitative measurement of habitat selection, and classified remote sensing imagery to directly evaluate space use and habitat selection for these gulls and how it changed throughout the rice harvest cycle. Analysis of over 45,000 GPS fixes and 14 classified remotely‐sensed images from winter 2016‐17 showed dynamic space use driven by the harvest‐related flooding across the rice harvest cycle. Prior to harvest, gulls foraged in rice paddies during the day and roosted in adjacent waterbodies (the River Guadalquivir, and fish ponds) at night. During harvest, they spent nearly 100% of their daily cycle within the rice fields, foraging in harvested paddies and roosting in post‐harvest, flooded paddies. After harvest, they roosted in flooded paddies at night and foraged at landfills in the surrounding landscape. Gull space use at landscape and paddy scales was closely linked to dynamic land and water management over the rice agricultural cycle, illustrating how human activities influence the movements of ecologically important, human‐associated bio‐vectors like gulls. The frequent early‐spring movement patterns of gulls between landfills and agricultural fields makes them an important bio‐transport link for potentially toxic materials and pathogens between waste sites and places where food is grown for human consumption.
http://jncc.defra.gov.uk/page-1412
Urban-nesting by Herring Larus argentatus and Lesser Black-backed Gulls L fuscus in Britain began in the 1940s, but became established as a national phenomenon in the late 1960s and early 1970s. Since that time, numbers have grown exponentially, fuelled by ample food, high breeding success and apparently limitless habitat. Many towns and cities in Britain & Ireland now support growing colonies and it is estimated that, in 2004, the total population of roof-nesting gulls exceeded 120,000 pairs. Herring and Lesser Black-backed Gulls are opportunistic and omnivorous, taking advantage of a wide range of feeding situations. The urban breeding population in the Severn Estuary Region has increased from an estimated 2,632 pairs in 1994 to 23,930 pairs in 2004. Further increases on this scale would see the population in this region exceed 200,000 pairs by 2014 and a national population of more than one million pairs of urban-nesting gulls.
The BOURC Taxonomic Sub-committee (TSC) recently published recommendations for the taxonomy of the Herring Gull and Lesser Black-backed Gull complex (Sangster et al. 2007). Six species were recognised: Herring Gull Larus argentatus, Lesser Black-backed Gull L. fuscus, Caspian Gull L. cachinnans, Ye I low- I egged Gull L. michahellis, Armenian Gull L. armenicus and American Herring Gull L. smithsonionus. This paper reviews the evidence underlying these decisions and highlights some of the areas of uncertainty.
The distribution and feeding range of Herring Gulls and Lesser Black-backed Gulls breeding on the Dutch Wadden Sea islands were assessed, using the results of ship-based surveys in the southern North Sea. The occurrence of both species in association with commercial fishing vessels is described in relation to distance to the coast and distance to the colonies. The feeding range of Lesser Black-backed Gulls (95% of all birds within 135 km of the colony) was considerably larger than that of Herring Gulls (95% within 54 km), and this difference could not be explained by differences in flight capacities. Feeding success and vulnerability to robbery of both species as scavengers at fishing vessels are described. Neither the vulnerability to robbery indices, nor the feeding success indices of both species did support earlier suggestions that Lesser Black-backed Gulls may have outcompeted Herring Gulls at (nearshore) fishing vessels. The feeding range of Lesser Black-backed Gulls could not solely be explained by a general avoidance of Herring Gulls near the coast, nor by the presence fishing vessels further offshore in comparison with the coastal zone. It is concluded that the large feeding range was motivated by a third, but unknown factor. The reduction of fisheries near the coast has probably led to a reduction in feeding opportunities for scavengers near the coast.
Abstract
The occurrence of mammalian prey in the diet of two species of large gulls, Laridae, was investigated in order to quantify and compare the predation on mammals from coastal and inland colony sites. Specialised coastal nesting birds and a majority of individuals in an inland colony were found to feed on mammals frequently. The encountered mammalian prey included hedgehogs, shrews, voles, mice, moles, rats, rabbits and hares. Most mammalian prey may have likely been obtained on inland fields, perhaps during ploughing or similar activities of farmers, some may have been captured within the colonies, and some will have been the result of scavenging at roadsides. Many coastal mainland colonies of gulls have recently collapsed as a result of persistent predation by red foxes Vulpes vulpes. In addition, gulls breeding along the coast in the Netherlands increasingly suffer from shortages of food (mostly marine fish and intertidal invertebrates) during chick-rearing in recent years. Inland breeding did become more frequent and will further increase as a result of both factors, so that the gulls are expected to increasingly focus on alternative foraging habitats and prey species, mammals included.
Keywords: Apodemus sylvaticus, Arvicola terristris, Clethrionomys glareolus, Erinaceus europaeus, Lepus europaeus, Microtus arvalis, Microtus oeconomus, Mus domesticus, Oryctolagus cuniculus, Rattus norvegicus, Sorex araneus, Talpa europaea, predation, Laridae, mammalian prey, diet
This paper reports the results of a survey of large gulls breeding in Cumbria in 2009, together with an assessment of recent population trends. The survey found totals of 15,489 apparently occupied nests (AON) in 43 colonies for Lesser Black-backed Gulls Larus fuscus, 4,747 AON in 40 colonies for Herring Gulls L. argentatus and 85 AON in seven colonies for Great Black-backed Gulls L. marinus. A substantial part of the populations for all three species was concentrated in a few large coastal colonies, but there were many smaller colonies, mostly of roof-nesting birds in coastal towns, as well as a number of generally small colonies inland, chiefly in quarries or on islands in lakes. Since the 1998–2002 Seabird 2000 census, coastal colonies for all three species have shown a marked reduction in breeding numbers, but increases at those in urban areas; the declines far outweighed the increases, however. Despite the overall downward trend in the breeding population in this period the number of colonies increased. The factors responsible for these changes include the food supply, disturbance by man, and, to a lesser extent, disease.
Fishing boats in the North Sea and west of Britain may discharge 95 000 tonnes of offal and 135 000 tonnes of whitefish discards each year, enough to feed two million scavenging seabirds. Fulmars Fulmarus glacialis take most offal. Success rates in obtaining discards are gannet Sula bassana>great skua Stercorarius skua>great black-backed gull Larus marinus>lesser black-backed gull L. fuscus>herring gull L. argentatus>kittiwake Rissa tridactyla and fulmar. Gannets mainly exploit discards in spring, when they cause a reduced feeding success in, and partially displace, herring gulls from feeding at boats. Lesser black-backs show a greater tendency than herring gulls to feed at boats rather than at refuse tips. Numbers foraging at boats in the Clyde. W Scotland, in summer are large in relation to breeding numbers for lesser and great black-backed gulls. Discards are important for adult gulls of these species in summer. Discards can be an important part of herring gull chick diets but are less important for adults. Planned net-mesh changes to reduce discarding and a trend to use offal rather than discharge it may have pronounced effects on scavenging seabird populations. -from Authors
About 70% of the local herring gull Larus argentatus population fed at refuse tips throughout the year. Tips were also of considerable importance to lesser black-backed gulls L. fuscus in summer and winter, and to great black-backed gulls L. marinus in winter (c. 45% of birds). Common gulls L. canus and black-headed gulls L. ridibundus fed mainly on fields (c.90% and 70% of birds, respectively) and these areas were also used by c.50% of lesser black-backed gulls in winter. Littoral and inshore areas were utilized mainly by great black-backed gulls throughout the year (c.50% of birds) and by lesser black-backed gulls in summer (c.20% of birds). Foods provided directly or indirectly by man were clearly of major importance to all species. Findings are discussed in relation to the partitioning of food resources by gulls, their increasing populations and possible control measures. -from Authors
This paper summarises the January 1993 Winter Gull Roost Survey and evaluates the results of this and the four previous surveys of wintering gulls, carried out in 1953, 1963, 1973 and 1983. In total, 2,594,491 gulls were counted in Great Britain during the 1993 survey: 1,263,208 at inland sites and 1,331,283 on the coast, comprising an estimated 1,682,385 Black-headed Gulls Larus ridibundus, 429,331 Common Gulls L. canus, 60,830 Lesser Black-backed Gulls L. fuscus, 376,775 Herring Gulls L argentatus, 43,108 Great Black-backed Gulls L marinus and 2,062 gulls of other species. A further 19,030 gulls were counted in Northern Ireland, 3,853 in the Isle of Man and 8,477 in the Channel Islands. Using thresholds of 1% of the respective minimum British populations, 22 sites of potential national importance were identified for Black-headed Gull, 28 for Common Gull, 19 for Lesser Black-backed Gull, 19 for Herring Gull and 20 for Great Black-backed Gull. Areas in which gulls were counted varied between surveys, but gulls at inland sites in England were counted in all five surveys. All five 'key' species increased at inland sites in England between 1953 and 1993, in particular Lesser Black-backed Gulls. The increase in wintering gull numbers in Great Britain has probably led to greater numbers of gulls using individual roosts and more roost sites being occupied. More recently, however, there have been some declines, notably of Herring Gulls.