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2020 Status Assessment:

Lesser black-backed gull

Assessed Area:
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Key Message              |        
Background Information    |
    Geographical Range & Distribution            |
   Population/Abundance    |
        Condition
Threats and Impacts            |
            Measures that address key pressures
       |                      Conclusion (including management considerations)

Key Message

The status of the Lesser black-backed gull Larus fuscus fuscus breeding population is still vulnerable, but there is supposedly no trend in the population size  in OSPAR region I since the last assessment (Figure 1). The direct causes of the population development are still not fully understood. Identified threats are climate change, environmental pollution and other anthropogenic stressors, predation, competition, and food limitation.

Assessment of statusNon-Breeding Distribution Non-Breeding Population sizeBreeding DistributionBreeding Population sizeCondition i.e. breeding productivityPrevious OSPAR status assessmentEvidence of Status
RegionINANA←→2←→1235Poor ↓1
II      NA
III      NA
IV      NA
V      

NA

 

Assessment of key pressuresPollutionFood limitationsClimate changePredationThreat or impact
RegionI←→3?←→1↑5←→3
II    NA
III    NA
IV    NA
V    NA

 

Explanation to table:

Distribution, Population size, Condition

Trends in status (since the assessment in the background document)
↓     decreasing trend or deterioration of the criterion assessed
↑     increasing trend or improvement in the criterion assessed
←→     no change observed in the criterion assessed
trend unknown in the criterion assessed

Previous status assessment: if QSR 2010 then enter regions where species occurs (○) and has been recognised by OSPAR to be threatened and/or declining (● ). If a more recent status assessment is available, then enter ‘poor’/’good’

Status*(overall assessment)

red – poor
green – good
Blue cells – ? status unknown, insufficient information available,
NA - Not Applicable
*applied to assessments of status of the feature or of a criterion, as defined by the assessment values used in the QSR 2023 or by expert judgement.

 

Key Pressures

↓    key pressures and human activities reducing
↑    key pressures and human activities increasing
←→     no change in key pressures and human activities
? Change in pressure and human activities uncertain

Threat or impact (overall assessment)

red – significant threat or impact;
green –no evidence of a significant threat or impact
Blue cells – insufficient information available
NA – not applicable

 

1 – direct data driven,
2 – indirect data driven,
3 – third party assessment close-geographic match,
4 – third party assessment partial-geographic match  
5 – expert judgement.

Confidence

High confidence in the status assessment because of the quantitative data used, across the entire fuscus distribution. Confidence in OSPAR region I is slightly lower due to small sample size (two monitored colonies).

Lower confidence in threat assessment because the understanding of singular as well as interactive effects of climate change, environmental pollution, competition with intermedius and the Herring gull, predation, fishing, and other threats remains poor.

Background Information

Year added to OSPAR list: 2003 (OSPAR 2003)

The original evaluation of the Lesser black-backed gull Larus fuscus fuscus against the Texel-Faial criteria referred to decline, rarity and sensitivity, with information also provided on threat.

Global/regional importance: The entire breeding population of the fuscus subspecies was at the last assessment (2009) estimated to be 18 –19 000 pairs, whereof approximately 2500 pairs bred along the Norwegian and Russian coastlines within OSPAR Region I Arctic waters. The rest of the population breeds around the Northern Baltic Sea in Sweden, Finland, Russia and Estonia. The fuscus subspecies leave the OSPAR area after breeding and spend the winter in the Middle East, eastern Mediterranean and northeast Africa, and occasionally northwest Africa.

Decline: The fuscus subspecies was considered to be strongly declining already in 2002, with a then crucial decline estimated to 90% since 1970 (ICES 2002). There were also reports of disappearance from the Murman coast of Russia.

Sensitivity: The fuscus subspecies was originally listed as sensitive due to the small breeding population being restricted to a few breeding sites. It was considered especially sensitive to oil pollution, predation and disturbances.

Anthropogenic pressures and biological factors: The likely principal threats to the fuscus subspecies were changes in the abundance of prey species, pollution such as PCBs, and competition with and predation by the Herring Gull Larus argentatus.

Last status assessment: 2009. OSPAR (2009) concluded that the subspecies continued to qualify under the OSPAR criteria due to its strong population decline, current small population size, and the limited number of breeding localities, uncontrolled threats, and inadequate conservation measures. This concern has been corroborated by the current assessment.

Geographical Range and Distribution

The Lesser black-backed gull has a complicated taxonomy with five subspecies. The subspecies fuscus breeds in the White Sea and at a few breeding sites in northern Norway, along the Baltic coasts of Sweden, Finland, and Estonia, including inland lakes in Finland and Russian Karelia.

The geographical breeding range is declining outside the OSPAR area; within the OSPAR area this is presently not known.
Outside the breeding area the subspecies is challenging to monitor as it is a long-distance migrant wintering primarily in the lakes in and around the East African Rift (Uganda, Kenya, Tanzania and Ethiopia), but also the southeastern part of the Mediterranean Sea, the Red Sea and the Arabian Sea.

Figure 1. A. Breeding distribution and B. main migratory flyways (lines) and wintering areas (end arrows) of the Lesser black-backed gull Larus fuscus fuscus. OSPAR regions I-V are denoted by Roman numerals.

Figure 1. A. Breeding distribution and B. main migratory flyways (lines) and wintering areas (end arrows) of the Lesser black-backed gull Larus fuscus fuscus. OSPAR regions I-V are denoted by Roman numerals.

Method of assessment: 2b,3b – Source: monitoring programs in Russia and Norway, but also national surveys and monitoring programs in Finland, Sweden, Estonia, as well as data for Denmark.

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Population/Abundance

Trends in the number of breeding pairs (Figure 2) demonstrate a stable trend in the Lesser black-backed gull Larus fuscus fuscus in OSPAR region I since the last assessment. The seeming population drop in the Baltic Sea 1996-2000 and subsequent recovery 2000-2004 is driven by uncertainty in the Swedish surveys between 1996-2004. The trend is in reality most likely flatter during the first half of the study period (1990-2005). Whereas the trends are robust, the actual estimates are more uncertain (Figure 2 and Table 1). The number of breeding pairs in the Baltic Sea is considerably higher than in OSPAR region I.

Method of assessment: 3a – Source: national surveys and monitoring programs in Finland, Sweden, Estonia, Russia and Norway

Table 1. Predicted number of breeding pairs and relative abundance (a proportion of the baseline in 1990 set at 1,0) of Lesser black-backed gull Larus fuscus fuscus
OSPAR Region20082020
No. pairsRelative abundanceNo. pairsRelative abundance
I2 4002,62 4002,6
Baltic Sea9 0000,557 5000,47
Total11 4000,669 9000,58
Figure 2. Trends in the number of breeding pairs of the Lesser black-backed gull Larus fuscus fuscus during the period 1990-2020.

Figure 2. Trends in the number of breeding pairs of the Lesser black-backed gull Larus fuscus fuscus during the period 1990-2020.

Condition

Overall, breeding success in the Lesser black-backed gull Larus fuscus fuscus is exceptionally low, in OSPAR region I as well as in the Baltic, although it varies strongly between colonies and among years. Breeding success is in general too low to maintain a stable population size, although data from the last 20 years indicate that the population in OSPAR region I might on average just reach the minimum 0,45 chicks per breeding pair per year required to maintain a stable population size (Hario & Nuutinen 2011), given adequate adult survival rates.

Method of assessment: 2b – Source: current literature, expert judgements, and indirect data.

 

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Threats and Impacts

Threats appear to be continuing or increasing in OSPAR region I. Climate change and environmental pollution remain serious threats. The threat from predators in the breeding colonies appear to increase. The Lesser black-backed gull Larus fuscus fuscus is potentially still suffering from changes in prey abundance and composition. There is also competition from the larger subspecies intermediusand the Herring gull Larus argentatus. Other local threats are culling around fur farms and misidentification during hunting (among immatures, fuscus are mistaken for Herring gulls). The general population decline across the entire distribution suggests that the decline might be the result of several anthropogenic stressors and increased predation pressure.

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Measures that address key pressures from human activities or conserve the species/habitat

Russia and Norway have introduced national legislation, as well as the HELCOM countries Denmark, Estonia, Finland and Sweden. The subspecies is on the national Red list in all the above-mentioned countries except Norway which is not recognizing subspecies. Russia and Norway, in addition to the mentioned HELCOM countries, have taken measures to protect at least some of the key areas. Similarly, there are some MPAs, although none provide the highest level of protection. Russia and Norway have monitoring programmes in place, and Norway have undertaken some awareness raising activities. In addition, Norway has an ongoing bycatch monitoring project and have implemented actions from the Nordic Action Plan for Seabirds.

The Lesser black-backed gull Larus fuscus fuscus is a long-distance migrant and there are currently a few monitoring and conservation efforts on the wintering grounds, although yet none along the migratory trajectory.

 

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Conclusion (including management considerations)

The present status assessment confirms the vulnerable status by a small population size, but demonstrates no trend in the population size of the Lesser black-backed gull Larus fuscus fuscus in OSPAR region I since the last assessment. In the Baltic, there is a decided decline in numbers. The majority of the population is however located in the Baltic Sea. Outside the OSPAR area, the breeding range is likely in the process of shifting slightly northwards.

Threats are continuing or increasing in OSPAR region I. Climate change and environmental pollution remain serious threats, while the threat from increased predation on eggs and offspring seem to increase. Studies from the Baltic indicate that chick mortality due to organochlorine pollution has abated somewhat. Apart from the stable population development in OSPAR region I, the population decline of the Lesser black-backed gull Larus fuscus fuscus across almost its entire range is consistent with the general seabird declines. This suggests that the decline cannot be attributed to single causes but might be a result of a combination of several anthropogenic stressors, pathogens, predation, competition and food limitation.

The Lesser black-backed gull Larus fuscus fuscus, is therefore still justified for inclusion in the OSPAR List of Declining Species.

There are still no specific conservation measures targeted at protecting the fuscus subspecies and the threats remain uncontrolled.

 

 

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Knowledge Gaps

The assessment was based on counts of nests or individuals during the breeding season at two monitored breeding colonies within OSPAR region I. Our understanding of the population development would benefit from inclusion of breeding success, and juvenile and adult survival into the present monitoring programs, and from monitoring also at the wintering grounds outside the OSPAR area.

The assessment of threats suffers from a lack of understanding of the joint impact of the stressors potentially responsible for the continuation of the population decline. 

Method used

Main source of information:

3. Assessment derived from a mix of OSPAR data assessment and assessments from third parties

Assessment is based upon:

a)    complete survey or a statistically robust estimate: this status assessment was greatly improved compared to the background document (OSPAR 2009), by the inclusion of survey data from the national monitoring programs in Finland, Sweden, Estonia, Russia and Norway, as well as data for Denmark.

Baggott, C., Helberg, M. & Muuse, M. (2018). Breeding ‘Baltic gulls’ from the Horsvær archipelago in Norway and the occurrence of such birds in Britain. British Birds 111: 499-511. 

Banks, P.B., Norström, M., Ahola, M., Salo, P. Fey, K. and Korpimäki, E. (2008). Impacts of alien mink predation on island vertebrate communities of the Baltic Sea Archipelago: review of a long-term experimental study. Boreal Environmental Research 13: 3-16.

Bevanger, K. & Thingsnes, P. G. (1990). Decrease in some central Norwegian populations of the northern subspecies  of the lesser black-backed gull (Larus fuscus fuscus) and its possible causes. Fauna norvegica Series  Cinclus Cinclus 13: 19-32.

Bignert, A., Olsson, M., Persson, W., Jensen, S., Zakrisson, S., Litzén, K., Eriksson, U., Häggberg, L. and Alsberg, T. (1998). Temporal trends of organochlorines in Northern Europe 1967-1995. Relation to global fractionation, leakage from sediments and international measures. Environmental Pollution 99: 177-198. 

Bustnes, J.O., Anker-Nilssen, T. & Lorentsen, S-H. (2010a). Local and large-scale climatic variables as predictors of the breeding numbers of endangered lesser black-backed gulls on the Norwegian coast. Journal of Ornithology 151: 19-26. 

Bustnes, J.O., Barrett, R.T. and Helberg, M. (2010b). Northern lesser black-backed gulls: what do they eat? Waterbirds 33: 534-540.

Bustnes, J.O., Borgå, K., Erikstad, K.E., Lorentsen, S-H. and Herzke, D. (2008a) Perfluorinated, brominated, and chlorinated contaminants in a population of lesser black-backed gulls (Larus fuscus). Environmental Toxicology and Chemistry 27: 1383-1392. 

Bustnes, J.O., Erikstad, K.E., Lorentsen, S-H. and Herzke, D. (2008b). Perfluorinated and chlorinated pollutants as predictors of demographic parameters in an endangered seabird. Enrivonmental Pollution 156: 417-424.

Bustnes, J.O., Helberg, M., Strann, K-B. and Skare, J.U. (2006). Environmental pollutants in endangered vs. Increasing subspecies of the lesser black-backed gull on the Norwegian Coast. Environmental Pollution 144: 893-901.

Bustnes, J.O., Moe, B., Helberg, M. and Phillips, A. (2013). Rapid long-distance migration in Norwegian lesser black-backed gulls Larus fuscus, fuscus along their eastern flyway. Ibis 155: 402-406.

Byaruhanga, A., Kasoma, P. and Pomeroy, D. (2001) Important Bird Areas in Uganda. Kampala: East African Natural History Society.

Cherenkov, A., Semashko, V. and Tertitski, G. (2007). Current status and population dynamics of nominate subspecies of Lesser black-backed gull Larus fuscus fuscus in the White Sea. Ornis Svecica 17: 29-36.

Christensen-Dalsgaard, S., Anker-Nilssen, T., Dehnhard, N., Strøm, H., Bustnes, J.O., Benjaminsen, S., Descamps, S., Erikstad, K.E., Fauchald, P., Hanssen, S.A., Langset, M., Lorentsen, S.-H., Lorentzen, E., Moe, B., Reiertsen, T.K., Systad, G.H.R. (2020). http://www.seapop.no/no/filer/pdf/arsbrosjyrer/seapop-arsbrosjyre-2019-web.pdf SEAPOP report: 28 s (in Norwegian).

Erikstad, K.E., Fauchald, P., Hanssen, S.A., Langset, M., Lorentsen, S.-H., Lorentzen, E., Moe, B., Reiertsen, T.K., Systad, G.H.R. (2020). Sjøfugl i Norge 2019. Resultater fra SEAPOP-programmet. SEAPOP report: 28 s (in Norwegian).

Elts, J., Kuresoo, A., Leibak, E., Leito, A., Leivits, A., Lilleleht, V., Luigujõe, L., Mägi, E., Nellis, R. and Ots, M. (2009). Eesti lindude status pesitsusaegne ja talvine arvukus 2003-2008. Hirundo 22: 3-31. (In Estonian with English summary)

Erikstad, K.E., Bustnes, J.O., Lorentsen, S-H. and Reiertsen, T.K. (2009). Sex ratio in lesser black-backed gull in relation to environmental pollutants. Behavioural Ecology and Sociobiology 63: 931-938.

Fauchald, P., Barret, R.T., Bustnes, J.O., Eristad, K.E., Nøttestad, L., Skern-Mauritzen, M. and Vikebø, F.b: (2015). Sjøfugl og marine økosystemer. Status for sjøfugl og sjøfuglenes næringsgrunnland i Norge og på Svalbard. NINA rapport 1161, 44pp.

Gaginskaya, A.R., Semashko, V., Tertitsky, G. and Cherenkov, A.E. (2011). Notes on migrations and wintering paces of the lesser black-backed gull Larus fuscus fuscus.  The Russian Journal of Ornithology 622: 3-8. (in Russian)

Götmark, F. (1984). Food and foraging in five European Larus gulls in the breeding season: a comparative review. Ornis Fennica 61: 9-18.

Hario, M. 2006: Diurnal attendance of nominate Lesser Black-backed Gulls Larus f. fuscus at a Ugandan lake – implications for the conservation of a globally threatened subspecies. – Bird Conservation International 16 (4): 293-297.

Hario, M., Hirvi, J-P., Hollmén, T. & Rudbäck E. (2004). Organochlorine concentrations in diseased vs healthy gull chicks from the northern Baltic. Environmental Pollution 127: 411-423.

Hario, M. & Nuutinen, J.M.J. (2011). Varying chick mortality in an organochlorine-“strained” population of the nominate lesser black-backed gull Larus f. fuscus in the Baltic Sea. Ornis Fennica 88: 1-13.

Hario, M., J. Rintala and J. Tanner. 2009. Culling project on herring gulls of the central Gulf of Finland 2004-2007. Riista- ja kalatalous - Tutkimuksia 4/2009, Finnish Game and Fisheries Research Institute, Helsinki, Finland. (In Finnish with English abstract).

Hario, M. & Rintala, J. (2016). Population trends in herring gulls (Larus argentatus), great black-backed gulls (Larus marinus) and lesser black-backed gulls (Larus fuscus fuscus) in Finland. Waterbirds 39: 10-14. 

Hario, M. and Rudbäck, E. (1996). High frequency of chick diseases in nominate lesser black-backed gulls Larus fuscus fuscus from the Gulf of Finland. Ornis Fennica 73: 69-77.

Hario, M. and Rudbäck, E. (1996). Dying in the midst of plenty- the third-chick fate in nominate lesser black-backed gulls Larus f. fuscus. Ornis Fennica 76: 71-77.

Helberg, M., Systad, G.H., Birkeland, I., Lorentzen, N.H. & Bustnes, J.O. (2009). Migration patterns of adult and juvenile lesser black-backed gulls Larus fuscus from northern Norway. Ardea 97: 281-286.

ICES (2002). Report of the Working Group on Seabird Ecology (WGSE). ICES CM 2002.

Juvaste,R.(2002) Onnea Äänisen aalloilla ja selkä-lokin hätää Laatokalla 2000-2002. Siipirikko 29: 43-48 (in Finnish with English summary).

Juvaste, R., Arriero, E., Gagliardo, A., Holland, R., Huttunen, M.J., Mueller, I., Thorup, K., Wikelski, M., Hannila, J., Penttinen, M-L. & Wistbacka, R. (2017). Satellite tracking of red-listed nominate lesser black-backed gulls (Larus f.fuscus): Habitat specialization in foraging movements raises novel conservation needs. Global Ecology and Conservation 10: 220-230. 

Lif, M., Hjernquist, M. Olsson, O. & Österblom, H. (2005). Long-term population trends in the lesser black-backed gull Larus f. fuscus at Stora Karlsö and Lilla Karlsö, and initial results on breeding success. Ornis Svecica 15: 105-112.
Lund Bjørnås, K. (2017). Population trends of breeding birds along the Swedish coast. Master thesis, Lund University, Sweden. 

Lyngs, P. (1992). Ynglefuglene på Græsholmen 1925-90. Dansk Ornitologisk Forenings Tidskrift 86: 1-95 (in Danish). 

Nordström, M., Högmander, J., Laine, J., Nummelin, J., Laanetu, N. and Korpimäki, E. (2003). Effects of feral mink removal on seabirds, waters and passerines on small islands in the Baltic Sea. Biological Conservation 109: 359-368.

Olsson, O. and Hentati-Sundberg, J. (2017). Population trends and status of four seabird species (Uria aalge, Alca torda, Larus fuscus, Larus argentatus) at Stora Karlsö in the Baltic Sea. Ornis Svecica 27: 64-93.

OSPAR (2009). Background Document for Lesser black-backed gull Larus fuscus fuscus. https://www.ospar.org/work-areas/bdc/species-habitats/list-of-threatened-declining-species-habitats

OSPAR (2017).Marine Bird Abundance [Online]. London, UK: OSPAR. Available: https://oap.ospar.org/en/ospar-assessments/intermediate-assessment-2017/biodiversity-status/marine-birds/bird-abundance/

Strann, K.B. and Vader, W. (1992). The nominate lesser black-backed gull Larus fuscus fuscus, a gull with a tern-like feeding biology, and its recent decrease in northern Norway. Ardea 80: 133–142.

Valkama, J., Saurola, P., Lehikoinen, Al, Lehikoinen, E., Piha, M., Sola, P. and Velmala, W. (2014). The Finnish bird ringing atlas. Vol II. Finnish Museum of Natural History. (In Finnish with English summary)

Wikelski, M., Arriero, E., Gagliardo, A., Holland, R.A., Huttunen, M.J., Juvaste, R., Mueller, I., Tertitski, G., Thorup, K., Wild, M., Alanko, M., Bairlein, F., Cherenkov, A., Cameron, A., Flatz, R., Hannila, J., Hüppop, O., Kangasniemi, M., Kranstauber, B., Penttinen, M-L., Safi, K., Semashko, V., Schmid, H. and Wistbacka, R. (2015). True navigation in migrating gulls requires intact olfactory nerves. Scientific Reports 5: 17061.

Wistbacka, R., Remes, H., Back, R., Rönnqvist, R., Liljeqvist, F., Velmala, W. & Hultén, T. (2019). Övervakning av silltrutens beståndsutveckling och ungproduktion i Pörkenäs-nejden år 2019. Arbetsrapport (in Swedish). 

Wistbacka, R., Liljeqvist, F., Jåfs, Å., Back, R., Velmala, W. & Wistbacka, P. (2020). Inventering av20 fågelskär i Torsö skärgård år2020. Arbetsrapport Jakobstadsnejdens Natur och Ostrobothnia Australis (in Swedish).

 

Audit trail

Sheet reference:

BDC2020/Lesser_black-backed_gull, Larus fuscus fuscus