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Marine Birds Thematic Assessment

Executive Summary

Marine birds in the OSPAR Maritime Area are not in good status. Widespread declines in breeding productivity and population abundance have been observed in all OSPAR Regions assessed. Most marine birds were already not in good status in 2010 but additional deterioration has been observed for many species in the current assessment. 

Climate change is considered a major cause of marine bird declines, mainly via changes to their food supply. Anthropogenic activities exert additional pressures such as direct mortality, habitat loss / degradation and disturbance. The decline of marine bird populations will adversely affect the ecosystem services they provide, primarily by leading to imbalances in the food web, and will cause negative impacts on various ecosystem and cultural services as well. Good progress has been made since QSR 2010 to develop the ecological coherence of the OSPAR network of MPAs, including, for example, the designation of the North Atlantic Current and Evlanov Sea basin (NACES) MPA. However, given the continuing poor status of the marine bird species assessed, it is unlikely that these measures on their own are sufficient to reduce the key pressures from human activities. Addressing the decline in marine birds has been identified as a priority for OSPAR in NEAES 2030. OSPAR has committed to taking appropriate actions to prevent or reduce pressures to enable the recovery of marine species and benthic and pelagic habitats in order to reach and maintain good environmental status, including action to halt the decline of marine birds. The latter will be addressed by OSPAR’s forthcoming Regional Action Plan on Marine Birds, which will build upon the evidence provided by QSR 2023 to recommend action to reduce and eliminate, where possible, the main pressures and activities impacting marine birds.

Q1. Identify the problems? Are they the same in all OSPAR regions?

Most marine birds are predators. They feed on invertebrates living within or on top of the seabed or on fish and plankton within the water column above. The size and condition of bird populations is therefore dependent on the size and condition of prey populations. The declines in both breeding productivity and population abundance in many marine bird species appear to be due to a shortage of prey. In general, those species that feed on small fish at the sea surface are struggling more than others to find enough food, though this varies with region. Links between seabird breeding productivity and increasing sea temperatures strongly suggest that climate change is driving at least some of the observed declines in their prey. Over-fishing has also played a part in some regions in the past and fisheries are currently competing with seabirds for sandeels in the Greater North Sea. 

Climate change is also having a direct effect on marine birds that is evident through changes in the range and distribution of some species. There has been a north-eastward shift in the wintering range of many wader and wildfowl species (so-called “short-stopping”), leading to apparent declines in the Celtic Seas, which are partly offset by increases outside the OSPAR Maritime Area in the Baltic Sea. The breeding ranges of some seabird species are predicted to shrink northwards and this appears to be happening already with the disappearance of breeding colonies of black-legged kittiwake (one of the OSPAR threatened and declining species) from the Bay of Biscay region.

Fisheries are currently competing with seabirds for sandeels in the Greater North Sea. ©

The 2010 Quality Status Report highlighted that the key pressures on marine birds were: the removal of prey species (e.g., by fishing), loss of and damage to habitats, and the introduction of non-indigenous species. It stated that some pressures were increasing in the OSPAR Maritime Area and were exacerbated by climate change. The synopsis of this 2023 report is that the pressure on marine birds from climate change is being exacerbated by additional pressures from direct mortality, habitat loss / degradation and disturbance. 

Our need to address climate change - a major cause of marine bird declines - has led to unintended additional pressures on marine birds. Since the 2010 Quality Status Report there has been considerable expansion of renewable energy infrastructure, especially offshore wind farms, particularly in the Greater North Sea. Disturbance by windfarms at sea has permanently displaced birds from foraging areas or other important areas, leading to habitat loss; there is also a risk of mortality resulting from collisions with wind turbines. These impacts are likely to increase as renewable energy production is expanded offshore in most Regions. However, the cumulative impacts on bird populations of renewable energy production have yet to be adequately assessed.

Disturbance from other activities such as aggregates extraction, oil and gas production, shipping, and tourism can lead to temporary loss of habitat, which could have more significant impacts during the breeding season. These activities are predicted to change little in the future, except tourism, which is predicted to increase in most Regions. 

Pressure from invasive predatory mammals has caused the loss of safe breeding habitat in the past. The largest seabird breeding colonies in all Regions occur on islands that are currently free of mammalian predators, but these are potentially at risk from future incursions, possibly facilitated by human activities such as tourism.

Seabirds and some waterbirds are accidentally caught and killed in fishing gear (commercial, recreational or artisanal) in the OSPAR Maritime Area. The population impacts of incidental by-catch mortality on birds are largely unquantified, but there is some evidence to suggest these could be significant in some areas and fisheries. Marine litter is another cause of increased mortality in seabirds, through ingestion or entanglement, but the level of population impacts is currently unknown.  

Finally, an emerging threat comes from Highly Pathogenic Avian Influenza - although this was assessed as relatively low impact in QSR 2023. Major impacts (outside the reporting period) have already been seen in 2021 and 2022, also impacting seabird species which in previous outbreaks remained uninfected and thus unaffected.

The decline of marine bird populations will adversely affect the ecosystem services they provide, primarily by leading to imbalances in the food web. Healthy bird populations also contribute to the natural seascape and play a key role in ecotourism and the maintenance and enhancement of related economic activity. Their decline is therefore likely to impact other services including recreation, education, science and research, spiritual, artistic and symbolism, visual amenities and ecosystem species appreciation.

Q2. What has been done?

OSPAR has identified nine bird species of particular concern within the North-East Atlantic and agreed on recommendations for actions to be taken by Contracting Parties nationally and collectively in order to protect and conserve these species. Progress has been made in efforts to strengthen data collection and management to support policy action and knowledge exchange. Good progress has been made towards the ecological coherence of the OSPAR network of Marine Protected Areas (MPAs), for example by extending the area coverage contributing to the protection and support of marine bird species.

The designation of the North Atlantic Current and Evlanov Sea basin MPA in 2021 represents an important step forward for protecting the foraging grounds of many marine birds. This site is an important feeding and foraging area on the high seas, used both by seabirds breeding on the coasts of the North-East Atlantic and by birds migrating across the globe or nesting in other parts of the world. The NACES MPA is one of eight sites in areas beyond national jurisdiction (ABNJs) that have been designated to protect marine birds.

Measures taken by OSPAR to manage particular human activities or pressures relating to pollution, marine litter and physical damage are relevant for improving the status of marine birds:
The adoption of the 2017-2025 Roadmap for the implementation of collective actions within the Recommendations for the protection and conservation of OSPAR listed Species and Habitats (The Roadmap), has supported the implementation of collaborative efforts across the thematic boundaries within OSPAR and also helps to inform or support actions implemented at the national level.

Q3. Did it work?

Dead gannet. © Shutterstock

Of the nine species identified for protection by OSPAR, five have been assessed for QSR 2023 and are still threatened and declining. In addition, the Iberian race of common guillemot became extinct shortly after it was listed. Furthermore, given the continuing poor status of other marine bird species assessed in this QSR, it is unlikely that the measures currently being implemented are succeeding in reducing the key pressures and human activities.

Notwithstanding this, good progress has been made to develop the ecological coherence of the OSPAR network of MPAs to protect OSPAR listed bird species. There is a need to better understand what role the MPA sites play at particular life history stages of marine birds, and therefore the purpose of an MPA in relation to marine bird conservation. OSPAR MPAs provide an opportunity for addressing impacts from disturbance and habitat loss, and possibly impacts from fishing (i.e. over-exploitation of marine bird prey and incidental by-catch).

Marine litter causes harm to marine birds through entanglement or ingestion (although these impacts, particularly at the scale of populations, remain unclear). OSPAR has been at the forefront of international efforts to tackle the marine litter problem since the adoption of its first Regional Action Plan on Marine Litter (RAP ML) (2014 to 2021). The Marine Litter Thematic Assessment reports positive signs of a decrease in the quantities of litter found on OSPAR beaches and of floating litter in the North Sea over the last 10 years. When considered against the upward trend in plastic production and consumption in Europe over a similar period, this suggests that progress has been made in preventing plastics from entering the marine environment.

An assessment of oil discharges and spills shows that measures under OSPAR's Offshore Oil and Gas Industry Strategy 2010-2020 have led to decreases in the discharges of both hydrocarbons and the most harmful offshore chemicals. This will have positive impacts on marine birds.

Other competent bodies with complementary competencies to those of OSPAR have implemented measures at regional level that are important in addressing the state of marine birds in the North-East Atlantic. A number of region- and species - specific action plans have been implemented under the European Union, the Arctic Council Conservation of Arctic Flora and Fauna (CAFF) and the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), by the Nordic Council and under national action plans. Regional and species-specific action plans can help to provide an overview of the regulatory landscape and highlight the value of developing an OSPAR-scale action plan that can build on and strengthen existing responses.

Q4. How does this field affect the overall quality status?

Seabirds are important top predators in the marine ecosystem. The status of marine birds impacts other features, and as top predators, seabirds can be a visible signal of the overall health of the ocean that – unlike some other components – is relatively easily monitored. The decline of marine bird populations will adversely affect the ecosystem services they provide, primarily by leading to imbalances in the food web, and will cause negative impacts on various cultural services as well.

Two common indicators were used to assess the status of species breeding and / or overwintering in all OSPAR Regions except the Wider Atlantic. Overall, more than a quarter (and often considerably more) of species were found to be in poor status in each of the four Regions assessed. A retrospective analysis showed that the QSR in 2010 would have reached the same conclusion if the same indicators had been used then. However, in all four Regions the proportion of species in good status has decreased by approximately 10% since 2010.   

When the assessment was broken down into five groups according to foraging behaviour, grazing species was the only group where more than 75% of species assessed were in good status. This group was made up of a small number of duck and goose species, which winter along the coast of the North Sea and Celtic Seas and feed on saltmarsh vegetation and eelgrass beds.  

A large number of wader species were assessed in the Greater North Sea and Celtic Seas, where the majority overwinter in often huge concentrations on a range of intertidal and adjacent habitats, from rocky coasts to estuaries, feeding mainly on invertebrates. Most of these species breed in the north of the OSPAR Maritime Area and elsewhere in the Arctic and sub-Arctic. These birds breed at low densities across large areas of tundra habitat and therefore cannot easily be counted or assessed there - this explains why no such assessment was possible for Arctic Waters. Approximately one third of wader species in both the Greater North Sea and Celtic Seas were in poor status in 2010, but now that applies to more than half in Celtic Seas and 40% in the North Sea. This regional difference is consistent with a north-eastward contraction of the wintering range of Arctic-breeding species in response to milder winters further north resulting from climate change. In the birds’ Arctic breeding grounds, climate change impacts on food supply have reduced productivity and increased mortality from predation.

Only a few benthic-feeding seaduck species, which feed on invertebrates - mainly molluscs in or on the seabed - were assessed and around half were in poor status, both now and in 2010.

Waterbird and seabird species that forage in aquatic habitats were assessed in all Regions, except Wider Atlantic owing to lack of data reporting. They were divided into species that dive below the surface to chase and catch fish and those that feed on fish, plankton or detritus at the surface. In the Celtic Seas and Greater North Sea, a higher proportion of surface feeders were in poor status, and this was also the case in 2010. This would suggest that surface-feeding species suffered more limited food supply than species that could dive into the water column and catch prey at various depths. However, in Artic Waters the opposite is true, where currently 75% of water-column feeders are in poor status compared with 40% of surface feeders. The reasons for this discrepancy are unknown.

Percentage of species assessed that had a relative abundance above the threshold values in each functional group. Calculations are based on the whole set of species assessed within each Region, thus including species observed in different sub-divisions. Number in parenthesis is the number of species in each grouping. No assessments are available for the Wider Atlantic. From: OSPAR QSR2023 Indicator Assessment - Marine Bird Abundance

 Norwegian part of Arctic WatersGreater North SeaCeltic SeasBay of Biscay and Iberian Coast
Functional GroupBreedingNon-BreedingBreedingNon-BreedingBreedingNon-BreedingBreedingNon-Breeding
Surface feeders67% (6)67% (3)36% (14)60% (5)58% (12) 75% (8) 
Water-column feeders50% (8)25% (4)86% (7)75% (4)100% (6)33% (3)  
Benthic feeders 50% (4)0% (1)33% (3) 0% (2)  
Wading feeders  40% (5)63% (24) 47% (17)  
Grazing feeders 100% (1)100% (1)100% (5)80% (5)  
Breeding / Non-breeding total57% (14)50% (12)50% (28)66% (41)72% (18)48% (27)75% (8) 
All54% (26)59% (69)58% (45)75% (8)
Above threshold value (75%) 
Below threshold value (<75%) 

Q5. What do we do next?

Addressing the decline in marine birds has been identified as a priority for OSPAR in NEAES 2030. By 2025 at the latest, OSPAR will take appropriate actions to prevent or reduce pressures to enable the recovery of marine species and benthic and pelagic habitats in order to reach and maintain good environmental status, as reflected in relevant OSPAR status assessments, with action by 2023 to halt the decline of marine birds (S5.O4). A Regional Action Plan on Marine Birds will act upon the evidence in this current assessment to recommend action to reduce and eliminate, where possible, the main pressures and activities impacting marine birds. These recommended actions will consolidate those already in operation under the OSPAR Recommendations for the nine threatened and/or declining bird species and through existing species action plans such as those under the EU, CAFF and AEWA and national strategies. This is an important area of work that will be drafted in consultation with the OSPAR / HELCOM / ICES Joint Working Group on Marine Birds and will help to build a coherent response.

Climate change has been identified in this assessment as the main cause of the continuing declines in the status of marine birds in the North-East Atlantic. Climate change mitigation underlies all other responses, and without such action adaptation is likely to be ineffective. The pressure on marine birds from climate change is being exacerbated by additional pressures from direct mortality, habitat loss / degradation and disturbance. As part of its efforts to ensure sustainable use of the marine environment, OSPAR has committed to continue its work with the relevant competent authorities and other stakeholders to minimise, and where possible eliminate, incidental by-catch of marine mammals, birds, turtles and fish so that it does not represent a threat to the protection and conservation of these species, and will also work towards strengthening the evidence base concerning incidental by-catch by 2025 (S7.O6). This will increase the focus on the effects of incidental by-catch, including for marine birds. OSPAR should also take into consideration relevant incidental by-catch studies conducted in the framework of OSPAR, the European Commission, ICES, ACCOBAMS and ASCOBANS and their future conclusions. 

By 2023, OSPAR will develop common principles, and by 2024 develop guidance, to promote and facilitate sustainable development and the scaling-up of offshore renewable energy in a way that minimises cumulative environmental impacts (S12.O4). This will help to address emerging threats of habitat loss and disturbance from the growing development in offshore renewables. There are also other areas where marine birds could benefit from OSPAR’s work, including that on the restoration of benthic habitats , particularly for benthic feeding and grazing birds.

The effective implementation of many of these objectives will depend heavily on national action, which should continue to be reported through, for example, the implementation reporting requirements under the Recommendations on threatened and/or declining species and habitats. For migratory species, such as many marine birds, national action is not enough. To protect and conserve such species, regional or international collective actions will be crucial, as detailed in the OSPAR Roadmap. OSPAR recognises the need to increase its focus on identifying and implementing collective actions that add value to existing national actions and to the efforts of other international organisations. Overall, the 2019 implementation reporting indicates that there is a good level of engagement in implementing national actions within the Recommendations, in particular within the areas where the species and habitats are considered to be under threat and / or in decline. The level of engagement in collective actions is clearly at a lower level, with some of the more complex actions not having been progressed.
Many of the actions focus on monitoring and assessment, relatively few on response, but in either case there has been only modest progress. OSPAR will therefore develop a series of biodiversity action plans, starting with marine birds and coastal shelf benthic habitats, in order to identify priority response measures which are well-defined, add value and can be delivered within the resources available to the OSPAR Contracting Parties. 

The 2023 QSR provides a powerful evidence base for action. OSPAR will strengthen its capacity to use this evidence base, and all future assessments, to support engagement with other international partners. Engagement cannot be an end in itself; the development of a practical approach to ecosystem-based management (EBM) will provide the opportunity and the mechanism to share evidence and common objectives for a more sustainable use of the marine environment (see cross-cutting SX.O2 of the NEAES 2030). Working with partners and drawing on international best practice, OSPAR will consider the design and implementation of a pilot project on EBM in one of the OSPAR Regions.

Progress against all of these challenging objectives for biodiversity will be tracked through OSPAR’s NEAES Implementation Plan. A planned review in 2025 will provide an opportunity to adjust the NEAES and, if necessary, take further action to protect and conserve marine birds.

Marine Birds Assessments


Lead authors: Volker Dierschke, Stefano Marra, Matt Parsons 

Supporting authors: Adrian Judd, Federico Cornacchia, Emily Corcoran, Ian Mitchell, Morten Frederiksen, Graham French, Marco Fusi, Hannah Wheatley, Holly Baigent, Janos Hennicke

Supported by: OSPAR/HELCOM/ICES Joint Working Group on Seabirds (JWGBIRD), Biodiversity Committee (BDC), Intersessional Correspondence Group on the Quality Status Report (ICG-QSR), Intersessional Correspondence Group on Ecosystem Assessment Outlook (ICG-EcoC), Intersessional Correspondence Group on Economic and Social Analysis (ICG-ESA), Climate Change Expert Group (CCEG), and OSPAR Commission Secretariat

Delivered by

This work was co-funded by the European Maritime and Fisheries Fund through the project: “North-east Atlantic project on biodiversity and eutrophication assessment integration and creation of effective measures (NEA PANACEA)”, financed by the European Union’s DG ENV/MSFD 2020, under agreement No. 110661/2020/839628/SUB/ENV.C.2.


OSPAR, 2023. Marine Birds Thematic Assessment. In: OSPAR, 2023: Quality Status Report 2023. OSPAR Commission, London. Available at: