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Seabirds and Waterbirds

Seabirds and Waterbirds
What is already happening?
  • UK and Ireland seabird and waterbird indices show declines since the 1990s, partly reflecting population responses to changing climatic conditions across species’ annual cycles and ranges. 
  • Declines in breeding seabird numbers have been linked to climate-mediated changes in fish prey species, affecting reproductive success and survival. Strong winds, heavy rain and rough seas can also impact reproductive success and overwinter survival for some species. 
  • Declines in UK waterbird breeding populations and north-easterly shifts in waterbird winter distributions in Europe are also consistent with a warming climate.

Medium evidence, medium agreement

Since the last MCCIP Report Card, significant reviews have evaluated the evidence on the impacts of climate change on seabird populations in the North Atlantic (Hakkinen et al., 2022; 2023; Johnston et al., 2021; Searle et al., 2022). The evidence for effects on different seabird demographic rates varies in extent, and there is significant variation in responses between species and locations, reflecting complex mechanisms. Furthermore, comparatively few studies have considered the direct effects of extreme weather events. There has also been an increase in the number of papers examining population and distributional responses of Palearctic waterbird species to climate change, across their ranges and annual cycles, with a particular focus on the importance of protected area networks. While, for both groups, there is improved understanding of the environmental drivers behind these changes, there remains a need for improved demographic monitoring to understand the underlying processes. As such, the overall assessment is unchanged.

What could happen in the future?
  • Climate change is projected to have mixed impacts on the breeding and non-breeding numbers and distributions of seabird and waterbird species in the UK and Ireland. Recent studies highlight the value of protected area networks in supporting resilience of species as they respond to climate change. 
  • Many UK and Irish seabird populations are at or near the southern limit of their breeding range and/or are highly sensitive to changes in prey availability, limiting their resilience to climate change. Some species may struggle to shift their breeding locations northwards due to low natal and breeding dispersal rates. 
  • Arctic and sub-Arctic breeding waterbirds that winter in the UK and Ireland are amongst the most vulnerable due to climate change impacts in their high-latitude breeding grounds. 
  • Direct impacts from changes in severe weather events and sea-level rise may increase for both seabirds and waterbirds in the future.

Low evidence, low agreement

In association with reviews of the evidence for climate change impacts on seabirds, there have been further studies predicting future changes in populations and their distributions (Cleasby et al., 2021; Davies et al., 2021; Searle et al., 2022). Recent modelling studies of future changes in the populations and distributions of waterbirds have taken a more-holistic approach, predicting responses across species’ ranges and annual cycles. These studies corroborate the conclusions of a previous large-scale review of climate impacts on migratory bird populations submitted to CMS (UNEP/CMS/Conf. 8.22) that identified Arctic-breeding waterbirds as amongst the most vulnerable to climate change (Robinson et al., 2009). Nevertheless, the approaches of such predictive studies remain limited and there remains a high degree of uncertainty associated with specific projections for individual species for both groups, given variation in mechanisms across the annual cycle, and also at a country level. As such, we regard both the extent of evidence and level of consensus across species groups as low.

Key Challenges and Emerging Issues

Previous MCCIP Report Cards for seabirds and waterbirds have identified overlapping knowledge gaps which remain relevant and challenging to address. We bring together and expand on these here, based on the current summary, highlighting associated emerging issues.

(a) Increased and improved monitoring and modelling of population responses to climate change

Challenges remain in ensuring that monitoring and analysis of trends in seabird and waterbird populations and demographic parameters (breeding productivity, survival) are robust. The potential for improving and integrating demographic monitoring of UK seabirds is currently being reviewed by the Seabird Monitoring Programme. There is also significant potential to improve and expand existing volunteer-based monitoring of the abundance, productivity and survival of Arctic and sub-Arctic breeding waterbirds in their temperate non-breeding grounds. However, a major challenge exists in monitoring these non-breeding populations as distributions shift north and east of areas currently covered by volunteer-based schemes in Europe. 

Integration of data from wider and improved monitoring, through national schemes, of abundance, breeding productivity and survival in population models, in conjunction with improved mechanistic understanding of processes, is required to better identify the causes of population and distributional change and predict the future impacts of climate change on populations. Where possible, individual-based approaches can also increase the ability to robustly attribute and predict population responses to climate, and to investigate the resilience and evolutionary adaptation of seabird populations to climate change. In understanding overall impacts on populations, we re-iterate the need for a holistic approach, considering direct and indirect mechanisms of climate change, and carry-over and density-dependent effects across the annual cycle.

(b) Improved understanding of interactions between climate and other drivers of population change

Whilst climate change is regarded as a major threat for seabirds, other pressures are identified in national seabird conservation strategies, such as Highly Pathogenic Avian Influenza (HPAI), offshore wind developments, invasive non-indigenous species, reduction in food from fishing, habitat loss, fishery bycatch, pollution, litter, and disturbance, which may interact with the effects of climate change. Similarly, waterbirds face pressures from anthropogenic threats including agricultural intensification, conversion of tidal flats and coastal wetlands by human infrastructure developments and eutrophication of coastal systems, as well as infectious diseases, such as HPAI.

Improved understanding of the interactions between climate and other environmental and anthropogenic pressures in explaining patterns of population change over time (Figures 1 and 2) is a priority for future research for both species groups and would enable improved prediction of future population responses, be that additive, antagonistic or synergistic.

(c) Improved understanding of adaptation to climate change 

There is an urgent need to understand the potential for measures to help seabird and waterbird populations adapt to the impacts of climate change, or to increase their resilience. The value of protected area networks in buffering climate change effects is already noted, and there is considerable potential for measures (e.g. managed realignment and habitat creation) to mitigate the potential losses of the intertidal habitats of waterbirds or of low-lying seabird breeding colonies due to rising sea level. However, the use of such measures to alleviate pressure on seabirds and waterbirds is a significant challenge because of the limitations in manipulating (i.e. engineering or managing) the marine environment.

Given the need to understand how climate change might impact seabird and waterbird populations across their annual cycles, any policies to promote their protection in the context of climate change require international solutions. Existing focus has been on the overarching value of protected area networks, but improved understanding of specific management practices that benefit adaptation for individual species and reduce the impacts of climate change would be of value to inform future policies.

* Image - Niall Burton, BTO