Between 2000 and 2008, the total number of seabirds breeding in the UK is believed to have decreased by approximately 9%. Breeding success has also declined over the same period. Climate change is partly responsible.

Trends vary between regions. Populations in the Irish Sea region increased on average by 37% during 1986-2007, in contrast to populations in the Eastern English Channel region, the Minches and Western Scotland region and over the Scottish Continental Shelf, which declined on average by 35-48% over the same period.

Mean breeding success has declined since 2000. As with population size, regional differences were apparent. Extremely low values were recorded for the Minches and Western Scotland in 1993, 1998 and 2005-7, but were generally higher than the other Regional Seas. Breeding success for the Scottish Continental Shelf region was lower than average, with mean success in this region very low in 1998, 2001, 2003-5 and 2007.

Evidence suggests climate change, in particular warmer winters, has resulted in major changes in the plankton in the North Sea that have probably reduced the availability and nutritional quality of seabird prey such as sandeels. Data on breeding success of species most sensitive to food shortages such as Arctic skua, kittiwake and shag suggest that climate impacts are greatest in the northern North Sea and Scottish Continental Shelf.

Continued poor breeding success and reduced survival will lead to further declines in some seabird populations in the short and long term.

Models predicting the future range of seabirds under climate change suggest that, by the end of this century, great skua and Arctic skua will no longer breed in the UK and the range of black guillemot, common gull and Arctic tern will shrink so that only Shetland and the most northerly tips of mainland Scotland will hold breeding colonies.

Climate-linked reductions in food supply can have a dramatic impact on the social fabric of colonies, with cases of infanticide recorded in guillemots for the first time.

Increased storminess may reduce available breeding habitat for shoreline-nesting species (e.g. terns), wash away nests and create unfavourable foraging conditions leading to starvation.

What is already happening: Medium

What could happen: Low

The level of confidence hasn't changed since the 2007-2008 card. The amount of evidence on what is already happening is moderate since aspects of the ecology of seabirds are comparatively well understood. Consensus on the key drivers of seabirds is also moderate. In contrast, there is little strong evidence about what will happen in the future, because of the combination of the uncertainty surrounding climate change projections, and the knock-on effects, including how climate will interact with current and emerging drivers of change such as fisheries, marine renewables and disease. For these reasons, there is less consensus and in particular model confidence with future changes than with current changes.

The top priority knowledge gaps that need to be addressed in the short term to provide better advice to be given to policy makers are:

1. In the short-term we need to better understand the nature of the interactions between climate, plankton and sandeels in order to predict the likely magnitude of future impacts on seabirds and to devise measures that may mitigate the impacts of climate change. A particular priority is information on sandeel population dynamics that provide the link between seabirds and secondary production. For instance, it is unclear why sandeel recruitment is negatively correlated with SST (see Arnott & Ruxton, 2002). We need a better understanding of the nature of the relationship between sandeel populations and secondary production, predation, fisheries and density dependent factors such as cannibalism (van Deurs et al., 2009). .
2. Whilst the focus to date has been on the interaction between seabirds and sandeels, other fish species are important prey for some species in certain regions. Of most significance is the little attention that has been given to the likely impact of rising SST on sprat and herring, which predominate in the diet of piscivorous seabirds in regional seas west of the UK e.g. in the Irish Sea and in the Minches and Western Scotland. Seabirds breeding there have generally had more successful seasons than around the North Sea up until 2005, after which birds appear to have been struggling to find enough fish and have consequently had poor breeding success. Work is required to determine whether these food shortages in the west are a result of increasing SST or some other factor. An understanding of the relationship between emerging species and climate change is also likely to become increasingly important.
3. It is becoming increasingly apparent that a number of factors can affect seabirds simultaneously. These interactions are likely to be complex but are poorly understood. An important priority for the future is to quantify the interactions between climate change and other drivers such as fisheries, disease and marine renewables.

There is strong consensus that these represent important knowledge gaps.

Seabirds provide an important source of income for some local economies - seabirds have a wide appeal to people: spectacular 'seabird cities' and enigmatic species like the Atlantic puffin draw visitors from near and far.

Mitchell, I. and F. Daunt (2010) Seabirds in MCCIP Annual Report Card 2010-11, MCCIP Science Review, 11pp. www.mccip.org.uk/arc