New research led by the BTO shows that the UK’s internationally important seabird populations are being affected by fishing activities in the North Sea. Levels of seabird breeding failure were higher in years when a greater proportion of the North Sea’s sandeels, important prey for seabirds, was commercially fished. The UK’s seabirds are under pressure from human activities, such as resource extraction and fishing, as well as climate change. Under the European Marine Strategy Framework Directive, the UK is legally bound to make sure human activities are kept at levels consistent with “clean, healthy and productive” seas, and as top predators, monitoring seabirds can give insights into the state of the wider marine environment. In many species, counts of breeding individuals reflect population-level impacts of environmental pressures, but this is not necessarily the case with seabirds. This is because seabirds are long-lived and can delay breeding for several years after they reach maturity, or skip breeding seasons when conditions are poor. Scientists at the BTO and JNCC have now shown monitoring seabird breeding performance to be the way forward. The study, using long-term datasets from the JNCC’s Seabird Monitoring Programme for nine seabird species, showed the knock-on effects of fishing activities in the North Sea on seabird breeding at colonies on the east coast of England and Scotland. Sandeels are typically fished for use in animal feed and fertilizer. There is a large fishery on Dogger Bank, which is within the foraging range of many seabirds. In years when a greater proportion of the North Sea’s sandeels was fished, rates of seabird breeding failure rose. The study also found that seabirds breeding on the UK’s western colonies are faring better than those on the North Sea coast. Population declines and elevated breeding failures were found for eight out of nine species at North Sea colonies (with Kittiwakes particularly badly affected), compared to three out of nine on the west coast. The results demonstrate that seabird breeding can show how these key species are responding to environmental pressures before such changes become evident at the population level. Detecting such impacts as early as possible is a priority, as the management of the marine environment is changing, with expansion of offshore developments, the introduction of marine protected areas, and modification of fishing discards policy.

New research by the BTO reveals that most seabirds fly near the sea surface, avoiding collision with wind turbines by flying under the blades. Those birds that fly higher above the sea are at greater risk of collision. Building offshore turbines higher above the sea surface, or installing fewer large turbines instead of several smaller turbines, could reduce the number of collisions. In a project funded by The Crown Estate via the Strategic Ornithological Support Services (SOSS) work programme, BTO scientists examined the importance of flight heights in determining the risk posed to seabirds from collision with offshore wind turbines. Innovative statistical techniques were used to combine data from over 30 sites and a detailed description of the proportion of birds that fly at different altitudes were produced for each species. Results show that many species, including Puffins and Arctic Terns, spend most of their time within 5 m of the sea surface, while gulls flew more regularly at 20 m above the sea surface. These findings are particularly critical, in the light of the high number of offshore wind farms which are currently proposed in UK waters. Although wind farms are a key part of the government’s strategy to meet its renewable energy targets, they may potentially affect local birds, including protected and declining species. In severe cases, birds can collide with turbine blades and die. Estimates of the proportion of birds flying at different heights are fed into an assessment of the potential impact on wildlife for each wind farm, and can influence the likelihood that proposed renewable developments will go ahead. The results presented in this study show that if turbines are located higher above the sea surface, more birds will naturally fly underneath the turbine blades. The authors also suggest that seabird collision risk could be reduced by installing fewer but larger turbines, which produce the same energy output as a greater number of smaller turbines.

Although climate change is altering species’ distributions and populations, it is unclear how these impacts occur. New research led by the BTO (in collaboration with scientists from the Cambridge Conservation Initiative), reviewed almost 150 published studies to show that the main impacts of climate change occur through altered interactions between species within an ecosystem, rather than direct responses to climate. Each species shares an ecosystem with other species, some of which it might eat, and others that might eat or compete with it. This study found it was changes to the populations or activity of these other species that were responsible for many of the impacts observed. For example, Arctic Foxes have been affected by declining Lemming populations linked to changes in snow cover, and expanding Red Fox populations. In the UK, upland birds such as the Golden Plover are affected by increasing summer temperatures, which cause problems for their Cranefly prey. Importantly, as much conservation action is concerned with managing species’ populations (for example controlling invasive species or reducing predation risk), the conservation tools to reduce the impacts of climate change on species are already available, meaning that vulnerable species can be helped to adapt. For example, degraded peatland habitats in the UK uplands could be restored to boost Cranefly populations, and increase their resilience to climate change. Whilst this work identifies the sorts of species most vulnerable to future climate change, there is little information from the tropics, where most species occur, so more monitoring and research is required. This study highlights the need to consider the complex ecological relationships between species when assessing the impacts of climate change at a global scale.