How Birds Use Our Waters – Part 2: UK Territorial Waters
May 28, 2021
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In my last post in this series, I looked at how our coasts are crucial in supporting a huge diversity of bird species all year round. This time, I travel further out into our territorial waters, to see how the fate of the seabirds which call our shores home is inextricably tied to the health of our oceans.
What do we mean by territorial waters?
The term ‘territorial waters’ is often used as a broad term to encompass the seas which are under the jurisdiction of a government. This includes the territorial sea, which extends 12 nautical miles from the coastline, and the Exclusive Economic Zone, which extends a further 200 nautical miles out – unless there is another country within these limits. In the UK’s territorial waters, the government has control over all economic activity including fishing, mining, and energy production. It also has a responsibility to protect the incredibly diverse wildlife which calls these waters home, to make sure that we are surrounded by thriving, healthy seas.
It might surprise you to find out that the UK has the fifth largest Exclusive Economic Zone in the world, as it is responsible for the waters surrounding its overseas territories as well. This includes such far flung places as South Georgia and the South Sandwich Islands, Saint Helena, Gough Island, Tristan de Cunha, and the Pitcairn Islands. These overseas territories hugely increase the UK’s influence over the oceans, as well as the wildlife it is responsible for – a responsibility which is shared with the local governments of these territories. This also vastly increases the number of seabird species which occur in waters under UK jurisdiction, giving us an even greater role on the world stage in protecting them. For example, these territories are home to a quarter of the world’s penguins and a third of the world’s breeding albatrosses!
Why are our territorial waters important for seabirds?
Most seabirds are hugely dependent on the ocean as a source of food and are drawn to ‘hotspots’ of high productivity where prey is more abundant. These ‘hotspots’ are especially important during the breeding season, as seabirds need to have plenty of nutritious food within close range of their colonies so that they can provide enough for their hungry, growing chicks. The distances and locations they travel to find food will vary depending on the species, and even between individual birds, but seabirds must be able to balance feeding their chicks with their own energy needs. If they cannot, the adults must prioritise their own survival over that of their chicks, opting to try again the next year. Therefore seabirds thrive and successfully raise chicks in colonies where they can access abundant, reliable sources of food that they can travel to without exhausting themselves completely. The seas around the UK are highly productive, and this combined with the wide range of suitable habitats along our coastlines support the huge numbers and diversity of seabirds which live here. This is also true for UK overseas territories, with places like Gough Island supporting large colonies of breeding seabirds, including endangered sooty albatrosses, Atlantic yellow-nosed albatrosses, and the critically endangered Tristan albatross.
The availability of prey can be influenced by numerous factors which often interact in complex ways, such as ocean temperature, ocean currents, the topography of the seabed, and the time of year. Seabirds must time their breeding efforts for when conditions are just right and there will be plenty of food to raise their young. This means that their populations are highly sensitive to any changes in the marine environment that might affect how much prey there is, where it will be, and when it is around.
Our territorial waters are not just important during the breeding season, with some seabirds staying through the winter months whilst others disperse out into the open ocean or migrate to other shores. The birds that stay need to be able to find food to sustain them through the cold winter months, and whilst they are not tied to feeding their chicks at the colonies, stormy weather can rapidly deplete energy supplies and affect their ability to feed, with exhausted birds dying from hunger and exposure. These seabird ‘wrecks’ can be particularly bad in some years, such as in 2014, when thousands of dead birds washed up on our shores. Bad weather in winter can also have knock on effects in the breeding season, with storms in late winter and early spring influencing the ability of seabirds to get in prime condition for courtship and the demands of raising young.
Threats in our waters
What is clear is that seabirds require healthy, biodiverse, and productive oceans in order to give them the best chance of breeding and surviving all year round, and we therefore have a responsibility to ensure that this is the case where we have jurisdiction. However, some of our internationally important populations of seabirds, such as northern fulmars, European shags, Arctic skuas, and black-legged kittiwakes are declining alarmingly.For other species the picture is mixed, with Atlantic puffins doing poorly in places like Shetland and the Isle of May in the Northeast but faring better at Skomer and Skokholm Islands in Wales. Whilst the causes are often unclear as to exactly why these trends are occurring, with complex interactions between multiple stressors, we can identify some key factors in these declines:
Climate change
Warming oceans are affecting the availability of some prey species, such as sandeels, which are heavily relied on by birds like puffins and kittiwakes during the breeding season as a source of plentiful, nutritious food. Climate change is also increasing the incidence of severe storms, resulting in more seabird ‘wrecks’. The European shag is suffering this fate, being a coastal species which does not venture far from its colonies and having plumage which is not as waterproof as other seabirds it finds it difficult to escape bad weather and is therefore more susceptible to death by exposure. Climate change is going to be difficult to deal with, but the best way to ensure resilience against it is to deal effectively with other threats, such as overfishing, which are easier to deal with.
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