How Birds Use Our Waters – Part 3: The High Seas

June 24, 2021

In this series, I have focused on birds as often overlooked inhabitants of the marine environment, heavily dependent on it as we are for food, the air we breathe, and the regulation of our climate. This time we complete our journey, finally arriving in the ‘High Seas’, the parts of our ocean beyond national jurisdiction which cover a staggering 50% of our planet’s surface area! Along the way we have discovered how a great wealth of bird species rely upon the UK’s coastlines and territorial waters all year round, including our overseas territories, and we have talked about how our country has a huge responsibility to protect globally important bird populations.

However, most of these birds are not just tied to one country but are international in their lifestyles. For example, almost the entire world population of Manx shearwaters (Puffinus puffinus) breed in the UK, but they only spend part of the year on our shores. From July to March they migrate and winter in the South Atlantic, mainly off the coasts of Brazil and Argentina. Even during the breeding season they can feed many hundreds of kilometres away if conditions are right, way beyond the national jurisdiction of any country. Whilst we can try to protect birds at their breeding grounds or within territorial waters, in order to ensure a stable future for all bird species this needs to happen in all of the areas which are important for them, including the High Seas.

What exactly are the ‘High Seas’?

The High Seas exist beyond national borders and are a global commons to be used collectively by all nations, although these international waters have been historically hard to govern. The United Nations Law of the Sea Convention (UNCLOS) tries to regulate specific activities within the High Seas, such as deep-sea mining and overexploitation of fish stocks, but only 1.2% is formally protected. Human rights abuses and illegal activity are rife, and where there is regulation or oversight it is in relation to resource extraction rather than ocean protection. Whilst there is no clear legal framework for the management and development of Marine Protected Areas (MPAs) in the High Seas, what is clear is that these vast and deep waters support an incredible amount of biodiversity, much of which we know hardly anything about!

Birds without borders

At one time the movements of birds throughout the oceans were a complete mystery, with anecdotal evidence of individuals seen by ships or washed ashore providing only small clues as to their movements. The development of ringing schemes began to enlighten us, with birds caught and given unique metal bands which allowed us to identify individuals if they were ever recaptured. It is the staggering pace of development in tracking technology within recent years however which has now given us unparalleled insights into their exact movements at sea, although we have still only scratched the surface.

For example, we now know that Manx shearwaters have a hugely complex migration pattern with many stopovers, travelling south from the UK along the coastlines of western Europe and Africa, eventually crossing over to South America, where they spend the winter in the highly productive waters (see Part 2) off the Patagonian Shelf. After wintering here they then head North, following the coast up to North America before crossing over the Atlantic and back to the UK for the breeding season. Though there is some variation to this route, a Manx shearwater which lived to 50 years old could have travelled around 8 million kilometres in its lifetime, which is roughly ten trips to the moon and back! Another astounding migration is made by one of our rarest breeding birds, the red-necked phalarope (Phalaropus lobatus), with only a handful of breeding pairs in Shetland and the Western Isles. In 2012, geolocators revealed that one male bird had left Shetland in August and crossed the Atlantic Ocean to Canada, from where it moved down to Florida, crossed the Gulf of Mexico into the Pacific Ocean, and spent winter between the Galapagos Islands and South America until April, when it returned by the same route.

In a comprehensive recent study, an international team of researchers found that some of the more extensively seafaring species, the albatrosses and large petrels, spend almost 40% of their lives in the High Seas – birds such as the Tristan albatross (Diomedea dabbenena), 99% of which breed on Gough Island, a British overseas territory. Though tied to the colony around the central South Atlantic during the breeding season, non-breeders move extensively throughout the southern oceans, using areas off of South America and South Africa, searching for locations with high ocean productivity where food is abundant. Incredibly, increasing evidence suggests that these birds – which belong to the ‘procellariformes’ or ‘tubenoses’ – may be able to smell their way across the oceans, using odours to pinpoint foraging locations and find their colonies.

The importance of a High Seas Treaty

Unfortunately for birds living extensively in the High Seas, this is a large proportion of their lives where they are even more vulnerable to threats such as being caught in fishing gear or losing food resources to overfishing, threats that are easier to deal with in territorial waters. Many of these species are therefore some of the most threatened, and whilst bilateral agreements exist between certain countries to protect birds which occur in their territorial waters, such as between Japan and Australia, the High Seas are the most important at-sea area overall for albatrosses and large petrels. Species breeding in the UK and its overseas territories have some of the strongest links to the High Seas, as well as to countries such as Brazil and Argentina. What is clear is that coordinated cooperation between the UK and other nations to protect birds both within territorial and international waters is the best chance we have of halting and even reversing the path to extinction.

In August of this year, the UN General Assembly will meet for the Intergovernmental Conference on Marine Biodiversity of Areas Beyond National Jurisdiction (BBNJ) to work on a treaty which will decide on the “…conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction…”. This is a once in a generation chance to modernise governance of the High Seas with a strong treaty which can help to reach the target of 30% protection of the oceans by 2030. Proper protection of important marine areas for birds can help to regulate or even exclude fisheries with damaging practices which are one of the main reasons for the declines in albatrosses and large petrels. This, coupled with other measures such as the eradication of invasive predators decimating breeding colonies will allow populations to become much more resilient in the face of climate change, the effects of which we are already beginning to feel. Whilst it is too much to go into here, there are a lot of great resources explaining the High Seas Treaty and the desired outcomes by the High Seas Alliance and Greenpeace, for example.

Through this series, I hope that I have managed to convey just how connected the fate of the birds which call our shores home are to the health and protection of the entire ocean, not just our own waters. Protecting the incredible abundance and variety of these species depends upon dealing with threats both where they breed and spend their time at sea, and I hope that future generations will be able to marvel at their incredible lifestyles as I do, as I hope now you will too.

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