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31 Jul 2020

Seabird conservation

Written by Susan Bain, Western Isles Manager
Two puffins standing on a grassy cliff edge on St Kilda.
Puffins on St Kilda, which is the biggest seabird colony in the north-east Atlantic
Seabirds are one of Scotland’s great wildlife spectacles and National Trust for Scotland properties are some of the best places to experience them.

Often overlooked or despised as the stealer of chips and ice cream on seaside picnics, some seabirds have an image problem. But they are a vitally important part of our coastal ecology and Scotland is one of the best places in Europe to see seabirds. Scotland is important globally for its large seabird colonies, supporting over 65% of the British and Irish seabird population. Many of these breed on Trust properties, from Rockcliffe on the Solway Firth to Unst in Shetland and from St Abb’s Head on the east coast to St Kilda at the furthest western edge, each place providing the perfect habitat to successfully raise young.

Nowhere in the UK has more seabirds than the tiny archipelago of St Kilda, with large colonies of gannet, fulmar and puffin. As you approach St Kilda by boat you’ll start to be accompanied by more and more seabirds: tiny puffins diving with a flash of orange feet as the boat approaches; shearwaters and petrels always just above the waves (and mesmerisingly never being caught by one); and gannets soaring above, seemingly effortlessly.

Large numbers of gannets soaring above cloud-covered cliffs on St Kilda.
Gannets soaring above the St Kilda cliffs

St Kilda is a perfect place for all of the 17 species of seabird that nest there. With no land-based predators, like rats or stoats, to eat their eggs and chicks, a range of habitats from cliff ledges to grassy slopes, and surrounded by an ocean teeming with life, it’s no wonder that St Kilda is home to hundreds of thousands of birds at the height of summer.

It’s highly likely that the first people on St Kilda also followed the birds to their island home and settled there. Although they took thousands of eggs, they seem to have done so in a sustainable way with rules governing what areas and how many could be taken. It should be noted, though, that the great auk – the large flightless ‘penguin’ of the north – became extinct in the 19th century due to over-exploitation across its range, with one of the last birds being killed on St Kilda in 1841.

Today the birds on St Kilda are protected and it’s recognised as one of the most important breeding areas in the North Atlantic.

Seabirds spend most of their lives at sea but do have to come back to land to breed and raise young, and it’s during those few short summer months that we’re able to study them. We count seabirds and their breeding success not only to better understand the birds themselves, but also to give us an indication of the marine ecosystem. Since they depend on the sea for their sustenance, seabirds reflect changes in the marine environment and help us understand how things are changing.

A woman kneeling on a grassy rock-strewn slope, cupping a baby bird in her hands.
Sarah Lawrence, St Kilda Seabird and Marine Ranger, holding a baby Leach’s storm petrel, which successfully fledged from one of our artificial nest boxes

It’s not always easy or straightforward monitoring seabirds – they choose their nest sites carefully and are often in difficult to reach places. On St Kilda you have to have a good head for heights and not mind coming back covered in mud, bits of dead fish and bird poo!

Some species, like kittiwakes and guillemots, can be counted by telescope and the colony will be visited several times throughout the season to see the development of egg to chick and get more accurate data. Puffins are trickier to study as they nest in burrows, so the only way to assess if there’s an egg or chick is to quickly reach in and see what you can feel. This can often end in a sharp nip from an adult bird! To get data on the colony of Leach’s storm petrels, which normally nest within scree slopes, we began a programme of artificial nest boxes several years ago so that we could better understand the life cycle of this tiny seabird. Year by year more boxes are used and we’re beginning to get really useful information on hatching and fledging.

The information we get every year from St Kilda is shared with colleagues in the UK and across the globe to build up better local and regional pictures. Some species are doing well and others have decreased alarmingly. The gannet population on St Kilda has remained pretty stable for the last 20 years, but the kittiwake population has declined by a staggering 90% since 1994 and there’s now a real risk that this species will vanish from St Kilda’s cliffs in the near future.

Puffins are also declining in numbers, but not so rapidly. Puffins are a long-lived species that raise just one chick a year, so it can take a while for trends to become clear. Last year on Dun, part of the St Kilda archipelago, we found a dead puffin just inside a burrow. It had been ringed on the same island in 1981, making it 38 years old.

However, the Atlantic puffin is declining across its range and has been classed as ‘Vulnerable’ by the International Union for Conservation of Nature (IUCN 2020). It’s a red flag that this species is experiencing difficulties, and with nearly one quarter of the UK’s population of Atlantic puffin breeding on St Kilda this is the place to understand the problems.

Shortage in food supply due to climate change is believed to be one of the major reasons in their dropping numbers. Sea temperatures around Scotland are increasing and marine species are changing, meaning that the fish that some bird species depend on just aren’t there anymore.

It’s important to keep monitoring. If we don’t understand what’s happening then we can’t manage effectively and we can’t provide information to the policy makers to make sure that we pass on this wonderful wildlife legacy to future generations.

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