3 Sept 2024

From the edge of the world 2024 – part 3

Written by Tim Wallis, Biosecurity Volunteer

A view standing on a clifftop and looking down along an extremely rugged and steep coastline. The sea crashes into the rocks from the right.

A view down the west coast of Hirta, towards Mullach Bi

Our guest blogger Biosecurity Volunteer Tim Wallis shares a report of his time spent on St Kilda.

After just over three weeks on the island I’m now into my final week here, and it’s probably the wildest weather I’ve seen so far – continuous rain and gusts of up to 50 miles per hour all day. So, a good opportunity to sit indoors and write a blog post about what I’ve been up to!

I came to do the biosecurity volunteer role on St Kilda as a four-week sabbatical and a break from my regular job as an RSPB Warden at Conwy Nature Reserve in North Wales. The role is mostly concerned with preventing any non-native invasive species, particularly rats and other predatory mammals, from being accidentally introduced to the island, which could have a devastating impact on many of the breeding seabirds here. Any landing crafts bringing supplies to the island need to have a system of checks in place to ensure there are no stowaways, and boats have to be closely monitored during the loading and unloading of cargo on the slipway.

This would normally be the responsibility of the biosecurity volunteer. However, while today’s weather may be the worst seen in several weeks here, it has generally been an exceptionally windy August, and the rough seas have meant we’ve seen very little in the way of visitor boats, let alone any landing craft. There has still been some biosecurity monitoring and recording to do though. Bait stations are positioned all around the village, and more sparsely around the rest of the island, which are monitored monthly for any signs of invasive mammals. The bait stations contain harmless wax blocks; bite marks on the blocks can be used to identify any animals present. Fortunately, the only marks so far have been from the resident St Kilda fieldmice, which were probably brought to the islands thousands of years ago and do not pose any known threat to the seabirds.

A man-made cairn-like structure stands on the edge of a grassy cliff. Beyond it, out to sea, is the island of Boreray. The sky and sea are deep blue.

Boreray seen from the summit of Conachair in better weather

Aside from the biosecurity role, I’ve also been assisting Craig, the Seabird and Marine Ranger, with ongoing monitoring of St Kilda’s internationally important population of breeding seabirds, including puffins, Leach’s storm petrels and great skuas. There has been particular concern for St Kilda’s great skua population since an outbreak of avian influenza in 2021 and 2022 led to a decline of two thirds. The National Trust for Scotland has increased monitoring efforts for this species, while ensuring that disturbance is kept to a minimum, or avoided where possible.

Concern over slow start to seabird breeding season

There has been plenty of opportunity to see a variety of other bird species when out and about around the island, while also recording any rarities and anything else of interest. It’s been wonderful to encounter so many seabirds on a daily basis, with great skuas seen all over the islands, and Arctic skuas often flying around the village. Fulmars are also present just about everywhere around the coastline; I’ve probably never been anywhere else where they can be seen in such high numbers. Puffins were still present around their breeding colonies earlier in August but have now largely dispersed out to sea along with most of the other auks, apart from one or two black guillemots which have often been present in the bay. Gannets are often seen close in as well, while sea-watching has revealed Manx shearwaters further offshore, and several sooty shearwaters.

An Arctic skua, with dusty brown feathers and black legs, stands on a flat stone in a field.

A fulmar, which looks like a gull with a bump on its beak, sits on a grassy ledge on a steep cliff.

A close-up of a puffin's face, turned to the side to reveal a spectacular brightly coloured beak.

Other notable birds have included two pectoral sandpipers, a great northern diver summering in Village Bay, and a whooper swan that has been present on the north side of the island in recent weeks. A juvenile black redstart was an unexpected catch earlier in August by external researchers who were studying the movements and behaviour of the St Kilda wren.

However, the overall star bird during the time I have been here has without question been an American cliff swallow, which spent two days with us on 11 and 12 August. This was an extremely exciting sighting – a first for St Kilda and the Outer Hebrides, and only the second record for Scotland.

A sandpiper with a spotty brown back and throat, and a white tummy, walks across a patch of grass. It has long yellow legs.

A great northern diver, with a dark brown back and white chest, bobs across the greenish water.

A small swallow, a little more orange than the swallows normally seen in the UK, crouches on a patch of grass beside a rock.

Aside from birds, other sightings of interest have included several minke whales, a pod of around a dozen bottlenose dolphins (one of the less recorded dolphin species out here) and numerous grey seals.

My visit here also coincided with a group of researchers from the Soay Sheep Project, and it has been fun to spend some time helping the group with catching sheep and getting various data from them for their studies of this unique island population – a very interesting experience!

Four chunky grey seals lie on a seaweed-covered slab of rock, with the grey sea to the left.

A brown, short fleeced sheep stands in a field. It has short pointed horns.

Above all, taking up this role has brought me a fantastic and unique opportunity to visit St Kilda, with the chance to thoroughly explore many areas of the amazing coastline and hills all around the island as well as the natural history and interesting archaeology. I am very grateful to the National Trust for Scotland for making this opportunity available, and of course to the rangers here – Sue, Craig and Clare – for their hospitality.