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16 May 2022

From the edge of the world 2022 – part 4

Written by Sue Loughran, St Kilda ranger
Two people sit on a grassy and rocky hillside. It appears very windy. They are setting up a bait station, which consists of a deep plastic tray with a little entrance hole at the side and a bait disc inside.
We’ve been setting up bait stations all across the island.
In the last few weeks, we’ve been working with Sarah Lawrence (Biosecurity for LIFE Project Officer) to improve our biosecurity measures for the islands of St Kilda – but what does biosecurity actually mean in practice? And how can everybody play their part?

One of the major threats to the islands of St Kilda is the possibility of an invasion of non-native species. Most notably, this would be the accidental introduction of the brown rat. The archipelago is one of the most important sites in the North Atlantic for breeding seabirds, and the introduction of rats would be catastrophic for the nesting birds. We need to keep a vigilant watch for any signs of rats coming ashore and must work very quickly if we have evidence of their presence.

Biosecurity for LIFE is a partnership project between RSPB, the National Trust for Scotland and the National Trust. It is funded by EU-LIFE. Sarah Lawrence is very familiar with St Kilda, as she was Seabird and Marine Ranger here in 2019. In her new role as Biosecurity for LIFE Project Officer, she arrived laden with information for us to give to visiting yachts. She also brought key information on how to set up a network of baited stations and all the necessary ingredients to make tasty wax bait.

A young woman wearing a padded purple coat sits beside a small stone structure on a windy hillside. She holds open a plastic bait station, which contains a numbered reference, a bait disc and a note advising 'Contains harmless flavoured wax'.
Sarah Lawrence from the Biosecurity for LIFE project

The first part of our biosecurity response is to have a permanent set of baited boxes situated around the islands. The bait is harmless to wildlife and is a mixture of wax and a strong flavouring, such as chocolate or coconut. It’s designed to be attractive to rodents, who will nibble on it and leave their tell-tale chew marks behind. We’ve set up a network of 12 such stations around Village Bay, and a further 14 around the rest of Hirta.

We spent a few long and very enjoyable days hiking around the island setting up and marking the stations with GPS. We now have to check the village stations every week – we look for chew marks, smooth back or replace the blocks, and record what we find. The rest of the stations will be checked monthly. All of this data is then recorded and sent back to the Biosecurity for LIFE project, who have a support team available should there be positive sightings.

Our job is complicated by the fact that we have a large population of endemic St Kilda mice, and so skill is needed in identifying which species made the chew marks. If rat chew marks are detected, a large and immediate response is triggered, aimed at eradicating the invasive population as quickly as possible. The plan is to extend the range of these stations to include the other islands within the St Kilda archipelago later this year.

Just as important as carrying out surveillance is the process of active prevention. The Biosecurity for LIFE project works on small islands around Britain and aims to educate the public in the importance of preventing the spread of invasive mammals. Their leaflets give practical advice to travellers about taking care when packing and checking for signs of rodents in their luggage. Here on St Kilda, we try to give this information to as many visiting yachts as possible. We also require all passengers to approach the jetty by open tender (a boat without an enclosed cabin), as this makes it less likely that a rat could be unwittingly brought ashore.

The landing craft that brings supplies to the Qinetiq base on the island several times a year has to undergo stringent checks, both prior to and whilst sailing to St Kilda. A dedicated watch person observes the slipway whilst the vessel is loading and unloading, and the whole process is also filmed to check for rodents.

Three leaflets and posters, advising about how to protect against invasive non-native species, are displayed against a plain grey background. The leaflet on top is titled What is biosecurity? and features a photo of a rat and some seabirds. The poster behind it has a drawing of a yacht, with some numbered points about how to check for unwanted visitors.
Some of the material produced by the Biosecurity for LIFE project

In addition to mammalian biosecurity, we also work hard to prevent the spread of non-native pathogens between islands. All visitors are asked to walk over a foot mat impregnated with disinfectant when they arrive and leave. This aims to prevent the spread of bacteria, fungi, spores and viruses and is another facet in our biosecurity plan.

A woman wearing a white face mask pours a bucket of liquid over a large mat on a stone jetty.
The foot mat at the main entrance to the island

We’re really trying hard to keep the islands safe and hope that you will help us whenever you visit. We look forward to welcoming you in the most biosecure way possible!

From the edge of the world

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