Prehistory And Predators

The Orkney Islands is an archipelago of about 70 islands with 20 inhabited. Lying 16km off Scotland's north coast they cover almost 1,000 sq.km. More than half is Mainland, home to most of the 22,000 residents.

Orkney is world famous for its stunning Neolithic monuments; the Standing Stones of Stenness, The Ring of Brodgar, the village of Skara Brae and Maeshowe, a chambered tomb. Orkney is also important for wildlife with significant populations of seabirds, rare hen harriers, nesting waders and the endemic Orkney vole that sustains Short-eared owls, Orkney's only nesting owl.

In 2010, stoats colonised the Orkney Islands. Although native in Britain, they are invasive on the islands and left unchecked they will have serious ecological impacts. An ambitious trapping programme to eradicate them is now underway.

Predator Eradication Project

Island Size
​​Large
523 sq.km
Target Predators
Stoats
Eradication Methods
​Kill trapping
Project Stage
Early stage
eradication
​Visited
​September 2018

Orkney Islands Image Gallery

Click on an image to see a larger view with caption.
​Read more about predator eradication on the Orkney Islands below.

Eradicating Stoats

The Problem

Since stoats were first recorded on the Orkney Islands in 2010, records of sightings confirm their range has expanded across Mainland Orkney and the neighbouring islands of Burray and South Ronaldsay. Their abundance has also skyrocketed.

These three islands are now linked by the Churchill Barriers, a network of causeways that were ordered built by Winston Churchill during WWII to close the minor entrances to the safe harbour of Scarpa Flow. They were constructed by Italian prisoners of war.
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The first official response to this colonisation event was to encourage a community based volunteer trapping programme. However, the scale of the landscape and the speed that stoats were expanding their range soon defeated these efforts as a sufficient intensity of control could not be established and maintained.
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The Task

Easier said than done, the task is to eradicate stoats using an intensive landscape scale trapping programme.

The project is using lessons learned from trapping American mink on the Scottish Hebrides. The scale is huge with in excess of 10,000 traps being deployed and monitored by trained trappers.

Since 2010, a record has been kept of all reported stoat sightings. By comparing this with records of stoat captures will help to identify stoat "hotspots" and gauge the success of trapping to reduce the density and distribution of this invasive predator.
The Gains

The key gain of the project will be the avoidance of losses.

The agricultural landscape with its stone walls is very suitable for stoats. Their speed of spread and increase in abundance suggests there is little to limit their population. Preventing their colonisation of nearby large islands, such as Hoy will be a significant achievement.

Left unchecked, stoats will prey on ground nesting birds and the Orkney vole that is prey for short-eared owls and rare hen harriers. Protecting these species will help maintain the Orkney Islands biodiversity and status as an ecologically significant wildlife habitat.

Understanding Colonisation

On a map, the Orkney Islands appear remote. For five millennia humans have travelled to, from and between these islands.

History shows they have been at the forefront of social and technological innovation for centuries and these developments have been exported far and wide. The Vikings even voyaged as far as North America during their time on the islands.

The Orkney Islands are wild, they are not remote. ​Throughout history, significant influxes of people have been needed to build cathedrals and wage war. Captain Cook's ill-fated third voyage to the Pacific even made its first British landfall on the islands. Despite this constant transit of people, stoats did not colonise the islands until 2010.

So Why Didn't Stoats Arrive Sooner?

Trade and transport are always a risk for biosecurity incursions. High volume, rapid and frequent trade and transport magnify these risks.

Today trucks can be at a ferry terminal from anywhere in Scotland in a matter of hours, they can drive onto a ferry and arrive on the Orkney Islands in little more than an hour.  They can then drive throughout the islands before unloading their cargo.

If they were to transport hay for feeding livestock on one of the island's many farms it is not hard to imagine the hay being loaded from a dry Scottish barn complete with a nest of stoats to arrive on the islands within days, if not hours.

Biosecurity in the modern world is about managing risks. However, when a risk materialises the consequences can be catastrophic and very difficult to mitigate, as the stoat colonisation of the Orkney Islands demonstrates.
Page Header Image:  The neolithic Ring of Brodger stone circle, Mainland, Orkney Islands, Scotland.