Invasive non-native species are one of the greatest threats facing nature. Today, at the start of the annual Invasive Species Week, Adam describes how the Orkney Native Wildlife Project is on the frontline of tackling this threat.

With a man at each ore, the skiff cut quickly through the breakers in the bay. Around them, and beyond the crescent of white sand, the forest climbed skyward. Mist crawled along its canopy, and above the crashing of the waves, the steady roar of birdsong echoed across the water. Behind the skiff, in the mouth of the bay, sat the ship. Great wooden ribs rising from the water, speckled with barnacles. 

The deck heaved with men preparing to go ashore. Above them, the ship’s cat napped in the rigging, while deep in the hull, the rats that it was supposed to be catching sculked among rotting sacks of wheat.   

As the men pulled the skiff through the surf, a lone rat climbed onto the gunwale and leapt into the water. They watched as it swam, ran across the sand, and vanished into the clamour of the forest. Over the next 400 years, this rat, its descendants, and the animals which were supposed to control them, would silence much of the birdlife responsible for the forest’s roar.   

Global impacts

‘Invasive non-native species’ are plants and animals which have arrived in a place through human activity, and have a damaging impact on native wildlife. They have been responsible for 40% of global extinctions in the past 400 years.   

On islands where native wildlife has evolved for a world without mammalian predators, the arrival of rats, mice, cats, ferrets, mink and stoats, has had catastrophic consequences. Islands make up less than 6% of the earth’s surface, yet 60% of all extinct species died out on islands. Despite this loss, perhaps 20% of the world’s birds still live on islands, as do 37% of all critically endangered species.  

Across the globe, efforts are now underway to eradicate invasive predators to protect native wildlife. While it is too late for many species, there are still places in the world where we have a chance to prevent spectacular losses, instead of reacting to them.   

Orkney's importance for wildlife

Orkney is one such place. Its scarcity of mammalian predators has made it a haven for ground-nesting birds like Lapwing, Oystercatcher, Curlew, Short-eared Owl, and Hen Harrier, Britain’s rarest bird of prey.   

 A hole in grass made by an Orkney vole

A vole hole (run) made by an Orkney Vole. 

Orkney typifies the disproportionate importance of islands for biodiversity. Although it makes up less than 1% of the UK’s landmass, it accounts for 11% of our breeding seabirds. This includes a quarter of all Arctic Terns. Orkney is also home to the Orkney Vole, a species found nowhere else in the world!  

Tackling the arrival of stoats

Stoats were first reported in Orkney in 2010 and pose a serious threat to native wildlife. We know this because they were introduced to New Zealand in 1879 to control invasive Rabbits. Over the following 150 years, they contributed to the extinction of the Laughing Owl, Bush Wren, and the native thrush. All ground-nesting birds. To this day, stoats continue to endanger the iconic Kiwi, while Rabbits remain a problem. 

A stoat (in brown summer plumage except for its tail which is winter white) with a vole in its mouth

Stoats are skilled predators and favour easy prey likes voles.  

The Orkney Native Wildlife Project (ONWP) was set up to prevent a similar tragedy from befalling Orkney. Stoats are voracious predators, and need to eat a quarter of their bodyweight a day just to survive. This equates to one Orkney vole per day, or two and half Lapwing chicks. In human terms, it is akin to having to eat 41 portions of fish and chips, every day, or you’ll die.   

This appetite, coupled with a rapid rate of reproduction, means that Stoats have the potential to devastate Orkney’s native wildlife. As of May 2023, the ONWP has managed to remove over 4,400 Stoats from across Orkney. This is the biggest invasive predator eradication in the Northern Hemisphere, and the biggest Stoat eradication in an inhabited area, anywhere in the world. As such, the project has worked with over 850 landowners to date.   

A trapper kneels beside a box housing lethal humane traps recording information on a notebook

A trapper visiting one of the trap boxes and taking detailed records.

The project uses a network of over 7000 trap boxes, most of which contain two lethal, humane traps. This is supplemented by Europe’s first detection conservation dog team! These six dogs (5 spaniels and Spud, the Labrador) are either trained to detect stoat poo or actual stoats. They can be used to search large areas or respond to public sightings to check if stoats are present and pinpoint their exact location.   

A dog handler cups the chin of one of the stoat detection dogs, Riggs

Riggs, one of six detection dogs that are part of the project team, with handler Lindsey. 

How people are paving the way to success

Sightings are integral to the project’s success. While operating in an inhabited area poses challenges, the abundance of people who are willing to report their stoat sightings is a huge asset. Orkney’s unique wildlife draws nature enthusiasts from all over the world, and this tourism has helped Orkney to maintain flourishing communities across its 20 inhabited islands. The nearly 12,000 volunteer hours that the ONWP has received is just one example of how local communities are working to protect their native wildlife. And we should take the chance to again acknowledge and thank the hundreds of landowners who have granted the project access for wildlife monitoring, trapping and dog searches.   

This work to remove stoats may be starting to show results. Since the start of the project, there has been an increase in successful curlew nests and last year, three quarters of oystercatcher nests survived. Taking action within the first decade of the invasion means that the catastrophic loss of native wildlife seen elsewhere in the world is not inevitable here.  

A close up of a curlew bathing at the edge of a pool

Curlew is one of the species benefitting from the removal of invasive non-native stoats

In Orkney, we have an opportunity to change the narrative around invasive species from simply saving what is left, to protecting all that we have.  

The Orkney Native Wildlife Project is a partnership between RSPB Scotland, NatureScot and Orkney Islands Council with generous support from the National Lottery Heritage Fund and EU LIFE. Find out more at where you can also sign up for regular updates, or follow the project on Facebook 


Header photo: Close up of a short-eared owl in flight (with its right wing curved in front of its body and left wing outstretched) at Durkadale in Orkney.  Ian Francis