New report shows reduction in invasive Stoats is making a positive difference for wildlife.
5 min read
A vole found only on Scotland’s Orkney islands has had its best season yet according to the latest report. An increase in Orkney Voles comes as the removal of non-native invasive Stoats progresses, thanks to the Orkney Native Wildlife Project.
The Orkney islands have a rich natural heritage. They host 15% of the UK’s Hen Harrier population, 6% of its breeding seabirds, and are the only place on Earth where the Orkney Vole exists. They are also a vital waypoint along the East Atlantic Flyway, a migratory corridor used by more than 150 bird species journeying between the Arctic and Africa.
However, non-native Stoats looked set to devastate the islands’ wildlife. First discovered in Orkney in 2010, Stoats have no natural predators, breed quickly and eat mammals and birds, and their eggs. A 2015 study warned that without intervention, Stoats would have a devastating impact on Orkney’s wildlife, particularly Orkney Voles, Hen Harriers and Short-eared Owls.
Determined to prevent this, the Orkney Native Wildlife Project resolved to remove the Stoats from the islands. In 2019, this ambitious partnership between RSPB Scotland, NatureScot and Orkney Islands Council began working with local communities in a world-first Stoat removal programme. In the last six years more than 8,500 Stoats have been removed, and this latest data demonstrates how these efforts are making a positive difference for the wildlife
The 2025 monitoring report shows that activity of Orkney Voles in spring reached the highest levels since regular surveys began, and autumn activity was also high.
It also found that the number of confirmed Hen Harrier breeding attempts was the highest it has been in more than a decade, and the number of Short-eared Owls recorded during the breeding season remained high, having recovered from low levels reported in 2019-20.
Orkney Voles are surveyed by looking for signs such as droppings and grass clippings (which are left behind from feeding). In spring 2025, the number of signs spotted were the highest recorded in any year since annual surveys began in 2019. Across 22 sites surveyed on islands with Stoats, vole signs were found in one-third of the small survey squares searched.
In 2025, volunteers from the Orkney Raptor Study Group confirmed Hen Harriers breeding in 74 locations on islands with Stoats – the highest number since 2012. Sadly, this did not result in record breeding success due to wet weather at a critical time resulting in high chick mortality.
Despite this, it is thought nearly 60 chicks still successfully fledged in 2025 from 57 monitored nests.
“We can reverse species declines if we take action!”
For Short-eared Owls, which are notoriously hard to survey, birds were confirmed at 55 locations on islands with Stoats during the breeding season, with proven breeding at 16 and nests found at six places by the Orkney Raptor Study Group. The results show an ongoing increase in Short-eared Owls at breeding sites since the Orkney Native Wildlife Project began.
Welcoming the news, Anne McCall, Director of RSPB Scotland, said: “The Orkney Native Wildlife Project is showing that we can halt and reverse species declines if we take action to address the threats Scotland’s wildlife is facing.
“Invasive non-native predators are a significant threat to much of the iconic wildlife found on Scotland’s islands. There are many factors that influence survival. However, to give species like the Orkney Vole their best chance, removing invasive non-native species like Stoats from islands is essential.
“Orkney supports a significant proportion of the UK’s breeding Hen Harriers and is the only place in the world where the Orkney Vole is found, so this news is deeply heartening.
"Everyone involved in the progress so far should be incredibly proud. Now we need to all come together to finish the job as soon as possible to not put what we’ve achieved at risk."
There is more work to do, but these results show the difference this ambitious undertaking can make.”
This reversal in fortune for Orkney’s wildlife would not be possible without the continued support from our partners, funders, local communities and many others – including RSPB members and supporters. Thank you.
