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This blog is designed to provide regular updates regarding the ongoing situation on Rousay, where the presence of a stoat was confirmed on 7 May. The most recent updates are directly below and the oldest at the bottom of the page. We have also included answers to some of the questions we are being asked.

Latest update - 12 June

Since the last update staff and volunteers have been continuing to monitor the traps and cameras. No stoat has been caught and we've not seen any further images. We also want to say a huge thanks and warm welcome to new volunteers that have joined the efforts. We held a morning of training with them and the existing volunteers so they are now assisting with trap checks as well as the mammoth task of collecting and checking images from the trail cameras.

We currently have 53 additional traps deploed, 22 trail cameras and 5 AI thermal cameras.

We are in the process of getting more cameras into the field, but also looking at how we can monitor more of them remotely to be more efficient. Signal conditions have been challenging, but we think we are close to finding a solution. We are also keen to find a way to do an automated initial filter of images from the standard trail cameras as each one produces an average of 1000 images a week to be checked.

Questions

  • How did the stoat get to Rousay?

    We can’t be certain, but stoats are excellent swimmers and Rousay is close enough to the Orkney Mainland (where stoats have been since 2010) that a stoat could have swum across. It is also possible that it was accidentally transported or that someone chose to break the law and deliberately release it. Stoats are not native to Orkney, and they couldn’t have got here naturally, but since their arrival they have spread to colonise the Orkney Mainland and the Linked Isles. Until now, they had been successfully contained to these isles and Orkney’s other islands remained stoat-free.

  • How concerning is this?

    Stoats are not native to Orkney. They have no natural predators here and an abundance of year-round food (in the form of Orkney voles) means their population can grow very quickly and remain very high. Their arrival poses a serious threat to Orkney’s internationally important wildlife including curlews, hen harriers, red-throated divers, Arctic terns and the Orkney vole which is found nowhere else on earth. The only way to protect this native wildlife and the parts of the economy that rely on it is by eradicating stoats. Since 2019, the project has removed more than 8500 stoats from the Orkney Mainland and Linked Isles, and native wildlife has started to recover.

    So, the confirmation of a stoat on Rousay is deeply concerning news for the community, for nature and for Orkney as a whole. Even by Orkney’s high standards, Rousay is an important place for nature, particularly for breeding seabirds and birds of moorland, peatland and lochans like curlews, red-throated divers, hen harriers and short-eared owls. It’s also one of the islands in Orkney that is home to the Orkney vole.

    We are likely to know more in the coming weeks about exactly how big the issue is. This will of course depend on whether we catch the stoat quickly. We will also start to gather evidence to determine whether this is a female or male stoat. A sole male stoat will have a negative impact on the island but only for the remainder of its life. A female stoat, which would almost certainly be pregnant, is a very different scenario.

  • Why does it matter whether the stoat is male or female?

    Assuming that there is only one stoat on Rousay, it makes a huge difference whether that stoat is male or female. A single male stoat will have a negative impact on the island but only for its lifespan; we don't know how old it was when it arrived but stoats only tend to live for 1-2 years.

    A female stoat is a different scenario, because female stoats are almost always pregnant. This is due to a combination of early sexual maturity and something called 'delayed implantation' which means that soon after a stoat's eggs are fertilised, the embryo's development is paused. Then up to 10 months later, they implant and develop fully. This guarantees that stoats give birth in spring when there is plenty of food and better weather.

    Because female kits can be impregnated as early as 20 days old (often even before they open their eyes), it is possible for a mother and all female offpring to be pregnant before the kits are old old enough to leave the den. In spring, females give birth to large litters of 6-12 kits (sometimes more), so the problem immediately increases from 1 to maybe 13 individuals to catch. Then in 10-12 months’ time, the male stoat kits will reach sexual maturity and can impregnate their siblings increasing the scale of the issue again.

    That's why we are working so hard not only to try to catch the stoat but to also gather evidence to help work out if there is more than one as well as any clues as to whether it is male or female. At the moment, there's no evidence it's more than one and not enough information to be certain whether it is a male or female. But every bit of information helps to build a picture of what is happening.

  • Isn’t the spread of stoats useful as they control rats?

    Actually, there is no evidence that stoats are an effective way to control rats. Experience from New Zealand shows they had no significant impacts on either the rat or rabbit populations there. And a study about the diet of stoats in the UK that looked at the stomach contents of 570 stoats found rat in just two. So, if folk are seeing fewer rats since stoats arrived, it is unlikely that it is because stoats have eaten them.

  • There are stoats in Shetland – why is this different?

    Stoats are likely to have been in Shetland since the late 1600s, and their numbers remain low and stable. This is probably because there isn’t as much easy prey for them, whereas Orkney has widespread populations of voles. It’s also thought stoats in Shetland are mainly feeding on rabbits so, for the most part, are not a threat to native wildlife. In Shetland, other invasive mammals such as polecat ferrets are of more concern.

4 June

Since our last update the team have been continuing to work with local volunteers to monitor the camera and trap network as well as begin to expand the response based on evidence found in the field. Although we have not had any more public sightings since the start of April, two dog searches at the start of this week did discover fresh scat (poo) in a location approximately 2km from the original sighting at the western end of Muckle Water. Alongside this, one of our cameras detected a stoat near the original public sighting location over the last weekend (30th-31st May). We also had an image of a stoat from one of our cameras on the north side of the island a few days before this.

A new network of cameras and traps was established, by the team of local volunteers, the day after the fresh scat was discovered at the western end of Muckle Water. The discovery of the fresh scat is very useful as this allows us to continue to build a picture of the extent of the problem, although more evidence is needed before we can draw any solid conclusions.

We currently have 53 additional traps and 23 cameras (including 5 AI cameras) on Rousay as part of the response.

The distance to Rousay from the Mainland is close enough that stoats may have crossed Eynhallow Sound by swimming.

28 May

Since the last update, a dog search found scat in a slightly different location to the south of Muckle Water and the team has set up additional traps and cameras in that area. The traps have been checked, with no stoat caught, and are being checked again today. No further sightings have been reported.

We currently have 35 additional traps and 20 cameras (including 5 AI cameras) on Rousay as part of the response.

Want to know more? We will be at The Pier Cabin from midday until 6 pm on Monday (1 June) and folk can drop by at anytime for a chat, to ask questions or to find out how they can get involved. We are then meeting with the Rousay, Egilsay and Wyre Development Trust to provide them an update.

Update – 21 May

With the support from the community volunteers, on Monday (18 May) the team checked the traps and cameras in both response areas. No stoat had been caught in the traps and no new stoat images were seen on the cameras either. The next check is today (Thurs 21 May). With support from NatureScot, we are also sourcing more cameras that can send alerts and images via SMS. These should help by allowing us to monitor what’s happening without having to return to the cameras unless batteries need replacing - providing they can overcome the signal challenges currently affecting some of our other kit.

Intensified response

The following day, 8 May, the team return to place additional traps and cameras and conduct further dog searches. The dogs find some old stoat scat. The team return three days later (11 May) to meet up with trained incursion response volunteers from the community and conduct another dog search around the edge of Muckle Water. They find some more old scat.

Stoat presence confirmed

On 7 May, during a check of the images captured by the trail cameras deployed on Rousay, two images of a stoat are found. They are from the same camera near the north-east side of Muckle Water.

A trail camera on Rousay captured an image of the stoat on 7 May

Initial response

Following each sighting, members of our trapping team head to Rousay on 9 and 14 April to deploy extra traps – in addition to those already on the island as part of preventative biosecurity measures – along with cameras, including AI cameras, and detection dogs, searching for signs of stoats. They don’t find any signs of stoat presence during these searches.

Initial sightings

On 8 April, after seeing one of the project’s posters, a tourist reported they may have seen a stoat near Muckle Water on 6 April. Two days later, on the Friday evening, another visitor to Rousay reports a second potential stoat sighting via the project website. It was from near Westness from 8 April.

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