What can Australia learn from Scotland in managing invasive non-native species?

Michael Reid, who is Director of Biosecurity Strategy from Agriculture Victoria in Victoria, Australia, visited Scotland recently as part of a Churchill Fellowship study tour exploring international approaches to invasive non-native species management.  The Scottish Invasive Species Initiative were delighted to host Michael for a few days to show him some of the current work underway in Scotland and to facilitate discussion with other projects active here.  You can read a summary of the visit here but Michael has shared some initial reflections on the visit from his perspective below.     

Australia is no stranger to alien invasive species – with a menagerie of introduced pests roaming, snorting and spreading their way across our vast landscapes – from camels, blackberries, deer, rabbits, toads and pigs, to name but a few of our more well-known ones. But, unfortunately, the problem isn’t going away; it is getting worse. Our lead scientific research agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), recently warned in their Plagues and Predators report that a disaster unfolds in our backyards – with invasive species being the primary cause of native animal and plant extinctions.

Rabbits seeking shade in a drought in Australia
Rabbits are an invasive species in Australia, causing environmental harm and impacting hundreds of vulnerable native species. Image courtesy of Rabbit Free Australia.

Although Australian invasive species may differ from the American mink or grey squirrels, the people factor is the common variable linking Scotland to Australia. Managing invasive species can often be considered a technical issue – which it is, but it is also much more than that. Fundamentally, it is a people issue – how people do (or do not) come together to manage invasive species effectively. Our policies, programs and institutions all shape their management. Also, who determines what is effective?  It’s difficult, it’s complex, and human dimensions can be messy.

Neds Corner Station – a 30,000 ha conservation reserve in the far north-west of Victoria, Australia, managed to protect and restore native species

In my experience, programs that engage and work with the people at the ‘coal face’ increase the probability of achieving change over the mid to long term. This reflects the old African proverb –

“If you want to go fast, go alone; however, if you want to go far, go together”.

Spending time with the Scottish Invasive Species Initiative, I learnt about the local-level politics of invasive non-native species, the importance of building ownership and the critical work of volunteers in delivering programs that operate at scale. 

Rabbit warren in Australia – there are no quick fixes to tackling alien invasive species

Secondly, it reminded me that managing alien invasive species is a mid to long-term game — the biology of the issue matters. The sheer numbers, the geography, mobility and the people factor mean that there are ‘no silver bullets’ (quick fixes) or ‘golden hammers (over-reliance on traditional tools’). Further, issues like the social license to operate seem more challenging. However, this shouldn’t be an excuse for inaction. Instead, we must engage broadly and bring in new ideas and experiences. Bringing in new voices and experiences and learning from others locally, nationally and globally offers the opportunity to re-frame and think differently about how to address invasive alien species in the future collectively.

Learning Network Participants at Neds Corner Station

Having had the recent opportunity to be a part of a Churchill Fellowship, I have been tramping around the globe exploring community-led responses to invasive species across New Zealand, South Africa, the United Kingdom and the United States of America. One common thread is that there is a lot to be learned from our collective experiences in managing invasive species – whether it is the removal of American mink from the Tay Reedbeds or stoats from the sub-tropics of New Zealand. Over the next few months, I will be looking to distil these lived experiences across each region and help facilitate these learnings – stay tuned.

My Experience as a Seasonal Project Officer with the Scottish Invasive Species Initiative

Owen Barron, Seasonal Project Officer, SISI Project, October 2022

We asked Owen Barron, Seasonal Project Officer for the Esk and Tay catchments, about his experiences working on the SISI project this summer.

My experience as a Seasonal Project Officer with the Scottish Invasive Species Initiative can be summarised in three words: physical, challenging and rewarding.

After following the project from the outside as an interested Animal & Conservation Biology student, then as a mink raft volunteer through my previous job as a Countryside Ranger, when I saw the job advertised I knew I had to get involved. I started my role on the 25th of April, just before the plant control season started in earnest.

Seasonal Project Officer Owen spraying giant hogweed

The project aims to increase native species biodiversity through the eradication of invasive non-native species. The invasive species I have mainly been dealing with include giant hogweed, giant knotweed, Japanese knotweed and American mink. Through no fault of their own, they find themselves here in Scotland and outcompete native species. Invasive non-native plants often grow in monocultural stands, which reduces native species biodiversity – and that’s where we come in!

First Thing’s First – Training Time!

When I started in post, I didn’t have the required qualification for pesticide application, so gaining this was an essential first step.  A course was quickly booked for me free of charge (as it can be for volunteers wishing to get involved with the project) and I completed the two-day training sessions.  I was nervous of the assessment after theory training, but after a few nights of study I felt much more at ease and completed the practical assessment without too much difficulty.   

I now have my herbicide spraying and injection certificates, which I will have indefinitely. Within a couple of weeks of starting my new job I’d gained a new professional skill and was ready to take this into the workplace!

Getting ready for some pesticide application practice during training – alongside volunteers and land managers who are working with the project

I work in the Tay and Esk catchments (Perthshire and Angus) alongside Project Officer Mark Purrmann-Charles. I was eased into the role with an introduction to the project area and shown around the offices, but then I was sorted out with equipment and we were straight out to survey the North Esk River for giant hogweed. When covering such a vast area and balancing several roles at once, time really is of the essence, and the mink and invasive plants don’t wait around for you!

Giant Hogweed Season

A crucial factor which allows us to cover different species is that their control seasons come at different times of the year. We start off the year with giant hogweed, with the control season running from May until July.

Cutting off giant hogweed flowers (from a safe distance) to prevent seeding

I was nervous about getting up close to these massive plants as I had heard stories about them and researched them online – they had turned from plants into monsters in my mind!

Another thing I realised at the start of the job was that I was not as fit as I thought I was. We tend to cover several miles in a day, trekking over difficult riverside terrain whilst wearing full protective clothing – this keeps us safe when working with chemical pesticides and also from the brambles, nettles, thistles, giant hogweed, and anything else that decides we are the enemy! On a warm day in June, it gets very sweaty and challenging. Without our volunteers who join us for the larger areas we would really struggle to treat all the areas in time before the plants set seed.

Getting set up with volunteers to spray some giant hogweed at Canterland beat (North Esk)

Throughout June and July I was mostly working on the North Esk and the South Esk, which are my local rivers – I’ve seen so much more of the wild spaces on my doorstep and explored places I never even knew existed prior to this role. I can proudly say I survived my first ever giant hogweed season and with no sap burn!

American Mink Control

American mink activity picks up around August as this is the time of year when juvenile mink start to find their own territory. My focus shifted from giant hogweed control to getting in touch with the 70+ mink volunteers throughout Angus, Tayside and Perthshire, to see how things were going and if they needed any new equipment.

One challenge I’ve faced is finding my way to some more obscure places and the hardest part has been trying to trust Google Maps. There have been several occasions when Google Maps has tried to lead my poor Fiesta across non-existent roads, through rivers and even changed to a totally different route mid-journey. Despite arguing with the voice coming out my radio almost every day, I’ve managed to get to my destinations and meet many amazing people that support the project and help keep Scotland’s wild spaces beautiful and healthy.

Mink raft set up with volunteer Mike at Stanley Mill – which has now successfully caught 3 mink!

Once a member of the public gets in touch via our website or email, I am responsible for setting them up as a volunteer. I first make contact over email to gain the necessary information (e.g. their address for ‘trusty’ google maps) before heading out to meet them and getting them up to speed with exactly what is involved in being a mink raft volunteer. I help the volunteer to find a suitable location for the raft, demonstrate how the equipment works and complete some registration papers with them. Connecting members of the public to conservation efforts is something I really take pride in doing and it’s brilliant meeting all the people that wish to take part.

Japanese and Giant Knotweed Season

Next is knotweed season, which has seen me through to the end of my seasonal contract and concludes my short but action-packed time with the project. The main area of treatment will be on the River Tay, and I’ll be swapping my knapsack sprayer for a large needle for stem injections. I hadn’t seen much of Perthshire, so I was excited to get started. However, one thing I felt apprehensive about was the flies as I heard they are much worse than on the Northeast coast and I already felt like I was being swarmed! There can be 50 flies pestering me but none at Mark – maybe that’s nature testing me even more to make sure I’m up for the job.

Survey mode – scanning the riverbanks for knotweed stands with Project Officer Mark

After a few weeks of getting up to speed, I was given the opportunity to lead on a control site for Japanese knotweed. I contacted our team of volunteers to see which days they were able to come out, then looking at the weather forecast we scheduled potential dates. On the day I would have to decide whether to go ahead with treatment or not, as the treatment can be ineffective if the plant is wet prior to control or if it rains too soon after, and strong winds also make conditions unsuitable for spraying. I then contacted the landowner to get permission to access and park on the site. We met at the location, got kitted up to start, and followed a rough plan for injecting the larger knotweed stems with neat chemical and spraying the smaller plants with our knapsacks. I was very happy that I was not on my own as it ended up taking much longer than I had anticipated, even with two of us!

After leading on this site by myself, I now realise the importance of surveying and monitoring as these allows you to find exactly where the target species is present and how best to plan treatment days. Follow up surveys are useful to determine if treatment was successful and if any follow-up control is required. If the initial treatment did not deliver the results you hoped for then it is essential to reflect on what factors may have caused this. For example, at my first control area I noted that it was fairly windy during treatment and it rained unexpectedly half an hour after the last section of knotweed was treated – and this was the knotweed which did not respond to treatment as well as the other three sections.

Japanese knotweed site before treatment
Japanese knotweed site after treatment

The weather has been a massive challenge throughout the project as well. You can have the most perfectly planned out control season and be as efficient as possible, but then the wind picks up and you are unable to spray, or the rain comes on and treatment will be ineffective as the pesticide is diluted, or it’s too warm and it’s unsafe to be working in full PPE, and then to top it off the first frost comes earlier than expected – which is the cut-off point for knotweed control season as the plant becomes inactive.

Final Thoughts

A massive factor contributing towards the success of the project is the time that our volunteers put in. Monitoring mink rafts, joining us for tough days of plant control, getting trained up and taking ownership of their own area to control invasive non-native plants – all of this would prove to be too much for a relatively small team of people without the support of our dedicated volunteers.

I have been impressed seeing images of giant hogweed and Japanese knotweed forests 4 years ago and comparing these to the same location today. Seeing native wildflower meadows replacing monocultures of invasive plants is hard evidence of success – and that is what makes all the nettle stings and sore legs worth it.

Off for a bit of spraying

I enjoyed every minute of the job and really feel like I’m part of something making a big positive difference, which is what I put myself through 4 years of university for in the first place! You would struggle to find a role that offers so much experience and conservation action in such a short timescale as a Seasonal Project Officer with the Scottish Invasive Species Initiative does.

Owen is now a Conservation Officer with Saving Scotland’s Red Squirrels – working in the Tayside and Angus areas. Thanks for all your hard work Owen and best of luck with the new job!

To find out more about the Scottish Invasive Species Initiative and how to get involved, you can visit our website, follow us on social media or contact us on sisi@nature.scot

My placement with the Scottish Invasive Species Initiative

Peter Stewart, PhD Student, Durham University, June 2022

I am a PhD student in the Conservation Ecology Group at Durham University. My PhD focuses on how invasive species alter the behaviour of native animals and the ecological consequences of these behavioural changes. I’ve been exploring this topic in the field through studying the invasion of prickly pear cacti (Opuntia sp.) in Laikipia County, Kenya.

My PhD is funded by NERC through the Iapetus2 Doctoral Training Programme. One of the cool things about Iapetus is that we have the opportunity to take a placement as part of our PhD.

I was looking for a placement which would allow me to apply my skills and knowledge to invasive species management in Scotland, while simultaneously expanding my knowledge and gaining experience in the broader Scottish environment and conservation sector. I reached out to the Scottish Invasive Species Initiative earlier this year after finding out that they offer placements and joined the project at the beginning of April.

Peter Stewart, PhD Student at Durham University

River Dee and River Don with the River Dee Trust

I spent the first month of my placement with the River Dee Trust, working on the Dee and Don rivers. One of the great things about working on a river is you get to experience a variety of activities in a wide range of habitats, from small streams on the upper catchment to the river mouth. This was ideal for me, as it’s just this kind of variety that I was looking for on a placement!

Many of the activities on the Dee revolved around the Atlantic salmon – one of the most important species in Scotland, both for the health of the ecosystem and also for their role in the Scottish economy. In April the focus is on monitoring the salmon smolt – adolescent salmon which are moving out towards the sea, while undergoing an array of physiological changes that will allow them to cope with marine life. A healthy run of smolt is vital for maintaining a healthy population of adult salmon which will later return to the river to breed.

Smolt are monitored using rotary screw traps, which allow fish to swim in from upstream but prevent them from swimming back out due to the rotating drum. Each morning I went with Trust staff Pamela and Al to check on the traps, which are situated on two of the Dee’s tributaries – the Tanar and the Beltie Burn. We’d measure the length and weight of each fish and take scale samples from some individuals to determine their age – before returning the fish to the river downstream of the trap. The traps also caught sea trout, as well as other species such as lamprey and minnows. We even caught an adult pike on the Beltie, which was certainly a surprise!

A snowy morning at Glen Tanar smolt trap
Sea trout (top) and Atlantic salmon (bottom) smolts

Working with the smolt was a great opportunity to learn more about their importance for the river, as well as to gain practical experience identifying and handling salmon and sea trout – there’s certainly a knack to handling slippery fish!

Another way that smolt are monitored on the Dee is through using acoustic tags, which emit a noise that can be picked up by hydrophones placed in the water. I helped deploy several of the acoustic receivers, which sit at the bottom of the river weighed down with a 40kg link of anchor chain – luckily we did this when there was still snow on the ground, meaning we could easily slide the anchor along the bank until we were at a suitable site! I also helped deploy some of the sentinel tags, which are secured directly in the river close to the receiver.  As long as the tag’s continuous pings are picked up by the receiver, we know the system is working.

I was also keen to see some of the habitat restoration work being undertaken on the Dee. This includes tree planting on the riverbank and the installation of “large woody structures” (i.e., big piles made from wind-blown trees!) in the upper portions of the river. These trees and structures improve the habitat for the fish and provide shade which protects them from extreme summer temperatures. I visited the restoration project on the upper River Muick with Pamela, and helped Colin to maintain tree enclosures on the Clunie Water.

Tree enclosures on the banks and large woody structures in the channel on the River Muick

During my time on the Dee and Don I also got to experience some of the invasive species management going on in the area. Jan, the Invasive Species Officer, showed me how to deploy and check a mink raft, as well as how to identify some of the key invasive plants including giant hogweed and American skunk cabbage. I was especially interested to learn about the skunk cabbage, as this wasn’t a species I’d heard much about before my placement.  My placement with the River Dee Trust was just a little too early in the year to really get stuck in with the control of invasive plants – that would have to wait until May when I changed placement host.

American skunk cabbage – early season
American skunk cabbage – flowering

River Deveron with the Deveron, Bogie and Isla Rivers Charitable Trust

In May I moved over to the River Deveron, to work with the Deveron, Bogie and Isla Rivers Charitable Trust.

In this half of the placement I’ve mostly been working with Karen, the Scottish Invasive Species Initiative Project Officer on the Deveron. One of the main species we’ve been tackling is giant hogweed.

We started off by visiting the MacDuff sheep grazing trial where a flock of sheep are being used to control giant hogweed in a patch of woodland in partnership with the local farmer. We deployed a couple of trail cameras to keep an eye on our woolly friends – hopefully we’ll get some great footage of them munching through the hogweed!

Deploying camera traps at the MacDuff sheep grazing trial site
The MacDuff hogweed-munching sheep!

After visiting the sheep, I helped Karen with the fixed-point photography surveys which are used to monitor giant hogweed and the other invasive plants at control sites. The surveys involve returning to the same locations at the same time each year and taking photos so that the change in invasive plant abundance can be measured over time. Comparing the sites I was seeing to the images in the previous years’ catalogue, it was great to see that there was far less hogweed than in the older photos – the management which the Scottish Invasive Species Initiative has been coordinating over the past few years is definitely having an impact. You can read some of the site case studies from the project to see how the photography and monitoring is important in showing that real progress is being made with these plants.

We then moved on to some hands-on giant hogweed hunting, treating several sites with herbicide. This is currently the main method for controlling the species (as well as many other invasive plants), so it was great to get some experience and to learn about the factors which you have to consider when designing a management programme.

Out spraying giant hogweed with Karen and Tom

I also helped out with outreach events. We had a couple of schools visit at the Markie Water near Haugh of Glass. I helped to run the mink raft demonstration alongside the Trust Director, Ritchie, as well as Melville the outreach mink! To help explain how we monitor for mink using clay pads in the raft, I had stretched my arts and crafts skills to prepare some lino prints of a few of the key species which might leave their tracks on the raft.

Set up for the Markie Water school visit
Melville the outreach mink!
Demonstrating mink raft’s clay pad – mink, water vole, otter, and duck prints

Overall, I’ve had a great time on my placement with the Scottish Invasive Species Initiative – and learned a great deal about invasive species management and conservation in Scotland. I’d like to give a big thanks to the Dee, Don and Deveron teams for making my placement so enjoyable!

To find out more about the Scottish Invasive Species Initiative and how to get involved, you can visit our website, follow us on social media or contact us on sisi@nature.scot

For more information about the work of the River Dee Trust please visit their website

For more information about the work of the Deveron, Bogie and Isla Rivers Charitable Trust please visit their website

Alien Detectives in Wester Ross

A pandemic tale of 17 schools, 31 classes and more than 440 pupils

Lorna Brown, Education Officer, Skye and Lochalsh Rivers Trust
November 2021

I visited my first school with the Scottish Invasive Species Initiative ‘Alien Detectives’ education programme in December 2019 – little knowing a pandemic lockdown with associated school closures was just around the corner. However, the teachers in Wester Ross are keen and resourceful and so, with their help, we carried on.  Two years on, at least one class, and in some cases the whole school, in all 15 of Wester Ross primary schools can say that they are Alien Detectives – having learned about the problems invasive species can cause, how to identify species that might pop up in their area and what to do about it if they do. 

The first school was Poolewe Primary School.  I went armed with home-made invasive species games – including fishing rods made from birch twigs, string and magnets and ‘lochs’ shaped and cut from old window blind material.  Straight away the pupils were enthusiastic and instantly engaged.  

Removing invasive species from the loch.

It was clear that the class were most concerned about the plight of the water vole due to the spread of the non-native American mink – possibly because they all had, through play, seen the world through the eyes of the water vole for a little while.  In a mink-themed game of tag the water voles quickly lose their ‘safe bases’ as mink are small enough to capture them in their burrows (hoola hoops in the playground).  Cries of “That’s not fair!” echoed the playground as pupils quickly understood that, indeed, it isn’t fair for the water voles in real life either.  

Playing the mink – water vole tag game

A few schools later and I was getting into the swing of things – so were the pupils!  At Badcaul Primary School pupils spread the Biosecurity word by producing and acting in a ‘Check Clean Dry’ demonstration at the ‘First Cast’ of the year on the opening of the Dudonnell River.  The anglers and ghillies, heeding the wise and stern words of the younger community members, left clutching their Biosecurity bags and Virkon disinfectant whilst promising that they would always remember to ‘Check, Clean and Dry’ their kit after every fishing trip.  Full of enthusiasm, I booked more school dates – including a programme of activities at Gairloch High School.

Local anglers and ghillies get the message loud and clear!

Then the pandemic hit, the schools shut their doors and the pupils (and everyone else) stayed at home.

However, thanks to teacher enthusiasm and flexibility, the Gairloch pupils completed a valuable but reconfigured project.  They produced fantastic posters about the American mink which I used to advertise for new local volunteers to run mink rafts when lockdown eased.

In parallel, the Scottish Invasive Species Initiative Project Officers used lockdown to develop a whole suite of presentations, games, activities, crafts, quizzes and puzzles to bolster the online educational resource – Alien Detectives – all ready for use as school access slowly became possible again.  I was delighted to see that the water vole – mink tag game had snuck in there too.  These extensive resources meant that, over time, most of my little box of home-made activities worked their way into the log basket by the fire…

Although school access remained impossible for external bodies, I had a sneaky way to get the Alien Detectives project moving – in my role as local supply teacher.  The pupils were delighted to trial the project resources – a big favourite being the Invasive Species Top Trumps games – which were played often and competitively!

Playing invasive species ‘Top Trumps’

But by far the most fun activity was designing their own invasive species. We followed the “Design your own Alien Species” activity notes and then brought the aliens alive using junk modelling.  The classroom studio may have been a huge mess after the modelling – profuse apologies given to the cleaner at the end of the day – but the class were extremely (and rightly) proud of their creations as they presented them to the whole school the next day confidently explaining all the special characteristics that made them successful invaders.

“Design an Alien Species”

New lockdowns continued into 2021 and outside organisations were still not allowed inside schools as they returned.  Our response was simply to take the project online and to get creative in the supply of materials to each class.  Empty school grounds were visited at weekends to leave a box of resources in 48-hour quarantine before use – polytunnels were a favourite storage place.  The project was then delivered through video conferencing learning sessions.  Whilst power point presentations were straight forward and simple games that involved the pupils leaping up or sitting down manageable, things got a bit more interesting when we used the activity box (previously stashed in the poly-tunnel), I supported as best I could from my kitchen!

Taking the project online and resource boxes

As classroom access has returned the number of classes I visit has increased.  I‘ve learned along the way too – finding that whilst it is possible to run workshops with six different classes in one day leaving games for each teacher to use and pass on, I probably wouldn’t recommend it…

So, what are my reflections on this whole invasive species in schools experience?  After two years, 17 primary and secondary schools, 31 classes and more than 440 pupils the invasive species word has well and truly been spread across Wester Ross – and my little birch magnet fishing rods are still going strong.  I know (I probably knew this already as a teaching professional) that every class and group is different – and that pupils routinely amaze with their questions, insights and ability to see the invasive species problems and solutions very clearly. 

I’d encourage anyone who works with young people to introduce them to the invasive species topic – it’s a fun, insightful subject and learning area and, with so many activities and games already produced and freely available in the Alien Detectives resource pack, no prior knowledge of the subject is required. 

So go on, have a go – you might find your inner mink….

All the Alien Detectives activities and resources are free to download and use for personal and educational use. The resources are self-explanatory and there are full instructions and answers with every activity.

If you are within our project area (approx. Highland, Grampian and Tayside) our project staff may (subject to availability) be able to work with your class to help deliver the topic of invasive alien species. Please contact us on sisi@nature.scot if you are interested.

For more information about the work of the Scottish Invasive Species Initiative please visit our website –


For more information about the work of the Skye and Lochalsh Rivers Trust please visit the website –


Zapping invasive plants – a trial on Exmoor

Holly Moser, Exmoor Non-Native Invasive Species Project Officer
September 2021

As many of you may be aware invasive non-native species (INNS) control can take many years and here at Exmoor National Park Authority we have been going at it for the last sixteen! A major part of our work, our knotweed control programme, has been running since 2005 and has resulted in a large reduction of the knotweed species, particularly Japanese and Himalayan knotweed across the National Park.

Each year we seek permission from landowners to treat knotweed using the conventional method of spraying glyphosate. Currently, thanks to the funding, we can offer this service free of charge. Our contractor completes the treatments between September and November when the herbicide is most effectively drawn down into the rhizome system.

Spraying Himalayan knotweed

This autumn we will be visiting 95% of the 850 plus knotweed sites we can treat using glyphosate, probably the highest percentage ever achieved on the programme! This may sound a lot but many of these sites are being monitored and may no longer need treatment because there is no visible growth showing. It is vital that we continue to monitor these sites because knotweed rhizomes can stay dormant underground for something like up to ten years, which means shoots can sneakily reappear!

On Exmoor there are several knotweed sites we cannot treat with herbicide because they fall on organically certified land and we have not found a suitable “organic” alternative to glyphosate treatment. This land provides a serious reservoir for invasive species to flourish, particularly where a plant is situated close to a watercourse allowing them to spread easily. There is also a lot of controversy surrounding the use of glyphosate as a herbicide and the future of its application is uncertain. So it is crucial that we expand our toolkit of methods to control INNS and find solutions for control on organic land.

In 2017, we began trialling Rootwave Pro which has proved to be very effective on annual weeds and was first trialled on Japanese knotweed in 2016 in Gloucester, by the Environment Agency. This technology forces an electric current of up to 5000 volts down through the plant, raising the temperature and boiling the plant cells. It’s very dramatic to watch – lots of steam and popping and banging! The plant is left to decompose, and you can see the effects of the treatment within a few weeks. I have to admit it is satisfying watching a plant which is causing so many problems and is so difficult to get rid of, turning yellow and wilting without the use of herbicides to treat it.

The Rootwave machine. You rub the electrode up each stem for approximately 30 seconds. It is a very dramatic treatment with lots of steam, popping and banging!

How are the trials going so far?

In 2017 and 2018 the National Park commissioned Ubiqutek, the manufacturers of Rootwave Pro, to carry out one treatment a year on five knotweed sites. It soon became clear that one treatment a year might not be enough because the knotweed continued to throw up lots of little shoots.

Left: 2017 – Japanese knotweed before any Rootwave treatments took place.
Right: 2018 – after a single treatment in 2017.

Luckily the project was able to use our new funding to purchase our own Rootwave Pro so that we could continue these trials and increase the frequency of treatments. We were also able to train up several local contractors to operate the machine. So we can now carry out up to three treatments a year on 28 different sites including other INNS: American skunk cabbage, giant hogweed and montbretia.

Although we have made great progress carrying out multiple treatments a year it has not been smooth sailing…

There are several factors to consider when using Rootwave Pro:

  • First the location. The machine needs to be transported to site on the back of a 4×4 or ATV due to its size and weight and you are also limited to a 27 metre long treatment cable from the vehicle. Although we would not expect to find knotweed on some of the most remote parts of Exmoor this has been a limiting factor for us. The technology is however adapting quickly and who knows how long it will be until Rootwave can be carried on your back…
  • Secondly, it cannot be operated if it is raining. On Exmoor this is a challenge, especially with the wetter summers we are now experiencing. However wetter ground is better for conducting electricity so if your operator is able to drop everything and fit in a couple of hours when the rain has stopped then rainy days don’t have to be a write off.  Having the flexibility to change plans and carry out a treatment when the time is right is definitely a bonus!

Of course, we have also had to deal with the elephant in the room which is affecting everyone. Busy schedules and short time windows impacted by the pandemic and combined with the British weather have not made it easy for our contractors. The result is that we have struggled to complete three treatments a year at all of our sites as we had first planned.

What results have you seen since you started the multiple treatments?

It’s important to point out that we are only in our second year of multiple treatments and the very early stages of this trial, but despite all the challenges things are looking quite promising.

It’s clear that every site has reacted differently to each treatment as you would expect when there are so many factors like competition from other species, ground substrate and moisture content in play. In our first year of multiple treatments, some of our knotweed sites continued to show vigorous growth. This is to be expected – invasive species, by their very nature, are tough to control.

Left: May 2020 – young Japanese knotweed appearing before Rootwave treatments took place.
Right: September 2020 – two months after the second treatment of the year.

Other sites looked more positive with less regrowth appearing. At this site (image below) our contractors reported only a handful of stems after its first ever treatment.

Left: August 2019 – before any Rootwave treatments.
Right: August 2020 – two months after its first ever treatment.

We have also seen similar results over the years at the sites that were first treated in 2017. Below you can see a comparison of two sites that received a single treatment in 2017, 2018 and 2019 and two treatments in 2020. These photos were taken in September. Both sites are yet to receive a treatment this year which makes a good comparison to September 2017 when the sites hadn’t been treated at all. Again, some sites have continued to show quite vigorous regrowth (top two images); while at others the difference is more obvious (bottom two images).

Two Japanese knotweed sites treated using Rootwave – single treatment in 2017, 2018 and 2019 and two treatments in 2020.
Top left: Site 1 before (Sept 2017), Top right – Site 1 after treatments (Sept 2021)
Bottom left – Site 2 before (Sept 2017), Bottom right – Site 2 after treatments (Sept 2021)

For our other species it is a similar story that multiple treatments for several years looks like it could be the way forward. We were however delighted to see that one of our skunk cabbage sites, where there was a single plant, does seem to have disappeared for the time being after its first year of multiple treatments.

Left: June 2020 – a single skunk cabbage plant before any Rootwave treatments.
Right: June 2021 – after two treatments in 2020.

So we are seeing some interesting results in the early stages and these trials are playing an important role in broadening our options for INNS control. Like any trial, there are always lessons learnt to be passed on and we have definitely had our fair share. Check our website for updates as our trials progress and please do get in touch if you have any questions.

Tel: 01398 322259

Email: ennis@exmoor-nationalpark.gov.uk

The Exmoor Non-Native Invasive Species (ENNIS) project is trialling innovative approaches to invasive species management and working with the local community to map and control invasive non-native species such as Himalayan balsam, American skunk cabbage and American signal crayfish. If you would like to find out more about the project please follow this link to our ENNIS website.

The ENNIS Project is funded by the European Agricultural Fund for Rural Development and Defra.

Flying, Flinging and Floating – Seed dispersal by Giant hogweed and Himalayan balsam

Vicky Hilton, Volunteer & Communications Officer, Scottish Invasive Species Initiative
September 2021

Here at the Scottish Invasive Species Initiative our invasive plant control seasons for giant hogweed and Himalayan balsam have now drawn to a close and thousands of plants have been sprayed, cut or pulled – removing these pesky plants for another year and critically preventing seeding and spread.  However, that’s not the end of the story.  In the soil lie dormant seeds: snoozing silently but waiting their chance to germinate.  And beyond our control areas are plants which are now about to do what they do best – scatter their seeds for future germination.

When it comes to invasive plants seed production and dispersal is usually significant and impressive – the ability to reproduce quickly, and in numbers, is one trait that makes these invaders spread successfully and be worthy of the status of ‘invasive’.

Plants have limited mobility and rely upon a variety of dispersal methods to transport their seeds, and so reproduce, away from the parent plant.  Seeds are more likely to survive away from the parent plant – they can reach habitats favourable to survival and with less competition and larger distance seed dispersal can allow plants to colonize altogether new geographical areas.

Giant hogweed and Himalayan balsam are both highly mobile species – they are good at seed dispersal and spread readily to new areas.  While this makes good evolutionary sense for the plant in ensuring its survival and success as a species – for those of us working to stop the spread of these species it certainly brings challenges.   

Understanding how these species disperse their seeds and how long these seeds persist in the soil helps enormously with the planning of control work.  For example, both these species use flowing water as a dispersal mechanism – meaning that control work needs to start with the most upstream plants in a river catchment. Treating plants downstream first would be futile as seeds from those upstream plants will wash down and re-infect cleared areas. 

Giant hogweed

Giant hogweed plants flower only once after growing for 2-5 years (longer if conditions aren’t ideal).  After seeding the plant dies.  Although that might give hope of successful control, in reality if the plant sets and spreads seed then the damage has already been done. A single flowering plant will produce between 10,000 – 50,000 seeds, with 20,000 seeds per plant being typical – and each seed can remain viable for many years. 

The dry flattened oval seeds are produced at the end of August.  Each is approximately 1cm in length with brown lines extending about three quarters of the length.

As the seeds are shed from the towering 2m high seed heads their winglike membrane allows them to be caught by the wind and dispersed over short distances (2-10m).  As they drift away from the parent plant they often fall into a river or burn where the water can carry them long distances to new areas.  Studies have shown that giant hogweed seeds can float for up to three days – in that time seeds could be moved huge distances in normal flows and even further in flood events.

Humans can also give a helping hand and be responsible for spreading giant hogweed seeds.  This can be accidental e.g. when seeds are caught and transported on vehicles or in shoe treads – or via transportation of seed contaminated soil.  

If seeds land on a suitable area of ground (there is usually plenty along a riverbank) they will settle into the soil and overwinter to allow maturation and breaking of dormancy.  Germination occurs from January to March with approximately 90% of seeds successfully germinating. Those seeds that don’t grow in the first year can lay dormant in the soil – the seed bank – for many years.

The consequence of this seedbank means that control works will need to be repeated on the same site for several years until the seedbank is depleted and the site truly clear of hogweed. Viable hogweed seeds have been recorded up to seven years after seeding occurs.  This reflects what we witness in the field – we have sites new to the Scottish Invasive Species Initiative where after control for four consecutive years, we still see significant regrowth of seedlings each year.   However, at sites where control has taken place for six or seven years (by previous and the current project) we see significant decreases in annual seedling reoccurrence giving hope that we are closer to achieving hogweed eradication in some locations.

Himalayan balsam

Himalayan balsam is an annual plant with a cycle of growing, flowering, seeding and dying all in one year. As such its survival from one year to the next depends entirely on successful seed production – so prevent the seed production and you remove the plant. 

Balsam seeds are produced in a seed pod, or capsule, which hangs on a long stalk alongside the flowers. The kite-shaped green pod is 2-3cm long and 8mm wide and contains on average 6 seeds per pod (between 4-16 seeds can be present).  The small round seeds are initially white, turning black as they dry.  On average 700-800 seeds per plant are produced.

When it comes to seed dispersal – balsam is the master.  It uses ballistic seed dispersal – exploding seeds pods – to forcefully fire the seeds up to 7m from the plant.  The seed pods are dehiscent – meaning that when mature they will spontaneously explode at the slightest disturbance. The capsule splits along the longitudinal edges – which are built in lines of weakness in the pod – firing out the seeds as the sections curl back.

These expelled seeds are often carried by humans – unintentionally caught on clothes and picked up in shoe treads – and there have also been observations of seeds being transported locally (up to 10m) by small rodents.  But mostly the spread of balsam seeds is aided by flowing water – fresh seeds can be transported within the sediment of riverbeds – particularly during the high flows present during flooding.  The dry seeds are buoyant and can float over large distances in the water currents – before being dropped into new areas to successfully colonise and continue their spread.

Himalayan balsam seeds also have a high germination rate – approx. 80% – but the good news is that balsam does not have a persistent seed bank.  Seeds only survive in the soil for around 18 months.  This means two to three years of control work at a site can be all that is required for successful balsam removal – as long as new seeds are not being brought into the site to replenish stocks!

A note on Japanese knotweed

Japanese knotweed (one of our target species in the project) is not of concern when it comes to seeding – it spreads solely by root and stem fragments.  While it does produce tiny white flowers each year it doesn’t set seed.  In Britain Japanese knotweed plants are all female with male sterile flowers. Its vigorous powers of vegetative reproduction mean that it has been able to spread to all parts of the British Isles without the aid of sexual reproduction – therefore it is classed as a single, exceptionally widespread clone.

Stopping the Spread

Everyone can help in stopping the spread of giant hogweed and Himalayan balsam seeds by practising good biosecurity – checking boots, equipment and vehicles for seeds and carrying out regular cleaning of these items between visits to different countryside sites.  You can find more information on good biosecurity practice on our website.

Autumn is the season

Of course, although we’ve covered giant hogweed and Himalayan balsam specifically here as problem and target species of the Scottish Invasive Species Initiative, do remember that not all plants are invasive.  Autumn is the main season for the setting and dispersal of seed of the majority of plants in Britain so now is a great time to see plant reproduction in action. 

As you’re out and about in the coming weeks take a second to appreciate the evolutionary genius of our plants as they spread seeds by wind, water, explosion, adhesion, using hooks to attach to passing animal traffic and as part of enticing fruits and berries for animal helpers to enjoy and transport.  You’ll be amazed at how many different tactics and methods there are – tell us how many you see.  

For more information about the work of the Scottish Invasive Species Initiative please visit our website – www.invasivespecies.scot

Top tips for getting started with Tracks, Trails and Signs.

James Symonds, Project Officer, Scottish Invasive Species Initiative
July 2021

Being able to recognise animal footprints is essential in our American mink monitoring work. As the monitoring rafts we use record the prints of visiting animals on a clay pad being able to correctly distinguish a mink from an otter print can be the difference between a successful mink capture and wasting our time. But, for me, animal tracking is so much more than that – it’s a glimpse into the secret world of the animals around us.

Having a basic understanding of animal tracks and signs can transform time spent in the outdoors from catching a simple breath of fresh air into a fascinating adventure of intrigue and mystery.  But be warned – it’s addictive!  I have lost count of the number of hours spent investigating some a patch of sand on a riverbank or examining around a tree stump looking for clues.

An otter walked here before you!

Most wildlife is cautious of humans, often with good reason, so the likelihood of seeing animals out and about is often low. The time of day, the time of year and the type of weather can also affect what you are likely to see.  But, by looking out for animal tracks and signs, you can build a picture of what animals live in the area, and what they’ve been up to. You might not see a pine marten or a tawny owl by day but the print or pellet you find can confirm their presence and inform a suitable place for an evening spotting session or trail camera placement. At the end of the day though, I get a buzz just knowing that these animals are out there.

Tracks and trails

Animals move about constantly within their habitats – particularly in the daily search for food – and when they do, they leave behind tracks (footprints) or trails (paths). A good clear track can give an instant animal identification or provide a good idea of the size and type of the animal in the neighbourhood.

Trails can also give a good idea of an animal or its size but can be misleading – popular routes are often used by many different species. However, they are always worth following in search of tracks and other signs en route.

Top tips for identifying that track

  • Use a field guide
    It takes experience and practise to know what it is you are seeing – so take out (and use!) a field guide.  If you forget take a photo of the track and have a look at the guide when you get home.
  • Look for the features in the print
    How many toes? Do you see claws? What shape is the pad?  These type of track features in combination help to eliminate species from your enquiries and guide you to the likely suspect.
    Look at the top row of images below; Left – four toes with claws, Centre – five toes with claws, Right – four toes no claws
  • Note the size of the print
    Size is important.  If you don’t have a ruler with you, take a photo with something in for scale e.g. a key or coin and work out the size later.
    Bottom row; Left – less than a 1p piece, tiny! Centre – several £1 coins wide with distinctive claw marks.
  • Are you seeing front or rear feet?
    Often a mammal’s fore and hind feet are shaped differently and leave different prints. For example, a rodent may have a different number of toes on the fore and hind feet.  Perhaps you are seeing two types of prints but these can be from the same animal – so take a note of each print features and size.
    Bottom row: Right – one animal but hind feet larger and appear in front of the fore feet

Top row (L to R): Dog, Otter, Cat. Bottom row: Water vole, Badger, Squirrel

Remember – when looking at prints you should take ground conditions into account.  A soft substrate e.g. sand, silt, clay or snow is more likely to give a nice clear full print with all features visible – just like in the books!  However, a hard substrate e.g. firm mud may result in a partial print – perhaps only showing some of the toes or omitting claw marks and so lead you to a false identification.  So, take what you see with a pinch of salt – the print itself might be misleading!

Tracks tell a story

Usually where there is one print there’ll be more, so have a look at the arrangement of the prints.  Animals move with different gaits – walking, trotting, running, bounding – each method of travel leaves a specific ‘print pattern’.  This tells us how the animal was moving, but often the fore and hind prints overlap each other so recognising gaits comes with practice and experience!

There may be more than one species of animal or bird track present – this can be where the detective work really starts.  Which animal was there first? Is one set of prints on top of the other?  Are you seeing a predator and prey?  And it’s always worth following multiple tracks to see if they tell a story – they might end in a pile of feathers and make it easy to deduce what went on at the scene!  

Looks like there was a party here! How many different prints can you spot?

Feeding signs

I was once told that tree stumps are either a table or a toilet! This couldn’t be more true.

Tree stumps are great places to look for feeding signs. There are a myriad of common feeding signs but have a look for some of these –

  • Stripped pine cones
    Most likely a squirrel or mouse if on a ‘table’ – but don’t discount birds like woodpecker or crossbill.
  • Nibbled nuts
    Mice and voles make a fairly neat hole edged with teeth marks, whereas a ragged hole with rougher edges and peck marks around is more likely to be a bird like great tit or woodpecker. A nut split in half is the work of a squirrel – look for the little hole at the top which it gnaws first.
  • Damaged bark
    The biggest clue here is in the height of the barking.  If it’s a few feet up the tree it’s a fair bet it’s the result of deer (or sheep).  If nearer ground level then think smaller mammals and rodents – rabbits, voles or beaver.
  • Nibbled trees
    The nutritious and juicy shoots and tips of small trees are often preferentially nibbled by grazers.  This is usually the work of roe deer – but don’t discount other herbivores like hares.
  • Bird remains and feathers
    If you find the remains of a bird with practise you’ll soon learn the differences between the kill of a predatory mammal (head bitten off and eaten, feathers bitten off in clumps, crushed bones) and of a bird of prey (beak and skull lying around, feathers plucked and scattered, breast meat eaten).
  • Pellets
    Many birds cough up pellets after feeding containing the undigested and indigestible bits of their prey such as fur, feathers, bones and insect cases.  As well as owls, all birds of prey, gulls and crows all produce pellets.  Dissecting a pellet is easy and provides a great insight into what the bird has eaten eating to a whole other world of mini skull and jawbone identification.

Feeding signs of predatory mammals are rarely found as small prey is generally eaten whole at the kill location and larger prey is usually taken back to a den or sheltered feeding site for more leisurely and safer consumption.


Cause and effect and all that.  Animals that leave feeding signs will inevitably also leave droppings, or more accurately – scat!  Droppings consist of the indigestible parts of food, such as fur, feathers, bone, chitin, plant matter, mucous and lots of bacteria.

All this excrement is different, identifying features include:

  • Size
    Note the size of the dropping but be aware that this is not always a reliable indicator.  Size is dependent to some extent on the animal’s age and can also be affected by the composition of food in the diet.
  • Shape
    Smooth or crinkly, straight or twisted, blunt or tapering?  All helpful to note.  At first glance a rabbit dropping looks quite similar to a roe deer’s but look again. The rabbit dropping is round and the deer’s is ‘tic-tac’ shaped with a little pinch at the end.
  • Colour 
    This is very influenced by what the animal has eaten.  For example, it will be very obvious if a bird or mammal has been eating berries!
  • Smell
    Fresh mammal droppings in particular have a strong scent – often “enhanced” by the addition of scent from anal glands.  Scent is a helpful identifying feature, but having a good sniff can be a bit of a sensory risk!  It might be sweet and vaguely pleasant e.g. otter (jasmine tea / fishy) or badger (musky) or it could be pretty foul e.g. mink (sharp and repellent)  If you’re feeling brave – have a sniff!
  • Content
    The contents of the dropping won’t always help you identify the animal – but will tell you what the animal has eaten.  Remember, an animal’s diet may change seasonally with the availability of food.  Do you see bones, fur, fish scales, grass?
  • Position
    Some animals will deposit droppings in specific places – a badger digs a small hole, known as a latrine, and repeatedly uses it. Both otter and mink will mark a territory by leaving spraint on a prominent riverside rock.

Other signs

Every animal needs somewhere to live or lie up – so another often easily spotted sign of animal presence are their homes and holes. 

It’s always worth a glance into the trees to see if there are signs of nests or dreys or excavated holes in trunks.  Underfoot look out for holes or burrows dug into the ground.  Some residents can be easily deduced – a badger sett for example is large and quite distinctive.  But remember, holes may have had multiple different occupants over the years or may be abandoned so the animal who originally made the residence may not be the inhabitant now.  Sometimes, of course, there is no hole and nothing more than a patch of flattened grass reveals an otter resting spot.

There are many other indicators of animal presence – sounds, smells, scrapes, feathers and fur and hair are other great indicators.  A walk along a fence will often uncover fur snagged on wire where an animal has passed under, over or through. There are signs everywhere you look, believe me.

Give it a go

So why don’t you get outdoors and give it a go?  Move slowly and open your eyes, ears and nose to the whole environment around you – you’ll be surprised what you can find.  Your walks may take a little longer but that’s a good thing right?

I cannot emphasise enough the importance of a good field guide. I always carry ‘Animal Tracks and Signs’ by Bang and Dahlstrom – an excellent resource. The Field Studies Council also produce a huge range of excellent (and compact) fold out guides which I highly recommend.

Finally, another mantra passed on to me when it came to tracks and signs and which I always keep in mind is that ‘Common things happen most commonly’.  Your imagination and enthusiasm can run away with you at times so before declaring you are on the trail of a mythical beast from ancient folk lore just have another look, consider the context and you may come to conclude it is perhaps just a very large fox that has gone before you!

Now enough reading, get outside, start collecting chewed cones, smell some animal droppings and have some fun!

For more information about mink monitoring rafts and the work of the Scottish Invasive Species Initiative visit our website www.invasivespecies.scot

Coronavirus, community conservation and the green recovery

Can a community and volunteer based approach to conservation projects lead the green recovery after coronavirus?

Callum Sinclair, Project Manager, Scottish Invasive Species Initiative
May 2021

As we emerge from the 2021 lockdown, we reflect on the impact the coronavirus pandemic has had on the Scottish Invasive Species Initiative.   As a project we weathered the Covid storm surprisingly well.  Although activities were constrained, we kept invasive plant species in check and maintained our mink monitoring and trapping network.  We credit this to taking a community-based approach to invasive species management – and so we pondered what we have learnt and whether other projects could take a similar approach to help deliver a ‘green recovery’ after the pandemic.

Community volunteers in Nairn.

Community control vs Covid

At the heart of the Scottish Invasive Species Initiative are the local people who care for their local environment.  An initial and ongoing programme of awareness raising and education activities raised the profile of invasive species and their impacts. This generated significant buy in and enthusiasm to get involved from land managers, local groups and organisations, businesses, and individual volunteers.  Having recruited and enthused, we support and enable people to actively volunteer by providing training and helping them gain qualifications and experience.  This network of committed people is gaining the skills needed to make a difference to their local places – in this instance controlling invasive non-native species – both now and in the future.

When the spring 2020 lockdown occurred we weren’t, like everyone else, able to carry on as usual. It was unclear if we were about to lose a year and give up the gains made by the project since 2018.  Rather than regress, however, what we witnessed instead were the investments in embedding skills and training with local communities paying back. Farmers and land managers used their staff (trained by us) to carry on giant hogweed treatment when we couldn’t, and local people headed out to pull Himalayan balsam at sites we’d worked on together previously.  Mink raft monitoring volunteers used their daily exercise to visit and check their rafts – telling us that this small activity gave them a purpose and made them feel they were making a difference during an immensely difficult time.  The project didn’t grind to a halt – far from it – in fact we perhaps were able to snatch a glimpse of what might happen when the Scottish Invasive Species Initiative is no more.

We believe that this approach – investing in communities, training volunteers and engaging people locally can provide effective and sustainable benefits – as endorsed by the enthusiasm of our volunteers and partners to carry on invasive species control when we weren’t around. 

To date volunteers have contributed a total of 2,181 days to control invasive plants and 119 volunteers have been put through their pesticide application course.

Building community resilience

Taking a community and volunteer-based approach – rather than just employing contractors on an ongoing basis – also provides benefits to the people involved.  Volunteering, pretty much any volunteering, is much more than just the activity itself.  In our case people are making a real contribution to their local environment. But the benefits are much wider than that. Being involved within their community, meeting other people and socialising, being physically active and engaging with nature – these all contribute to improved physical and mental wellbeing.  We believe these benefits have helped give people greater personal resilience to the individual and collective stresses we have all felt during the coronavirus pandemic.

Our engagement work in communities is wide and varied.  It ranges from providing education resources for remote use and our direct education work in schools, to partnerships with farmers and universities to find alternative and innovative techniques for invasive species control.  Engaging and enabling land managers to be a central part in the  development of potentially more sustainable and affordable invasive control methods – such as sheep grazing to control giant hogweed – helps these businesses to see alternative control strategies and be more resilient to future change.

Our Macduff sheep grazing trial in partnership with a local farmer is investigating if and how managed sheep grazing can be used as a form of chemical-free, low intensity giant hogweed control.

Environmental benefits

This community-based approach, as well as empowering people, also has environmental benefits. 

Invasive non-native species require long term management and commitment.  They often produce large numbers of seeds or have persistent rhizomes and require treatment year on year. The American mink needs ongoing control to continue to depress population numbers and counter inward migration. These animals travel great distances to secure new breeding territories and can quickly repopulate previously managed areas. Having an upskilled, enthusiastic and committed local community group willing to, for example, ‘adopt’ a section of river to deliver annual plant control and/or mink control can be effective through their collective efforts – both  providing sustainable and economically effective approaches to management.

Thanks to the monitoring and trapping work of 360 volunteers maintaining 670 rafts and traps, 388 mink have been removed. This provides benefits to the local native wildlife populations, particularly water voles and ground nesting birds.

Reaping the rewards

Restored river habitats and, in turn, landscapes that are free from invasive species give so much back to us.  Our rivers are important for recreation and provide brilliant opportunities to exercise and have fun or places for quiet reflection to boost mental wellbeing.  The connection between people and nature – widely recognised as providing significant health benefits – is further enhanced when people have directly contributed to the care and conservation of the environment.

The importance of connecting with nature has been widely recognised throughout the pandemic.  Many of us discovered, or rediscovered, our local green spaces and enjoyed, and needed, the serenity these places and being outdoors brought.  

As we carefully step into what, we hope, will be our recovery from the pandemic, we have the opportunity as a society to reshape and rethink the way we do things.   We can find new and sustainable ways to work which provide long-term benefits both to people and the environment – the “green recovery”.  For us at the Scottish Invasive Species Initiative we’re not sure that is actually such a new thing – it’s the ethos by which we’ve worked since we started.

Our rivers are important places for recreation and reflection.

Is the model sustainable?

The approach we take – working locally with partners, communities and individuals – undoubtedly benefits both people and the environment and fosters strong connections between the two. 

Volunteer input to the project – 9,794 volunteer days contributed, equal to 46 full time equivalent staff from March 2018 to March 2021 – is incredible and encouraging.  The work completed through these contributions, given by 650 people, would simply not be affordable to the project otherwise.  Each and every contribution – large or small – is important to us but, perhaps more significantly, important to the person donating their time.

The Scottish Invasive Species Initiative continues to build this community network so the work we have started can be a self-sustaining after we have gone.  The work continued by our volunteers and community network during the 2020 coronavirus lockdown suggests this can be the case. But we recognise that to sustain, connect and coordinate a volunteer network to a common and shared purpose will need support and resources.  Maintaining enthusiasm, preventing ‘volunteer fatigue’, continually recruiting and supporting volunteers, training and providing local co-ordination are all essential to the success of this approach. However, the scale of return we find would suggest these investments are both extremely cost effective and environmentally beneficial.

The scale of achievement in 2020, despite working restrictions due to the pandemic.

So, while the coronavirus pandemic has reached every part of our society and touched so many of us personally, we believe there are lessons from the period that can help us in the future.  Investing in people and communities is always worth it to build support, capacity and commitment.  When investments are maintained the benefits continue.  If those investments cease, then the goodwill and benefits generated from all that has gone before are lost. 

As a project we have emerged relatively unscathed from the coronavirus lockdown – we know many have not been so fortunate. We believe the community-based approach we have adopted and the hard work and dedication of our many, many volunteers have been central to this.  We simply can’t thank these people enough.

To find out more about our work and how to get involved visit our website, follow us on social media or contact us on sisi@nature.scot

Stopping mink in their tracks – tips and tricks of the trade

Karen Muller, Project Officer, Scottish Invasive Species Initiative.
May 2021

Sleek, dark brown fur, flashes of white under the chin and a bounding gate or streamlined-shape cutting through water – the invasive non-native American mink. In the last 50 years they have become a more common sight along our Scottish watercourses and coastlines than we – and our native wildlife – would like. 

The devastating impacts of this adaptable and ferocious predator are clearly apparent – mink predation contributing to significant declines of native wildlife species, particularly water voles and ground nesting birds.

Over the last 15 years much mink control has taken place in Scotland.  However as these are wily creatures who think nothing of travelling 80km to find new breeding territories and craftily avoid entering traps their removal is not straightforward.  So, here are some tips and hints from the Scottish Invasive Species Initiative for successful mink trapping and how to out-trick these irreverent tricksters.

Please note – this article is not a guide to trapping.  Trapping should only be undertaken by trained people who understand their responsibilities regarding animal welfare, humane dispatch and relevant legislation.

American mink (photo credit – Liam Skinner)

Understand your foe

Mink are very adept semi-aquatic predators, active during the day and night and feeding opportunistically on a wide range of prey, such as fish, amphibians, birds (and their eggs), rabbits and other small mammals.

They are solitary and territorial animals – a female territory will cover around 1-3kms while male territories are usually larger (5kms) and can span across several female territories.  It’s worth noting that territories in good quality habitats will be quickly recolonised if the original occupant has died or been removed.

A good territory will be close to freshwater and often along a river in low altitude farmland, marshland or woodland edge with a plentiful supply of food e.g. rabbits.  Coastal areas are also popular – but mink still need a freshwater source nearby to clean their coats regularly.

To trap or not to trap – that is the question

As traps must be checked every 24hrs trapping can be time consuming, so it is worth monitoring for mink presence first and only starting trapping when you know mink are in the neighbourhood.

Mink monitoring is done by using a floating raft with a clay pad – to record footprints.  The raft is easily switched to trapping mode by adding a live capture trap when you know mink are present.  Read more about mink monitoring rafts on our website.

The mink monitoring raft – the clay pad sits inside the tunnel.

It’s also worth remembering to keep in touch with neighbouring monitoring rafts – our mink control is part of a large scale effort and so if you find mink signs let your neighbours know so trapping effort can be co-ordinated. The chances are that, due to their transient nature the mink you detected might have already carried on upstream and already be in your neighbour’s patch!

Alternatively, you can use a trail camera, or look for field signs if you don’t have a monitoring raft.   Check muddy or sandy banks for tell-tale footprints, bridge arches or prominent rocks for scat and look for flattened trails on riverbanks. 

Key trapping times

The best times for catching mink are pre- and post- breeding periods when mink are mobile and so there is a greater likelihood of catching them. Trapping success at these times will have a greater impact on the overall mink population.

Between January and March, many mink are transient and travel widely outside of their territories – males searching for a mate and young females searching for a breeding territory. Catching mink at this time will avoid successful breeding and prevent new mink being added into the population mix.

In summer family groups emerge from the den and by early autumn young mink are starting to leave their natal home territory but still congregate quite locally. These juvenile mink are extremely inquisitive and naïve making them easier to catch – so from July – October is the second critical trapping time.

Young female mink caught in trap.

The ‘how’

There are many native and domestic animals which can frequent the same habitats as mink – so we use live-capture traps and release non-target species unharmed.  Placing the trap on a floating raft on water further reduces the likelihood of catching non-target species as many of these are less likely to make the swim to the raft and trap.

Always cover your trap with a wooden tunnel for shelter and securely tie both the trap and tunnel to the raft.  This prevents the trap being dislodged by an angry mink or another animal and avoids the risk of accidental drowning.  Raft and traps units should be disabled or removed if the river is going to be in flood.

Live capture trap set on a mink raft, under the tunnel.

Location, location, location

Finding the right spot in the river for your mink raft and trap is the number one deciding factor in capture success – so here’s some handy hints to help you site your kit effectively on the water:

  • Look for confluences, where two water bodies join – you are doubling your chances that a mink will come across the trap by following either of the rivers or burns.
  • Find freshwater sources along coastlines – sooner or later mink are bound to search them out and use them.
  • Use pinch points – where mink are naturally forced through smaller gaps – as mink traffic can be funnelled towards your trap.  These can be:
    • under/near bridges or on bridge foundations/arches
    • culverts
    • weirs
    • in-stream islands
    • inflows and outflows on lochs
  • Select a sheltered spot out of the main flow – mink are good swimmers but they are not daft and will use the most efficient route to pass through their territories. Slow glides and slack water which make for easier swimming are ideal.

Remember – the location is no good if you can’t safely reach it in both high and low flow conditions – double check this first.  Also ensure if placed near a structure like a bridge or culvert that your raft will not cause a blockage in a flood.

A perfect spot at the confluence of two water courses.

A raft set up won’t be suitable for all locations – sometimes you can set a ground trap.

In these cases, you need to think like a mink!  Consider the likely routes mink use to move around.  In coastal areas, on beaches, this could be along the bottom of cliffs or harbour walls or between rock outcrops or prominent rocks.  Inland look for trails through vegetation along the bank, along hedges or fence lines, or fallen logs and wood and rock piles – even better if you find a well-situated log or rock pile and can fit the trap amongst them.  A mink might go for a rummage there for their next meal.

Note – If using a ground trap ensure the location is not at risk of flooding or within the tidal area. If in doubt put your trap on a raft, tied with enough slack that the raft can move in the case of water levels rising unexpectedly.

Please keep in mind that, any spot, even if it ticks all the boxes above is likely to be of little use if it is in too public a place.  We have had equipment vandalised or removed in the past and, given that if you catch a mink it will need to be despatched this task is not one which should have an audience and you certainly do not want a member of the public approaching a trapped animal.  If in doubt – find another place.

Ground traps; under a rock (L) and in a well camouflaged tunnel (R)

So, you’ve found your spot; you’ve set up your trap – time to open the box of tricks! Read on.

Trapping Hacks

Mink are curious, and you may never need to reach deep into your bag of tricks.  But if after a few weeks you are not having success then it may be time to try something a little different.

Location and set up:

  • Move your raft slightly -Try swapping to the opposite bank or a move upstream or downstream by 200 metres. Mink are fickle and these moves can often make a difference!
  • Change the direction of the trap opening – Footprints on your clay pad may give a clue to the general direction of mink travel so switch things around to see if that helps.
  • Try a double ended trap – Set two rafts with two traps opening in opposite directions. Or if on land set two traps up back to back.
  • Use camouflage – Your mink might be shy, so blend the unit into the environment. Pile some vegetation on top of a floating raft and tunnel and weigh it down with rocks.  If on land, cover it with small logs, branches, or rocks.
  • Make it obvious – This is a bid of a reverse to the camouflage suggestion above but, in non-public areas, you could also play to the mink’s curiosity and have the raft/trap in plain sight.  Sometimes the animal can’t resist the urge to explore the new addition to its habitat.
  • Make the tunnel appealing – Stuff some dry grass or other vegetation between the trap and tunnel – it creates an appealing tunnel to explore and a trapped animal to make a cosy nest from material pulled through the cage.  Make sure vegetation won’t be a hindrance when it comes to animal dispatch.  There is an added bonus here – if you catch a mink this vegetation will be saturated with scent and might entice the next one to the trap too!
  • Make sure it’s stable – If trapping on land, make sure your trap is stable – use stones or wood if needed. A wobbly trap can dissuade a mink from entering it or worse, set the trap off when knocked from the outside.

Go mad with camouflage (L) or line the tunnel with dried grass (R)

Baiting is usually unnecessary but if you do feel you need a little bit of extra help, you can try baiting with food, visual attractants or scent:

  • Food – Stab a cat food pouch a few times and hang it in the back of the trap or season your raft with a bit of oil from a tin of sardines or something else debatably “delicious” smelling. Don’t use actual food – you’ll attract every animal in the neighbourhood!
  • Visual attractants – Hang a bit of tin foil or a budgie mirror in your trap to grab the mink’s attention – get creative!
  • Scent – A scent lure holds the biggest potential, because mustelids use scent marking to communicate with each other. So, use of scent can be effective in enticing territorial animals to investigate a trap more closely – even the wily ones that turn their noses up at anything else.  There are options of how to do this but whatever you do – wear gloves!

You can collect your own scent – though this often isn’t for the faint hearted.  You can –

  • Relocate scent doused vegetation, tunnels, or traps after a mink dispatch to a different raft – though that may be impractical on a day to day basis.
  • Harvest your own scent – This is perhaps not for the squeamish or faint nosed – but I have experimented with scent harvesting from dispatched mink. A biodegradable cigarette filter, held in forceps, is saturated with “Eau de mink” from their anal scent gland. This can be done by just bringing the filter contact with their anus or, if we take it a step further to harvest even more scent, can be brought into contact with a scent gland after it has been extracted from the mink.  Not for everyone this!

Wire is threaded through the filter which is then hung from the cage grid above the trap treadle to entice the mink to enter as it takes a closer sniff.  These “scent bombs” can be stored in sealed plastic bags and added to traps as needed. This method has been used in other mink eradication programmes in preference to baiting with food.  An advantage of scent is it is more likely to specifically attract mink compared to food aromas which may also attract non-target species such as rats, otters or the odd adventurous cat.

Finally, a tip that makes your life easier – especially if your trap is located on a small island, or in a difficult to reach areas.   Attach a flag to your trap door as a visual aid to check on the status of your trap – some trap designs are better suited to this than others, and some are not suited at all but it can be really helpful. When the trap door is open the flag is up, when the trap door closes the flag goes down and is no longer visible – time to check on the trap!  You may even be able to check on your flag with binoculars from a distance. Watch a video of Karen demonstrating the signal flag.

All of the above should give a good starting point.   But of course, sometimes you may still catch nothing – remember you are pursuing a wild animal which won’t always behave as we hope or expect it to.  Be flexible and try something new now and again.

A bit of patience and luck results in a capture.

Sometimes, of course, it’s not you or the trap itself.  Perhaps the mink was transient (just moving through) and won’t come back, maybe it found itself in a different trap in the area or met its demise in a natural way, or possibly there is too much disturbance at your location and the mink doesn’t take time to investigate.  Or maybe you have a wily and cautious animal which simply won’t enter the trap pretty much whatever you do!

Despite our best efforts, there is always a little bit of luck and patience involved in mink trapping. Remember no signs of mink is a good sign – but please remain vigilant so we are ready when an animal heads your way, don’t get disheartened and don’t give up.  And while you’re there,  remember to take a moment to enjoy the native plants and animals living and thriving around you, breathe some fresh air, listen to the birds and relish the opportunity to get to know parts of your local river better you’ve never explored before.  Nature is good for you!


Read more about the Scottish Invasive Species Initiative Mink Control Project on our website (www.invasivespecies.scot). Most of our rafts and traps are looked after by volunteers, if you’d like to find out more about getting involved read more about volunteering or contact us on sisi@nature.scot

Please note – our mink project only operates in Northern Scotland – specifically Highland/Eastern Perthshire, Angus, Aberdeenshire, Moray, Inverness-shire, Ross-shire and West Sutherland.

A day in the life of a SISI Project Officer

James Symonds, Project Officer, Scottish Invasive Species Initiative
November 2020


We asked our very own James Symonds, what a typical day of a Scottish Invasive Species Initiative (SISI) Project Officer looks like.

As a Project Officer, I am responsible for the management and co-ordination of invasive species control across four rivers in Moray and Speyside; the Rivers Spey, Findhorn, Nairn and Lossie.  Our main species of concern are; American mink, Giant hogweed, Japanese knotweed and Himalayan balsam – although we also have an interest in White butterbur and American skunk cabbage.

But what does a day in the ‘office’ look like for a SISI Project Officer?

Well that changed significantly this year with the coronavirus pandemic, but following lockdown we managed to get back out in the field to continue our work – albeit with changes to our work practices to keep everyone safe and whilst balancing home working and home schooling challenges.

My typical workday starts the same as any other for a father of 2 small humans – unsocially early! After making my way to the coffee pot and feeding the rabble I can check my work phone. I am checking my “Mink Police” app for any mink traps activated overnight and to see if any volunteers have been in touch about their mink monitoring rafts or traps.  All clear!

The Mink Police units are great innovations. Live capture traps, by law, have to be checked at least once in a 24hr period to meet animal welfare protection requirements.  The Mink Police units, using a combination of technology and magic, send multiple daily updates for specific trap locations which negates the need to physically check each trap in person each day. They allow me to remotely check the traps wherever I have access to Wi-Fi or mobile signal and, most importantly, notify me instantly if an animal has been caught.  This means that traps can be deployed to areas where, for example, mink have been sighted in physically difficult access locations or where we don’t have an elusive local ‘trapping volunteer’ to do these daily checks.  Using Mink Police units I can monitor multiple traps across a wide geographical area myself.

Mink Police unit mounted on top of a live capture trap

After finally managing to get a shower and get breakfast, I double check the weather for todays planned activity – Giant hogweed spraying. The weather looks good so I drop a text to all of the volunteers who have offered their help to reconfirm the meeting time and place.

I visit the stores and pick up all equipment required for the day and make sure I stock up on the ever-essential tea and biscuits on the way to site.

After a quick meet and greet with today’s volunteers, I go through the essential risk assessment and tools talk.  Much of the time we work on uneven terrain alongside rivers and today we are working with Giant hogweed – a dangerous plant with photo-toxic sap.  We also have in place additional COVID-19 working adaptations which need to be explained.  Safety and volunteer welfare is our number one priority.

Volunteer spraying Giant hogweed

We kit ourselves out with protective clothing, fill our knapsacks and set to work.  Today we are spraying in about six acres of riparian woodland with frequent sizeable Giant hogweed stands.  One of my volunteers is new, so I work alongside them offering support and supervision.  Pre-coronavirus there would be a team of volunteers working with me – battle hardened and dedicated hogweed assassins who gained their pesticide application qualifications with us – but today it’s just three people to keep numbers low and allow for social distancing.  We work in a rough line moving in a zig-zag upstream hoping to catch all of the hogweed we see on the way.

We started at 10.00 am it’s now 12.30 pm – definitely time for a proper break.  We put our knapsacks down and set up camp on the riverbank.  On a normal volunteering day I would  pull out the Kelly kettle, tea and biscuits – chocolate hobnobs if they are lucky – offer a demonstration on how to light the kettle using a fire steel and natural tinder and the volunteers would have a go at fire lighting themselves.  This year we’ve had to ask volunteers to bring their own flasks which is a shame as we like to offer additional activities alongside the hard work of plant spraying.  We appreciate the time our volunteers give to us and want to keep each day varied and fun for them – that way they might come back again!  

Putting the kettle on!

I check my phone and whilst we were working a trapping volunteer has called – she has a mink in a trap on another river. I phone back and she confirms the trap was empty last night but a mink has been caught this morning.  I’ll visit as soon as I am finished on site.

We spray for another 70 minutes and manage to cover the whole woodland.  My volunteers (and myself) have worked hard today but it’s been good fun.  As a reward I let them all go home early, 2.45pm instead of 3pm!  I’m nothing if not generous….

After the plant control equipment is cleaned down and packed in the car I can make my way to the mink in the trap. It’s a large mink and I have the unhappy task of humanely dispatching the animal.  This is done quickly, quietly and discretely with a high-powered air pistol. I take some basic measurements and sex the animal – a male.  You can tell this by feeling for a small bone between the hind legs – the baculum – present only in males. You can work out what this identifying feature is I’m sure!

Non-native American mink caught in trap

Dispatching mink is not something I or the project enjoy – but it is essential.  The mink is a voracious predator and their presence has a devastating impact on native wildlife.  For example, since the introduction of mink, Water vole numbers have declined by over 94% across the UK – largely due to predation.  They also have a negative impact on populations of native ground nesting birds, amphibians and fish species as well as taking domestic fowl.

I get home, change a nappy, check my emails and follow up with volunteers planning on coming out tomorrow.  The weather is looking wet so instead of spraying Giant hogweed we will decapitate the flower heads using pole saws – always fun!  I am just about to email a few volunteers about later in the week when my 4-year old runs in and rugby tackles me – it’s time to finish work for today.

Using a pole say to remove flower heads from Giant hogweed

Invasive species control work is seasonal so once we are done with Giant hogweed, we move on to pulling or slashing Himalayan balsam – great for all the family to get involved in and then, as autumn looms on the horizon, we move on to spraying or stem injecting Japanese knotweed.

The specific threats these plants pose vary in one way or another but what they all share is the fact that they are so successful in our climate and our native flora cannot compete. If left unchecked we face a massive loss to biodiversity, destabilisation of our riverbanks and very different ecosystems to the native ones that should be present. 

Injecting herbicide directly into Japanese knotweed stems (L) and slashing Himalayan balsam (R)

It’s been a productive day and there is a tremendous sense of achievement seeing what a huge difference can be made in such a short space of time with so few people.  I have missed the larger volunteering groups this year, it’s always good to get a big crowd out, but we soldier on for now and hope to get everyone back together next season.  The volunteering opportunities we have been able to offer this year have never felt so important – as well as helping nature they provide valuable time outdoors and social opportunities just when we’ve all needed these the most.

Volunteer groups 2019

If you’d like to find out more about getting involved and volunteering with James and the Scottish Invasive Species Initiative read more on our website.