Assessing the damage of the Tay Reedbeds blaze

Mark Purrmann-Charles, SISI Project Officer
May 2020

The fire takes hold at the Tay Reedbeds. (Image- Vicky Turnbull / RSPB Scotland)

On 27th April the Tay Reedbeds burned.  Following a rain-free month, the tinder-dry reedbeds spectacularly caught alight and fire ran along 3km of the River Tay’s north bank.  When it was over, an estimated 120 hectares of reedbed habitat – around 30% of the total area – had been destroyed in a matter of hours.

A Helicopter dropped water on the fire which destroyed the dry reeds. (Images – Vicky Turnbull / RSPB)

Mainly lying along the north bank of the Inner Tay Estuary, the Tay Reedbeds are the UK’s largest continuous reedbed and home to a vast range of wildlife – notably important breeding bird populations, many of which are endangered or rare species.

For example, the reedbed is thought to support up to 50% of Britain’s bearded tit population and last year at least five marsh harrier pairs nested there – incredible considering there are fewer than 20 breeding pairs in Scotland.  A range of notable bird species including water rail, redshank, reed bunting and reed warbler also call the place home.  Needless to say the area has a collection of designations – The Firth of Tay and Eden Estuary Special Protection Area and Special Area of Conservation and The Inner Tay SSSI to name but three.  The Tay Reedbeds are undoubtedly a special place.

Aerial view of Tay Reedbeds (Image P&A Macdonald/SNH). Bearded tit (Image Gus Guthrie)

We have been working at the reedbeds since 2019 – specifically to protect bird species from the non-native American mink.  Mink, well established in the wild having been brought to the UK in the 1930s for fur farming, can cause huge damage to ground/near ground nesting bird species by predating young and eggs.  With the support of local volunteers, landowners and RSPB Scotland, which has a reserve there, we have established mink monitoring and control across the reedbeds.

It is hard to know exactly how many mink operate in the reedbeds – in 2019, we caught eight in the five traps and monitoring rafts we operate there.  We also recorded mink tracks at all five sites, suggesting so far we’ve removed only a proportion of the total present.  The wider area provides excellent mink habitat and the reedbeds a happy hunting ground – together providing a prime breeding location for mink.  Therefore, the mink control we carry out is important not only in protecting the breeding birds on site but also in preventing the area acting as a breeding ground from which mink disperse into surrounding areas.

American mink in trap at Tay Reedbeds in August 2019 (Image – SISI)

With a large portion of prime nesting habitat now destroyed or degraded for this season, bird breeding will undoubtedly be affected – next year hopefully regrowth will support nesting in these areas again.  Species that have yet to nest or are able to attempt nesting again in 2020 will use remaining good habitat areas or be forced to sub-optimal locations.  This could leave them exposed and vulnerable to predation from mink.

Destroyed reedbed (Image – Alison Thornton / SISI). This dead chick was a casualty of the blaze (Valerie Stewart / SISI)

With the current COVID-19 movement restrictions we can take only limited action right now.  Where they can, local volunteers on their daily exercise outings are assessing damage and identifying surviving areas of reedbed – when complete we will relocate rafts and traps to protect these locations. Amazingly all our mink monitoring rafts survived the blaze – although some are a little singed around the edges! 

Mink do not live in the reedbeds, instead they access the area to hunt before returning to home territories in the surrounding countryside.  We know many of the access routes mink use and have caught them on these highways – since the fire some of our surviving rafts on these routes have already recorded tracks confirming mink remain at large.

Remarkably these mink monitoring rafts survived – although they were a little charred!
(Image – Alison Thornton / SISI)

We won’t catch all the mink, but if we can continue to reduce the population hunting the reedbeds, as well as the wider population in the area this will help native species make the best of what is clearly a bad situation and prevent the fire causing lasting impact.

The Scottish Invasive Species Initiative could not be successful without the hard work and commitment of volunteers. Those working on the Tay Reedbeds are among our most dedicated volunteers and care deeply about the nature and wellbeing of the area. We will work with them, landowners and RSPB Scotland to support site recovery for wildlife and everyone to enjoy.

One of several Scottish Invasive Species Initiative (SISI) volunteers on the Tay Reedbeds, Valerie Stewart.
(Image – Alison Thornton / SISI)

Perhaps you’d like to get involved with the Scottish Invasive Species Initiative at the Tay Reedbeds or where you live?  Visit our website and get in touch (sisi@nature.scot) and we can make plans for when COVID-19 restrictions are eased.

Buttery Business

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

White butterbur (Petasites albus) is a rather lovely plant in many ways. Its white, Hyacinth like flowers are, along with the Snowdrop, some of the first to be seen in the new year and can brighten up those winter walks along our rivers. In summer its plate-sized leaves create an overlapping mat of terrestrial lily pads that catch the breeze and flutter to and fro in a shimmer of white and green, very striking indeed.

White butterbur in flower in late February

However, its delicate appearance belies an insidious nature.

Native to the mountainous areas of Central Europe and the Caucuses it was, along with most invasive non-native plants species, introduced to Britain as an ornamental plant. Its introduction was earlier than most of the headline grabbing exotics like Japanese knotweed, 1683 to be precise, perhaps due to its natural range being so much closer to home. It was recorded in the wild by 1843 and is now firmly established and naturalised across much of Britain, with the North East of Scotland seeing the highest concentrations of plants.

White butterbur is a rhizomatous plant, meaning the plant has a network of roots (the rhizome) underground that are interlinked and plants grow from this root system. When the leaves die back in the late summer the plant puts energy back in to the rhizome where it is stored over winter ready for its early flowering and rapid growth in the new year. This is where its insidious nature starts to become evident.

Exposed rhizomes on the edge of a river bank

Because of the substantial energy stores in the plants rhizome it can grow rapidly as soon as conditions allow. By mid-April early May, just when our native woodland plants are really wanting to get going, it already has a dense mat of foliage covering the woodland floor. This mat completely shades the ground meaning no other plants can access the sunlight so essential for their growth. With little or no competition, the rhizome has enough energy to spread laterally potentially, or eventually, taking over entire woodlands.

Dense carpet of White butterbur leaves on the River Fiddich

As White butterbur prefers deciduous wet woodland, it is very common along the river networks of the North East of Scotland. When the rivers flood and erode their banks, fragments of this rhizome are broken off and washed down stream where they settle and create a new stand of White butterbur and so the plant spreads, eventually taking over entire woodlands along water courses to the detriment of our native flora.

Nowhere have I seen this more evident than on the River Fiddich, a sizeable tributary of the River Spey. From its confluence with the Dullan Water in Dufftown to where it meets the Spey at Craigellechie, White butterbur has become the dominant species along its course. Anywhere that is prone to flooding is a mass of White butterbur and very little else, hectares upon hectares of ecological desert.

White butterbur dominating the river banks

In these areas even young trees struggle to break through the darkness of the butterburs low lying canopy. Trees younger than perhaps 20 years are hard to find raising the question of the woodlands very existence. So what can be done?

There is, in fact, very little research out there on the control of White butterbur so here at the Scottish Invasive Species Initiative we have set up some trial sites to see what works and what doesn’t, you can read more about the details of our trial and findings here.

Early indications suggest, perhaps unsurprisingly, that application of a systemic herbicide is the most effective way of treating the plant. The most effective time to spray it seems to be once the plant is in full leaf, June onwards. At this point the biomechanics of the plant shift and instead of directing energy in to growth, energy is being transferred back in to the rhizome for over wintering, this greatly improves translocation of herbicide from the leaf that is sprayed to the rhizome which is where it is needed! That being said I have treated White Butterbur effectively in late April but these were small poorly established patches.

If your daily exercise is currently taking you for a walk along a river bank keep an eye out for this pretty little invasive (below left) and its cousins, the purple flowered native Common Butterbur, Petasites hybridus (below centre) and the formidable Giant Butterbur, Petasites japonicus (below right) with its more elaborate flower spikes and creamy flowers, the leaves of this one can get to 90cm across!!

Finally – how do you think the Butterburs got their name? Answers on the back of a postcard…

An update on our Mink Control Project

March 2020, SISI Admin

Our Mink Control Project aims to significantly reduce the population of the invasive non-native American Mink across our project area. Mink are opportunistic hunters and voracious predators, and have a devastating effect on our native wildlife, particularly on ground nesting birds and water voles.

American Mink – (c) Liam Skinner

We have established a network of monitoring rafts and traps across the 43 river catchments and coastal areas in our project area. Nearly all of these rafts and traps are looked after by volunteers, whose support is essential in the success of this project.

Below are a series of distribution maps we have produced to enable our volunteers and project partners to see our progress so far in setting up the mink monitoring network and our results in capturing mink, across 2018 and 2019.

1 – Distribution of rafts & traps operating in 2018 and 2019.
There are a total of 321 rafts & 245 traps (some are combined units) across the project area, looked after by 335 volunteers.

2 – Regional maps. These show the distribution of rafts & traps across the different regions at a larger scale (same data as above)

Use the arrows to scroll through the set of regional maps.

3 – Capture locations. This maps shows all the capture locations across the whole project area.
N.B. Some locations have multiple captures.

4 – Capture locations by density. This set of maps show the capture locations by density; single capture at site, 2-5 mink caught at same site and more than 5 mink caught at same site.

You can read more about our Mink Control Project and the American Mink on our website.

If you’d like to find out more about adopting a mink monitoring raft or trap please don’t hesitate to contact us, email; sisi@nature.scot

Mink monitoring raft

Deploying a natural enemy for one of the UK’s most invasive weeds

Wayne Coles, CABI
Jan 2020

For 180 years Britain’s waterways have gradually become clogged and choked with what the Victorian gardeners thought in 1839 was a pretty addition to the nation’s landscape.

But Himalayan balsam (Impatiens glandulifera), also known as Touch-me-not Balsam and Policeman’s Helmet, is no longer regarded as a visual delight but rather a blight upon Britain’s riverbanks, streams, ponds, lakes, damp woodlands, roadways and railways.

Himalayan balsam was brought to the UK by the Victorians as an ornamental plant but it has since become the scourge of the nation’s waterways – Photo: CABI

In fact, the plant – whose native range is the foothills of the Indian and Pakistani Himalayas – is considered one of the UK’s most widespread invasive weed species competing with native plant species for space, light, nutrients and pollinators, thereby reducing local biodiversity.

Though it dies back in winter, Himalayan balsam is – amongst other places – causing a nuisance on the River Tweed in Scotland as part of a nationwide invasion which in 2003 the Environment Agency (EA) has estimated would cost £300 million to eradicate. The plant has since continued to invade new areas.

Nevertheless, science is trying to fight back against the Himalayan balsam ‘menace’ with a biological weapon in its arsenal – the fungal agent Puccinia komarovii var. glanduliferae– that will be released into Scotland in 2020.

Dead plant material from Himalayan balsam can also enter rivers and increase the risk of flooding.

It was back in 2006 when CABI was asked by the EA, the Department for Environment, Food and Rural Affairs (Defra) and the Scottish Government to find a reliable. effective and safe natural enemy to help control Himalayan balsam – a journey which has seen scientists adopt a ‘classic approach’ and return to the foothills of the Himalayas for a natural solution.

After sourcing a rust fungus from the Puccinia species and bringing it back to CABI’s quarantine facilities in Egham, Surrey, for further analysis and rigorous testing scientist now believe they have a tangible biological solution for the invasive weed which will be released with funding from Scottish Natural Heritage’s Biodiversity Challenge Fund in partnership with the Tweed Forum.

Kate Pollard, a Research Scientist at CABI, said, “The highly damaging fungus was identified by CABI in the foothills of the Himalayas, where it infects leaves and kills seedlings of the plant, helping to maintain population levels.

Extensive laboratory testing was undertaken under quarantine conditions to confirm that the fungus was highly host-specific, infecting only Himalayan balsam, and safe for release.

“Approval to release the rust into England and Wales was granted in 2014 and since then, the rust has been released at 47 sites across 19 counties. Field results are promising with high levels of infection, spread and overwintering recorded at a number of sites.”

The rust fungus Puccinia komarovii var. glanduliferae could go a long way to helping to solve the River Tweed’s Himalayan balsam invasion – photo: CABI

Prior to the ‘appliance of this natural solution, Himalayan balsam on the River Tweed has been tackled using a combination of hand-pulling the weed, thanks to an army of volunteers, and spraying.

The fungus has previously been released at a site along the River Tweed on the English side of the border. It is hoped that the release later this year will help step up the fight against Himalayan balsam on the waterway further as part of a concentrated longer-term solution.

Reference
Environment Agency. (2003). Guidance for the control of invasive weeds in or near fresh water. Environment Agency, London, UK

Find out more about CABI’s work to release biological controls to fight Himalayan balsam from the dedicated website.
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Did you know?

Himalayan balsam is Britain’s tallest annual plant with each plant tending to be around 1-2 metres high, although they can reach a height of 2.5 metres in some cases!

According to Section 14 of the Wildlife and Countryside Act 1981, it is an offense in England and Wales to allow Himalayan Balsam to spread into the wild. Therefore, it is highly recommended that you remove Himalayan Balsam from your grounds or garden.

It is important to make sure that when disposing of Himalayan balsam, the waste disposal site has a permit to accept and dispose of invasive species. As GOV.UK explains, you can be fined up to £5,000 or be sent to prison for 2 years if you do not properly dispose of Himalayan balsam and other non-native invasive plants.

The puzzle of polecats in Scotland

Lizzie Croose, Vincent Wildlife Trust
December 2019

What is a polecat?

The polecat is a native mustelid (member of the weasel family) and is closely related to the pine marten, stoat, weasel and otter.

Once widespread in Britain, the polecat population declined during the 18th and 19th century, primarily due to persecution, and became confined to a refuge in mid-Wales, Shropshire and Herefordshire by the early 20th century. A decline in gamekeeping and the banning of the gin trap in the 1950s led to a reduction in persecution pressure, which allowed polecats to start to recover during the 20th century. Subsequently, the population has re-colonised much of its former range in Wales and England and Vincent Wildlife Trust has been assessing the changing distribution of polecats in Britain. It has carried out three national distribution surveys, the most recent during 2014-2015.

Polecat – (c) Anne Newton

What is the status of polecats in Scotland?

Whilst polecats are doing well in England and Wales, this recovery has not been seen in Scotland and polecats are still absent from large parts of the country. It’s thought that polecats became extinct in Scotland during the early 20th century, although it has been suggested that a small population hung on in Caithness and Sutherland. Polecats have since been reintroduced to parts of Scotland, including Argyll, Loch Ness-side and Perthshire, with mixed success. The population in Perthshire and Angus seems to be well-established, comprising a mixture of polecats and polecat-ferrets, but the status of the population in Argyll is unknown. Additionally, there have been a small number of polecat records in Dumfriesshire, likely originating from animals which have spread from Cumbria, and isolated records in Caithness and Sutherland. The origins and status of polecats or polecat-ferrets recorded in other areas of Scotland, like the polecat-ferrets recently caught by Scottish Invasive Species Initiative in a mink trap in Moray, are a bit of a mystery.

Polecat family in Somerset – (c) Clive Sawyer

The hybridisation conundrum

Polecats may breed with feral or escaped pet ferrets and produce hybrids, called polecat-ferrets, which can cause a lot of confusion. So how can you tell if an animal is a polecat or a polecat-ferret?

Distinguishing between true polecats and polecat-ferrets can be problematic. Guidelines were developed by VWT and Andrew Kitchener of National Museums Scotland for separating true polecats from polecat-ferrets on the basis of pelage (fur) characteristics. In general, polecat-ferrets tend to be paler in appearance, usually have more extensive pale facial markings than true polecats and may have a pale throat patch and one or more pale paws. By contrast, true polecats have darker pelage and a well-defined white ‘mask’ on the face. There are more detailed guidelines on VWT’s website: https://www.vwt.org.uk/wp-content/uploads/2015/04/polecat-ferret-leaflet-.pdf.

Polecat – ferret showing cream throat patch (a ferrety feature) – (c) Brian Birch

However, genetic analyses by Cardiff University has cast doubt on this identification protocol. This study showed that the match between phenotype (what the animal looks like) and genotype (its genetic signature) is not perfect, so some animals that look like true polecats actually have ‘ferrety’ ancestry, and vice versa. This work also found that 31% of wild polecats analysed had ‘admixed ancestry’, meaning they had both polecat and ferret genes, with the most ‘pure’ polecats being found well within the polecat’s core range in Wales and the west of England, whereas the most ‘ferrety’ polecats are found towards the edge of the polecat’s range and in reintroduced populations, such as in Scotland. No ‘F1’ hybrids, meaning a first generation offspring of a polecat and a ferret, were detected in the study, which suggests that breeding between the two is probably rare now and the hybrids we see today are probably a result of extensive hybridisation in the past.

The challenges of confidently identifying polecats and polecat-ferrets present a problem for naturalists and biological recorders who need to determine how to classify an animal, particularly in areas where polecats are newly re-colonising and are relatively rare. It can also lead to confusion from a legal standpoint, since polecats have some legal protection and it is an offence to intentionally set a trap for a polecat without a licence, whereas ferrets have no legal protection.

Polecat – ferret at Montrose Basin – (c) Andy Wakelin

But does it really matter if some of our polecats have some ferret genes in their ancestry and a wild polecat’s great-great grandmother was a ferret?! We recommend taking a pragmatic approach, which acknowledges that polecats may be slightly more diverse in appearance due to this past hybridisation with ferrets and that hybrids carry valuable polecat genes and, as such, should be seen as a valid contributor to the polecat population. There is also evidence to suggest that the true polecat phenotype is dominant over the ‘ferrety’ phenotype. Crucially, ferrets often don’t fare well in the wild as they tend to be docile, tame and less alert and therefore lack the survival skills that wild polecats possess. As the polecat population expands its range, the polecat phenotype is becoming more widespread and it doesn’t appear that the presence of hybrids is acting as a barrier to its ongoing recovery. All of this means that there is a good case for saying “If it looks like a polecat and acts like a polecat, let’s call it a polecat.” That said, it is sensible to try to reduce the number of ferrets ‘lost’ in the wild, to make sure that the opportunity for any future hybridisation between polecats and ferrets is minimised.

Young polecat in north Wales – (c) Nikki Charlton

What is the future for polecats in Scotland?

Polecats are still absent from most of Scotland and a sustainable population recovery would need to be achieved either by expansion of the existing populations, such as the one in Perthshire, and/or reintroductions or reinforcements. As current evidence indicates that polecats are declining across much of the rest of Europe, we should be pleased to have one of the few recovering populations of polecats in Britain.

If you see a polecat, please report it to your local biological records centre.

Further reading

  • Read the recently published book Polecats by Johnny Birks.
Polecat – (c) Peter Seaman

The Good, the Bad and the Balsam

Karen Müller, Project Officer, Scottish Invasive Species Initiative
September 2019

Himalayan balsam season has drawn to a close. On our river banks, our staff and volunteers have downed tools for another season. The time has come for the last of the pink-petaled invaders still left standing to be pinging their seeds from ripe pods in an endless effort to increase their range. But with thousands of plants degrading in piles on the banks and tens of thousands of seeds prevented from ever reaching nurturing soil we are happy to call this a job well done, for now.

It’s time to reflect on the last few months – our highs and lows, ayes and nays, lessons learned and casting our eyes to the future.

Getting to grips with balsam

This year’s waves of heat and rain appear to have been particularly favourable for balsam, with many areas dazzling with shades of pink. To counter this, a continuous thwacking of weed whackers, scythes and strimmers against balsam stems, the sound of soil releasing roots and the popping of hollow stems under the weight of more balsam being added to piles has filled the air over the last few months. There has been a flurry of volunteer activity across the project area, making it possible that river banks from Tayside to Sutherland have decidedly less of a pink hue to them.

Volunteers come in all shapes and sizes and the one lovely thing about balsam is that its control is suitable for a wide range of ages – from primary school children to people living out their best life in retirement – and can be done in larger groups. It’s the perfect way to meet new people, partake in a hands-on activity with your kids or spend some relaxing time in nature while trying something new and helping the environment. Whether it is anglers, dog walkers, bird watchers pulling a few plants when they are out and about or individual people, schools or organisations that specifically join us project officers for a balsam bash – many a mickle makes a muckle in the battle against balsam.

Compared to other invasive plant control, balsam provides instant gratification when you look back on the area you are working on – nothing makes your chest swell with pride like knowing you have just built the highest balsam pile yet of the season. And let’s not stop there, optical illusions, balsam snowmen, a spot of friendly competition who can build the biggest pile or who can scale the finished pile the fastest and stand victoriously at its summit – the pile is your oyster.

Unquestionably, balsam control is not always all sweetness and light –the plant is willing to make use of many kinds of growing spaces and so we found ourselves thigh deep in ‘bogs of eternal stench’ or crawling around in gorse on more than one occasion. Did it stop us having fun? Of gorse not!

Through the good times and the tough, plenty of opportunities to whip out the Kelly kettle, freshly brewed tea and coffee (not the instant kind, mind!) and, most vital, chocolate biscuits, support us in keeping our volunteers in top motivation.

Time to reflect and perfect

So, what have we learned over the past two seasons through trial and error? For one, we have stocked our armoury well with strimmers, scythes, weed whackers and gloves since last year – something to counter anything the balsam might throw at us.

Selectively pulling balsam from amongst other vegetation seems to have the least impact on non-target species, if compared to mowing down stretches of bankside vegetation at more badly infested sites. But, if you’re working on borrowed time, you sometimes have to face the hard hitting questions. Mowing is effective in terms of time and effort and, thus, usually prevents a much larger proportion of seeds from dropping. So, do we mow in the hope that after a couple of seasons we have adequately reduced the density and can move on to pulling the balsam up? Or shall we pull regardless of the fact that much less can be achieved in the same amount of time? It is important to ponder these quandaries and often we have to make decisions on a case by case basis, depending on the existing vegetation, how dense the balsam has become and its potential to spread from there.

As it gets later in the season the balsam is really out to impress, growing up to two meters in height. At times the stems are growing horizontally along the ground before reaching its flowers towards the sky and roots start to form on higher leaf nodes, digging into the soil where the stem touches the ground. The trouble with this is the increasing likelihood of snapping the stalk during pulling, followed by the balsam stubbornly re-growing from the left over stem. A weed whacker can be really handy here to slash the stalk below the first node closest to the ground and curbing the balsam’s ambitions once and for all.

Casting our eyes on the future, there are always things to improve. For one, we still need to understand the distribution of balsam throughout our catchments better, so that we can control it strategically from the most upper extent moving down the river. We really appreciate reports of sightings to help us with that. The species is widespread and we know that long-term, sustainable solutions require landowners who actively take responsibility and more volunteers to support the effective removal of the plants annually. While many landowners, local communities, environmental groups and countless more are already getting involved we need to increase these efforts catchment wide moving forward.

Last but certainly not least, both this year and last year it is a must to acknowledge that every single one of our enthusiastic volunteers is absolutely wonderful and invaluable! You make it a joy to get to grips with balsam and you make the improbable possible. Not all heroes wear capes – some wear waders and gloves!

If this has inspired you to get involved with the Scottish Invasive Species Initiative or you’d like to find out more, visit our website www.invasivespecies.scot or email sisi@nature.scot

Getting to grips with Invasive Species -Top Five Tips for Balsam Bashing

A great blog here from the folks over at Nairn Green Hive project who’ve been working on the invasive Himalayan balsam around Nairn with us.

Nairn River Enterprise and Green Hive

Green Hive volunteers relax with James (SISI co-ordinator) on the  biggest balsam pile after our balsam bashing experience at the Riverside Fun Day

We’re fast approaching the end of the season for Balsam Bashing – a massive thank you to everyone who has helped out and spent time clearing Himalayan Balsam this year, the Riverside and surrounding area looks completely renewed after all your hard work!

Green Hive volunteers working alongside Scottish Invasive Species Initiative (SISI) have managed to clear over 2 acres of balsam from our banks!

We would also like to thank James the SISI co-ordinator for taking time with us to train and demonstrate various methods for invasive species removal. You can have a read through the “species spotlight” on Himalayan Balsam on the Summer 2019 SISI newsletter here

In the next couple of weeks the balsam plants will have ripened their seed pods, making removal very…

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