Mousa Biosecurity Trail

Guest blog from Holly Paget-Brown, Biosecurity for LIFE

At Biosecurity for LIFE we are working hard to raise awareness of the threat of invasive predators and put in place systems to prevent their accidental introduction to islands. In particular we are focusing our efforts on 42 specially protected islands that are designated for breeding seabirds, including 7 in Shetland. Biosecurity is the practice of protecting places from the threats to wildlife posed by introducing new diseases or types of plants or animals that do not naturally occur there. Seabirds often choose to nest on islands with no land predators and are particularly vulnerable to introduction of predators such as rats, stoats, mink, and feral cats. Biosecurity for LIFE will work to ensure that the UKs important island seabird populations are provided with safe places to breed and build long-term resilience considering the other significant threats. It will also aim to ensure that island communities are engaged and central to the implementation of successful biosecurity measures.

What better way to learn about the environment and island biosecurity than being a warden for the day?

On Mousa in Shetland we now have our ‘Be a Warden’ trail set up and open. Here children (and of course adults!) can have fun learning about biosecurity and getting hands on with an RSPB warden’s duties for a day.

When you arrive on the island you can pick up a backpack with tools you’ll need and a map for your walk around the island.

As you go around you can look out for the native seabird and plant species present on the island that it’s important to protect from invasive species. Mousa is special as it is home to thousands of European storm-petrels as well as many other seabirds such as great skuas and Arctic terns.

The warden’s pack you can take around Mousa with you. Photo by Holly Paget-Brown

One of the key reasons European storm-petrel flock to Mousa is because it has no mammal predators living on it! This makes it a safe place to breed. Storm petrels nest in the Broch on Mousa and in other areas such as on the stony beach (photo at top of page by Holly Paget-Brown). It is important to keep Mousa free from invasive mammalian predators  so our special native species can continue to thrive.

Keep an eye out for the surveillance that’s out on the island and see if you can spot any rodent teeth marks on the wax block in the ‘warden’s box’. This is a useful tool used on many islands to help monitor whether there are any rodent species present. The smell of the chocolate wax attracts them and they leave distinctive gnaw marks which can help to identify if they’ve reached an island.

You’ll learn about some key things to remember when you’re on Mousa and other seabird islands:

  • Don’t disturb the wildlife
  • Stay on the path
  • Take your rubbish home with you
  • Rats and mice like to hide in bags and boxes: check your bags for stowaways before getting on the boat
  • If you see an animal that shouldn’t be there, report it!
  • Don’t climb on the stone walls, there may be storm petrels nesting in there
  • Inspire others to do the same

So if you’re on Shetland why not take a trip to Mousa and find out more about biosecurity and our incredible native species!

As well as when on Mousa, keep an eye out on other seabird SPA islands in Shetland for invasive predators and follow the other key biosecurity guidelines you’ve learnt on your visits.

The map to follow around Mousa with a few things to look out for along the way. Photo by Holly Paget-Brown

Mammalian predators aren’t the only non-native species in Shetland, there are many in the marine environment as well. As you walk around Mousa or if you’re ever close to the seashore or out for a swim, why not keep an eye out for some of our non-native and indicator marine species. Take a look at the Shetland Community Wildlife Group’s guide to species of interest here: Identification Guides | Shetland Community Wildlife Group.

Introduced animals in Shetland

Guest blog by Paul Harvey, Shetland Amenity Trust

Yesterday we considered a few invasive plants that have the potential to wreak havoc among our native plants, today it’s the turn of animals. Let’s start with land mammals. There was no land bridge between Shetland and the British mainland or continental Europe after the last ice age some 10-12,000 years ago. It is therefore highly likely that all of Shetland’s resident land mammals, yes even the Otter, were introduced to the islands by humans. Some of these were unintended consequences of human activity but some were by design. Bats do of course occur naturally, albeit rarely, as they can fly but alas it seems that we have insufficient volumes of flying insects in our short, cold summers to enable them to colonise the islands. They could yet do though on the back of global warming, and currently breed as close as Orkney.

Potentially the most serious of these introduced land mammals for our native wildlife is one of the most recent and was indeed deliberate. In the 1980s, a few folk thought it was a good idea to introduce ferrets to control rabbit numbers. Well, that turned out well. The ferrets flourished, bred, started to revert back to animals that look much more like their polecat ancestors and seem to have had little impact on the rabbit population. They almost certainly have, however, contributed to the declines observed in some of our ground-nesting native birds and also help themselves to domestic ducks and poultry when the opportunity arises. If you are in any doubt as to how successful this introduction was then just look at the number of polecat x ferret road kills in autumn when the animals are starting to struggle to find food. It is unlikely that this species could ever be eradicated from the Isles now even if someone was to throw a six or seven figure sum at the task.

Stoats were also introduced deliberately, or so the story goes. Some time before the 17th century they were apparently brought in and released by the King’s falconer to spite some local folk who had refused to give their levy of hens demanded as food for his young falcons. They too will feed primarily on rabbits but I’m sure are not averse to a clutch of birds’ eggs or a brood of young birds if they happen across them. They, though, seem to have reached an equilibrium in Shetland, are rarely seen in comparison to the burgeoning population of ferret x polecats and seem to present less of a threat to our native birds.

Stoats (photo at top of page by Jim Nicholson) were supposedly introduced over 300 years ago but their population has not increased as markedly as the polecat x ferret which was introduced just over 30 years ago.

Another guilty party is our much-loved Hedgehog. I love hedgehogs too but only where they belong and that does not extend to Scottish Islands! Here they do untold damage as they stumble around munching any eggs that they come across. They have been known to devour practically the entire contents of an Arctic Tern colony here in Shetland. The problem is our ground-nesting terns and waders have just not evolved to co-exist with these alien mammals.

Hedgehogs (right) although cute can cause havoc for ground-nesting birds when they are introduced to offshore islands like Shetland.

Photo by Jim Nicholson

Most of the mammals I have mentioned to date have not been introduced (or at least successfully introduced) to our outer islands, which is a blessing for their native birds. One alien mammal has, though, been introduced to every island with human inhabitants and perhaps leads to more controversy than any other. The good old domestic cat. The problem is some of these cats become feral and then breed with other domestic, or feral, cats and before you know it there is a significant population of ‘wild’ feral cats. Seabirds really have no defences against those feral cats that choose to make their homes on the slopes of our seabird colonies. Why wouldn’t you move onto a cliff with an endless supply of cheap food. Radio-tracking has shown that even our beloved pet moggies – go far, far further from home than we realise after the hours of darkness. Who knows what dastardly deeds they get up to? The impact of cats is well illustrated by the story of Noss National Nature Reserve. Cats once roamed the island under the auspices of bringing the local rabbit population under control. Scottish Natural Heritage came to an agreement with the owner to remove cats from the island and since then Storm Petrels have started to breed there.

Pink-barred Sallow moth – Photo by Jim Nicholson

Some moths like this Pink-barred Sallow (above) have probably arrived in Shetland as eggs or larvae on introduced plants but they do not appear to have an impact on native species and add a nice splash of colour to the islands.

What of other animals? There is no doubt that a whole variety of invertebrates have colonised the islands after being brought here as eggs or larvae among plants. Many of these may well be harmless and some e.g. moths add extra colour to the scene but others are more sinister. The boom in horticulture in Shetland has certainly made the island a prettier place to live but it is also responsible for introducing the New Zealand Flatworm the length and breadth of the isles. This species was first introduced to the UK in the 1960s. It lives on earthworms covering them in its digestive juices to dissolve them before sucking them up. Earthworms are a vital part of a healthy soil and the fear was that the flatworms would destroy earthworm populations and therefore soil fertility. Although the flatworms do reduce earthworm numbers it seems that without human interference they are not good at getting around so remain largely restricted to human-altered habitats. Thus far they have not had quite as disastrous an impact as first feared.

The New Zealand flatworm – Photo from FERA, courtesy of GB NNSS

Humans have an unenviable reputation for casing untold damage to natural habitats through a variety of processes – but the introduction of alien plants and animals is near the top of the list. The ecology of some island groups has been fundamentally altered through such introductions – only 17 of the 50 or so honeycreepers that once lived on the Hawaiian islands remain, the others are extinct; habitat destruction, introduced mammalian predators and diseases associated with introduced mosquitos have all taken their toll. And of course, the loss of these honeycreepers, some of which were key pollinators of endemic plants, has led to the loss of some plants too. Here in Shetland we have been spared the worst of these excesses but we should remain cautious about the impacts of introduced animals on our native fauna.

Introduced Plants in Shetland

Guest blog by Paul Harvey, Shetland Amenity Trust

Around a third of the species of flowering plants that one might come across in the Shetland countryside are not native to the islands. That’s a staggering 300 or so species that were deliberately, or accidentally, brought into Shetland by humans! The majority of these were brought here to brighten up gardens, or their seeds arrived as contaminants of agricultural crops.

Most have not moved far – maybe they’ve jumped (not literally) over a garden dyke or fence, or rely on the ground being ploughed for more crops. Some may provide an additional nectar source for insects – very welcome in areas where native flowers are beheaded by sheep before getting a chance to flower, but others contribute very little to wildlife and some may even be detrimental. Native wild plants and animals have adapted together, so can be useful to each other for example through pollination, or are in a continuous battle where the insect consumes the plant and the plant tries to evolve defences to keep the insects at bay. And of course their flowers, leaves and seeds, and the insects attracted to them, provide food for birds. These complex relationships simply don’t exist with many non-native species.

A good number of these non-natives have, however, found the Shetland environment very much to their liking and have spread through the islands to the extent that they look perfectly natural here. And indeed some of these co-exist with the native flora and fauna without causing any issues. A few, though, are more problematic. Here we consider three such species.

Japanese Knotweed

Japanese Knotweed is native to eastern Asia and was brought to the UK in 1850 by botanist Philip von Siebold. We don’t know when it was brought to Shetland but it was first noted at Kergord in 1952 and now occurs at quite a few places in the islands. It is most easily seen at the Dale of Walls where it occurs along the burn either side of the bridge across the road.

Down south this really is the archetypal triffid –  it spreads very quickly suppressing any other plants in its vicinity. It dies back in winter and then new stems arise from rhizomes that are deep underground. Even though it rarely sets seed in the UK new plants can arise from even a tiny bit of a rhizome – hence it is classed as controlled waste under the Environmental Protection Act needing to be disposed of at licensed landfill sites. Eradication is problematic and often involves calling in professional help. Indeed, if you’re trying to buy a house and Japanese Knotweed is known to be present then it’s unlikely you’ll get a mortgage until it’s eradicated – more expense!

Fortunately, here in Shetland it doesn’t appear to spread so quickly and at most of the sites I have seen it, its distribution hasn’t changed that much. I have had to give one potential house buyer in Lerwick the bad news on one occasion though, so beware!

Photo by Paul Harvey

Japanese Knotweed at the Dale of Walls (above). Here it dominates part of an old croft garden and appears to be slowly spreading along the burn. Fortunately, in Shetland this invasive plant only spreads slowly unlike its counterparts down south where it can soon spread and take over large areas.

Ground Elder

Ground Elder is a member of the carrot family that was introduced to the UK by the Romans as a medicinal and culinary herb. Its leaves are quite tasty – a kind of lemon come celery taste – and presumably that is what encouraged folk to bring it to the islands and plant it in their gardens. Don’t eat too much though as I have read that after flowering it can have a mild laxative effect. And therein lies the problem. Once established it takes over – forming a carpet of green, outcompeting and shading out all other flowers; that’s an awful lot of salads… and potentially toilet roll. Although not being subject to the same legislative issues as Japanese Knotweed, eradicating Ground Elder is a real challenge, as like the knotweed, it seems to be able to regrow from just the tiniest piece of white root that you might accidentally leave behind when attempting to remove it.

Ground Elder (right and in banner) grows quickly in spring and can soon dominate roadside verges, waste areas and gardens.

Picture by Jim Nicholson

Monkeyflower

The final plant I want to consider is Monkeyflower and its various hybrids and forms. This one is much more controversial as it has become much-loved by many Shetlanders. It actually originates from North America, is undoubtedly attractive and seems to thrive in Shetland in wet places; ditches, loch margins and marshy ground. It was brought to the UK in the mid-1700s and found growing wild by 1830. Beeby was the first to note it in Shetland in 1886 at the Loch of Clickimin, although it was restricted to just two or three sites until at least the 1920s. Since then, it has expanded markedly and despite its pretty appearance it might be having a negative effect on some plants and animals. The jury is still out but it certainly has a tendency to form extensive mats and dominate some damp areas and ditches at the expense of our native flora.

Monkeyflower (right) comes in several colours from yellow through to a burnt orange. This is the most common colour. Although attractive, the plant can soon clog-up and dominate ditches and wet, marshy areas.

Photo by Jim Nicholson

In their native ranges these plants are kept in check by insects, fungi and other predators but once introduced into a new environment where these natural predators are absent they can explode and replace our native plants. Whether we have learnt the lessons from such introductions is something of a moot point. Folk should be particularly careful when dumping garden waste away from their gardens. As well as being illegal fly-tipping, this can also lead to the spread of invasive plants including those outlined here.

This feature is also available at the Shetland Amenity Trust website.

Welcome to INNS Week!

This week is the UK’s Invasive Species Week which aims to raise awareness of the issues that invasive species can cause and of the work being done to prevent their spread and reduce impacts.

So what is an invasive non-native species and why do we worry about them? Non-native species (which can also be called alien or introduced species!) are animals and plants which have been moved to new locations outside their native range. The majority of these don’t cause any problems but a few can have drastic consequences in their new environments, harming other wildlife or causing problems for the people that live and work there – these are known as invasive non-native species (or INNS).

Non-native species are moved by humans – either intentionally such as for food or as pets, or accidentally as hitchhikers on boats, equipment or with other organisms. For instance, people think the invasive wireweed Sargassum muticum (header photo) was introduced to Europe when it was used as packing material for oysters being moved from the USA to France in the 1960s. It’s now widespread across a lot of the coasts in the south of the UK, and a species we’re keen for folks to keep an eye out for on Shetland’s coasts.

Non-native species can be introduced into any type of habitats – on land, into rivers, or into seas. And species that are part of our native wildlife here cause problems in other parts of the world. For instance our native green shore crab (Carcinus maenas) which is a normal shoreline species in the UK has competed with native crabs after its introduction to the USA and is considered a pest. It’s always fun chatting to other non-native species researchers from across the world, as we’re often studying the same species but consider each other’s native species the problem – it gets a bit confusing!

Image by Sara Redstone, GBNNSS – Oak processionary moth caterpillars devouring an oak tree.

The environmental problems caused by invasive species can range from impacting individual native species to completely changing the structure of habitats. Where invasive species can cause the most environmental damage is to places where the native species do not have any natural defenses. One example of this is the introduction of predators such as rats or mink to islands with nesting birds which naturally have no land predators. The lack of familiarity with novel species can also cause problems for people as well. For instance, caterpillars of the oak processionary moth which was introduced to England in 2005 can cause rashes and breathing problems due to tiny toxic hairs if people disturb them.

Invasive species can also cause costly problems for people by affecting industries, for example the introduction of sea-squirts Styela clava and Didemnum vexillum have caused problems for aquaculture by fouling gear and increasing cleaning costs. In the Black Sea, the introduction of the invasive ctenophore Mnemiopsis leidyi (a small jellyfish-type animal) contributed to the decline of commercial fish stocks in the 1990s by competing with fish for food and eating small fish larvae. It’s hard to predict which species will cause problems so it’s best to take a precautionary approach and try not to move species around.

The invasive sea-squirt Styela clava fouling aquaculture gear in Canada.

Biosecurity

It can be very hard to control a species once it has arrived and begun to spread. The best idea is to stop new species from ever arriving, and to be especially cautious when we want to protect vulnerable habitats or where people’s livelihoods might be affected. We use the term Biosecurity for actions taken to protect places from the introduction of new non-native diseases, plants or animals. This encompasses a wide range of activities and behaviours we can take personally or which are built into how businesses operate.

As individuals we can do things like make sure our boots are clean of mud and seeds before travelling away and back from holiday, cleaning the gear we use to paddleboard, swim or kayak, or stowing food securely and checking for rats or mice when travelling on boats to smaller islands.

Coming up this week

This week we’ll be sharing some information about what non-natives are found in Shetland, and some of the research and work going on to prevent spread into and around the Shetland Islands. We’ll be posting a blog a day and sharing information and resources on social media, so follow along!

Tuesday – Marine non-native species monitoring at UHI Shetland

Wednesday – Introduced plants in Shetland – Guest blog by Paul Harvey, Shetland Amenity Trust

Thursday – Non-native mammals in Shetland, and a flatworm all the way from New Zealand – Guest blog by Paul Harvey, Shetland Amenity Trust

Friday – Keeping an eye out for rodents on Mousa – Guest blog by Holly Paget-Brown, Biosecurity for LIFE

If you want more information on invasive species in the rest of the UK, have a look at the GB Non-native Species Secretariat website!

Shetland’s Marine Non-native Species

Can you help spot marine non-native species in your local area?

For a number years, Shetland UHI has been looking for and keeping records of marine non-native species arriving in Shetland. Non-native species are those which come from elsewhere in the world and have become established here, usually transported on hulls of boats or ballast water. In the past, species were also transported with shellfish aquaculture when novel species were brought into and trialled across Europe (back in the 1960-1980s). Shetland UHI has been monitoring ports and marinas, as this is usually where species enter first.

Download our INNS Guide here…

We have found that, compared to elsewhere in the UK, Shetland has relatively few non-native species, perhaps reflecting Shetland’s cooler waters, making it harder for some species to colonise. However some INNS have been found in Orkney and Norway and can compete with native wildlife and smother aquaculture structures which have caused economic impacts elsewhere in the UK. It is therefore important that we monitor hotspots such as piers and marinas to record and findings of INNS and implement an eradication strategy.

We have created a INNS and Indicator Species Guide to help communities identify INNS in their local area and by reporting them quickly, are helping to keep the numbers of INNS in Shetland low. Very few non-native species make it into the ‘wild’, they prefer man made structures so piers, marinas and the underside of buoys are a good place to start your search.

Two species we would be particularly interested in records of are the Orange-tipped Sea Squirt (Corella eumyota) and Wireweed (Sargassum muticum), both originally from Japan.

Copyright Lisa Humphray

Lisa Humphray recently spotted the non-native Orange-Tipped Sea Squirt in Scalloway harbour while turning over rocks on the beach. This is only the second time it has been found in the ‘wild’ in Shetland and indicates it may be spreading beyond marinas and harbours. We’d be really interested to hear if anybody else finds it, as it would help us to understand how fast it is spreading around Shetland. It loves living right at the bottom of the shore and under rocks. At marinas it may be found on the underside of floats and buoys.

The second species we’d like you to look out for is Wireweed. It has been spotted twice in Orkney but hasn’t yet managed to become established. It can drift long distances in the current, so could easily make it to Shetland too. In Orkney it was found in the ‘wild’ rather than at a marina. Once established it can grow rapidly, clogging boat propellers and smothering our native animals.

GBNNSS © Crown Copyright 2009
Paul Brazier (CCW) © Crown Copyright 2009

We also don’t know if either the Orange-tipped Sea Squirt or Wireweed can survive Shetland’s wet ,windy and cold winters, so year round and year-to-year data is really important to understand how a species is establishing and spreading, particularly as the climate changes.  

For more information have a look on Shetland UHIs webpage on non-native species here.