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Problem Invasive Species In The UK

Updated on April 5, 2020
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Cynthia has a degree in History and Business Economics. She loves archaeology and would happily spend every holiday exploring ancient sites

Harlequin Ladybird
Harlequin Ladybird | Source

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Introduced Species in the UK - Animals

Introduced species of animals are causing problems in almost all of the countries in the world. Just because Great Britain is an island, does not mean that we do not also have our fair share of invasive species, and environmental groups are warning that these alien species could be costing our economy as much as £2 billion per annum.Britain’s waterways seem to be particularly at risk, and the Environment Agency has even gone as far as producing a ‘Top Ten’ of the most destructive UK invasive species that are threatening our rivers, lakes and canals.Many of the common invasive animal species in the United Kingdom were brought here in the eighteenth and nineteenth century as parts of private menageries or to ornament the country estate of a nobleman.Inevitably some of these animals escaped and managed to set up breeding colonies.In more modern times, people have started to keep exotic pets and when they have got fed up with caring for them or they become too expensive to keep, they release them into the wild.Yet more invasive species arrive as stowaways in food imports and packaging, and there is often a story in the British press about an exotic spider or a scorpion being found in an imported bunch of grapes or bananas.

Some of these invasive animal species have competed with our native animals and driven them out and destroyed plant life and habitat, while others, up till now, seemed to have caused no damage to the environment of the British Isles. Culling of invasive species to keep their numbers down is always a contentious issue. On the one hand, there is the need to protect Britain’s native animal species, plants and eco-systems, and on the other these animals are here through no fault of their own and every animal deserves to be treated humanely and not be killed in a violent, painful manner.

Grey squirrel in St James's Park, London
Grey squirrel in St James's Park, London

Grey Squirrels

Grey squirrels are a familiar sight in the gardens and parks of the United Kingdom. They are very cute animals and it is very amusing to watch them, but it is important to remember that the grey squirrel in not a native British species of rodent. Grey squirrels were imported from North America in 1876. They adapted very successfully to life in the UK and it is estimated that there are now around 2 million of them living in the British Isles. They have successfully competed against the native red squirrel and driven them from their habitat, so that they only survive in remote pockets of the UK. It is estimated that there are only around 120,000 red squirrels left. Grey squirrels also cause a lot of damage. They gnaw at the bark of trees and damage them and can also cause a lot of destruction if they manage to get into the roofs and attics of people’s houses. They are also endangering native bird species as they get into nests and eat bird’s eggs and they destroy many native plants.

However, recently a new squirrel invader from America has appeared in the United Kingdom in the form of the black squirrel. At first it was thought that these black squirrels were genetic mutations of the local grey squirrel population, but work done by researcher’s shows that genetically they are descendants of American black squirrels that have escaped from zoos. They are doing to the grey squirrels what the grey squirrels did to our native red squirrels, which is successfully competing against them and they are bidding to become the dominant squirrel species in Great Britain.

Harlequin Ladybirds

The Harlequin ladybird has been called the most invasive ladybird on earth. They were first discovered in the British Isles in 2004. They had originated in East Asia, spreading through Europe, and it is estimated that there are now at least a billion of them in the country. They threaten the native species of ladybird as they do not have a dormant period before breeding and have a longer active period than our native ladybirds. The Harlequin ladybirds also adapt to a very wide set of habitats and eat a very wide range of food, thus taking valuable resources from our native ladybirds. The Harlequin is a large ladybird and is very variable in appearance. Their destructive habits also include eating the eggs of butterflies and moths and causing damage to some soft fruit.

American Mink in the UK
American Mink in the UK | Source


Mink were introduced into Britain from North America in 1929 to be bred for their fur in mink farms. However, the fur industry declined dramatically in the last decades of the twentieth century and many mink were either released by animal liberation groups, escaped or were released by the owners when their fur business failed and have managed to colonise most of the UK’s waterways and riverbanks, driving out many of the native species, such as the water vole. Mink are vicious and effective predators and they seem to be almost impossible to eradicate. Their main prey is fish, but they will also take rabbits and other small mammals. They cause significant problems for ground nesting waterfowl and birds, as the mink raid their nests and eat their eggs and chicks. There is even film footage of mink swimming out to remote Scottish Islands and gorging themselves in nests of seabird colonies. These seabird colonies have no natural, native predators so are being devastated by the mink. However, there is some evidence that the return of the otters to our rivers is leading to a decline in mink numbers. Otters are a native British species and it appears as both the mink and the otter are semi-aquatic mammals they are competing for space and resources, with the otters coming out on top. As both species are predators they probably directly aggressive when contact between the species does occur.

Bennetts Wallaby or Red-Necked Wallaby

Wallabies are the only marsupials currently living in the wild in the UK. Wallabies were brought into the UK from Australia initially in the nineteenth century to grace private animal collections and zoos and some have escaped and formed breeding populations. They favour open grasslands and heathland and the climate of the UK is similar enough to that of their native Tasmania for them to flourish. The most famous wallaby colony in the UK is in the Peak District. However, it is believed that many of these wallabies perished in the really cold weather of the winter of 1963. Recently a picture was published in the British press of a lone wallaby in Derbyshire, which is believed to be the last surviving member of the group. However, there are still groups of wallabies breeding in Sussex and other areas of the UK. A recent development in the UK is that wallabies are being bred and sold to people with large gardens to keep their lawns in trim. Inevitably some will escape and as they are only sold in pairs, will be able to set up more breeding groups. To date no damage to native plant and animal species or the environment has been reported by wallabies, but this could change if their numbers grow.

Muntjac Deer
Muntjac Deer | Source

Muntjac Deer & American Oyster Drill

Muntjac Deer – Muntjac deer are a small, ornamental deer species that was introduced into the UK from south-east Asia in the early part of the 20th century. The male Muntjac deer are characterised by their distinctive large canine teeth or tusks. They have bred very successfully in the UK because they can adapt to a wide range of habitats, although they prefer dense woodland. They are also believed to be moving into urban areas. The female Muntjac deer are continually in season, so they are pregnant most of the time producing between one and two young a year. Muntjac deer cause a lot of damage to native trees as they eat young saplings and take off the bark of older trees. There is also evidence that they cause damage to ground cover plants in woodland environments.

Native oysters in the United Kingdom are being invaded by a snail-like creature that originates in the United States. There has been a huge decrease in the numbers of British oysters because an American sea snail called a ‘tingle’ or American oyster drill has started to prey on them. The ‘tingle’s native habitat is the Atlantic coast of America, but it has found its way to the south coast of England where it is causing mayhem in the local oyster population. The ‘tingle’ bores a hole into the shell of the oyster and then eats them. There are fears that some oyster breeding grounds in the UK could soon be destroyed, and that oyster stocks are falling to alarmingly low levels. One of the main areas for oyster fishing in the United Kingdom is on the Solent, and the commercial fishermen there and scientists are warning that the oyster fishing industry in that area is in imminent danger of collapsing. One of the main worries is in the decline in the stock of juvenile oysters, which has a huge impact on future breeding and fishing.

Chinese Mitten Crab
Chinese Mitten Crab | Source

Chinese Mitten Crabs

Chinese Mitten Crabs have been known as an invasive species in Great Britain since 1935 when one was caught in the Thames. It is thought that the Chinese Mitten Crabs were first introduced into British waters in the ballast tanks of ships, having been pulled into the ballast tanks when the ship was taking on water in a foreign port. A further specimen was collected in a reservoir in Yorkshire in 1949 and then in 1973 further Chinese Mitten Crabs were taken from the Thames. The Chinese Mitten Crab is now thought to have reached as far up the Thames as Staines, and be present in the Medway, the Tyne and the Tamar. It is feared that the crabs will encroach on all of the Thames catchment area and these invaders have been caught in most of the rivers that enter the Thames east of Staines.

The Chinese Mitten Crabs potentially pose a significant threat to our native crayfish, and because they are a burrowing crab they can cause a lot of damage to UK riverbanks and embankments and clog up drainage systems. The Chinese Mitten Crab is capable of making migrations over land and can go significant distances. In 1995 they were seen coming out of the Thames at Greenwich and heading for the High Street! Chinese Mitten Crabs can pose certain problems if they are going to be eaten, as they have a high tolerance for heavy metals such as cadmium and mercury, and they are also hosts to the oriental lung fluke. So if the crab is not cooked properly or eaten raw this parasite can be passed onto humans, although this is thought to be unlikely in the UK.

Killer Shrimp

The killer shrimp is a relative newcomer in the UK introduced species list, but it has already been identified by the Environment Agency as one of the most destructive to our waterways and native species. The killer shrimp is only about two inches long and is a native of Eastern Europe, but has slowly been spreading like a plague across Western Europe.It is thought to have been brought to this country on dirty fishing tackle, so this is a warning for anyone who fishes, camps or hikes abroad to thoroughly clean your equipment and boots before you return to the UK. This tiny shrimp is such a menace because it has a truly voracious appetite and is rapidly eating its way through our stocks of young fresh water fish, native shrimps and invertebrates The killer shrimp also has the habit of killing its prey and then leaving it uneaten, and it is thought that some of our insect species, such as water boatmen and damsel flies could be threatened with extinction, which would cause a huge disruption in the native species’ food chain.

UK Animals - The Grey Squirrel

These are just a few of the invasive animal species that are currently breeding in the wild in the United Kingdom. Conserving the native species of Britain and the British countryside is an ongoing challenge; but it must be a challenge where the welfare of any invasive animals is taken into account. If it is decided that a cull of an invasive species is absolutely necessary, it needs to be undertaken as humanely and with as little suffering to the animals involved as possible

Copyright 2010 CMHypno on HubPages

Grey Squirrel Image – by KGGucwa, Creative Commons Attribution-Share Alike 3.0 Unported

Harlequin Ladybird Image Andy Potter Wikimedia Creative Commons Attribution Share Alike 2.0 Generic

Muntjac Deer Image Jay Haywood Wikimedia Creative Commons Attribution Share Alike 2.0 Generic

Chinese Mitten Crab Image Christian Fischer Creative Commons Attributions Share Alike 3.0 Unported

American Mink Image Peter Trimming Wikimedia Creative Commons Attribution Share Alike 2.0 Generic

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2010 CMHypno


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    • CMHypno profile imageAUTHOR


      8 years ago from Other Side of the Sun

      Glad that you enjoyed the hub whowas. Much as I love them, I agree that cats cause a lot of problems for our native species, and I am a firm believer that only licensed breeders who have been properly vetted should be able to breed cats and dogs, and that all puppies and kittens should be neutered before they go to new homes, unless they are going to another licensed breeder. I can already hear the howls of protest from pet owners at these suggestions, but I can add others such as cats should have bells on their collars and be kept in at night.

    • profile image


      8 years ago

      A great hub and it raises some very important issues for future conservation in the UK.

      I do think that controlling exotic, inroduced species is necessary in order to protect the balance of an already unsteady set of ecosystems, maintain biodiversity and protect our native species.

      One invasive species that has exploded all over the UK and causes untold damage to some of our rarest and most beautiful birds and small mammals is none other than the domesticated cat. They are responsible for more species destruction than humans. And that really is saying something.

      The problem with cats as opposed to dogs and other pets, is that they run wild, go feral, breed randomly and are entirely beyond the control of their 'owners'. Add to that that they are instictive and unbridled killers who kill and continue to kill even when they are not in need of food - and they make no distinction between a common tree sparrow and a rare bunting or warbler- and you see that we have a real problem with them.

      I realize that to suggest an outright cull would never be acceptable. However, I do think that general sterilization of the cat population over time and the legal obligation to obtain (and pay for) a licence to keep one, would be a good step forward.

    • CMHypno profile imageAUTHOR


      9 years ago from Other Side of the Sun

      Hi Brian, thanks for reading about UK invasive animal species. I have never come across any reports of turkeys going wild in the UK, and becoming a problem. However, there are some huge turkey farms over here, especially in Norfolk, so I can't believe that at least some haven't escaped in the past

    • profile image

      Brian Simpson 

      9 years ago

      Has there evr been any instances of Turkeys going wild in British forests like they are wild in such forests in USA?

    • CMHypno profile imageAUTHOR


      9 years ago from Other Side of the Sun

      Unfortunately the invasive species never seem to be too keen on chomping on each other, and always seem to prefer eating off the native menu! Thanks for reading about invasive species in the UK and leaving a comment, Dolores

    • Dolores Monet profile image

      Dolores Monet 

      9 years ago from East Coast, United States

      Invasive species can wreak havoc on the environment. Maybe the minks can kill off the gray squirrels!

    • CMHypno profile imageAUTHOR


      9 years ago from Other Side of the Sun

      Hi Harlan, sound like you have a situation where one introduced species is causing a lot of damage. Hopefully something can be done to rectify what is happening

    • Harlan Colt profile image

      Harlan Colt 

      9 years ago from the Rocky Mountains

      The long term effect is after a long hot summer, you get a lot of dry vegetation in the mountain slopes that the deer and elk normally graze down. We get a lot of fall storms with lightening. Fires start and it goes up like a tinderbox. Later it snows on the mountain. In the spring there is no vegetation to hold the soil down so it flows down the mountain into the rivers, carrying tons of debris with it. The salmon come to lay their eggs, but the rivers are so full of silt, it looks like chocolate milk rushing by. Somewhere down the river a logjam will form and cause flooding usually destroying a roadway or man-made structures. I have even seen deer and elk in the spring get on a hillside of mud because of large million acre fires - and can't get back up and slowly slide down into the river and drowned. So one little species in the wrong place can cause a whole lot of damage. I was reading about a small island where in WW2 the Japanese let some rats go and now the native birds are endangered because the rats eat their eggs... so they went and recently killed all the rats - something like that. One of those TV shows on Animal Planet or something.

      - Harlan

    • CMHypno profile imageAUTHOR


      9 years ago from Other Side of the Sun

      Hi Harlan, thanks for reading the hub on invasive species in the UK. While in theory it a good thing to re-introduce apex predators, your experience with re-introducing wolves back into Idaho, shows that great care needs to be taken or even more problems are created. Will we ever stop meddling?

    • Harlan Colt profile image

      Harlan Colt 

      9 years ago from the Rocky Mountains

      I live in Idaho USA. Here they have imported, (in 1993) on purpose, 500 breeding pairs of Canadian Wolves. These animals are a non-native species. Today our deer end elk herds are down 85% from normal levels.

      Idaho had a native wolf, but it was about 50 pounds smaller than this wolf. The idea was to restore wolves. Why they didn't work to restore our native wolf is a mystery to me. Today they are now working on passing a law to eliminate these large devastating wolf packs.

      -Nice work here,


    • CMHypno profile imageAUTHOR


      9 years ago from Other Side of the Sun

      Hi Nicky, you are so right in that it is not the invasive species fault, and it will always be very difficult to halt the spread of these animals, while still treating them in a humane way

    • Nicky Smart profile image

      Nicky Smart 

      9 years ago from United Kingdom

      Thanks hypnodude - there are so many invasive species causing problems around the world. The grey squirrels are cute, we have three or four of them in our garden, but they have driven our native red squirrels out. Not their fault, humans brought them to this country!

    • CMHypno profile imageAUTHOR


      9 years ago from Other Side of the Sun

      Hi Alicia, there are quite a few wallabies loose in the UK, and with the trend of buying pairs of wallabies to maintain lawns growing, there will probably be more. These cold winters we have been having lately might stop them spreading, and in fact will benefit our native British species as several invasives have spread due to the warmer winters we experienced during the last decade. I love wallabies but they do not belong here anymore than rabbits and red foxes belong in Australia

    • AliciaC profile image

      Linda Crampton 

      9 years ago from British Columbia, Canada

      Your hub was very interesting. I had no idea that there were wild wallabies in Britain! I’m glad that you pointed out that we need to protect the native wildlife and also treat the invaders humanely.

    • CMHypno profile imageAUTHOR


      9 years ago from Other Side of the Sun

      Glad that you enjoyed reading about invasive species in the UK and thanks for reading the hub, ThoughtfulSpot

    • ThoughtfulSpot profile image


      9 years ago from PA

      Really interesting article. Thanks CMHypno!

    • CMHypno profile imageAUTHOR


      10 years ago from Other Side of the Sun

      Hi Jehnavi, I agree with you, there have been persistent sightings of big cats in the UK, with certain areas like the Forest of Dean and Exmoor seeing regular predation of livestock. Farmers know what they are talking about, and know that their animals could not have been killed by any of the UK's indigenous predators.

    • CMHypno profile imageAUTHOR


      10 years ago from Other Side of the Sun

      Thanks hypnodude - there are so many invasive species causing problems around the world. The grey squirrels are cute, we have three or four of them in our garden, but they have driven our native red squirrels out. Not their fault, humans brought them to this country!

    • hypnodude profile image


      10 years ago from Italy

      Another great hub, reminds me of the damages the giant catfish is causing to European rivers. I've seen those grey squirrels in UK, the pity is that the only way to control them is to kill them unless the red ones can find a new niche. At least otters are doing a good job. I love them.:)

    • CMHypno profile imageAUTHOR


      10 years ago from Other Side of the Sun

      Hi Hello, hello - I just hope that the black squirrel doesn't put even more pressure on our native red squirrels. Glad you liked the Hub.

    • Hello, hello, profile image

      Hello, hello, 

      10 years ago from London, UK

      Thank you very much for an interesting read. I didn't know about the black squirrel and I hope it will not spread like the grey. I don't mind if it get the grey population down.


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