Problem Invasive Species In The UK
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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 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.
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.
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 & 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 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.
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
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Grey Squirrel Image – by KGGucwa, Creative Commons Attribution-Share Alike 3.0 Unported