Non-native species and their effects in the UK

In Britain there are a staggering 2900 species that are not native to the United Kingdom. Many non-native species are harmless and cause minimal damage to the environments in which they live and occasionally they are important in helping an ecosystem thrive.

However, some non-native species prove to be harmful to the environment. In fact the government spend a staggering £1.5 billion each year simply to control the numbers of these non-native animals and plants.

 (The European Rabbit which was introduced during the middle ages has adapted well to Britain but is causing problems by destroying agriculturall crops. However they are important for maintaining habitats for bees and butterflies).

Did you know? – The UK is home to 7 species of deer, but out of these 7 species only 2 are native to the UK. These are the ‘red deer’ and the ‘roe deer’. The other alien species are ‘Sika deer’, ‘fallow deer’, ‘muntjac deer’, ‘chinese water deer’ and ‘reindeer’ (also known as caribou in North America). However, there are advantages to this introduction of deer species. The chinese water deer is extremely rare globally and they are virtually non-existant in their native range. As a result of this scientists from China have come all the way to Britain to study this species.

The sika and fallow deer cause an enormous amount of damage to agriculture and woodlands (habitat distruction) which is not only harmful for us, but also the native wildlife. As wolves, bears and lynx no longer live in the UK the govrnment has to cull up to 300,000 deer each year to simply prevent their numbers from rapidly increasing.

Invasive species can cause problems for Britain’s wildlife in following ways:

1) Hybridisation
2) Increased competition
3) New predators
4) New diseases

An excellent example of increased competition in the UK is with the grey squirrels outcompeting the native red squirrels. Grey squirrels are native to Eastern North America, but were introduced into Britain during the 19th century. Grey squirrels carry the ‘squirrel parapox virus’ which is harmless to them, however it is lethal to the red squirrel and many die within one week of contracting the disease. Also a grey squirrel can remember where it has placed its food for up to 62 days while a red squirrel can only remember for 35 days.

 (The Red Squirrel has suffered sharp declines across the UK due to the introduction of grey squirrels, the only places you can see these beautiful mammals are in Scotland, Northern Wales and parts of England).

There is also great concern that the Asian hornet (now introduced into France and much of mainland Europe may well cross the English Channle to reach the UK. The Asian hornet is a major predator of pollinating insects. However they much perfer honey bees. This would have a very negative impact on food production and not to mention the economy. In fact the bee’s service are valued at over £600 million each year in the UK alone. If this hornet arrives in Britain it will cause the numbers of pollinating insects to dwindle even more.

Alien species can either be harmful or beneficial but we cannot predict the damage done by each species so prevention is always better than cure.

For more information on non-native animals in the UK, please go to the dazzam nature UK website at

Thank you for reading!


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