Most plants and animals that are brought to Britain do not harm the environment. However, there are some that may do just this.
Some alien species of plant and animal come into direct competition with a native species for space and food. For example, the native Red Squirrel is now in the minority, as the Grey Squirrel that was introduced into Britain from America is better at getting food and space. This means that the Red Squirrel is dying out as it has little food or space to live in. You can download a Squirrels Fact File from our Worksheets page
Some of these alien species may prey directly on the animals and plants already in Britain, while others such as the Rhododendron, can damage woods and riverbanks. Some alien species can also cause a major problem for humans, especially if they bring with them diseases that are harmful to us.
When alien species become a problem, measures have to be taken to control them. In the case of the Grey Squirrel, there are now areas of woodland in Scotland in which only Red Squirrels are allowed to live, to keep the Red Squirrel population alive.