Aliens amongst us

When a species arrives in a place where it does not belong it is known as "non-native" or as an "alien".  Sometimes these species settle into their new environment without much fuss or simply fail to become established.  Other times the alien species start spreading, taking up space occupied by native species.  These invasive aliens can threaten native species or cause economic damage.

Within Scotland, infamous non-natives include American mink , common rhododendron  , signal crayfish  , and sika deer .  Probably less well known is that species native to Scotland might not be native to certain parts of Scotland and if introduced are in effect non-natives.  An example of this is the introduction of the hedgehog to the Western Isles.

Possibly even less well known is that sometimes an introduced sub-species can cause problems for a native sub-species.  With so few Scottish wildcats remaining, interbreeding with domestic cats is threatening the existence of our "Highland tiger  ".

Since non native species might easily spread between Scotland, Wales and England, the Strategy to tackle them covers the whole of Great Britain.  The cost of non-native species to the British economy is huge, a report in 2010 estimated that non-native species cost the economy £1.7 billion, including a cost to Scotland of £251 million.

The Scottish Government is taking the lead in tackling non-native species in Scotland.