The grey squirrel is regarded as an invasive non-native species and has no protection under the Wildlife and Countryside Act (1981). They are listed in the IUCN international list of 100 worst invasive non-native species, which highlights the damage that grey squirrels cause to our native flora and fauna; a problem severe enough to be recognised at a level of global significance.
Grey squirrels were first introduced to England from North America in 1876 as an ornamental species to populate the grounds of stately homes. Around 30 separate introductions occurred until 1930 when the damage caused by the grey squirrel was recognised and it was made illegal to release a grey squirrel to the wild. Grey squirrels have rapidly spread and colonised much of mainland England with detriment to our wildlife, especially the native red squirrel, and to crops and tree species.