Indexer
Although Great Britain has a rich and diverse native wildlife, there are several species that would not be present were it not for human interference. Some of these introduced species are welcome additions, but others are much less so.
Parakeet – this bright green bird belongs to south Asia and sub-Saharan Africa, but it can also thrive in temperate climates such as that of western Europe (including southeast England where large flocks have established themselves). The current population probably bred from escaped cage-bird pets.
Muntjac – this small deer species was introduced from Asia around 100 years ago, but individuals that escaped from a wildlife park led to successful wild populations becoming established. 
Mink – these were introduced from America to be farmed for their expensive fur, but escapees soon found their way to England’s rivers where they caused havoc with populations of native animals such as water voles.
Grey squirrel – another American import that has had a devastating impact on native wildlife, particularly the red squirrel. The latter is now confined to a few isolated places in the British Isles, leaving the greys as the only squirrels that most people ever see. 
Red-necked wallaby – an escapee from wildlife parks that has bred in the wild in places such as Scotland, Sussex and the Peak District. Marsupials belong to Australia, not Great Britain! 
Red-eared terrapin – this is an American species of “water tortoise” that was brought from America to be sold by pet shops. Unfortunately, they can give a nasty bite, and many owners thought they were doing the right thing by releasing them into rivers and canals. Unfortunately, they now attack native wildlife such as ducklings. 
All in all, the import of non-native species has not always been a good idea due to the unintended consequences when escaped pairs create feral populations. It seems as though it is imports from the Americas that have proved to be most problematic!
(All the photos have been taken from copyright-free sources)
great pictures where you have taken it from ?
As stated above, all the photos were gathered from copyright-free sources.
Waaaoo beautiful animals I like animals
Good picture of a imal
Too bad so many of these are invasive breeds.
Great informative post, these tiny guys are adorable
So many interesting information connected with welcome & non-welcome nature additions! Thank you very much for it & let me to do my bit in your Christmas mood – https://virily.com/item/christmas-decor-devoted-mans-best-friend/
Thank you for sharing these stories of animals that are not natives of Great Britain.
Great post- I had no idea there were that many displaced-we in America have Python in Florida, Snakehead fish, Zebra Mussels-it”s kind of scary-animals belong where they were intended to be-Man messes up with the best intentions.
Your note on the grey squirrel rings too true. They are indeed invasive and destructive, as well as prolific disease carriers (partly due to prolific reproduction), but controlling them is opposed. It boggles the mind that it will take something like a plague outbreak before a widespread stand on proper management of them is acceptable. Thanks for an introduction to the muntjac.
I never thought that wallabies would be roaming free in England. They are native from Australia. I guess Great Britain has some temperate zones so that these critters can tolerate and thrive. I would love to visit Great Britain but only in the winter time as I am not a great fan of summer. I agree with you, though, that invasion of other species can be very detrimental to the native species.
interested in the environmental impact of the red ear terrapin ..I .I never imagined they would attack ducklings.
Mink is beautiful animal.
Very interesting topic….
Nice I like it looking great