What North American species have become invasive species or ecological hazards elsewhere?
Eastern gray squirrel
The common eastern gray squirrel which is present is huge numbers in Britain is one which definitely for us Brits gets on our nerves a lot. This is due to the eastern gray eating over seven times the amount that a grey squirrel can, they are also a carrier of squirrel pox which is devastating when the red squirrel contracts it. They were not always a pest with them being brought over for the wealthy and as their owners got bored of them they released them into the wild which they then thrived which then had a knock on effect for the red squirrels which were and are still native to the British Isles.