Saw those green parrots on Hampstead Heath during my infamous acid trip. I had no idea they were there or anywhere in London so it absolutely blew me away, like a visitation from the angelic host.
Small Asian mongooses were introduced onto the island in the early 20th century in order to reduce the venomous snake population (the island was apparently completely overrun). Whilst the mongooses completed this task, they also disposed of pretty much all the birdlife of the island. To this day, the island is notably short of hedgerow birds, such as sparrows. Mongooses are a hazard for domestic poultry, and are also known to cause damage in vineyards and orchards.