The English aristocracy in Edwardian times were big travelers and liked nothing better than to bring home exotic animals to show off. Some they brought home stuffed (yuck!) but yet others they shipped home alive to show off to their friends and keep in their private menageries.
"After dinner, we'll have port and cigars and then look at the striped horse they call a Zebra." Yes, the Edwardians loved menageries of all types--which is when this squirrel arrived. Regretfully they did not stop at simply stuffing them to bring them home, they brought them home like Noah, in pairs, two by two, which meant they reproduced...and reproduced...and reproduced. Until today they are no longer unique at all, but rather have taken over!
The black squirrel at one time was believed to be genetic mutation of grey squirrels, however genetic testing revealed it is exactly the same as the black squirrel found in the United States.
How did the black squirrels go from private zoos to your back yard? It seems these critters periodically ...uh...escaped.
It was not unusual for animals imported for the entertainment of the aristocracy to escape. The Beast of Bodim Moor is said to possibly be an escaped black panther from a private menagerie of this time. Since it was illegal to own and import these animals obviously it was tricky reporting that you had one that had escaped.
The first wild black squirrel was seen in 1912 near Letchworth in Hertfordshire. It is believed to have escaped from the private collection of the Duke of Bedford who owned Woburn in Bedfordshire. These black squirrels (the same species as the gray squirrels) are taking over and may soon outnumber the native red squirrels.
Another escaped critter causing problems in England is the edible dormouse (Glis glis). In 1902 a handful of these escaped. Today? Their numbers are estimated to be 20,000, all in a 25 mile radius of Tring. Cute? Yes. Problematic? Definitely. Not only are they noisy but the local homeowners complain edible dormice gnaw through electrical cables, strip bark from trees and produce huge amounts of waste.
So the next time you're on vacation and find a cute critter and think it would be fun to bring it home and sneak it through customs... don't do it! You could be a modern day Duke of Bedford (and we don't mean you'll receive a title from the Crown!). You could be permanently altering the environment.