Black wildebeest
Where it lives alongside the blue wildebeest, the two species can hybridise, and this is regarded as a potential threat to the maintenance of the species. The black wildebeest was once very numerous and was present in Southern Africa in vast herds, but by the end of the 19th century, it had nearly been hunted to extinction and fewer than 600 animals remained. A small number of individuals was still present in game reserves and at zoos, and from these, the population was rescued.
Black squirrel
Black squirrels can also be found in the United Kingdom, where grey squirrels were first introduced from North America at the end of the 19th century. They are concentrated in Eastern and South Eastern areas of England, but have been witnessed across the country. The origin of the UK's black individuals has been a topic of dispute, with initial research indicating that black-colored individuals are descendants of zoo escapees. Regardless of their origins, the black squirrel population in the UK continues to grow, and around the towns of Letchworth, Stevenage and Hitchin, as well as nearby villages such as Shillington and Meppershall in England, black squirrels are now as abundant as grey individuals. Black squirrels have been present and studied in Cambridgeshire since the 1990s; in the village of Girton three quarters of the squirrel population is black.