In the 18th century it got harder to find a home where the buffalo roam. The tremendous herds of American bison were annihilated with amazing speed, until only a tiny fraction of the population remained. Yet, some hope that the Wild West may once again reverberate with the thunder of millions of bison hooves.
The eastern subspecies of bison, known as the wood bison (Bison bison athabascae) is the largest land animal in the western hemisphere. Unfortunately a botched reintroduction program hybridized many of the remaining 1,500 wood bison with plains bison contaminated with bovine tuberculosis and brucellosis. By 1940, it was believed that the wood bison had been completely replaced by the hybrids. Then a population of approximately 200 was discovered near the Nyarling River in Canada in 1959. These pure wood bison survivors were the core of a resurgent population that now numbers approximately 11,000 in conservation herds.
Plains bison have improved their numbers as well. The IUCN counts approximately 20,500 plains bison in conservation herds. Another 500,000 bison live as livestock in captive commercial populations. However, some would like to see those bison out of their fences. An IUCN report suggested that restoring the massive herds of bison to the American landscape would be the best long term survival plan for the bison. The report noted that serious legal and infrastructural challenges stand in the way of returning the bison to their former range.