Canadian Bison and other Bovines

The American bison (Bison bison) is native to the prairies, steppe, and tundra of Canada and the United States. There are two living subspecies, the plains bison (Bison bison bison) and the wood bison (Bison bison athabascae). The plains bison is native to the southern prairie provinces, while the wood bison is native to the northern prairie provinces and the territories. The plains bison is smaller and leaner with shorter horns and a thinner coat, while the wood bison is darker with a shoulder hump closer to the neck. Before the arrival of the natives there was one, possibly two other species living slightly farther north, and the current species range and population was much higher before the arrival of the colonials. Both the European bison (Bison bonasus) and American bison are descendants of the steppe bison (Bison priscus) which until approximately eight thousand years ago could still be found in the more northern parts of the territories. 

It's unclear whether or not multiple bison species could have been present at the same locations. As far as can be determined, the modern American bison is descended from Bison antiquus which was itself a descendant of the giant Bison latifrons, the descendant of Bison priscus. At the end of the Pleistocene there were roughly three different bison species present in Canada, the steppe bison in the north, the modern bison in the center and south, and the western bison (Bison occidentalis), another offshoot of Bison antiquus, possibly living in parts of the northwest. 

The modern bison once numbered in the tens of millions but these days there are roughly one million left, mostly living on private ranches and nature reserves. Efforts have been made, and continue to be made, to expand this population and it's range. While it is doubtful that they will ever reach their original population, it is hoped that large herds can be introduced to several large nature reserves across the country. In regards to the steppe and western bison, it is hoped that the range of the wood bison can be expanded to include area once inhabited by those animals. Alternatively, those areas could be inhabited with another cold-weather bovid that shares some surprisingly close ancestry, the wild yak (Bos grunniens mutus). The wild yak can grow slightly larger than the American bison, similar to the steppe bison, and is the largest living bovid after the gaur of India. Wild yaks survive on the Tibetan plateau, but fossil evidence shows that they once had a much larger range that included areas of Beringia, the area made by the steppe crossing from Siberia to Alaska. Yaks may actually be more closely related to bison than they are to cattle (Bos taurus). At the very least there was hybridization between the two at some point, based on their mitochondrial lineages. Yaks might effectively be released in areas like northern Yukon, NWT, and the northwestern islands of Nunavut. European bison might also work as ecological surrogates but their ability to withstand arctic climates is less sure. 

Top to bottom: 

Plains bison - http://beartrust.org/wp-content/uploads/2013/01/Plains-bison.jpg
wood bison-  http://www.adfg.alaska.gov/static/species/speciesinfo/woodbison/images/wb_bull2.jpg
European bison - http://www.ffh-anhang4.bfn.de/fileadmin/_processed_/csm_Bison_bonasus_Foto1_77f20d495b.jpg
wild yak - http://m5.i.pbase.com/g1/62/942562/2/146679865.VIYcpNxB.jpg

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