The Bison of today are not purebred of yesteryear. they had a breeding program when they were about extinct crossing with cattle calling them cattalow. There are few instantiates where the DNA is pure. The cattle are not trampling the tortoise they are starving them to death, you cannot pasture cattle on the same area 12 months of the year. Plus the Yellowstone is a limited area compared to the range before the white man In Bred Hankering. Originally Posted by i'va biggen"Yellowstone is the only place in the United States where bison (Bison bison) have lived continuously since prehistoric times. Yellowstone bison are exceptional because they comprise the nation’s largest bison population on public land and are among the few bison herds that have not been hybridized through interbreeding with cattle. Unlike most other herds, this population has thousands of individuals that are allowed to roam relatively freely over the expansive landscape of Yellowstone National Park and some nearby areas of Montana. They also exhibit wild behavior like their ancient ancestors, congregating during the breeding season to compete for mates, as well as migration and exploration that result in the use of new habitat areas." http://www.nps.gov/yell/naturescience/bison.htm
The point is, Ekim the Inbred Chimp, the Yellowstone herd does not migrate from Canada to Texas: it doesn't need to migrate, and it stays fairly stationary in Yellowstone. At the very least, it is the conspicuous exception that proves your absolute wrong, Ekim the Inbred Chimp. Go screw yourself, Ekim the Inbred Chimp.