I'm working on a setting where one of the large continents is similar to North America before the arrival of humans, including a biome containing the three large grazing ungulate species: aurochs, bison, horses. I'm trying to figure out exactly what their ranges will be, and in particular, how they relate to each other.
All three are stereotypically animals of the prairies, but bison at least seemed to actually be able to live in quite forested regions. There is an account here of what seems to have been quite a substantial population of bison in Louisiana, which is nowhere near the prairies, and at first glance, entirely forested: https://heartoflouisiana.com/last-buffalo-in-louisiana/
I'm not quite sure how it is possible for a grazer to live in a forest, but there is a variety of bison called the wood bison https://en.wikipedia.org/wiki/Wood_bison confirming it is possible. Perhaps primordial forests are patchier, possessed of more meadows or at least margins of grass, than one might think?
Is this also true of aurochs and horses? Or put another way, if you make your way from forest toward prairie, would you be equally likely to encounter all three species at any given time? Or would you have a scenario where you could encounter bison in the forest, but would need to travel another few hundred miles up the Mississippi, say, before reaching prairies and encountering horses?