Everybody has lots of buffalo, and that's after I turned the frequency of the damn things down compared to everything else. ;)
As a matter of fact, I did bring up that type of combining gameplay while we were working on this. The grass tiles will tend to die off on the promontories, although like a lot of stuff in this that's emergent from rules that we implemented to produce other behaviour.
Forests do indeed exist, as well as some other terrain that lets you get more varied animals.
Really appreciate the feedback!