Chuck

It depends on the area, the buffalo, how shot up they are,
the cover, wilderness areas or a property where they are used to seeing vehicles / people - in other words, a whole range of things.

I have had totally wild one's in brush stay around and get inquisitive as well a piss off damn quick as soon as they get even a hit of something not being right.

I shoot most animals stationary - and other photos on here show similar so they will let you stalk up, that animal in the photo above has let them get very close IMHO.

Just my HO.