I totally agree that the variety of animals currently ingame is not exactly huge and should, at some point, be expanded - together with a number of fixes for existing animal-related problems.
However, I also firmly believe that we should not use this as yet another point where we go further away from realism - we have enough unrealistic things in this game already. By that I mean some of the animals listed in this topic. Don't forget after all, that even if a fictional continent, this is a medieval world and you can't erase the fact that the "Middle-Ages" is a timeline bound to a certain geographical area: Europe. And if we keep shouting for realism, then we should at least stick with that historical fact.
-)
Thus adding animals like Alligators, Cougars, Buffalos, Gazelles, etc. is, please don't take offense here, total bullshit.
I fail to imagine a medieval peasant hunting in the woods for a buffalo. roflmao.
Enough negative talking, aside of a few animals being unrealistic, I entirely support the general idea, though!