I know this has been requested multiple times back before this new forum type format, but since I can't see one here now, I might as well add it!
Now I believe the reason Tahr were not added to TA originally was issues with getting the males big manes of fur to work correctly. Having seen the excellent fur on the new red fox model, I would really hope that tahr could indeed be possible to create a decent model for now. I think they would be a fantastic addition to the reserve, and could hopefully see them even having zones way up high in the mountain. Players are able to make it right to the very top peak in the snow, I think it would be pretty neat if there was the odd rest zone up in the snowline. They also have a white fur variation naturally for an inbuilt rare fur (in fact looking at pictures of white tahr it seems like theres a sort of piebald variety with blue eyes and a little colour, then solid white individuals that look to be leucistic. Multimounts could include two tahr bulls fighting, a male with one or a couple of females, or perhaps a mount including tahr and chamois together (or even the other goat species as well).
Additionally to really bring TA together I would also suggest the Paradise Shelduck, an endemic waterfowl with a unique sexual dimorphism where the female is equally if not more attractive in plumage than the males. These guys could easily be found across the map, grazing in the open fields in their bonded single pairs or sitting in larger groups on the water. This is a species I think would be great where both males and females could make diamond, though since females do usually weigh slightly less perhaps female diamonds would be more rare. I think a must would be a multimount of a pair together.