How about a expansion with flying animals? Zoo Tycoon 2 Aerial Animals It could Have ajustable walls (like the tanks) with some kind of roof, Animals could be:
Flying Fox, Little Brown Bat, Fishing Bat, Albatross, Pelican, Royal Tern, Snowy Owl, Great Horned Owl, Barn Owl, Bald Eagle, Golden eagle, Red tailed hawk, Black vulture, Turkey vulture, Californian Condor, Raven, Pleted wood pecker, Toucans, Macaw, ring tailed Pheasent, great blue Heron, King fisher, Wood duck, Swans, Gerfalcon, Perigrin Falcon
*Incuded Biomes : Cave, Canyon, (Coastle, if you dont already have it)
*Animal food: Incect Swarm, Fish School, Live prey rodent, Seed.
*Animal enrichment: Rotten tree(wood peckers), Diving rock, Clay wall(Macaws) , Bird bath
*Shelters: Bird House L/S, Cliff Nest, Old Barn, Roosting Tree, LG Elevated nest box
What do you think, theres more ideas like these!
Carnem Princeps