Just noticed this thread and figured I would go through the current list of animals in walkthrough enclosures and give my thoughts:
Walkthroughs in Planet Zoo that exist in real life
Lemurs – Certainly here in the UK, it is unusual to find a zoo that doesn’t have a walkthrough enclosure for various species of lemur; the French enclosure pictured below has four different species
Capuchin monkey – At least one French zoo has a capuchin walkthrough, although to the best of my knowledge it only contains females, as the males are too territorial and aggressive to put among visitors
Japanese macaque – At least one Japanese macaque walkthrough does exist at a zoo in the Czech Republic; in Europe at least the Barbary macaque is also kept very commonly in walkthroughs with few problems
https://www.zoochat.com/community/media/japanese-macaque-walkthrough-at-olomouc-30-05-10.103682/full
Llama – They do exist, but I cannot find photos of them and they are surprisingly rare – at least one UK zoo removed llamas from their farm paddock when it was converted to a walkthrough
Peafowl – Nothing really needs to be said about this one
Greater flamingo – Again, flamingo walkthroughs seem quite common in zoos and don’t seem to present much of an issue
Walkthroughs in Planet Zoo that do not exist, but should be possible
Aardvark – I’m not aware of an aardvark walkthrough, but there probably wouldn’t be any safety issues with it; the only problem with such an exhibit in real life would be that aardvarks absolutely reek
Chinese pangolin – Again, probably no human safety issues – the reason why pangolins don’t live in walkthrough enclosures is likely a combination of scarcity of the species in captivity and that it would probably get stolen for the black market immediately
Small antelopes – While I do not know of any walkthroughs for Thomson’s gazelle, springbok or pronghorn, there are walkthroughs for similar antelopes such as the blackbuck pictured below so I could imagine it potentially working
Giant tortoise – While giant tortoises are sometimes kept in large indoor walkthrough areas, they are more often kept in areas within these displays separate from the public; however, I see no real reason why they cannot be in a proper walkthrough enclosure
Walkthroughs in Planet Zoo that would not work in real life
Giant anteater – Giant anteaters have killed zookeepers in real life; a walkthrough with them would be a disaster waiting to happen
Okapi – As mentioned before, okapi are high-strung animals and would do extremely poorly in a walkthrough enclosure
Species in Planet Zoo that could be kept in walkthroughs which are currently not
Red panda – Both Knoxville Zoo in America and the Chengdu Panda Base in China (the one pictured below) have walkthrough enclosures housing red pandas that appear to work well
Nyala – While nyala themselves are not kept in walkthrough enclosures to the best of my knowledge, the picture here shows a walkthrough for sitatunga, a very similar antelope species, at the Mesker Park Zoo in America
Dall’s sheep – In Europe, wild caprids are actually not unusual in walkthrough enclosures – the enclosure in this picture for example is home to five different species of caprid (Alpine ibex, chamois, mouflon, Cretan wild goat and Barbary sheep) as well as roe deer
On the subject of camels and reindeer
Bactrian camel – While the camels in Planet Zoo are domestic animals, they have big teeth and powerful legs which they will not hesitate to use; I know of no real walkthrough enclosure for camels and if they did exist I wouldn’t enter one if I was paid to
Reindeer – While domestic reindeer are fairly docile, the ones included in the game are supposed to be wild reindeer – these are much more aggressive and both sexes have antlers which makes them far less suitable than other deer species for walkthroughs
Perhaps as a compromise for the camels, it could be possible to give them very low barrier requirements – the picture below is from a zoo in the Netherlands, with just a small ditch and rope fence containing them
Some very odd walkthroughs
Bison – This wildlife park in the Netherlands has a walkthrough enclosure for European bison and (not in the picture) Przewalski’s horses; that being said I probably wouldn’t recommend this one for inclusion into the game
Crocodile – This walkthrough with Morelet's crocodiles exists in a zoo in Mexico; I would struggle to recommend a walkthrough enclosure for any crocodile, either in Planet Zoo or real life
the last one is probably only possible with really well fed crocodiles. They seem like fairly lazy animals if they arent hungry.
