As promised, these would be my top five for ZSL London - the first four are all, I would say, more or less doable. The fifth one is a more out-there option, not because it would not fit into the zoo, but because I don't think they have been kept in captivity before. Still, I think they would be interesting enough to warrant an attempt to establish them.
1. Saharan striped polecat - The treeshrew in Nightlife is too diurnal for such a display, and seems to be almost impossible to see. I would elect to replace it with a display housing a pair of these small mustelids. They are becoming more prevalent in Europe, and they would also warrant the addition of a desert-themed enclosure, which is something lacking in Nightlife. The fact that it is two separate exhibits means that they can be separated in the event of a successful birth.
2. A rare marsupial - I often think about what could replace the dead-end species at London; the invasive species that cannot be bred. In the case of the coatis at Animal Adventure, I think their enclosure is sufficiently large for some sort of marsupial. My favoured options would either be using both enclosures to house Tasmanian devils, using them both for quokkas, or using just the larger enclosure for quokka, with the smaller enclosure for another species such as brush-tailed bettong or long-nosed potoroo.
3. Kagu - This is a bird species I would love to see at London – they are very attractive, have a breeding programme and rank at number 5 on the EDGE list for birds. Finding a place to put it is more of a challenge – I do not know how suitable they would be for a walkthrough or mixed aviary such as the ones at the Blackburn Pavilion. I would perhaps consider putting them in one of the larger aviaries around the back of the gorillas, and would probably end up replacing the woolly-necked storks. Maybe, with some changes to the cage, some horned parakeets could be added there as well to make a nice New Caledonian mixed exhibit.
4. Striped hyaena - I would personally replace the African painted dogs with a breeding pair of these hyaenas. They would be the only ones in the UK, are a surprisingly beautiful animal and also need all the good press they can get – keeping a pair in an attractive enclosure in a well-visited zoo would probably do more good for the species in question than having more painted dogs.
5. Fried eggs earthworm, Archipheretima middletoni - Tiny Giants is one of my favourite zoo exhibits anywhere, and I could think of lots of species to add. To engage in fantasy, I would love to see London try and establish a breeding programme for this species. In addition to breeding them off-show, I would replace the old Bali starling aviary in the building (in the outer corner of the walkway, between the silkworm tank and the alcove for Fregate Island beetles) with a climate-controlled tank for these worms.
I think these could make a fantastic exhibit – they are nearly a foot in length, are diurnal, have indigo skin studded with white-and-yellow spots that resemble fried eggs, live on the surface of the soil and climb trees. While they are not listed by the IUCN, the Philippine montane forest they inhabit has shrunk by 90% in recent years. They would bridge the gap between the sections about the benefits of invertebrates (everyone knows how important worms are to the soil) and about invertebrate conservation.
Some other options I thought of, many of which involve either shifting or sometimes replacing existing species:
- Replacing the Outback exhibit with an enclosure for a large pack of dholes
- Returning giant anteaters to the zoo, in their former enclosure outside Tiny Giants
- For Tiny Giants itself, some additions could include - replacing the non-functional Micrarium with a tank for Barbados brown velvet worms, turning the deathwatch beetle display into a tank for a colony of a paper wasp species and replacing the jungle products tank next to the vampire crabs with a display for shore earwigs, to represent ZSL’s doomed effort to start a captive breeding programme for the now-extinct St Helena giant earwig
- Adding yellow-spotted bush hyraxes and white-cheeked turacos to the Monkey Valley walkthrough
- Adding tropical mockingbirds to the Galapagos tortoise enclosure, as a stand-in for the endemic Galapagos mockingbirds
- Adding long-eared hedgehogs to at least one of the connected grey slender loris enclosures in Nightlife
- Replacing the empty tenrec enclosure in Nightlife with a display for Etruscan shrews
- Shift the tambraparni barbs in Rainforest Life to mix with the Philippine crocodile, replace them with the emerald tree boas from SLORA and, in turn, replace their tank with a mixed dry forest-themed tank home to Peruvian bush anoles and Maranon poison-dart frogs
- Turn the roundhouse into a mixed enclosure for rodents, similar to the one (formerly?) at Munich, housing variegated squirrels, Desmarest's hutia and Azara's agouti
- As for the Casson, I would love to see it turned into a display about the EDGE programme, with more smaller animals kept inside, and perhaps also replacing the red river hogs with more threatened EDGE species. I would definitely approve of @Kalaw's suggestion of pangolins, and would also love to see Western long-beaked echidnas included - being the literal symbol of EDGE and due to be subject to an EEP