The original OT is a bit misleading. Currently, 18 species of European bats are known to live in the UK (and are only lying around when dead).
UK Bat Species - Bat Conservation Trust
So a better title might be "Exotic bats in the UK" instead.
Please keep in mind that there are Megachiroptera (megabats) and Microchiroptera (microbats) that should not be lumped together too eagerly in terms of certain aspects of husbandry and presentation.
In particular, the many insectivorous species among the Microchiptera are very difficult to keep alive and thriving over longer periods of time, also due to the insufficiency of the offered diet. The amount of work that has to be put into their husbandry does not equal their popularity among the visitors. Therefore, most zoos have stopped exhibiting insectivorous microbats and keep omnivorous/frugivorous microbats (such as Carollia perspillata, Phyllostomus discolor/hastatus etc.) and randomly Common vampires/Pallas's Long-tongued Bat or some particular megachiropterans instead. The only insectivorous bats I have seen so far in captivity are handicapped wild individuals/wild animals before release (like the noctules/Myotis sp. I keep now and then) and some exotic species (f.e. some Mustached Bats) in a few laboratories.
Lurking predatory bats such as Vampyrum spectum, Megaderma lyra or the Australian Ghost Bat would indeed be interesting alternatives and have been/are kept in captivity.
However, catch quotas are limited, and the red tape involved in obtaining and transporting is significant, if not impossible to conquer legally.
The latter is in general a big problem when obtaining all kinds of bats nowadays. Catch quotas are booked way in advance by scientific organisations/laboratories, and due to bats being connected to some of the deadliest zoonotic diseases known (or yet unknown), federal veterinary guidelines are not intended to let them in too easily.
Regulatory husbandry guidelines might also influence the husbandry, presentation and future of the bat species in zoos. Some species (not just bats...) breed better in smaller exhibits. So when the zoo has to follow husbandry guidelines that ask for a large enclosure size, this might result in less breeding success and, over the years, a breakdown of the zoo population. And once the private breeder or university providing the founding population quits, chances are high that the species will disappear from the zoos, as no self-sustaining population exists. Such is currently the case of the Common Vampire Bats in European zoos.
I'm also wondering whether walk-through exhibits with bats are not chronically stressful for the animals kept within. Not much has been investigated into it yet, but captive populations of bolding bats (that are certainly no Sulawesi naked bats...) should make one think...
For those who haven't had the chance so far to experience megachiroptera up close: they're really messy, they bite, they're noisy, they destroy the plants, they need plenty of room to exercise, they potentially harbour dangerous zoonotic diseases, they either breed like rabbits or drop their juveniles down the tree for whatever reason all the time, they can be ingrate patients, etc. etc.-so I can understand that quite a bunch of zoos are not particularily interested in keeping them.
Nevertheless: more bat species in zoo? If possible, why not? Maybe some of the Australian folks up on this forum can send some Ghost bats to Europe. You can have some
Rousettus aegyptiacus or
Pteropus rodricensis instead.
