What makes a great nocturnal display?
Several night houses, for example in Frankfurt and Berlin grew into evergreen visitor attractions, when many others were closed. What is responsible for this success?
Common factors is that exhibits were originally planned as big, so they survived the time as at least adequate. These houses were designed with curving corridor and exhibits of different size and approached at different angles, not as a row of identical vitrines. Artificial landscapes were contrasting with each other: rainforest- desert, treetops-ground level-underground etc. Importantly, they were done in good taste and attention to naturalistic detail. Small artificial landscapes in Grzimek house did not grow old in 40 years, they are as attractive as 100 years historic dioramas in museums or their big relative, African panorama in Hagenbeck.
Successful night houses present themselves today as scientific and beautiful exhibits. Interestingly, the public seems little attracted by shock, fear or ugliness, like snakes, bats fluttering close to human faces or rats in artificial sewer. Probably most city dwellers in recent decades associate nature with relaxation, not negative experiences of biting or agricultural pests. A today city dweller sees a Norway rat more commonly as a novelty pet, laboratory animal or children cartoon character than a cellar pest.
And crucially: good houses have separate ventillation for visitors and animals, which prevents strong natural smell of scent glands of many small mammals.
Among species, always favorite are cute nocturnal primates, small cats and fennecs. Visitors also clearly prefer exhibits with lots of activity and big social groups. Attractive are colonies of hectic leaf-nosed bats and hopping small kangaroos, springhaas and jerboas.
Other animal species are favorite of one zoo, usually because they have especially big exhibit and are therefore active, or live in an active social group.: e.g. colony of rock cavies in Berlin, which at night behave much like unrelated African rock hyraxes. In Frankfurt golden water rat became one of most popular species, although it is visually very similar to common rat. Reason is that it was swimming in attractive glass-fronted tank which visitors could lighten underwater with a small lamp. Here is another face of well known rule of modern zoos, that attractive presentation is as important as attractive animal.
In contrast, most small carnivores don't work very well. The reason may be common stereotypies in small space and strong scent glands.
Future
The booklet "Nachttierhäuser in Zoologischen Gärten" suggests that night animals should be again exhibited in daytime exhibits. This is not full solution. Naturally, animals traditionally exhibited in night houses contain species which are diurnal or active round the clock according to current studies. Others normally sleep in the open where they can be comfortably observed, like tree kangaroos, fruit bats, sloths and frogmouths.
However, many small and middle sized mammals are really completely nocturnal, both in the wild and in zoos. They include: possums, quolls, all smaller bats, hedgehogs and gymnures, mouse lemurs, aye-aye, lori and galago families, aardvarks, jerboas and many rodents, genets, black-footed and leopard cats. These groups are destined for nocturnal exhibits. Even more mammals are nocturnal almost completely, and they so-called daytime activity is occassional preening between sleeping bouts or basking in the sun. Examples are rock cavy, fennec and most small cats.
Trying to turn such animals into day activity by e.g. visitor demonstration is not natural. Waking up for presentations disrupts their natural circadian rythm. Alternatively, zoos must prevent animals them from hiding to make them visible. Aardvark in Emmen is exhibited in daytime, but has no hiding house but is sleeping in the open.
Overall, outside exhibits are not intriticallly better. Sometimes cited is the factor of wind or rain. However, I don't know many examples of small mammals enjoying the rain, unlike e.g. parrots, which often use it for bathing. Important factir is space actually available to animals and its use. Here day presentation can be not better but even worse than night house. Therefore, One factor possibly important for welfare of animals are low night-time temperatures in Europe. Many modern outdoor exhibits for small mammals have very small and basically furnished indoor part. However, this part is the main space used by animals many months a year. Tropical animals tolerate mid-day temperature in Germany most of the year, but nocturnal animals face much lower night temperatures. This is a topic for investigation.
One thing to investigate is providing not complete, but 80% switched day cycle with small outside exhibit. Therefore night animals can bask in the sun for several hours in the morning or evening, without disrupting their daily rythm.
Overall, nocturnal houses seem to have a problem of from not following trends in zoo design which changed aquaria, terraria, bird houses and other types of zoo exhibits during last half century. It is possible that big fixed costs of building prevent modernization. It is definitely important that construction of an zoo building should allow easy remodelling. Advancement of zoo science constantly changes standards of zoo design. Therefore a zoo should build exhibits which are easy to remodel in future. Night houses with fixed concrete vitrines are difficult to remodel.
Many night houses with small cages simply closed down. Too small exhibits of other animal groups, however, are usually rebuild in a larger scale. In modern zoo architecture, all exhibit types are build in previously unknown sizes, due to demand and new construction materials. Maybe it is possible to build night exhibits with area of many tens or over hundred square meters? They would provide adequate space for active larger mammals like aye-aye, kinkajou and other small carnivores. Nocturnurama in Kerzers contains individual enclosures 50m2, adequate for crab-eating raccoon. What is certain that small exhibits of traditional night houses are indeed suitable only for active animals size of about rat (or slow lori), or less active animal to size about a cat (or coendou).
Energy efficiency means that zoos might experiment with new technologies like LED lighting. Another possibility may be to illuminate at day not the whole exhibit, but only smaller animal living space or entrance to the den.
Design of nocturnal houses of today is almost always a row of glass-fronted vitrines. This is boring to visitors. The same was noticed about reptile terrariums, where attractive to the public are one or several terrariums built near thematically matching big animals. Night exhibits of 1-3 species near day exhibits may possibly be more interesting. Here interesting trend is Darwineum at Rostock, which presents galagos near big apes.
Artificial materials are overused in night houses. Natural ground and live plants are underused. Night house can in principle be build with natural ground, like a hothouse, and contain live plants which are shade-tolerant or regularly changed.
Overlooked problem may be cutting away outside stimuli like external sounds and smells, creating sensory deprivation chambers for animals. Here interesting design is again galago exhibit at Rostock zoo, which has strongly blackened window looking outside on the open air.
Current zoological trend of making artificial walk-through habitats is still very rare in nocturnal houses. Bird houses developed from rows of aviaries to walk-through tropical halls. Night houses might develop similarly. One example is Amersfoort with walk-through room for night monkeys, aguti and sloth.
Nocturnorama in Kerzers is currently the best example in Europe of this type. Its design is a single landscape hall where some animals are free-living, other poorly jumping species live in own enclosures separated by moats or low glass barrier, and carnivores and caimans have exhibits fully enclosed by mesh and glass. Especially interesting is the visitor path crossing a tunnel in artificial rocks, where some of the numerous leaf-nosed bats at Nocturnorama roost over visitor heads at very small distance.
Another example in the recent past was the bat cave in Rotterdam, not described in the text. It belongs to bigger night exhibits in Europa by size, although it contains really only one exhibit and one species. A very large and tall space under artificial rocks was developed as an artificial cave. Here visitors could walk among a very large colony of free flying egyptian fruit bats, which flew and fed very close to visitors. Unfortunately, a virus similar to rabies was discovered among the bats, and on precautionary grounds the colony was put to sleep, and the visitor path was separated by glass. The exhibit is nevertheless popular. Sometimes small animals are kept on the ground, e.g. one malayan civet. There is also a small additional terrarium for scorpions.
Animal presentation and public interactions are not used in nocturnal houses at all. This could be used, as small night mammals contain many attractive 'cute' species which can be good for animal interactions. Many rodents and small carnivores are also popular private novelty pets.
The only example of interactive exhibit I know developed incidentally in a night exhibit in the old Emmen zoo. This exhibit was located under the South American hothouse AmeriCasa and is not described in the article. Here night monkeys learned to jump across the water moat, and climb on the shoulders of the public. The exhibit itself was a straight corridor for visitors. On one side was a visually continous rainforest exhibit for South American mammals. The animals, which included sloth and a species of armadillo, were separated by a narrow water moat, not glass. At the end was also a small artificial cave behind glass.
Another suggestion that animal interactions are potentially hit with visitors is that wild living night mammals are locally additional tourist magnets of hotels or safari lodges. These are edible dormouse visiting country guesthouses in at least two places in Germany, genets in East Africa, olingo in Monteverde, Costa Rica, quokka in West Australia and possums in O'Reilly Lodge, Queensland. Long-tongued bats in one lodge in South America even feed from a hummingbird feeder held in hand by a tourist.
One trend not tested in night houses are rotation exhibits, a concept developed in several American zoos. This means building exhibits so that several species have access to the same several exhibits from their nest boxes, and on different days switch places in rotation. Two or more species can rotate this way. This may increase the total area and stimuli for animals, and mimic that animals visit different parts of territory different days. It remains to be seen whether it really has positive influence and what species.
but the other three species have always been fairly showy in diurnal enclosures, particularly burrowing owls.