In the collection of the Singapore Zoo there are amusing animals – plump loris belonging to the suborder of prosimii. These pretty furry “semi-monkeys” have a special grace for which they are also called “slow loris”.
These animals are extremely interesting. In addition to their appearance that excites tenderness, they have a very delicate psychology. For instance, it is very easy to bring them to stress or even to lethal outcome by washing their sent marks.
But the behavior of loris in nature has not been completely explored so far. Why so? Loris are nocturnal animals. At night, they roll into a ball and hide in the foliage hanging below a branch by all their feet. After dark, loris go out hunting. But what can an explorer see at night?
In a zoo, it is much easier to create conditions suitable for observation. For the sake of interest, explorers will gladly watch near the enclosure at night. And what about visitors? At night, the zoo is closed and in the daytime the enclosure looks uninhabited. It would be wrongful to deprive visitors of the pleasure to watch these amusing animals. What is to be done?
To solve this problem, the loris were moved to a covered aviary. At night a bright light is switched on and the loris sleep in the foliage, while in the daytime, when visitors come to the zoo, the light is dimmed so as to stimulate the animals' activity. It is natural that the delicate psychology of the animals was taken into consideration and they were given enough time to adapt themselves to the day and night interchange.

Information source: “Naturalist's Travel” by Pavel Lubimtsev.