Substrate preference during activity period by captive slender lorises

a: Substrate utilization in a cage furnished with equal amounts of smooth round timber perches of the following types: diameters 1.2 cm, 3.5 cm and 10 cm, each offered in three altitudes and three inclinations. (Data by G. Hoeschen; 10 animals; n = 5527 observations = 100%). Under normal conditions, animals show a clear preference for the upper part of the cage. Small diameters allow a safe grip with the rather small hands and are therefore preferred, especially in vertical substrates to which the animals have to cling. Lorises particularly use horizontal perches which allow energy-saving walking and resting on top. Typical loris behaviour also includes hanging postures for which thin horizontal perches are needed. Vertical substrates are mainly used for climbing up and down. The highly preferred thin horizontal perches in the upper part of the cage are particularly important for resting (b) and copulatory behaviour (c). Use of the perches in the lower parts of cage probably would have been better in a cage with undergrowth, and in periods with social stress inferior animals prefer the lower parts of cages, trying to avoid aggressive opponents.

d: An example for nice-looking, but inadequate cage design. The most important space in the upper part of the cage is wasted, energy-saving stay on horizontal branches is impossible. Large tree-trunks can only be used to a limited degree.