KMT.A. Tirtodiprojo and Hari Palguna and Paidi Kiswosuwarno

A free-ranging Proboscis monkey was observed for the month of March 1996 in the Gembira Loka Zoological and Botanical Gardens, Yogyakarta. The Proboscis monkey’s behaviour, its pattern of movement, and the type of food it consumed in the park were recorded..

The data shows that the Proboscis monkey has a zigzag pattern of movement. The place where the Proboscis monkey finds its food is far from its sleeping place. This differs from its behaviour in its natural habitat, where its sleeping place is the same as the place where it finds its food. An hour before going to sleep the Proboscis monkey leaves its feeding place and starts looking for a suitable tree top near the pond in which to sleep. The Proboscis monkey’s food consists of twenty-six kinds of leaves (it only eats the topmost leaves), 2 kinds of tree bark, a kind of wood fungus and 4 kinds of food that is given by visitors.

Proboscis monkey (Nasalis larvatus Wurmb. 1781), sub-family Colobinae, is endemic to the island of Kalimantan, and is listed as vulnerable on the IUCN Red List of Threatened Animals.

Keeping Proboscis monkey in a cage is difficult, and often ends in the death of the animal. This problem makes research on the free life of proboscis monkeys in an ex-situ habitat necessary to get information about the possibility of keeping proboscis monkeys properly and successfully. To answer the challenge, research on the free-ranging lifestyle of a female proboscis monkey was conducted on location in Gembira Loka Zoological and Botanical Gardens.

The research was conducted intensively in March 1996. Data on the Proboscis monkey’s behaviour was recorded using the scan technique, at 30-minute intervals, from 6 am until 6 pm.

Proboscis monkeys live in groups. Each group contains approximately 11 to 32 members, this is in turn divided into sub-groups. A Proboscis monkey produces 14 different sounds.

Proboscis monkeys are diurnal animals. Their daily activities in the natural habitat consist of eating, resting and moving. Proboscis monkeys express different behaviours at each of the 4 strata between the tree top and forest ground. Resting time is very important for Proboscis monkey, as it is during this time that food is digested. The place of rest is also the place where they find food (Bismark, 1987).

The pattern of the Proboscis monkey’s daily movements is to walk to a feeding place and then to rest, after that they move again to the next feeding place, rest and so on until evening when they move to location to sleep. Proboscis monkeys choose special places to sleep, usually on trees located either along rivers or beaches (Bismark, 1986).

Curtin and Chivers (1979) indicated two factors that influence the range of the territory:

1.  Distance traveled daily by each group
2. Distribution of the groups

The traveled area is also influenced by climate, position of trees for sleeping locations, relation with other groups and the weight of the Proboscis monkey. Research conducted in Sebuku, East Kalimantan found that theProboscis monkey’s diet consists mainly of the topmost leaves of various plants. The variety of food is shown in the table 1.

(Quoted from Sudrajat A, R, 1994)

Note: * Mostly consumed

The daily activities of the Proboscis monkey in Gembira Loka Zoological and Botanical Garden show a zigzag pattern of movements. This consists of activities to find food which are at different locations to its sleeping spot .

The zigzag pattern of the Proboscis monkey’s daily activities is an adaptation for finding food.

The Proboscis monkey’s behaviour at its food source differed from that at its sleeping location. This was probably due to feelings of fear or insecurity as a result of the presence of a large number of visitors during the day. This may be to avoid any attempted capture by the visitors. This behaviour is very much different from that seen in its natural habitat.

The sleeping spot on the tree near a lake is to serve as an escape route if there is an attempt at capture at night. When threatened the Proboscis monkey would drop into the lake and swim away from the source of danger. This behaviour is similar to that seen in its natural habitat.

During observation, the Proboscis monkey would bath 2-3 times a day at around 9:30 am and 1:30 pm. It would drop into the lake from a 2 meter-tall tree, swim to the edge, climb up the tree and drop into the lake again. These activities were repeated several times. Proboscis monkeys were not observed to perform this activity in the forest of Sebuku (Sudrajat, 1994). The behaviour of the monkey in this park may be to keep itself cool from the high temperature.

The variety of food consumed by the Proboscis monkey was mainly the topmost leaves of 26 different types of vegetation, the bark of twigs from 2 trees, 1 types of wood fungus and 4 kind of food given by visitors (Table 2).

Note: *) Mostly consumed

The variety of food was similar to that from the natural habitat i.e. mainly leaves from many different types of plants and some other parts of the vegetation.

Types of food given by visitors were Chiki Snack, candy, peanuts and boiled banana.

The above fact shows that Proboscis monkey can adapt to life close to humans.

In Gembira Loka Zoological and Botanical Gardens,