Wild chimpanzees at Bossou, West Africa

野生のチンパンジーでは、一日の三分の一から半分近くの時間を採食にあてています。 反面、動物園で飼育されている動物は、飼育員が決まった時間に与える食物をあっというまに食べてしまうため、野生に比べて採食時間が極端に短いとされています。 そこでわたしたちは、採食時間を長くし、道具を使ったり工夫したりしながら食べるようにさまざまなフィーダーを考案して、採食時間を引き延ばすための方策を検討しています。

Multiple Feeders at Kumamoto Sanctuary(KS)


We fill the pipes with several food items some chopped into small pieces like apples, grape fruit, or stuff them with grapes, raisins and peanuts. The pipe has many holes; two big ones are at each end, and many small holes are in the middle (small holes are smaller than chimpanzees' fingers). The chimpanzees encouraged poking at and roll the food over to the ends of the pipe where the bigger holes are using a branch, a stick or some other tools they might themselves create. These pipes are fixed onto the fence so that KS staff can add extra food easily from outside at any time.


When chimpanzees move the horizontal pipe they can get soy beans that are falling from the vertical pipe. Please watch the video showing a chimpanzee named Kenji, as he is operating the horizontal pipe. He is then skillfully digging out soy beans stuck with a branch and enjoying eating them.


We pour soy beans in hard plastic balls hanging from supporting beams or climbers. The balls have holes drilled into them or have a piece of small pipe inserted securely in them. When chimpanzees tilt the ball or shaking it in circular motion, they can get the soy beans out. They often spend long-long minutes shaking these balls.


This metal pipe-tube feeder has several small holes on the bottom that only about one, slightly roasted soybean fits through at a time. As the chimpanzee pokes at the soybeans with a delicately made stick he/she needs to prepare to get the bean out, he/she can get only one bean when it’s lined up properly with the hole. The chimps learned to extract the beans rather quickly with the small stick. They also get the beans out by blowing air into the hole in order to get the beans lined up.


These juice-dispensers are rather easy to use, however, still not all chimpanzees mastered it well enough. The tubes have holes also on the side facing towards the chimps. They cannot reach in to get juice using their hands or fingers; they must use a tool. These tubes are filled with a variety of juice, diluted often to reduce calorie intake but always attractive enough not to be ignored. The chimpanzee on the picture below is using a stick-tool, well prepared to achieve maximum efficiency. She chewed up the end of the stick so it can pick up such a huge quantity at one dip, like using a sponge. Without chewing up the end she could only lick the end of the stick. Who wants to spend that much time?! But many still do while some managed to learn the better technique from those who are more advanced!


Large dipping tubes are able to hold a lot of liquid. They are like tree holes in the wild that chimps use chewed up leaves (wads) as sponge to get some thirst-quenching amount of liquid (rainwater in the wild) at once. Many chimps use their bent fingers, (knuckles) hands, while some use leaves or other plant material, even chewed up cardboard box “wads” as aids to extract the content. Very popular since a lot of diluted juice can be obtained at once.


We cut old vinyl tubes or fire hoses into some 30-40 centimeter long pieces then stuff them with soft or hard goodies (“pellet-cakes” peanuts, sunflower seeds, beans or pellets). The fire hose version takes much more time to extract the food because the fire hose is flat. Besides we make knots on the fire hose pieces, hiding the food behind them. It takes time for the chimps to open these knots to get to the seeds. Again, some chimps occasionally reuse these tubes/hoses as parts of their beds.


We enwrap several nuts & seeds - such as peanuts, soybeans, sunflower seeds and so on- in a newspaper, and we form it into round shapes, like a ball. KS chimpanzees enjoy the 'newspaper balls' at their own pace. Each chimpanzee gathers as many “newspaper ball” as he/she can get, and then carries them to a quiet spot. Some chimpanzees open the paper balls carefully one by one, not to lose the nuts and seeds while munching on them. Some chimps just tears them with boldness. Several chimps occasionally reuse the newspapers when constructing their nests, (bed) daily.


These are pieces of burlap-sac sheets filled with some nuts or other chopped food pieces. Rolled up and fastened with knots on the line. Requires time to open them up by fingers or even by teeth as the material is quite tough to rip open. The “emptied” sac-pieces then can be used as pillows or for nesting material.


The hard cardboard tubes are also filled with goodies and then both ends are hammered closed. Not so difficult to open by teeth, so usually we fill them with some low-calorie seeds or food. They can be easily moved and later the leftover tubes are used often for nest building.


Since we cut and feed a lot of fresh leafy branches some of the thicker branches we reuse later. We dry them up, cut them to 30-40 cm long sticks, drill holes into them and then the holes that are smaller in diameter than the chimpanzees' fingers, we stuff the holes with fruit. Almost all chimps use sticks to empty the holes with great accuracy and time spent.


A bucket or container is filled with water and fruit pieces, frozen into ice and then distributed in hot summer days. Cool aid with “ice-cream”, good for sharing food and enjoying the ice as summer refreshment.


We favor “scatter-feeding” and most of the food we feed we cut them into smaller pieces. Some pieces are then scattered on the ground benches, shelves but most of the pieces we stuck into branches like fruit-trees. A great, colorful visual effect, this method highly promotes foraging and food gathering.


These puzzle-tubes with “windows” on them are filled with chopped food pieces and the tubes are hanging on ropes. They are closed up with a hole on the side and mobile with the short rope the puzzle-tube is attached to. We carefully prevent entanglement as we limit the length of the rope. Chimpanzees obtain the food by shaking these tubes or use sticks to extract the food particles through small holes. Getting the food out require patience and precise skills using tools.


These puzzle-tubes are also movable by the rope they are attached to and suspended by. These are like salt & pepper-shakers, filled with left over pellet-powder. The chimpanzee has to shake it in order to obtain the powder through small holes.


These types of puzzle-tubes contain either juice or seeds. A chimpanzee needs to use a stick to extract the juice through the small diameter inner tube or pipe. The seeds can be “lured out” [please see pictured chimpanzee operating this puzzle-tube] by inserting a stick into the small diameter inner tube and “guide” the seeds out through the inner tube. The seeds would also fall out if the chimpanzee shakes the tube side-ways or upside down.

Further reading


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