Monkey and Stinging Nettle
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Transcript: English(auto-generated)
00:00
All scenes shown in this film document spontaneous animal behavior and the greatest of care was taken to provide film material from the correct behavioral context. Farm Bockengut in Horrigan, Switzerland.
00:27
Summer 1994, 7 a.m.
02:07
Monkey and stinging nettle. Observations at the University of Zurich's research station for animal behavior.
02:22
This research station was founded in 1982 in order to investigate the behavior of these monkeys. There are 35 long-tailed macaques, Macaca fascicuaris, native to Indonesia.
02:45
The graduate student sent the monkeys outside this morning. Here, from the observation cabin, she is now checking whether all the monkeys in the group are well. The research team at the station also participates in the animal management.
03:02
And so a new day at the Bockengut research station begins. We are going to take part in such a day. And in doing so we will see how strongly animal husbandry, rich animal behavior and behavioral research are interconnected. The outdoor enclosure measures 25 by 40 meters and is covered with grass.
03:27
Apart from this there is a large area of stones with a pool and, as we have already seen, the sand field. There the graduate student had scattered corn and other grains before she sent the monkeys outside.
03:44
The monkeys have to collect the grains. This is fitting because in nature foraging is their main activity. This is Tifu. Let us watch how the monkeys behave in this outdoor enclosure this morning. Among the males Tifu holds a position in the lower part of the social rank hierarchy.
04:05
His tail was once bitten off in a fight. Madhu, the yellow lion. Madhu is the highest ranking male and Mandi is the highest ranking female.
04:20
We will get to see Madhu and Mandi several times in the course of the following scenes. Tiram, the 10 year old mother of two daughters, holds a middle position in the social hierarchy. She has dark fur, slender limbs and especially beautiful white eyelids.
04:44
Ukui, Madhu's 14 year old cousin, is the third highest ranking male. Seems restless, he also has dark fur.
05:01
Sometimes there are a few quarrels at breakfast times. Amazing how these little ones can drive away an adult.
05:27
That's why the somewhat calmer Tiram waits until the first rush to the sand field has settled down. Only then she also fetches her breakfast.
05:57
However, by now there are not so many corn grains left anymore.
06:02
So she has to look a bit more carefully for them. Usually everything is peaceful. After collecting breakfast everybody climbs up and chews the grains. It is now 8.30 a.m.
06:24
Professor Hans Kummer, the founder of the research station, and his assistant come to the enclosure. They are investigating tool use behavior in the long tailed macaques. Trawling for fruits.
06:46
Two of the monkeys, Madhu and Tubao, are using sticks to rake in food that is lying on the ground outside the fence. They know this technique. What we want to investigate now with this little pole is whether they will also reach upwards with the stick.
07:04
Thereby touching the banana directly in order to get it. Or whether they think it is sufficient to sweep the stick back and forth over the ground.
07:27
As you can see now, Tubao is correctly aiming upwards with the stick when the banana is high up on the pole. When the banana is on the ground, he works on the ground with the stick.
07:50
The experimenters are fascinated. The story of trawling for food was started by Madhu, the highest ranking male. There was an apple tree right beside the outdoor enclosure during that time.
08:02
And Madhu invented the technique of using sticks to rake in apples on his own, just like he is demonstrating now on this piece of banana. How will the technique spread in the group, the researchers asked themselves. To their surprise, they found that the other monkeys were also busy with sticks when Madhu was trawling for fruits.
08:25
However, they did not trawl for fruits. All they learned was sticks are fashionable. The fruits remained untouched. Months went by. It was not until a year after Madhu's first success that Ukui was also successful for the first time.
08:44
Let's watch how his technique has developed in the meantime.
09:15
Like a beginner, the way he is handling several tools at the same time.
09:20
And now the grip and go, like a beginner. And finally, after Tubao started to rake in fruits successfully, Mazuk was successful for the first time as well, almost two years after Madhu. How did his technique develop?
09:44
Mazuk is a bad fisher. He only succeeds very rarely, even when the fruit is lying on the ground. It is obvious why. He is pushing and pulling instead of sweeping sideways.
10:01
Thus, we are confronted with the surprising fact that only a few monkeys learned to rake in fruits, and that they did not imitate the successful behavior of Madhu. It is not as easy for monkeys to ape as it is for humans. What is especially interesting is that the first time Mazuk was successful,
10:21
he pushed the stick through the wire mesh above the ground, moved the stick up and down and in doing so touched the fruit accidentally. Since then, he is trapped in this dead end of inserting sticks above and pulling them in below.
11:10
Out of the three additional monkeys that learned to rake in fruits, only Tubao does it here regularly and efficiently. His only clumsy performance is that he often sweeps the fruits directly into the other's hands.
11:39
As Madhu always reaches outside through the gap below the wire mesh in his usual manner,
11:46
the working terrain will be raised a bit.
12:06
Madhu is reaching out through the wire mesh now, but the narrowness of the mesh hinders the movements of his arm. Madhu's motivation to work could be more enthusiastic as well.
12:22
Only Tubao is always motivated. Here is a new task. A plum is pinned onto a nail. In order to remove the plum from the nail, Tubao has to move the tip of the stick in a completely different direction than before, upwards.
13:24
Yes, Tubao is the master in trawling for fruits. This is not so surprising, because he exercises with sticks all the time. The animal caretakers know this trick already and as a precaution weigh down the doormat with stones.
14:02
You often get the impression that Tubao manipulates objects just to create interesting spectacles, as for example this water jet. And this interest in the effects generated is a very crucial trait for tool use behavior.
14:21
The other monkeys also manipulate objects, but not with as much imagination as Tubao does. About sticks and stones. Tifu likes to chew sticks. What luck that there are sticks lying around all over the place in the enclosure
14:43
and that the monkeys can break off sticks everywhere. This is how they have been able to invent trawling for fruits and this is why research on the monkeys' performance in trawling for fruits began. Tifu shows us lip-smacking.
15:01
It is a gesture of appeasement. He is doing this because Madhu is giving him an imposing look. It looked something like this. And now Tifu can continue with his favorite business, chewing sticks.
15:27
Tifu shows us another behavior that we often get to see at the Bockenwood station. Working with small stones.
15:43
There are small stones everywhere. For example, a small piece of brick and a pebble. Tifu is rubbing them on the ground and is then rolling them between his palms. We already saw this behavior in the sand field in the morning.
16:02
It serves the purpose of cleaning food and has a strong innate component. It is displayed in all kinds of object manipulation and nevertheless is performed in a slightly different manner in different field populations indicating that there is also a socially learned component.
16:40
Tiram knows what to do with bigger stones as well. But when low-ranking Rini starts to turn stones over she is completely absorbed by this business.
17:21
There might be something more to it why low-ranking Rini is engaged so intensively and persistently in this behavior. Females of Hemadryas baboons in the field show different interests in their non-social environment as well. Females on the social periphery, like Rini here at Bockenwood,
17:41
are much more interested in it than females from a more central position in the group. Thus, the richly structured enclosure may provide activities especially for the lower-ranking animals. Tiram lets himself be groomed now and then. But Rini is working in the stones.
18:03
Mardu and Ukui, the high-ranking males, are seen to turn over stones only rarely. Their interest is orientated towards another area, socializing. The dispute.
18:21
A dispute flares up. Jalan is fleeing. Petruk is chasing Ukui at high speed. Petruk, on the right side, holds the second highest position in the social hierarchy of the males. Ukui, on the left side, is the third highest-ranking male.
18:45
Mardu, the highest-ranking male, now comes to the front. Lower-ranking Jalan comes back again now.
19:00
Together with Petruk, he threatens Ukui at the back on the left. In doing so, he keeps glancing at Mardu. Mardu now appears in the picture on the left. Taking such reassurance from high-ranking individuals, forming coalitions and alliances, primates seem to display especially highly developed behavior in these aspects in the animal kingdom.
19:26
There are even some behavioral biologists who are of the opinion that intelligence in monkeys was evolved in the social context through the ability to use social tools.
19:49
The situation becomes calmer, but Ukui keeps going on. Borrows between Petruk and Ukui continue during the whole summer. Since Petruk's high-ranking brother has died,
20:02
Ukui attempts to challenge Petruk in the hierarchy.
20:47
Jalan is alone now. Without Mardu and Petruk in the rear, he is retreating and baring his teeth, which demonstrates his inferiority.
21:02
It might be appropriate to call Ukui's behavior an act of punishment, punishing Jalan because he and Petruk were threatening Ukui before.
21:20
Alternatively, Ukui was looking for any other convenient victim to pass on the aggression he had received himself earlier on, a behavior called redirected aggression. However, what we have seen is very typical for Ukui. He is always engaging in intrigues in the higher-ranking positions.
21:40
His whole biography is characterized by his attempts to achieve a higher social rank. Ukui is interested in social affairs. Tifu prefers to work with sticks. Let's watch what Tifu is doing by himself for the next few minutes.
23:51
Eventually, Tifu proceeds to look for new and interesting items.
24:23
Thus, the Makaks have different ways to occupy themselves at Bokengut, especially with the diversity available on the ground. Ground of natural diversity.
24:43
Naturally overgrown ground provides the source for the most diverse kinds of entertainment, and it also enriches the menu. Satay is tearing off whole bunches of grass, while Sebelas is more picky.
25:04
And there is always something interesting to discover in the ground.
25:21
Rini also discovers all kinds of small creatures under the stones. What do the monkeys see in the grass? A question the monkeys also ask. It's not only interesting to discover something on their own,
25:43
but also to see what other members of the group have discovered. From this point of view, natural ground even triggers social interaction. Rini has to make way for little Tarakan.
26:01
Yang Noor, however, does not let herself be driven away so easily. Pay attention to her ears. One time, two times. This was a subtle kind of threat in a monkey manner. Why is there this difference? Why does adult Rini accept being driven away by little Tarakan, but Yang Noor does not?
26:22
It's because Moor is a princess. Princess Moor. In the middle here, we see Moor again. Her mother, Mandi, is on the right side of the picture. And Mandi is the highest ranking female of the colony. To the left side is Moor's grandmother, Mayun.
26:51
Again, a dispute flares up. Moor is chasing Roti, and she is threatening her. Her grandmother, Mayun, immediately comes to her side, threatening Roti as well.
27:04
Roti has escaped to the pool. She is also baring her teeth there, expressing her submission. And now Mandi, Moor's mother and the highest ranking female, joins Moor and Mayun as well. Together, these three related females threaten Roti.
27:23
Eventually, Madhu joins them too. Roti flees. But Moor continues to threaten her. In doing so, she keeps glancing back to her relatives.
27:40
In macaques as well as in other animal species, the offspring often holds a position next to its mother in the social hierarchy. This phenomenon is called dependent rank. Roti knows all about the consequences of getting into a struggle with the daughter of a high ranking female. But something surprising happens.
28:02
Moor sits down beside Roti right after the dispute and starts to groom her. Such a show of friendliness after a dispute has already been investigated by behavioral scientists. And it has been shown here at this station that this post-conflict interaction does repair the social relationship.
28:28
It's the great reconciliation. We now understand why Princess Moor, contrary to low ranking Rini, will not be driven away while searching in the grass.
28:48
Even the smallest tots start exploring the plants.
29:05
And it was at this spot around rotten trunks where sanc foil and ground ivy are growing, where something happened a few days ago. The monkeys discovered a frog. This is not surprising because there is a pond right beside the monkey station.
29:33
Permeable enclosure, the frog. Frogs get into the enclosure from time to time.
29:41
This frog was so small that the monkey's slapping touches killed it. This is an exception. Although the frog is dead now and the monkeys are very curious about it, they also seem to be afraid of the frog. This is why bigger frogs leave the enclosure unhurt.
30:23
What is most interesting is that Roti, at the back, suddenly starts to investigate a very similar spot. And Rini is also doing the same in another spot. All the places the monkeys have investigated after the frog was discovered have had similar features to the location where the frog was discovered.
30:43
Around structures where sanc foil and ground ivy are growing. How do the monkeys organize their further search after a discovery? We will investigate this question again later on.
31:01
Not only frogs enter the enclosure, so do sparrows. Permeable enclosure, sparrows. Especially Saya keeps an eye on them.
31:40
Like a cat, Saya caught a sparrow in the tall grass.
31:43
She starts to eat it immediately. The young monkeys are approaching Saya and her catch to annoy her.
32:02
Why are the monkeys eating sparrows without hesitating? Why they don't relish doing so with soft-fledged frogs?
32:21
We can only speculate. Maybe there are so many poisonous frogs in the tropical home of the long-tailed macaques that, like in some other species, an inhibition to eat frogs is inherited. Princess Moo is especially rebellious. But research on these animals has shown that a monkey's possession will be respected
32:42
when the monkey is able to carry it close to its body. A piece of meat or a bone falls down sometimes. Tubao got hold of such a piece.
33:25
Saya the sparrow catcher. Permeable enclosure, the thunderstorm.
33:44
The rain makes the monkeys move. They are escaping to the shelters. However, not everybody gets on well with each other. It's no good trampling into such a snug group like a fool. You have to have good manners, even if you are in a hurry.
34:01
However, Tifu is agitated and clumsy.
34:20
Not everybody is happy with their choice. Unfortunately, most shelters are occupied already. Maybe here.
34:55
By lip-smacking and baring their teeth slightly, meaning, please be nice, it is easier moving together.
35:08
As you can see, such a thunderstorm with hail is a social event. Due to the permeable wire mesh, the enclosure is connected with its surrounding area. This provides a lot of additional environmental enrichment.
35:23
The monkeys eat hailstones, catch sparrows, react to frogs altogether, and a wet enclosure provides completely new experiences. However, let's return to the sunshine.
35:58
What we see here is penis touching.
36:01
It is a friendly behavior amongst the males. Even Madu is playing on such a beautiful day.
37:38
Madu.
37:43
During social play, infants gather knowledge about how their mates will react. Rhesus monkeys that grew up without social partners behaved helplessly in many cases.
38:00
Madu rarely plays. Most of the time he climbs onto an elevated spot where he prefers to sit down. From all the males, this behavior is most pronounced in the highest ranking male or alpha male. There is a particularly good view over the enclosure and hence over his group of monkeys.
38:21
It's obvious what Madu is doing here, watching and watching some more.
38:42
He does the following in between.
39:04
Madu's display behavior impresses the other monkeys. No wonder. Such ramshackle furniture is ideal for Madu to demonstrate his strength.
39:26
While Madu watches and carries out his displays, Rini is busy in the stinging nettles. Monkey and stinging nettle.
39:48
This unsightly herb is especially fascinating for the monkeys, especially towards midday who may see several monkeys inspecting the shrubs. They discover plant lice and ants and like to pluck the flowers and seed heads.
40:05
They sometimes eat the core of the stem.
40:39
Monkeys are also not immune to the nettles.
40:47
And whoever comes out of the stinging nettles should not be surprised if it stings a bit.
41:03
It's midday. Time to call the monkeys into the stable for feeding. The animal caretaker is operating the hydraulic sliding doors between the stable and the outdoor enclosure.
41:35
The monkeys know that it is lunchtime. The animal caretaker calls the monkeys inside with a specific command.
41:43
This is not so easy when the weather is so nice. However, the monkeys may not stay outside for several reasons. Some individuals have to be separated from the group for the following experiment and separating them is only possible in the stable. However, the monkeys are called inside even if no experiments take place in the afternoon.
42:05
This is to stick to the routine of going into the stable.
42:39
Low-ranking monkeys like Tifu and Rini here are allowed to use a separate entrance.
42:46
This entrance remains closed for high-ranking animals like Madu. This entrance leads to an enclosure that is separated from the other enclosures in the stable.
43:05
Thus, the lowest-ranking animals can be confident that they will not meet a high-ranking monkey behind this entry. This makes it easier to get them inside. Some monkeys take advantage of the fact that the highest-ranking group members are in the stable and use the opportunity for copulating.
43:25
Madu would immediately intervene in the copulation if he saw it. However, according to ethological investigations, the monkeys are not able to judge whether the alpha male can or cannot see them when he is in the stable. But the animals see whether he is present and they know in which situations they are rarely caught.
43:47
Meanwhile, the animals are waiting for food in the stable. Several such bigger compartments are connected by smaller ones. In the stable, the animal caretaker has already prepared the food.
44:08
One bucket of food is enough for the 35 animals. It's carrots and pieces of kohlrabi. The lowest-ranking monkeys will be fed first in a separate compartment.
44:35
Then, the animal caretaker scatters the food in the other compartments. It's not until the food is scattered everywhere that the caretaker comes back to
45:16
the lowest-ranking animals and opens the sliding doors to the rest of the group.
45:21
This procedure ensures that the lowest-ranking animals get their portion as well. Each of the compartments has at least two such gateways, so there is always a way to escape from the other monkeys. Much of the setup has been organized by the animal caretakers. Marion Marg explains them.
45:43
We covered the floor of the first compartment with wood shavings. In the evening, we scatter sunflower seeds here, so the monkeys spend a lot of time searching for them.
46:05
Here you see the bare ground, which doesn't provide much opportunity to keep the animals busy. We added this compartment ourselves. The monkeys can use this additional space when we need the compartments in the front for experimental investigations.
46:31
We put stones in this compartment. This is interesting for the monkeys because fruits and corn roll under the stones.
46:46
There is straw in this compartment. The monkeys also have to search for food here.
47:00
Of course, the area above the ground is constantly changed as well. After all, monkeys do like to climb. The station often receives cuttings from trees and bushes. Thin branches that can be broken off and peeled are very popular. This is real work for a monkey.
48:00
Meanwhile, the sparrows take the opportunity to bathe in the pool in the enclosure.
48:09
And the graduate students and the animal caretaker have lunch. What we can see right now, willingly sharing food, is a behavior that we have never been able to observe in our monkeys.
48:26
On the contrary. Our monkeys have cheek pockets that allow them to collect food for themselves in a hurry. Their cheeks are very elastic, and when they are filled, the monkeys can feed from the small stock.
48:44
In doing so, they pull food out of their cheeks with the typical movement of the hand. Let's stay here near the wooden chips and watch how the individuals search for seeds. Four-year-old Tubao. He is wantonly throwing chips about.
49:12
Seventeen-year-old Petruk. Easygoing. He is wiping the chips aside with little movements of a single hand.
49:27
This is Madhu, the only one who looks a bit fussy.
49:46
Tifu prefers to search near the gateway where there is a good view of who is coming and going and where he can make off if necessary.
50:08
Tuyu seems to be short-sighted. Dili's copulence gives her a touch of grandeur. All of them are searching in the chips, but especially the oldest female likes to nestle here.
50:51
Charlie Menzel and his assistant arrive at the station. American scientist Charlie Menzel is an animal behavior researcher. In the field, he has studied the behavior of the Japanese macaques that are closely related to the long-tailed macaques.
51:07
He wants to do some experiments with single individuals this afternoon. He tells the animal caretaker the names of the monkeys he needs for the experiment. And so, lunchtime is over for the animal caretaker.
51:22
She goes into the stable to separate the specified monkeys from the rest of the group. Techniques for separating individuals. Let's watch how the caretaker separates the animals.
51:43
She gives a particular command in order to separate an individual from the rest of the group.
52:07
When the required animal is separated in a compartment, she then opens the sliding door and sends the monkey into the cage at the front.
52:24
If there were several monkeys in the compartment, the other animals would also go outside. Now the caretaker attempts to separate the male tiger in a compartment on the other side.
52:44
However, some females upset her plans. So, the caretaker changes her tactics and sends all the animals into the adjacent compartment.
53:05
Then, she closes the sliding doors. The animals that were in the compartment on the left side before are now in this compartment on the right side.
53:23
Madhu is two compartments further up on the left. The caretaker closes the doors here as well. And so, we have the compartment with Madhu here.
53:41
Then there is a bigger empty compartment. And finally there is the compartment with some other monkeys. Now it is easy to get Ukui into the adjacent compartment. This is because Ukui always tries to be close to Madhu. And Madhu is in the second compartment on the left side.
54:10
Having exact knowledge about the individual's preferences, the animal caretaker is able to separate the required monkeys and to send them into the cage at the front.
54:28
Then, she prepares the corridor for the other monkeys so that they have enough room when they stay inside during the experiments.
54:51
The monkeys are sent into the back compartments now.
55:06
The experimental monkeys are taken into the free compartments. Tifu. In the next compartment. Ukui.
55:21
Then Masuk. Tiru. Jala. Last but not least, Tiga, the low-ranking, inconspicuous male.
55:43
Tifu, on the other hand, we got to know as a monkey that is very interested in sticks and stuff like that. And that is socially reserved. Quite the opposite to high-ranking Ukui who is hardly seen keeping busy with ecological matters. His entire interest is devoted to the social aspect of life.
56:05
Each of these individuals is integrated into a big group and has social competence. They can also acquire ecological expertise in the large and richly structured outdoor enclosure. Due to the methodology of separating individuals from the colony and letting them work in an experiment,
56:25
animals with social and ecological expertise can be tested on their knowledge in detail. Charlie Menzel is preparing such an experiment right now. The experiment.
56:42
I've just placed out four piles of food along this cement structure. The four piles decrease in visibility with the furthest pile usually containing a piece of banana or nectarine and six visible raisins.
57:02
The closest pile containing only two visible raisins. The purpose of the test is to determine how long-tailed macaques organized their search based on a small number of food locations. The hypothesis being tested is that macaques organize their search along visible environmental structures
57:24
such as that provided by the cement structure here rather than organizing their search according to purely spatial patterns. To test the two possibilities that visible structures and spatial order are important in the macaques search patterns,
57:44
we represent food in some distance from the cement structure. And these are based according to two rules. The first is located here in the open grass. That lies along the straight line defined by the initial four pieces.
58:10
The second location is here along the border itself. This test employs dyads. The reasons for using dyads of monkeys instead of single individuals
58:22
is that a higher ranking animal might be expected to display its information and act on this information it has more quickly when it is under some pressure from a competitor. The second reason for using dyads is that I would like to determine
58:40
whether there is any differentiation of search patterns when two individuals encounter a problem repeatedly. And I would like to know how this relates to their dominance ranks. This situation provides a number of advantages over a field situation. The first is that we can know the food distribution and control them.
59:05
The second advantage is we can pick particular individuals and present problems to them in a defined order. And the third advantage of course is that we can recall the travel paths and search behavior from a booth that overlooks this enclosure.
59:23
Okay, now let's see what they are doing. Tiga and Tifu will be tested first. Tifu has discovered the banana already. Let us recapitulate the experimental setting. There are four piles of food on a straight line along the concrete.
59:44
At the very back there is the well visible banana and some raisins. The piles of raisins become less visible in the front. The question is which food the monkeys will discover first in two additional locations.
01:00:00
hand that is located along the concrete as well or the food further in the front that is not located near the concrete but in a straight extension of the first four piles. A short sign with the sliding doors indicates to the animals
01:00:22
that the test will start immediately. By the time Tifu eventually comes into
01:00:47
the enclosure Tiga has eaten almost all food in the first pile. It is very important for wild monkeys to be on the lookout for where food can be found.
01:01:02
However monkeys in the field most often have a better knowledge of food dispersal than researchers do. This is not the case at Bockenwood. We know exactly which food has been overlooked and which information has been used by the monkeys because we distribute with the food ourselves. By
01:01:25
the way when food is provided on a straight imaginary line in a flat sand field the monkeys assume that they will find more food in a straight extension of the first food sites. Thus it's very interesting to see which food
01:01:40
location they will find first. After two minutes Tiga has found the last
01:02:25
food pile from the four that are easier to find. How will he proceed with this search if he does at all? There is a better view from the top. Now it is
01:03:03
crucial where Tiga scans the floor with his eyes. Three minutes after the
01:03:28
start of the test Tiga has found the food along the concrete. We can't make any final conclusion from a single test. Anyhow Tiga did not give up after the
01:03:44
first easier to find food piles and continued to search for food. Tifu is somewhere at the far back. It is only after a while that Tifu returns to the
01:04:00
experimental area. With a mouth-to-mouth contact Tifu at the back attempts to find out what Tiga has discovered. The monkeys in this group have social expertise and are kept in an outdoor enclosure of a size that
01:04:22
provides some degree of environmental complexity such as the ground vegetation. It is in this respect that research at Bockenwood aims at creating a situation that does not deviate too much from the field. By doing so Bockenwood attempts to create a bridging link between experimental research in the
01:04:42
laboratory that investigates the mechanisms of animal behavior and research that describes animal behavior in the environment where it evolved, namely in the field. The behavior of the monkeys is carefully
01:05:19
recorded in the observation cabin. However Tiga and Tifu have not
01:05:26
discovered the pile of food in the straight extension of the first piles of food. The monkeys are called back into the stable after they have stopped searching for five minutes and the assistant collects the food the monkeys have not found. Such tests were conducted on several days at different
01:05:43
locations, for example here where the vegetation provides a borderline or along the field of stones. Tuyu in the front has just discovered the food in the test location along the border of the stone field and Mazuk has just found
01:06:07
the last of the initial piles of food in the corner. It is also obvious where Mazuk continues to search in this case. This figure from the
01:06:47
experimental setting shows the results from 27 tests. There is a clear difference. The food in the test location along the border was found 17 times. The food in the straight extension of the first four piles was
01:07:04
found in only three tests. Statistical calculations reveal that there is only a likelihood of 2.5 percent that this difference is purely random. Thus we can confidently state that the food in the test location along the borderline
01:07:22
is more likely to be found. Now where did the monkeys search the ground with their hands? This is shown in this graph using the example in the field of stones. The darker the squares are the more often the monkeys search these
01:07:42
locations with their hands. Obviously the monkeys searched far more often from the corner along the border than along the straight line. This is Tiga at the spot where he has to decide whether to go on searching the imaginary
01:08:03
straight line to the left in the picture or along the border of the stone field at the bottom in the picture. Thus the monkeys do not
01:08:31
restrict their search behavior to the actual food site nor do they search randomly around it. Instead they take the local structures of the food site
01:08:40
into consideration. For example Tiga noted that the first four piles of food were located along the border of the field of stones. This information had more relevance for him than the fact that all first piles of food were located on the straight line. This experiment tells us that environmental
01:09:04
structures such as border lines are not meaningless features for the monkeys. They are structures along which behavioral processes preferentially take place. Environmental structures must be encouraged in animal husbandry in the same way. Surprisingly Tifu found the fewest food locations. This is
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surprising because Tifu often searches for objects in the grass or elsewhere when he stays in the big group. However in the experiment with Tiga he stays behind. Okui's performance was surprising as well. He almost never rummages around in the meadow while in the big group but he
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did so during the tests. Maybe Okui was less distracted in the reduced social environment of the tests. Being confronted alone with Tiga on the other
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hand seemed to make Tifu insecure he remained reserved in the tests. The
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monkeys are sent into the stable after the last test and the animal caretaker takes the opportunity to install some new furnishings. Very
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new and very old furnishings. Installing new furnishings and modifying existing furnishings is done according to the plans of the animal caretaker. She does this job with great enthusiasm and intuition. For
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example in former times all scaffolds for climbing were fixed to the ground like this one. Nowadays most of them are hung up from the ceiling so that they move freely. Moving climbing structures are small challenges for the monkeys. Beside the movable and new furnishings there are very old pieces.
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For example this hanging board might be the preferred resting place for a monkey. As time passes the board might not provide a comfortable resting place anymore. The monkey responds and looks for a new favorite resting place. And
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later on one side of the board will hang down suddenly providing a new possibility to climb from the ground to the ceiling. Thus much enrichment is provided by the furnishings if you let them become old and ramshackle. And
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much later on the whole board will fall on the ground. It will become rotten and interesting insects will be detectable below it and the rotten wood will be broken with the teeth. Or the board will be used as a mat to lie on in the meadow. But now we are curious about how the monkeys will
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react to the new furnishings. There is no particular reaction. It's not until
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Tubow comes outdoors that he approaches the new furnishings. He has a better view. Two and a half minutes have passed since the sliding
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doors were opened. And now the experimental subjects are back in the
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group again. Tifu is himself again and returns to his favorite
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entertainment in the big group. And Ukui as well. Constantly teasing and staying close to Madu. It is astonishing how the monkeys behave so differently
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depending on if two of them take part in an experiment together or whether they stay in the big group. Ukui is not interested in the bundle of branches. Tubow has some work to do. Not only is he the first one on the
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spot when there are new branches. When the monkeys are released into the outdoor enclosure right after lunch then he is often the first one at the pool as well. The pool. Long-tailed macaques are also called crab eating macaques.
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Whoever is afraid of the water would have problems catching crabs. Not all of the monkeys enjoy the summer afternoons splashing about in the water. The old ladies prefer a more peaceful time. And Tiram grooms her daughter Tiden. Her
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funny way of slapping her own ear is conspicuous. Tubow still wet from
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bathing continues playing on the scaffold. Then the play moves to the
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grass. It is obvious that Tubow feels good in the grass. The Swiss law for
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animal welfare stipulates that animals must be kept according to up-to-date knowledge. In the beginnings of the 80s when the research station was founded the research team was concerned that the natural ground could cause hygiene problems. Unlike concrete natural ground
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can't be hosed down. It was well worth taking that risk. The animals are healthy and they have not completely destroyed the vegetation. It is possible to keep macaques on natural ground. And this should be the standard for all zoological gardens. But the bockengut would be overcrowded without
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appropriate animal management. The frequency of aggression would drastically increase and the grass would be destroyed as well. In order to prevent this some monkeys have to be spayed and a few have to be put down. This is one of the sad jobs at bockengut. However an overcrowded population is no help to
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anyone especially not to the monkeys. In an enriched enclosure with natural ground vegetation however the monkeys not only have the opportunity to socialize but they also can be kept busy in ecological matters. I hope this documentary has shown you that the animals need this early evening. The bar
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like vocalizations often Monday starts doing it announced that it is evening feeding time. With this a day comes to an end at the bockengut
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research station.