HOPE Report No.33' 2004-11-03

Dr. Struhsaker's trip to Yakushima and Koshima

Date: July 2, 2004

Ryutaro Goto (sophomore, Kyoto University)

This summer, I was given the chance by Dr. Matsuzawa to travel to Yakushima and Koshima with Dr. Struhsaker as his guide. Below is a report of this trip.

Before the trip
I looked through two books written by Dr. Struhsaker, The Red Colobus Monkey and Ecology of an African Rain Forest, and learned a little about his work in Africa.

July 3rd
The First Meeting
Dr. Struhsaker was the main guest lecturer at this year's annual conference of the Primate Society of Japan. After the conference, he planned to travel to Koshima and Yakushima. The conference was to be held in Inuyama City; therefore, I left Kyoto for Inuyama to join him.
I first met him at a seminar room at the conference hall. He was engaged in a discussion with Japanese researchers, so we only shook hands and greeted each other briefly. But I was glad to find that he was a friendly tall gentleman. His beard suited him well.

Dr. Struhsaker's lecture
Dr. Struhsaker was the guest lecturer for the second "Imanishi-Itani Memorial Lecture," held to honor the late Kenji Imanishi (1902-1992) and Junichiro Itani (1933-2001). He talked about his conservation efforts in Africa, especially at Kibale forest in Uganda. I had the opportunity to learn about what he had been doing in Africa and about the importance of conservation.
After the lecture, someone from the audience asked him why he chose to observe without feeding the monkeys to get them used to humans, as is common in other field sites. He said that feeding wild animals creates an unequal and unnatural relationship between us and the animals, and therefore, we cannot observe their natural behaviour. He also pointed out that feeding them may bring human illnesses into the colony. I decided to keep this issue in mind as we visited Koshima and Yakushima, the two main field sites in Japan for studying monkeys.

July 4th
Visiting the Japan Monkey Center
The next morning, Dr. Struhsaker and I visited the Japan Monkey Center in Inuyama. This center has a large variety of primates. Under the hot sun, we observed the monkeys and apes. From his experiences in Africa, Dr. Struhsaker had a vast body of knowledge about the various species of primates we observed; it was as though he was guiding me through the center instead of the other way around.
He noted the cages of the Monkey Center were too small, with which I agreed. We unfortunately saw many abnormal behaviours, characteristic of primates kept in captivity. I strongly felt that enrichment of zoos is an important issue that must not be neglected.

At the Koshima Hotel "Tagiri-So"
After visiting the Monkey Center, we flew to Miyazaki. Mr. Suzumura (a technician at the Koshima Monkey Research Station) met us at the Miyazaki airport and took us to the Koshima hotel "Tagiri-So." It rained heavily in Miyazaki.

Mr. Suzumura told to us about Koshima Island in the car.
1. The distance between Koshima Island and the mainland is very short (about 300m). In recent years, sand was beginning to collect in the sea in between. Therefore, many people were starting to worry about what would happen if eventually, Koshima and the mainland became connected and monkeys came into the mainland. What would become of potato-washing?
2. Koshima monkeys are famous for potato-washing. But, Mr. Suzumura told us that the technicians gave potatoes only in special occasions, such as filming. Therefore, unfortunately, we would not have the chance to see the famous potato-washing behaviour. I found it interesting that monkeys remember how to wash potatoes though they are not fed potatoes regularly.
3. There were 9 baby monkeys at Koshima when we visited, and the youngest baby had been born only 2 weeks before. I was looking forward to seeing them.

We arrived at the hotel "Tagiri-So." Dr. Struhsaker had last been to Koshima in 1968. He told me that the roads had improved remarkably.
We had planned to meet Mito Satue, the discoverer of the cultural potato-washing behaviour and the owner of "Tagiri-So," at the hotel. Dr. Struhsaker had met her in 1968, and we were looking forward to seeing her. Unfortunately, she was currently visiting her son in Sante Fe, New Mexico, so we could not see her. But we met an interesting couple working at "Tagiri-So," Mikio Ikai and his wife, Midori. Mrs. Ikai had been working at an NGO in Ghana for 2 years, so her English was good, and Dr. Struhsaker enjoyed talking about Africa at dinner with her. Mr. Ikai was good at playing the African piano, and we listened to his music during dinner.

Heavy Rain
We had heavy rain that night, and the sea was stormy. It looked as though we would not be able to visit Koshima island the next day. I asked the fishermen whether they could sail across to the island tomorrow morning, and they replied bluntly that there was little hope of sailing in this weather. I negotiated with the fishermen and managed to have one of them promise take us to the island if the weather was good the next morning. Everything depended on the weather, and I must admit that I spent an anxious night.

July 5th
Good weather!
I woke up at 5:50am and found the bad weather had passed. I called the fisherman and asked how the sea condition was, and he said that we would be able to go to the island. I was excited and wanted to inform Dr. Struhsaker about the good news, so I went to wake him up, but he was not in his room. Wondering where he had gone, I asked Mr. Ikai. He told me that he was taking a walk. Soon, he returned to the hotel and told me that we could go to the island. He had gone to the docks to ask the fishermen whether we could go to the island. How active he is!!

Column 1 "What is the Koshima Island?"
Koshima is a small island of 30ha, surrounded by beautiful sea and covered with an evergreen broad-leaved forest. Various studies have been conducted there since 1947, when research of Japanese macaques began here. Since 1952, all individuals have been identified and their personal histories have been recorded, especially in their family trees with dates of their birth and death. Other information, such as socially pertinent incidents like changes in high-ranking males and females, individual transfer between groups, and their body weight has also been recorded. Many studies have been conducted on Koshima monkeys. The findings of cultural behaviour like potato-washing, especially, were an outstanding product of Japanese primatology in their early time, and as a result, Koshima is known world-wide.

Visiting Koshima Island
At breakfast, I handed the schedule I had written in English during the night before to Dr. Struhsaker. I hoped that this schedule would help my inexperienced tour-guide skills. We left for Koshima soon after breakfast, and we took a short boat ride. Because of the tides, we had only 1 hour in Koshima until the fisherman came back to pick us up.
When we got off the boat, we found monkeys gathering around the beach. The monkeys on the island are not weary of humans, so we could observe them from a close distance. We saw some that were grooming each other and mothers giving milk to their infants. Dr. Struhsaker filmed some of the monkeys and the beautiful beach.
After we came back to the mainland around 9:30am, we visited the Koshima Field Station. Because I had thought that we would not be able to visit Koshima, I wanted to ask the technician to take us to Sakurajima. They told us that they had plans with another group until noon, but that we would have a second chance to visit Koshima again with them in the afternoon. So, we changed our plans once again and went to Koshima once more on the Center's boat.
On the way, Dr. Struhsaker asked them about the accident of Kenji Yoshiba. Kenji Yoshiba was a researcher and had met Dr. Struhsaker before. He was killed in an accident in the sea near Koshima when he was still very young, as a result of a series of unfortunate events, such as bad weather and the boat engine malfunctioning.

Visiting Koshima again
We visited Koshima for the second time with Mr. Kanji and Mr. Suzumura (both technicians at the Field Center). This time, there were more monkeys than we saw in the morning. The technicians fed them some wheat and checked each monkey, identifying them by face. They also found a new baby, just born last week.
When Mr. Kanji and Mr. Suzumura gave the monkeys some wheat, the monkeys ate directly from the ground by flexing their forearms and bending down to lick the grains. Dr. Struhsaker told me that in the old days, the monkeys would throw the grains into the water and separated the wheat grains from the sand. This behaviour is called "wheat placer mining." During my visit, I never saw the monkeys washing the wheat grains this way. Had they lost their cultural behaviour?
I also heard that the monkeys used to sometimes swim from Koshima to other islands, but recently, this behaviour was rarely seen. I thought that this tendency might be related with the loss of the culture of wheat placer mining.
I learned much about the monkeys from Mr. Kanji while at Koshima.

Column 2 "Mr. Kanji's Explanations"
1. Boss monkeys do not exist
These days, groups that do not have "boss monkeys" are common in Japan. When we feed monkeys for observation, many individuals gather together, and there are more frequent fights for food than in the wild. Therefore, the social hierarchy can be seen more clearly, perhaps suggesting the presence of an especially dominant monkey. Feeding does make observation of the monkeys easier, but on the other hand, it makes for an unnatural circumstance.

2. About male monkeys
When male monkeys are about 5 years old, they become stronger and start to threaten low-ranking females. These conflicts become more serious as they age further, and young males often leave their natal troop and become peripheral males.
In the fall during mating season, they briefly return to their troop.
When males are about 10 years old, they return to their troop as low-ranking members. This time, they are kind to the female monkeys, participating in grooming and playing with children, and through these behaviours, they slowly rise in social rank.

3. About female monkeys
Female monkeys become more aggressive after giving birth to a child. They have to be assertive in securing food for their offspring; they can no longer afford to yield to others. Other monkeys abstain from attacking mother-infant pairs as well.
Also, female monkeys choose their male partners to their advantage. During mating season, they spend a lot of time with high-ranking males, enjoying their protection to avoid attacks from other males. However, recent research has shown that the offspring of these females are not necessarily fathered by the dominant males. Apparently, females are wise in their use of males.

4. Recent problems in Koshima?
Beginning in the 1980s, monkeys have started to eat raw fish after being exposed to the taste through stealing from fishermen, a previously unobserved behaviour.
The bait that fishermen leave behind causes problems as well. These contain high amounts of preservatives, causing the monkeys that ingest them to first become so well-muscled and deformed that even the technicians cannot recognize them by face, and then suddenly emaciated.

After visiting Koshima Island, we were taken to Sakurajima by Mr. Kanji. We enjoyed seeing the Sakurajima volcanoes from the car.
We arrived at the Sakurajima hotel late in the afternoon. Dr. Struhsaker said that his back and shoulders had become stiff from the long hours of sitting during the conference and traveling, so we decided to take a walk along the shore before dinner. During the walk, I asked him how I could go study in Kibale next summer, and he told me about the research going on there. I realized that I would have to work hard to earn enough money to be able to study there, and that I would have to refine my interest in the relationship between plants and chimpanzees even further, to find specifically what kind of questions would be suitable for me to pursue.
At dinner, we talked about the food in Africa, and Dr. Struhsaker also praised his wife's cooking at home. We drank a little liquor that was made of sweet potatoes, and he was surprised at the taste, saying that it tasted like alcohol from a lamp!

July 6th
Leaving for Yakushima
We left the hotel for Yakushima early in the morning. After being on the ferry for 3 hours, we arrived at Yakushima at 12:00pm.
On the ferry, we saw blood-type fortunetelling on TV. According to that, B had the best luck. Dr. Struhsaker's blood type was B, and he exclaimed, "B is positive!"

Column 3 "What is Yakushima?"
Yakushima Island is the southern limit of where Japanese macaques can be found, and a subspecies, Yakushima macaques (Macaca fuscata yakui), is unique to the island. Monkeys are distributed from the subtropical forest along the shores to the subalpine forest, close to 2,000m above sea level. In this area, a variety of field studies have been conducted, such as ecological and genetic studies on various kinds of species, including mammals, insects, turtles, and snakes.

Visiting the Forest of Ancient Cedars
We took a taxi from the port at Yakushima and went to Yakusugi Cedar Land. We saw hydrangeas by the road. Dr. Struhsaker commented that his wife liked them.
We arrived at Yakusugi Cedar Land and took a walk through the forest, where we found a lot of endemic plants along the path. Yakusugi Cedar Land is an old forest of ancient cedars and hemlocks. Some of the cedars in the forest are over 2000 years old. These ancient trees had innumerable wrinkles and various aerophytes that looked like real cedar branches, and the diversity of aerophytes made it look like there was a garden on the tree. These giant trees made me think of the insignificance of human beings within the context of the larger picture.
For lunch, we ate sushi by the riverside, where it was cool and fresh. Dr. Struhsaker wondered why we did not find any fish in this beautiful river.

Afterwards, we walked along the trail and came across a troop of monkeys. We were excited for the unexpected meeting, which was our first contact with monkeys in Yakushima. The troop disappeared into the forest.

We went to see the Kigen cedar, the second oldest cedar in the forest at 3000 years. We were amazed at the diversity of aerophytes.
The taxi driver, Mr. Kamata, had a lot of knowledge about Yakushima's environment and plants. Dr. Struhsaker said that he was not only a taxi driver but also a first-class naturalist.
I was glad that the knowledge of plants I had gained in Borneo was useful in talking about the plants of Yakushima in English.

Observing sea turtles
After leaving Yakusugi Cedar Land, we went to see the big waterfalls. From the car, we were lucky to see a deer, a snake, and many troops of monkeys along the road. When we were looking at the waterfalls, we were caught in a shower. The annual rainfall in Yakushima is 8000~10000 mm.

We arrived at the hotel, "Yakunoko," and met Tessei (the owner of the hotel), who took an active part in the conservation efforts of Yakushima forest. We also met Tomoyuki, who was attending school in the United States and thus spoke English well.
After dinner, we went to observe the nesting loggerhead turtles on Nagata beach. There, volunteers work to help the nesting turtles by cleaning the beach and preventing people from walking onto the beach when the turtles are there. Tomoyuki's father, Mr. Ohmuta, was a leader of this volunteer group and explained their efforts to us. Dr. Struhsaker was moved by their activity and efforts.

July 7th
Bird watching at Yodogo River
In the morning, we went to Yodogo River with Tomoyuki for some bird watching. Yodogo River was beautiful and cool, and the sound of the river was relaxing. We walked on the trail along the river. But we could not find any birds; I thought that perhaps we would have had better luck earlier in the morning.
Dr. Struhsaker was hiking briskly along the rocky areas, and Tomoyuki asked how old he was, amazed at his agility.

Mieko joined us
At noon, we met Mieko, a graduate student researching about how monkeys in Yakushima catch insects, at Yakushima Cultural Village. She and I had both participated in researching Yakushima monkeys last year, so we knew each other. At lunch, Dr. Struhsaker and Mieko talked about her research.

Monkey Watching
In the afternoon, we went to the west side of Yakushima Island with Mieko, where there is a good place for observing wild monkeys. We stayed there for short time, watching the monkeys that came by. Mieko told us about the conflicts between the local people and the monkeys, who often come by orchards and fields and eat the fruits and vegetables there. The local people are trying to prevent damage by installing electric fences, but this was unsuccessful because of the high cost, partially caused by vines becoming entangled in the fences. Each year, 400 monkeys are killed by farmers. While this island is blessed with a large population of monkeys, we must also recognize the problems that it causes for the farmers here.

I was excited to be given a DVD of red colobus monkeys by Dr. Struhsaker. Thank you very much!

July 8th
Monkey Watching
In the early morning, Mieko came by the hotel and brought us to the west side of Yakushima.
Early in the morning is the best time for finding monkey troops, since monkeys start to forage for food soon after getting up. We can follow the calls they make while eating to find the troops. After eating, however, they rest silently, making it difficult for us to find them.
We saw a few monkeys from the car and followed them on foot. They were eating leaves of ako (Ficus superba), yamamomo (Myrica rubra), and hime yuzuriha (Daphyniphyllum teijsmanii). Dr. Struhsaker videotaped some of the monkeys while they were eating, and I tried chewing on some of these leaves. Yamamomo was easy to eat, perhaps good for a salad. On the other hand, hime yuzuriha was bitter because of its high tannin content, making me think of chewing tobacco plugs in Borneo.

We followed the monkeys into the forest and found a troop eating mushrooms on a tree. Neither of us had seen this behaviour before.
When we were observing the monkeys, we heard the cry of a deer. It is a well-known fact in Yakushima that deer often follow monkey troops, looking for the fruit that they drop from trees.
Mieko went deeper into the forest in order to find the troops she usually observed. Dr. Struhsaker and I waited for her until she came back at 10.

At 10, Mieko came back and we had an early lunch in the car. Mieko had brought us rice balls and sandwiches, which were delicious.

After lunch, we went into the forest again. Mieko led us to the point where she had found some monkeys. Once we arrived, we looked for the monkeys by using a detector that reacts to the collar of the α female, and we were soon able to find the troop. There were many adult and juvenile monkeys on the opposite side of the river.

Why did the mother monkey neglect her baby?
When we were observing the monkeys, we saw a shocking sight. A baby monkey was following its mother and screaming for help. However, the mother completely neglected her baby. It seemed that the infant was unable to drink the mother's milk. Dr. Struhsaker said that he had never seen something like this before and was greatly concerned. Mieko also said that she had never seen such behaviour. After the trip, I received an e-mail from Mieko that said that the baby had later died. What made the mother neglect her baby?

After observing monkeys, we were thirsty and rather tired. Therefore, we went to drink some fruit juice at the Tropical Fruits Garden. The juice made us feel refreshed once again!

That night, we had originally planned a dinner party with some of the local people. But Dr. Struhsaker and I were both exhausted and unfortunately had to cancel our plans. Instead, Tessei cooked a small dinner for us, and the sukiyaki that he made was very delicious.

Turtle watching
After dinner, Dr. Struhsaker suggested that we going turtle watching on the beach, so we visited Nagata beach again. There were many more visitors than when we visited before. This made me worried about the turtles, but Dr. Struhsaker said that it was good to have so many people interested in the turtles and that it would also help with the volunteering efforts.
Dr. Struhsaker saw the light of some fishing boats on the sea and asked whether they were using fishing nets. He said that more than 90% of turtle fatalities are cause by fishing nets. I asked the volunteer guides, and they said that in Yakushima, fishermen mainly use poles and spears and rarely use nets, especially when turtles are around. Even after I told this to Dr. Struhsaker, he seemed a little worried.
Dr. Struhsaker does not eat shrimp, since they are bred in breeding farms that are made by killing mangroves. Shrimps are also caught using fishing nets, which kill many sea turtles. I thought he was a true conservationist, considering all aspects of the environment.

July 9th
At the beach
In the morning, Dr. Struhsaker and I walked along the beach. We found beautiful seashells and many sea turtle tracks on the sand. Dr. Struhsaker and I both picked up some seashells for his son.

Visiting the Recycling Center
We visited the Recycling Center directed by Tessei, the owner of our hotel, where we learned about their work to protect the environment. Extra wood is collected from all sawmills, and garbage from half of the island comes to the Center, where both of these are composted. This compost is then used by farmers and gardeners all over Yakushima, and the Center remains popular because of the constant demand for fertilizer.

Goodbye to Dr. Struhsaker
After we visited the Recycling Center, we went to the airport and said goodbye to Mieko. During our flight from Yakushima to Osaka, we were able to see Koshima and the beautiful Sakurajima volcanoes from our airplane window.
When we arrived at Osaka, we drank some beer and celebrated the completion of our trip. We left for Kansai International Airport Hotel by bus, and on the way, Dr. Struhsaker gave me some advice about my future, what I should do in order to accomplish my goals. He said that he would try to introduce me to the people at Kibale and tell them that I was interested in researching there. We said goodbye at his hotel.

During this trip, I was exposed to many kinds of interactions between humans and monkeys: researchers and monkeys, fishermen and monkeys, farmers and monkeys. Often, foods such as potatoes, fish, fishing bait, and fruit influence this relationship. I also learned about the various types of food monkeys eat in the wild, such as ficus and myrica leaves. It was interesting to know what kinds of plants they preferred and what chemicals these leaves contain.
I came to understand that while feeding makes observation easy, it also makes the behaviours of the monkeys unnatural. Without the help of food, we could never have achieved the deep level of understanding of their behaviours and society that we currently do. However, we sometimes mistake our current understanding as being complete. For example, until recently, we believed that each troop had a "boss" monkey. Therefore, we have to study their behaviour in the wild as well; both methods are essential.
On this trip, I was most surprised by the mother that completely neglected her baby. I also know of a mother that carried around the body of her dead baby for 2 months after its death. I had always thought that protection for offspring was a natural instinct. What causes the difference between the caring mother and the negligent one?

Dr. Struhsaker was a first-class naturalist who gave me important advice about my future. He is a true pantheist, admiring everything in the wild, and his concerns about environmental problems and conservations were contagious, motivating me to consider them as well. Thank you so much for being patient with my tour-guiding skills.
Dr. Matsuzawa gave me this precious chance. Thank you very much.
To Dr. Yamagiwa, Dr. Maruhashi, and Dr. Michael Huffman, Mr. Kanji, Mr. Suzumura, Mr. Tessei, and Ms. Mieko Kiyono, and to the people of Tagiri-So and Yakunoko, I express my gratitude. Thank you very much.

August, 2004

HOPE Project<>