| Project/Area Number |
07041135
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Field Research |
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| Research Field |
生態
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| Research Institution | Kyoto University |
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Principal Investigator |
SUGIYAMA Yukimaru Kyoto University, Primate Research Institute, Professor, 霊長類研究所, 教授 (20025349)
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| Co-Investigator(Kenkyū-buntansha) |
MASAWE Edeus Mahale Mountains Wildlife Research Institute, Director, マハレ野生動物研究書, 所長(研究職)
KOMAN Jeremy Laboratoire Monts Nimba, Director, ニンバ山研究所, 所長(研究職)
山越 言 京大理学研究科, 日本学術振興会, PD特別研究員
YOKOTA Naoto 0ita Junior College, Lecturer, 園芸科, 講師 (30158365)
MATSUZAWA Tetsuro Kyoto University, Primate Research Institute, Professor, 霊長類研究所, 教授 (60111986)
内田 亮子 千葉大学, 文学部, 助教授 (50283685)
佐倉 統 横浜国立大学, 経営学部, 助教授 (00251752)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥22,500,000 (Direct Cost: ¥22,500,000)
Fiscal Year 1997: ¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 1996: ¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 1995: ¥7,500,000 (Direct Cost: ¥7,500,000)
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| Keywords | Wild chimpanzees / Tool use / A1gae-scooping / Leaf-cushion / Termite-fishing / Fruit abvailability / 道具使用行動 / 季節変化 / 移出入 / 社会構造 / 地域変位 / 社会変動 / 植物季節 / ハンマー使用 / 食物選択性 / 採食品目 / 糞分析 / 主要食物資源 / 世代間伝播 / 臨界期 / 群間行動変異 / 文化的要因 |
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| Research Abstract |
1. During this study period, we found the following three new examples of tool use among wild chimpanzees at the main study area of Bossou, Guinea : l) Algae-scooping ; Chimpanzees use sticks approximately 50 cm long to scoop and ingest algae (pond scum) floating in ponds. Ghimpanzees select thin, light grasses or stems of ferns as sticks, and they remove hampering side-branches before utilizing them. Holding them in one hand, they extend the processed sticks as far as possible from the edge of ponds to scoop algae. 2) Leaf-cushion ; Chimpanzees arrange several large leaves on the ground and sit on them when the ground is moist in order to avoid getting wet. 3) Termite-fishing ; Chimpanzees insert thin stems of grasses into holes of termite mounds after breaking open the surface of the latter. Termites bite the intruding stems, and are thus lifted out of the mounds and subsequently eaten by chimpanzees retracting the stems. Termite, -fishing is widespread among chimpanzees in Gombe, Ea
… More
st Africa, but it has rarely been seen in West Africa. Our observations of Algae-scooping and Leaf-cushion constitute the first ever reports of these newly-found tools among wild chimpanzees. These discoveries lead to a claim that chimpanzees at Bossou have the largest repertoire of tools among all wild communities studied. There have so far been a total of 27 tools observed among wild chimpanzees, 18 of which can be seen at Bossou. We are now conducting an analysis of ecological factors to explain why chimpanzees at Bossou use such a large number of tools.
2. We measured the study site and made a survey map for the basis of research. We also investigated the flora of Bossou, the availability of main fruits, and their seasonal changes. This data was used to analyze the correlation between seasonal changes in fruit availability and the frequency of tool use. The latter analysis is now beginning to indicate that chimpanzees frequently use tools during fruit scarcity to gain access to foods that could not be acquired otherwise.
3. We observed parturition in a l0.5-year-old female. This fact along with accumulated data on population dynamics demonstrate that in wild chimpanzees at Bossou, the age of primiparity is lower and the inter-birth interval shorter than previously reported from East Africa. Less
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