シカの「落ち穂拾い」――フィールドノートの記録から辻大和観察のきっかけ

シカの「落ち穂拾い」

――フィールドノートの記録から


辻大和


観察のきっかけ



宮城県牡鹿半島の沖にある金華山は、面積約10平方キロメートルの小さな島だ。ブナやモミの原生林が残り、ニホンザルやニホンジカをはじめ、野生の生き物が数多く生息している。私はこの島で、サルの採食行動について研究してきた。
島には現在約二百頭のサルがいて、六つの群れを作って生活している。私が研究のために観察してきたのは、島の北西部にいる群れである。この地域には、サルの他に、三百頭近くのシカも生息している。ただ、サルは樹上を、シカは地上を主な生活の場としているため、この2種の動物は互いに無関係に暮らしていると考えられてきた。
ところが、2000年5月23日、いつものようにサルを観察していたときのことだ。フィールドノートに記録をつけていた手を止め、私は思わず目の前の光景に見入ってしまった。驚いたことに、数頭のシカが、サルが採食している木の真下に集まり、サルの落とした葉や花を奪い合うようにして食べ始めたのである。なかには、サルの重みでたわんだ枝に食いつき、普段は届かない所にある葉を食べているシカもいた。下は、その日のフィールドノートの一部である。
後日、文献を調べたところ、樹上の動物が落とした食物を地上の動物が採食するという行動は、ミレーの名画になぞらえて「落ち穂拾い」とよばれていることがわかった。ただ、その詳細が検討されることは、これまであまりなかったようだ。
「落ち穂拾い」に興味をもった私は、その後もシカの同様の行動を見かけるたびに、フィールドノートに次の項目を記録することにした。

結果 (英語) 1:

Deer "the gleaners"--From field notesTsuji YamatoObservation opportunityJinhua mountain off the coast of oshika peninsula, Miyagi Prefecture is a small island area of about 10 square kilometers. Remaining primeval forest of beech and fir trees, many inhabited by creatures of the wild Japanese Macaque and sika deer. I inquired about the feeding behaviour of monkeys, this island. Island currently has about 200 monkeys, herds of six lives. I've observed to study in groups in the northwestern part of the island. This area inhabits almost three hundred deer other monkeys. Be considered for just the monkey is arboreal deer ground main living area and has 2 species of animals live together regardless. It was however, 5/23/2000, as usual in monkeys had observed. Field notes on record were to stop, I was staring at the sight in front of me. In competing for gather beneath the trees to my surprise several deer are feeding monkeys, monkeys dropped leaves and flowers, began to eat. Engagement known by the weight of the monkeys in the branches, and was usually deer are eating the leaves away. Below is part of the field notes of the day. Action of terrestrial animals were eating food dropped arboreal animal found documents at a later date, was called "the gleaners", likening it to the famous millet paintings. Consider, however, that so far didn't seem. Decided to record the following field notes whenever I became interested in "the gleaners", see deer as well as behavior afterwards.

結果 (英語) 2:

And "glean" of deer - from field notes recording Tsuji Yamato observation of opportunity lies in Miyagi Prefecture Oshika Peninsula off the coast of Kinka, but small island area of about 10 square kilometers. The remaining virgin forests of beech and fir, including Japanese macaques and deer, wild creatures are numerous habitat. I on the island, has been studied foraging behavior of monkeys. The island There are currently about two hundred monkeys, we are living by creating a six herd. I've been observing for the study is the flock who are in the northwest of the island. The region, in addition to the monkey, are also living three hundred horses near the deer. However, monkeys are Ki-jo, deer because that is a place of the ground the main living, this two kinds of animals have been considered to be living independently of one another. However, May 23, 2000, it's about when I was observing the monkeys as usual. To stop the hand that wore the record in the field notes, I had involuntarily staring in front of the sight of the eye. Surprisingly, few heads of deer, gathered beneath the tree monkey is eating, is began to eat so as to compete for monkey of dropped leaves and flowers. Nakaniwa, and bite to the branches that bent under the weight of monkey, it had also deer eating leaves in the place where it does not reach normally. Below are some fields note of the day. At a later date, was examined the literature, act of eating food animals on the tree was off the ground animal is adopted, it was found that it has been called "gleaning" is likened to paintings of Millet. However, it is that the details are examined, did not seem too far. I was interested in "gleaning" is, every time you see the same behavior of then also deer, decided to record the following items in the field notes.

結果 (英語) 3:

"Gleanings from Mt. Kinkazan 」

―― field notes of deer records of Yamato Tsuji stress it is triggered by stress of Miyagi Prefecture oshika Peninsula, the area of about 10 square kilometres of small islands. Primeval beech and the rest of the fir, the Japanese sika deer and wild creatures that live there. On this island, I study on the foraging behavior of monkeys. The island is now about two hundred and six groups of monkeys living. I look for the study of theIn the northwest part of the island. In this area, monkeys, deer inhabit nearly three hundred. But the tree of life, and the main ground, these 2 kinds of animals have been living and thinking independently of each other. However, on May 23, 2000, as always when observing the monkey. To stop recording field notes, I unconsciously in front of my eyes, gazing into the scene. To my surprise, the number of the deer headThe tree on the right to eat monkey monkey dropped to scramble for leaves and flowers in the beginning. Among them, in the branches of the deflection of the weight, the deer is eating leaves is usually does not arrive. The lower part of the day field notes. At a later date, literature, action of animal food dropped arboreal animals and eat the millet masterpiece that is called "gleanings from." However, theIt is discussed in detail, and it didn't seem too. At the "gleaning" interested, then I see the same behavior of deer, to record the following items in the notes field.