長野県中央山地におけるニホンツキノワグマの食性

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タイトル別名
  • The food habit of the Japanese black bears in the Central mountain area, Nagano prefecture
  • ナガノケン チュウオウ サンチ ニ オケル ニホンツキノワグマ ノ ショクセイ

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The food habit of the Japanese black bears (Selenarctos thibetanus japonicus) was studied on Mt. Chausu (alt. 2.006m) in the Central mountain area, Nagano prefecture from August 1975 to December 1977. 135 droppings of the Japanese black bears and their feeding signs were examined in the upper part of low mountainous zone (alt. 1.100-1.600m), and their food habit was made clear from the middle of June to early December. This area consists of afforestation of Larix leptolepis and natural regenerated forests where Quercus crispula, Betula platyphylla and Abies homolepis are predominant (Fig.1) .<BR>The Japanese black bears are omnivorous but dependent on vegetable foods strongly. Though animal foods were predominant from June to July, from August to October vegetable foods were much eaten in addition to animal foods, and from November to December vegetable foods were markedly more important than in the former seasons (Table 2) . Insects were main animal foods which consisted of ants (Formicidae) and bees (Vespidae & Apidae) . Adult ants were most primary animal foods, which were eaten from June to December. Adult bees were eaten from September to December. Mammals (hares, Lepus brachyurus and Japanese serows, Capricornis c. crispus) were also eaten but showed low occurrence (Table 4, 5) .<BR>As to vegetable foods, berries and acorns were important. Berries, eaten from August to December, occupied important status till the middle of October, but thereafter showed low occurrence and lost the position. Acorns, eaten from late September to early December, were most important vegetable foods. As to berries Akebia and Araria elata were, as acorns Q. crispula were eaten most mainly (Table 6-8) .<BR>For the three years, alternate bearing occured in Q. crispula, of which acorns lean in autamn 1976, but rich in autamn 1977. This phenomenon influenced food habit of the Japanese black bears. Acorns of Q. crispula were almost not eaten in 1976, but were eaten by much in 1977 (Table 9, 10) .<BR>Broad-leafed forests which consist of Q. crispula and other various acorns and berriesbearing trees are so much important to the Japanese black bears. We should conserve broad-leafed forests in order to protect them.

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