Callosciurus prevostii (Desmarest, 1822)
森を育む三色のリス
The Tricolored Squirrel That Nurtures the Forest
体長約20～30cm、尾長約18～25cm、体重300～500g。東南アジアのマレー半島、スマトラ島、ボルネオ島などの熱帯林に分布するリス科の樹上性哺乳類です。日本では「ミケリス」の名で知られていますが、英名は19世紀フランスの博物学者・博物画家フロラン・プレヴォーにちなみます。背中の黒色、腹部の橙褐色、その間を走る白い帯という鮮やかな三色の体色が最大の特徴です。
地域ごとの体色の変異も大きく、30以上の亜種が知られています。典型的な三色型のほか、白い帯を欠く黒色と橙褐色の二色型が見られる地域もあります。この印象的な体色が進化した理由は明らかになっていませんが、樹冠を行き交う仲間同士の識別や、木漏れ日と濃い影が交錯する熱帯林で輪郭をぼかす保護色として機能している可能性が考えられています。
森林では主に樹上で生活し、鋭い爪と優れた跳躍力を生かして枝から枝へ軽快に移動します。平らでふさふさした尾は、跳躍時のバランスを保つだけでなく、空中で方向を変える舵の役割も果たします。活動時間は主に早朝と夕方で、夜は樹洞や枝の上に小枝や葉を組み合わせた球状の巣で休息します。単独、あるいは親子単位で暮らすことが多く、甲高い鳴き声や尾の動きを使って仲間とコミュニケーションをとります。
食性は果実や木の実、種子、花、芽を中心とする雑食性で、昆虫や鳥の卵なども食べます。鋭い爪で枝をしっかりとつかみ、逆さまにぶら下がって採食する姿も時折見られます。果実を親木から離れた場所へ運んで食べる習性があり、食べ残した種子が発芽することで森林の更新を助ける重要な種子散布者となっています。
Body length 20–30 cm, tail length 18–25 cm, and weight 300–500 g. Prevost’s squirrel is an arboreal member of the squirrel family inhabiting the tropical forests of the Malay Peninsula, Sumatra, Borneo, and surrounding regions of Southeast Asia. Its English name honors the 19th-century French naturalist and scientific illustrator Florent Prévost. The species is best known for its striking tricolored coat, consisting of a black back, reddish-orange underparts, and a bold white stripe separating the two.
Coat coloration varies considerably across its range, and more than 30 subspecies have been described. In addition to the typical tricolored form, some regional populations lack the white stripe and display only black and reddish-orange coloration. The evolutionary reason for this remarkable color pattern remains unknown, although it has been suggested that it may help individuals recognize one another or serve as camouflage by breaking up the animal’s outline in the dappled light of the rainforest canopy.
Prevost’s squirrels spend most of their lives in the trees, moving agilely from branch to branch with the aid of sharp claws and powerful leaps. Their broad, bushy tails help maintain balance during jumps and also act as rudders for steering in midair. They are most active in the early morning and late afternoon, resting at night in spherical nests made of leaves and twigs or in tree hollows. They usually live alone or in small family groups and communicate with one another using high-pitched calls and tail movements.
Their diet consists mainly of fruits, nuts, seeds, flowers, and buds, but also includes insects and bird eggs. They are occasionally seen hanging upside down while feeding, gripping branches firmly with their sharp claws. They often carry fruits away from the parent tree before eating them, and discarded seeds may later germinate, making the species an important seed disperser that contributes to the regeneration of tropical forests.
参考文献
Hoffman, H. 2003. “Callosciurus prevostii” (On-line), Animal Diversity Web. 2026年7月25日閲覧
“Prevost’s Squirrel” Coke Smith Wildlife. 2026年7月25日閲覧