Diet composition of sika deer in Kasuya Research Forest of Kyushu University in northern Kyushu, Japan

• Published in: Honyurui Kagaku (Mammalian Science) Vol. 65; no. 1; pp. 1 - 8
• Main Authors: Takatsuki, Seiki, Abe, Hayato, Katayama, Ayumi
• Format: Journal Article
• Language: English; Japanese
• Published: Kyoto The Mammal Society of Japan 2025; 日本哺乳類学会; Japan Science and Technology Agency
• Subjects: acorn; Animal populations; Deer; Diet; fecal analysis; Feces; food habits; Forestry research; Fukuoka; Grasses; Leaves; Plant growth; Population studies; Seeds; sika deer; Vegetation
• ISSN: 0385-437X; 1881-526X
• DOI: 10.11238/mammalianscience.65.1

We analyzed the diets of sika deer from Kyushu University’s Kasuya Research Forest based on point-frame fecal surveys conducted between February 2023 and January 2024. Leaves, mainly from evergreen species, accounted for 42.1% of the fecal contents in February, with the remainder comprising fiber and culms. In April, the leaf component decreased, whereas the fiber component increased to 45.8%. In August, grass leaves comprised only 11.2%, and culms increased to 56.5%, suggesting that deer ventured out of the forest to feed on grasses. In October, the leaf component decreased further, while culms decreased to 12.0% and the fiber content again increased to 39.0%. Acorns of Castanopsis cuspidata and seeds of pokeweed (Phytolacca decandra) seeds were recovered from fecal samples in October. In January, the leaf component decreased to 16.8% and the proportion of unidentifiable materials increased to 35.1%. The deer population in our study area increased rapidly over several years around 2010, profoundly affecting the local vegetation. The small occupation of green leaves in the deer diets (23–33%), even during the plant growth season, reflected the vegetation deterioration caused by the increase in deer.