Long‐term changes in food habits of deer and habitat vegetation: 25‐year monitoring on a small island

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AbstractHow vegetation change caused by ungulates affects other ungulate species has been well studied, yet how grazing the vegetation of the habitat affects a species own food habits is not known. Long‐term studies on the effects of sika deer (Cervus nippon) on vegetation have been performed, but not in the context of the species own food habits. I monitored grassland vegetation and deer food habits on an island in northern Japan for 25 years from 1975 to 2000. During the first decade, deer grazing caused the replacement of Miscanthus sinensis tussocks by a Zoysia japonica sward. Deer diets in 1976 were composed of equal proportions of M. sinensis, Pleioblastus chino, and Z. japonica, but after the 1980s, Z. japonica became their major food source. This is because of the high productivity of Z. japonica afforded by its morphology and physiology, as well as by the warm and humid summer climate of the Japanese archipelago. Although the vegetational changes were gradual, changes in the deer food habits were abrupt and the compositions were predominated by Z. japonica after the first decade. This study showed that an ungulate changed its own diet because of its effect on the vegetation by grazing, and that the changes in vegetation and deer diet were not synchronized over a 25‐year monitoring period.