Over the last decade, the population of Yakushika (Cervus nippon yakushimae) has rapidly increased in Yakushima. Consequently, most understory species has decreased their abundance and biomass except for some non-palatable one. It is expected that Yakushika is now depending on non-palatable species. The purpose of this study was to test this possibility by examining stomach contents.

We sampled stomach contents of 90 individuals culled by hunters in 5 areas under different deer density. We extracted DNA from those samples and determined sequences of the rbcL region after PCR amplification using the next-generation sequencer (MiSEQ). Then we identified plant species by searching identical sequences with BLAST.

We identified 99 plant species (average 23 ± 6.34 species per individual) were detected from 90 individuals. Of which 25 and 21 species were palatable and non-palatable plants, respectively. This result showed that Yakushika depends on both palatable and non-palatable species under high density. Among 5 areas, the proportion of non-palatable species was the highest in the highest density area.