Home > Research > Research Results > Research Results 2018 > Vertebrates can transport highly toxic Japanese star anise seeds

Update:April 16, 2018

Main content starts here.

Vertebrates can transport highly toxic Japanese star anise seeds


Article title

Highly toxic seeds of the Japanese star anise Illicium anisatum are dispersed by a seed-caching bird and a rodent

Author (affiliation)

Tetsuro Yoshikawa (a,c), Takashi Masaki (a), Makoto Motooka (b), Daichi Hino (b), Keisuke Ueda (b)

(a) Department of Forest Vegetation, FFPRI, Tsukuba, Ibaraki, Japan.
(b) Rikkyo University, Tokyo, Japan.

(c) Kyoto University, Kyoto, Japan.

Publication Journal

Ecological Research, 33(2):495-504, March 2018, DOI:10.1007/s11284-018-1564-6( External link )

Content introduction

The seeds of the Japanese star anise are disseminated via explosive fruit dehiscence within a very short dispersal distance (<10 m). However, Japanese star anise shows wide dispersion in warm temperate zones, likely due to the germination of seeds that were carried over long distnaces by vertebrates, which store seeds and leave some of them uneaten. Are there really vertebrates that intentionally eat Japanese star anise seeds that are known to be highly toxic? Based on the ecological study of Japanese star anise seeds on the Izu Peninsula, we found that varied tits picked the seeds from the fruit to eat or carry away. In contrast, more abundant birds, such as the brown-eared bulbul, were not interested in Japanese star anise seeds. In addition, anise seeds that fell to the ground were taken away by small Japanese field mice. When we examined the distribution of Japanese star anise seedlings on the site, we found that many grew next to fallen logs where small vertebrates, such as birds, prefer to store seeds. It appears that the varied tits and small Japanese field mice possess mechanisms to counteract the toxicity of Japanese star anise and contribute to long-distance dispersal of seeds for this species.


Figure. Number of times a vertebrate was observed 

Figure. Number of times a vertebrate was observed on a Japanese star anise tree.
We recorded the type of vertebrate and its behavior when visiting a Japanese star anise tree.

Observations were taken from 8 am to 3 pm on six days (sunny or cloudy) from September to October.

We conducted a total of 93.2 h of observations of nine Japanese star anise trees. The photo shows a varied tit picking the fruit of an observed Japanese star anise tree.