Plants of the genus
Arisaema (Araceae) are poisonous perennial herbs that produce an assemblage of fruits similar in appearance to peeled cobs of maize (sweetcorn). Since the ripe fruits are bright orange-red and very conspicuous, it has been believed that birds eat the fruits and disperse the seeds. However, although there are many species of
Arisaema in Japan, there is no detailed information on their frugivores. We used automatic cameras to examine foraging on two species of
Arisaema,
A. limbatum and
A. serratum, in secondary forests, mainly in Kanagawa Prefecture, southern Kanto District, central Japan. These species are very similar in appearance but their fruiting seasons differ: the former in midsummer, and the latter in autumn-winter. We discovered that for
A. limbatum the Brown-eared Bulbul
Hypsipetes amaurotis was an exclusively important frugivorous bird in the study area. However, for
A. serratum, several species — the Brown-eared Bulbul, Red-flanked Bluetail
Tarsiger cyanurus, Pale Thrush
Turdus pallidus, Copper Pheasant
Syrmaticus soemmerringii, Red-billed Leiothrix
Leiothrix lutea, Scaly Thrush
Zoothera dauma, Brown-headed Thrush
T. chrysolaus and Daurian Redstart
Phoenicurus auroreus — ate the red fruits. Among them, the first four species were regarded as being major frugivores of
A. serratum. Twelve mammal species were confirmed in close proximity to the fruits of
Arisaema. We observed that the large Japanese field mouse
Apodemus speciosus foraged the fruits of
A. limbatus and ate seeds rather than the fleshy fruit pulp, and so appeared to be a seed predator rather than a seed disperser. No other mammals were observed taking the fruits of
Arisaema.
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