Role of a seasonally specialist bird Zosterops japonica on pollen transfer and reproductive success of Camellia japonica in a temperate area

Camellia japonica is considered to be pollinated by birds, but to date no studies have clarified the contribution of birds to the seed production and reproductive success of this species. We conducted a pollinator exclusion experiment that showed that fruit set was sixfold greater in flowers visited by birds than in flowers without bird visitation. Field observations revealed that most of the visitations made by birds were of the species Zosterops japonica. Furthermore, the level of fruit set was found to be saturated after only five visitations by Z. japonica. These results demonstrate that Z. japonica is the most effective pollinator of C. japonica. Such a strong relationship between a plant and an omnivorous bird pollinator has rarely been reported in a temperate zone.