Pollination of the Rain-Forest Tree Syzygium Tierneyanum (Myrtaceae) at Kuranda, Northern Queensland

Abstract

The identity, abundance and foraging behaviour of pollinators of the self-compatible, mass-flowering Syzygium tierneyanum were investigated. Forty-five species of nectarivorous animals were recorded. Diurnal visitors included seven bird; nine butterfly. four moth (including two hawkmoth), two bee, two ant, one wasp, three blowfly, one fruit fly, two beetle and one weevil species. while nocturnal visitors included one bat and 12 moth (including three hawkmoth) species. Floral dimensions were such that only the vertebrate and larger insect species regularly contacted anthers and stigmas while foraging. Of these groups the feral honey bee (Apis mellifera) was the most common flowet visitor. Honeyeaters and hawkmoths appeared to be the most important native pollinators; they were abundant in the study area and visited numerous flowers (50-250) in quick succession (1-3 s per flower) on each foraging bout. The only major differences in foraging times observed in the pollinator array were between diurnal, diurnal and crepuscular, and nocturnal floral visitors. Spatial partitioning of the nectar resource was limited to one instance of territoriality involving a Macleay's honeyeater (Meliphaga rnacleayana) on a densely flowering branch prior to peak blooming time, occasional aggressive chases by honeyeaters, and a division of foraging modes into rapid, erratic flights of 0.5– 4 m between flowers (hawkmoths) as against nearest-flower movements (all other groups). This lack of major spatial partitioning may have been due to the mass flowering of S. tierneyanum and the resultant superabundance of nectar. The vast majority (c. 99.95%) of interflower movements observed in foraging bouts of birds (and of hawkmoths) were within the same plant. This suggests that most seeds of S. tierneyanum may be derived from self-pollination.