HABITAT PREFERENCES, DISTRIBUTION AND SEASONALITY OF THE BUTTERFLIES (LEPIDOPTERA, PAPILIONOIDEA) IN A MONTANE TROPICAL RAIN-FOREST, VIETNAM

In this paper, the butterfly community of the Tam Dao montane rain forest in northern Vietnam is described ecologically and biogeographically. A negative correlation between the size of species geographic range and maturity of the successional stage of its preferred habitat was found. This means that butterflies confined to the climax forest tend to have a small range of distribution of endemitic type, whereas species associated with disturbed ruderal and similar habitats are much more widely distributed. Within the forest, understorey species are most habitat specific and endemitic, with the most important conservation value. Canopy fauna is much more heterogeneous and diverse, containing also non-forest components. The pronounced temporal change in the forest community is determined by the relatively higher seasonality of species with biogeographical affinities to the seasonal 'East Himalayan' region. Apart from this historical component, the irregular migratory behaviour and response to the seasonal change in local environmental factors seem to be important. In the ruderal habitat, butterflies with large geographic range tend to have the highest population sizes; the reverse is true for the forest community. Differences in current and historical habitat commonness and disturbance intensity are proposed to explain this pattern. The present investigations of the butterfly community indicate the great importance of the Tam Dao rain forest for preservation of the biodiversity on frontiers between the Oriental and Palaearctic Regions.