Abstract
No comprehensive community studies have been done on the butterflies of the tropical monsoon forests of the East Himalayan region. We described the Papilionidae at one site within the continuous moist deciduous forest belt of Northeast India and their variation with season and forest type. We surveyed 20 permanent line transects, varying with respect to canopy openness and observed levels of disturbance. A total sample effort of 131 days during the dry and wet seasons of a two-year study resulted in 18,373 individuals identified from 28 Papilionidae species. Constrained canonical correspondence ordination was used to examine the effects of season, forest type, rainfall, year, altitude, and geographical position on the species assemblages. Results showed that rainfall, forest type, and season accounted for most variance in papilionid abundance. Rainfall was strongly correlated with the abundance of some species. Nine species were associated with gaps, 16 species were restricted to closed forest, and three species were encountered in both gaps and closed forest. Six species with narrow geographic range were found only in closed forest. The results confirm the strong seasonality of continental Southeast Asian butterfly assemblages.
Highlights
Studies focusing on insect seasonality have been carried out in many parts of the world including the eecouatorial tropics
Forest type, and season accounted for most variance in papilionid abundance
Evans [18] and Talbot [19] described 90 species from the Indian subcontinent; 15 species reported from Ceylon, 19 in South India, 6 in Baluchistan, 11 in Chitral, 50 in southern Burma, 13 in the Andaman and Nicobar islands, 31 in the Western Himalayas, and 69 in North-east India, which is a part of the Eastern Himalayas biodiversity hotspot
Summary
Studies focusing on insect seasonality have been carried out in many parts of the world including the eecouatorial tropics. Seasonal environments (tropical and temperate regions) and climate gradients like temperature and precipitation play an important role in defining the differences in habitat preferences, biology, adult activity, reproductive strategy, and adaptive polyphenisms of butterflies [13,14,15]. From the Indian subcontinent, 84 species had been documented, of which six are endemic [17]. In Assam, of the Eastern Himalayas, five species of Papilionidae were listed as endemic [18]. Evans [18] reported six species as endemic in the entire Sikkim-Assam region. As few Psyche studies have focused on butterflies of the Northeast Indian region, and in keeping with the conservation value of this ecoregion, with respect to the Papilionidae, we proposed to investigate the papilionid assemblage within a protected forest reserve in Assam
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