Species diversity and abundance of butterfly fauna in four selected habitats in Sinharaja man and biosphere (MAB) reserve

Abstract

Sri Lanka possesses a rich diversity of butterflies compared to other countries in the region, but studies on this interesting taxon remain limited. The present study on butterflies at Sinharaja forest was carried out as an effort of filling this gap to some extent. Data was collected from four different habitat types i.e. primary forest, second ary forest, disturbed areas and the Pinus plantation in the North-western sector of the Sinharaja forest close to Kudawa. Two study plots were established in each habitat type, and the butterfly sampling was carried out along four transects (100m × 5m) in each plot; two inside the relevant habitat and other two along the edge of the habitat. Sampling was conducted from 8:00 a.m. to 2:00 p.m. daily from mid April to end of June 2007. Shannon index (H′) was used to compare the butterfly species diversity. 124 butterfly species belonging to 10 families were recorded including 10 endemic species and 32 nationally threatened species. Rediscovery of the Brown Onyx (Horaga albimacula) after 80 years, and the Banded Redeye (Gangara lebadea subfasciata) and Lesser Gull (Cepora nadina) after 65 years are significant findings of the present study. Results reflect a differ ence in butterfly diversity and abundance between four habitats. 25, 37, 56 and 47 butterfly species were re corded respectively from primary, secondary, disturbed and Pinus forest habitats. The secondary forest was recorded to have the highest species diversity (H′ = 2.169) while primary forest show the least (H′ = 1.917). The primary forest and disturbed area, which had a contrasting difference in the butterfly species richness do not show a significant difference in their butterfly species diversity (H′= 1.917 and H′= 1.920 respectively). Butterflies of family Satyridae and Nymphalidae were the most and second abundant in all habitats, while different species of each family dominated different habitats. Satyrids were more abundant inte rior in forest habitats, while Nymphalids were more common along habitat edges.