BUTTERFLY DIVERSITY OF WALAYAR VALLEY, THE WESTERN GHATS, INDIA AND ITS CONSERVATION

The Walayar Valley is situated in the Palakkad Gap of the Western Ghats.  A portion of the valley lies in the moist areas of Kerala and the other part in comparatively drier zone of Tamil Nadu and hence it is in the transition zone. The valley consists of a variety of landscape elements, which include various types of forests, forest plantations, rocky patches, barren areas, areas under mines, human habitations and agricultural areas, which form the habitats of different species of butterflies.  No comprehensive studies have been conducted on the butterfly fauna of this valley and hence the present study was undertaken during 2012 to 2015. Altogether, 117 species of butterflies belonging to 5 families viz. Papilionidae (12 species), Pieridae (20 species), Lycaenidae (32 species), Nymphalidae (42 species) and Hesperiidae (11 species) were recorded from the study area.  The maximum number of butterflies were recorded from the Thorn forests (70 species), followed by Moist deciduous forests (65 species) and Dry deciduous forests (59 species) while in the modified landscape elements like agricultural areas, monoculture forest plantations and mining areas, the diversity was low. The species diversity indices such as Shannon - Weiner Index, Simpson Index and Margalef’s Index also followed a similar pattern. The tamarind plantations showed the highest Evenness or Equitability Index (0.9197), followed by mining areas (0.8967) and the Semi-evergreen forests (0.8033), while the Dry deciduous forests exhibited least evenness (0.7014). Sorenson’s Similarity Coefficient was found to be maximum between Dry deciduous forests and Moist deciduous forests (79%), followed by agricultural areas and Teak plantations (77%) and Teak plantations and Dry deciduous forests (66%). The least Similarity Index of 33 percent was shown by Riparian forests and Thorn forests. Other combinations showed values of intermediate ranges. The study has revealed the presence of six endemic butterfly species viz. Troides minos Cramer (Southern birdwing), Curetis siva Evans (Shivas sunbeam), Idea malabarica Moore, (Malabar tree nymph), Kallima horsfieldii Kollar (South Indian blue oakleaf), Cirrochroa thais Fabricius (Tamil yeoman) and Mycalesis patnia Moore (Gladeye bush brown) in Walayar Valley, which shows the biodiversity richness of the area. Apart from this, the valley also shelters 10 species of butterflies falling under schedules I, II and IV of the Indian Wildlife (Protection) Act, 1972, which further adds to the conservation importance of the area. Management measures to arrest the habitat destruction / deterioration by identifying various threat factors has to be undertaken. Habitat improvement by afforesting the degraded areas with native species, especially the butterfly host plants will go a long way in ensuring in-situ conservation of endemic and rare butterflies. Establishing of a Butterfly Park in Walayar Valley, captive breeding of endemic and rare butterfly species and re-introduction of stock in the wild are also suggested as ex-situ conservation strategy.