Siruvani hills located in the Coimbatore hills of Tamil Nadu has been identified as a butterfly super-hotspot after a six-year study (from March 2015 to December 2020) conducted by The Nature and Butterfly Society (TNBS). The hills are a part of the Boluvampatti forest range of the Coimbatore forest division, a combination of dry deciduous forest, moist deciduous forest, and tropical evergreen forest.
The TNBS study recorded the number of butterfly species appearing in various habitats of Tamil Nadu. The aim was to build awareness on conserving nature by identifying such hotspots. Data was collected through butterfly walks held in these habitats. The World Wildlife Fund (WWF), Coimbatore Nature Society (CNS), and The Nature and Butterfly Society (TNBS) jointly carried out the survey with the Forest Department in seven forest ranges of Boluvampatti, Coimbatore, Periyanaickenpalayam, Madukkarai, Mettupalayam, Karamadai, and Sirumugai. According to TNBS, if 25 per cent of the total state checklist species are found in a single region, it is to be identified as a hotspot.
Findings of the Study
The study, which describes the rich biodiversity of the region, states that the presence of butterflies indicates a healthy ecosystem.
The total number of butterfly species found in the state of Tamil Nadu is 325. Out of these, 240 species (which account for 74 per cent of the total species found in the state) are found in the Siruvani hills. These butterflies belong to six families: Brush-footed butterflies Nymphalidae. Blues (Lycaenidae), Skippers (Hesperiidae), Whites and Yellows (Pieridae), Swallowtails (Papilionidae), and Metalmarks (Lycaenidae). Among these, the Brush-footed butterflies are the most dominant. The Many-tailed Oakblue (Arhopala amantes) butterfly (having blue inner wings) is an iconic representation of these hills.
The report submitted by TNBS to the forest department records some species that have rare sightings in the Coimbatore forest division. These include Tamil Casteye (Zipaetis saitis), Malabar Tree Nymph (Idea malabarica), Nilgiri Tiger (Parantica nilgiriensis), and Tawny Rajah (Charaxes bernardus), Malabar Banded Peacock (Papilio buddha), and Malabar rose (Pachliopta pandiyana). The report mentions some rare butterflies from the Lycaevidae family that are spotted in this region: the Abnormal Silverline, Common Onyx, Dark Ceylon 6-lineblue, Malabar Flash, and the Kanara Oakblue.
About the Survey
The forest department of Coimbatore had called for an integrated survey on birds and butterflies in 2019. The survey, involving 15 teams, covers the ranges of the Coimbatore division for data on the occurrence of the species, their population, and associated environmental factors. The data is to help in assessing and planning conservation plans in future. It is meant to be a continuous assessment—to be carried out on an annual basis—to focus on bird and butterfly conservation (as they are good indicators of the ecosystem).
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