A butterfly species has been spotted in Assam after 90 years and interestingly during the 2020 Baghjan oil spill.
The butterfly, Lilac Silverline (Apharitis lilacinus), was previously known from North Lakhimpur, Assam, based on a single record by H. Stevens in 1925 – the only known record of the species in northeastern India.
A female Lilac Silverline was recorded on June 22, 2020, from the Dibru Saikhowa National Park, located across Tinsukia and Dibrugarh districts of Assam.
In May 2018, however, Monsoon Gogoi had spotted three butterflies of the same species, comprising one male and three females, at the D’ering Wildlife Sanctuary in Arunachal Pradesh.
This was the first record of the species from Arunachal Pradesh, which is endemic to India and Myanmar.
“These records show the importance of Brahmaputra grasslands in terms of butterfly conservation in northeast India. Brahmaputra floodplains are never focused in terms of conservation priority except for mega fauna groups like mammals and birds,” Gogoi told EastMojo.
According to Gogoi, the species was not recorded in the unprotected grassland habitat of the Brahmaputra floodplain during the study, which shows the importance of undisturbed grassland for the conservation of rare and little-known taxonomic groups.
The species found in northeast India, however, is slightly different from the one found in the rest of India as it has an extended orange colour on the tail and is brighter and more pigmented.
It could be a different subspecies and needs more study in future, the author said.
“Butterflies like heat and turmoil and so the heat probably helped the butterfly to be seen,” butterfly expert Monsoon Jyoti Gogoi told EastMojo.
“It was just recorded in Dibru Saikhow National Park, which is located opposite to the Baghjan oil spill. The butterfly was not moving for 10 minutes despite disturbing it and even after disturbing, it was settling in the same place, in a gloomy and rainy weather during Baghjan oil spill,” he said.
Studies have shown that butterflies are diurnal insects that are attracted to heat for basking in their wing.
On May 27, 2020, an oil and gas leak was reported from the Baghjan Oil field of Oil India Corporation in Tinsukia district of Assam. For the next 13 days, the oil leaked into the adjoining wetland and subsequently into the Dibru River (tributary of Brahmaputra), impacting several floral and faunal elements.
On June 8, 2020, the Baghjan Well No. 5 caught fire and subsequently, a part of the grassland was destroyed in the fire.
In order to investigate the ecological damage, especially with respect to birds and butterflies, the State Forest Department of Assam invited Bombay Natural History Society. A 10-day survey was carried out by experts to understand the impact of the oil well spillage and the subsequent fire outbreak on the birds of the area.
The team also carried out a rapid survey in Dibru-Saikhowa National Park and the Maguri-Motapung Beel area.
“We recorded a few species such as Common Grass Yellow, Grey Pansy, Peacock Pansy and Slate Flash butterfly within a km radius of the blast site. These species are common throughout the landscape. We observed two dead butterflies, namely Circe Hestina nama and Red spot Jezebel Delias descombesi, close to the blast site. This could be possibly because they have larger wingspan. Smaller butterflies may have perished in the fire. Altogether, 21 species of butterflies from the beel were recorded and many common species were missing, suggesting that the burning had a negative impact on the butterfly communities. We could not study moth fauna (night surveys) due to security and safety reasons,” the survey report said.
In Dibru-Saikhowa National Park, a total of 64 species of butterflies were recorded during the survey. However, no direct impact was observed on the butterflies inside the park.
“The area in which this disaster took place is one of the biodiversity-rich sites in Upper Assam. The impact of this disaster was seen more profound on the Maguri-Motapung Beel Important Bird Area and relatively less on the Dibru-Saikhowa National Park. The oil spill and subsequent burning has resulted in the mortality of several animals and has impacted a large portion of the IBA, making the environment non-conducive for their survival” the report by BNHS says.
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