NEW DELHI: Even tiny butterflies that fly low are fluttering above the usual altitude owing to climate change, a study has shown.
The Himalayas are home to more than 35 percent of Lepidoptera — the order of insects that includes butterflies and moths – species found in India.
At least 66 species have been found 1,000 metre higher than their previously recorded mean habitat altitudes.
Meanwhile, a species of butterfly –– papilio alcmenor, commonly known by the name redbreast in Mukteshwar area of Nainital district, has been spotted in Western Himalayas.
This species of butterfly, which is normally found in the Eastern-Himalayan region, was firstly discovered in the western Himalayas nearly 110 years ago.
Rising average temperatures in the Himalayan region have driven several dozen species of butterfly and moth to inhabit high up the mountains, an official study has found.
The survey, funded by the Ministry of Environment, Forest and Climate Change and carried out by the Zoological Survey of India (ZSI), identified at least 49 species of moth and 17 species of butterfly that have shown “considerable new upward altitude records”, with a difference of more than 1,000 metres between their current and previously recorded habitat altitudes.
Seven species in particular have started to inhabit altitudes more than 2,000 metres higher than the previous mean, officials said.
These include the moth species Trachea auriplena (Noctuidae), Actias windbrechlini (Saturniidae), and Diphtherocome Fasciata (Noctuidae).
“The Common Map and Tailless Bushblue butterflies were previously found at 2,500 m, as has been recorded in historical data. During our survey we recorded them at 3,577 m at the Ascott Wildlife Sanctuary in Uttarakhand, Dr Kailash Chandra, director of ZSI,” said, adding, “in Ladakh, the Indian Red Admiral butterfly was historically found at 3,900 metre; it is now found at 4,853 metre, an altitudinal increase of 950 metre’’.
The study found that eight moth species, including the mulberry silkworm moth and tiger moth, which would historically be found at 2,000 m, are now typically found at 3,500 m or higher altitudes. The findings of the study will be used as a baseline indicator to track the impact of climate change on animal species over the coming decade, officials said
But extension of the range of Lepidoptera due to climate change has been observed all over the world, Dr Chandra said. “The data and evidence-based study (in India) confirms this trend, and shows us which species are moving, and how,” he added.
Butterflies are sensitive species that are extremely susceptible to changes in climate. They are, therefore, good indicators of long-term change in climatic conditions, Dr Chandra said.
The four-year study tracked 1,274 species of moth and 484 species of butterfly in Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, North Bengal, and Arunachal Pradesh. It also identified 80 new species of butterfly and moth.
Receding ice caps and glaciers leading to paucity of water in the Himalayas has been a major reason for the altitudinal shift of the Lepidoptera. The increase in average temperature has also resulted in an altitudinal shift in vegetation – trees, shrubs, and plants that once grew at lower altitudes in the Himalayas are now found only higher up in the mountains.
Increasing human habitation, too, has contributed to the shift, Dr Chandra said. “For instance, Shimla and Darjeeling were two big hotspots of rich butterfly diversity. But expanding towns have encroached on virgin territory, and the space for the butterfly has shrunk,’’ he said.
The study identified two species richness hotspots – one in the hills of Darjeeling, where more than 400 species records were documented, and another in Kumaon, Uttarakhand, where more than 600 species records were found. In Himachal Pradesh, two high diversity areas were identified – Dharamshala and Shimla.
The study revealed a spurt in the richness of Lepidoptera biodiversity from the Western to the Eastern Himalayas – it found 211 species of butterfly in the West, and 354 in the East but its habitat is shrinking.
The ZSI predicts a decline of as much as 91 per cent for example, in the suitable area for the Notodontidae family of moths in Jammu and Kashmir, Himachal and Uttarakhand by 2050.
Butterflies like the Red Apollo are highly prized by collectors and are often poached. One butterfly sells for up to £100 on the international market.
Butterflies feed primarily on nectar from flowers and are important as pollinators for some species of plants. In general, they do not carry as much pollen load as bees, but they are capable of moving pollen over greater distances.