As reported on October 12, 2020, a survey, funded by the Ministry of Environment, Forest and Climate Change (MoEFCC), and carried out by the Zoological Survey of India (ZSI), has found that rising average temperatures in the Himalayan region (home to more than 35 per cent of Lepidoptera — the order of insects, including butterflies and moths) have driven several dozen species of butterfly and moth to habitats higher up the mountains. The report states that at least 49 species of moth and 17 species of butterfly have shown ‘considerable new upward altitude records’, with a difference of more than 1,000 m between their current and previously recorded mean habitat altitudes. Particularly, seven species, including the moth species Trachea auriplena (Noctuidae), Actias windbrechlini (Saturniidae), and Diphtherocome fasciata (Noctuidae), with mean altitudinal differences of 2,800 m, 2,684 m, and 2,280 m respectively, have started to inhabit altitudes more than 2,000 m higher than the previous mean. Eight other moth species, including the mulberry silkworm moth and tiger moth, are now typically found at 3,500 m or higher altitudes, which were previously found at 2,000 m.
Similarly, butterflies are good indicators of long-term change in climatic conditions as they are sensitive species and are extremely susceptible to changes in climate. As per the study, about 1,274 species of moth and 484 species of butterfly were tracked in Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, North Bengal, and Arunachal Pradesh, which also included 80 newly identified species of butterfly and moth. This movement of the insects could be possible because of the ZSI’s historical records of many species since 1865 to 2015, which were scanned and examined to make a comparative assessment.
Butterflies, namely, Common Map and Tailless Bushblue, were previously found at 2,500 m, as per the historical data. However, according to director of ZSI, Dr Kailash Chandra, they were recorded at 3,577 m at the Ascott wildlife sanctuary in Uttarakhand. Likewise, the Indian Red Admiral butterfly in Ladakh was historically found at 3,900 m, which is now found at 4,853 m.
According to Dr Chandra, the extension of the range of Lepidoptera has been observed all over the world due to climate change. The data and evidence-based study (in India) not only confirms this trend but also indicates which species are moving, and how much. An increase in the richness of Lepidoptera biodiversity from the Western to the Eastern Himalayas was also recorded—211 species of butterfly in the West, and 354 in the East. However, its habitat is shrinking, with a predicted decline of up to 91 per cent by 2050, as per ZSI.
Two species richness hotspots were also identified in West Bengal’s Darjeeling hills and Kumaon, Uttarakhand, where more than 400 and 600 species records were documented respectively. Similarly, two high diversity areas were identified in Dharamshala and Shimla (Himachal Pradesh).
Factors of Change in Attitudinal Shift
A major reason for this attitudinal shift is receding ice caps and glaciers, which have led to a scarcity of water in the Himalayas. Besides, the increase in average temperature has also resulted in an altitudinal shift in vegetation. For example, trees, shrubs, and plants that once grew at lower altitudes in the Himalayas are now found only higher up. Also, increasing human habitation is responsible for this shift as we see that Shimla and Darjeeling were two big hotspots of rich butterfly diversity. However, the space for the butterfly has shrunk because of expanding towns, which encroached on the virgin territory. Other reasons include high prizes for butterflies like the Red Apollo (up to £100) by collectors in the international market, due to which they are often poached. Therefore, some stringent mitigation measures have to be devised to protect butterflies and moths from both human beings and climate changing.
According to officials, these findings will be used as a baseline indicator to track the impact of climate change on animal species in the future.
Courtesy: Indian Express