Once you cross an imaginary line in the Himalayas – generally the point at which the hot biodiverse foot-hills end and the cooler lower mountainsides appear, a curious thing happens. The hotpot and profusion of tropical butterflies begins to disappear and some other species which are never seen in the plains begin to appear. Not just appear but also to dominate. These are the lepifauna of the temperate zone of the Indian Himalayas. The variety is less, but the butterflies stand out amidst the heavenly wild-flower, mountain peaked and glacial streamed countryside. God’s own country indeed. The three commonest butterflies that I came across in this North Sikkim trip were the Indian Tortoiseshell, the Dark Clouded Yellow and the Indian Cabbage White.In this blog, I shall be rambling about the Indian Tortoiseshell or Aglais cachmiriensis aesis (Kollar, 1844)(Family Nymphalidae).
My reacquaintance with Indian Tortoiseshells began on 16 Apr 07 in the Kalimpong Officers Institute, a hundred year old wooden building with an old British style garden – large trees, large lawns, lots of flower beds with profusion of blooms punctuated by very interesting bushes. The first butterfly I saw was a beautiful Painted Lady basking on the lawn – a bit faded from age with ragged wings, but still beautiful in her prime. As I eased up to capture her on camera, she was buzzed by a dark brown fast moving form. Startled, I looked up and found my very old friend – The Indian Tortoiseshell. With a chequered pattern and yellow, red, black and brown, it is quite striking to look at. That evening, there was a host of Tortoiseshells in the garden flitting in the warm sun and despite the stiff breeze in most of the exposed lawns. The breeze did not deter them at all and they zoomed around till sundown, defending their turf vigourously against all other butterflies.
The foodplant of the Tortoiseshell is the Stinging Nettle or Bichhoo booti (Urtica dioica Linnaeus) which is common between 1000 mtrs to 2500 mtrs in the Himalayas. I found stinging nettles at places all along the way to North Sikkim, very common in Chungthang and in the Lachung valley till around 9,000 ft. The nettles are found in profusion as rank undergrowth in the seamier parts of hill towns and also occassionally interspresed in the hedgerows along the road.
Beyond Lachung the vegetation changed and we had moss-covered conifers, rhododendrons of all sizes and colours and beautiful globed purple primulas; yet the Tortoiseshell remained ever-present right upto Shiv Mandir (approx ht 13,000 ft) and also along the Chhaten valley just short of Thhanggu (approx ht 14,000 ft). Beyond that strong prevailing winds really reduce the biodiversity to some lichens, dwarf junipers, snow pigeons and the yellow-billed and red-billed choughs. Unfortunately, there are no high altitude meadows a la Garhwal next to the road where we could see the very special Parnassius or Snow Apollos.
In 1993, when I had been to Nandadevi, I had seen ‘Torties’, as we referred to them, right upto Base Camp (16,000 ft) where they seemed perfectly at home in the glacial moraine, muddy ice and deadly cold ponds. One climber recorded a Torty at Camp II about 19,000 ft, but this is obviously a stray. Now here is something interesting – Torties, as per Haribal occur from 900 mtrs to 4,800 mtrs. Obviously, they feed on more than one hostplant – possibly high altitude Torties are feeding on a related spp of Nettle, Urtica hyperborea Jacquem ex Wedd, ( as per Polunin and Stainton recorded between 4100 and 5100 mtrs on stony high altitude steppes). Are they feeding on some other host plant too, in the middle elevations or are they locally migrating to higher altitudes? They were very common where their hostplants were absent!
Throughout my trip the Tortoiseshells were there in the high altitudes – a comfortable and reassuring motif in North Sikkim, that land of avalanches, flash floods, glacial lake bursts, lightning and snowstorms – a very scenic but potentially deadly terrain.