Vanya Jha writes about the migratory patterns of birds in the Sikkim Himalayas
The air was filled with songs of numerous birds. Suddenly, the valley where the Sikkim Manipal Institute of Technology (SMIT) is located reverberated with a new enigmatic birdcall “Cooooo-Cooooo”. The Indian Cuckoo has finally arrived. I noted the date 14 March 2008. Last year it had arrived a little earlier - on 9 March. I shared the celebrations with my Lepcha brethrens at its arrival. For them it is a bird of hope - a divine messenger sent by Goddess Mother Nazong nyo. Living here at SMIT, I consider myself extremely blessed to witness such a wide variety of flora and fauna. In this tiny area of about 34 acres almost 80 birds have been recorded. They enthrall in many ways including their migratory instincts and activities.
Well, all of us are familiar with bird-migration. Many birds have two homes located far away from each other. They fly enormous distances from one home to another every year religiously to avoid food scarcity, harsh weather or simply to breed. Observing them in these idyllic surroundings I gradually begin to discover that migration is not as simple as it is made out to be. Rather it has several hidden nuances not known to most of us. Birds cannot just be classified as migratory or non-migratory.
To begin with, we have Indian Cuckoos along with the Large Hawk Cuckoo and the Himalayan Cuckoo arriving with spring. Their calls are sweet music to our ears. But by the end of April the calls cease. By June-July they leave these environs altogether. The Spotted Dove and Bulbuls also arrive in spring but they are here till October or even November. But we have many birds such as Hoopoe that arrive in October-November and disappear well before the spring. Thus, we have spring migration and autumn migration.
I was to learn more. One bright December morning I heard a familiar call. I was amazed, because Spotted Doves should not be around here during December. I shared my confusion with Usha Lachungpa, a well-known ornithologist and a Senior Research Fellow at Department of Forest, Government of Sikkim. She smiled and told me that Spotted Doves and Bulbuls observe what we call partial migration. Most of them fly away to warmer regions in winter but some stay back. There is a misconception in the minds of people that birds migrate in order to escape harsh climatic conditions but this is not so because birds are biologically strong, they can survive fairly unfavourable conditions also. They migrate because of lack of food in that particular region. This explains why the morning calls of the Spotted Dove can be heard even in severe winters.
What is more, these birds also exhibit local migration, confirms Dr.B.K.Acharya, a well-known ornithologist and lecturer at the Department of Zoology, Sikkim Government College. During winters Doves and Bulbuls at higher elevations such as Ranipul or Gangtok shift to lower elevations (such as Singtam, Rangpo etc.) in Sikkim. Whereas birds of these species from lower elevations of Singtam and Rangpo migrate to perhaps Siliguri or further south.
Even as I digested these fresh facts on bird behaviour, Dr Acharya enlightened me further with a new phenomenon called reverse migration. Hoopoes arrive here in autumn from warmer Indian planes. Thus, they spend summers in warm planes and winter in cold mountainous regions! An interesting fact I stumbled around is that Lepchas associate Hoopoes with the arrival of guests. If a Hoopoe is seen, a guest will arrive soon in the village, believe Lepchas. This belief hides common sense. In the hills, rainy season certainly cannot be the time for social visits as rains are extremely heavy, terrain almost impossible and rivers at their most ferocious-self. Thus logically, social visit will start right after rains - in October, when the Hoopoe also arrives! Last year Hoopoes (a solitary pair) arrived at SMIT on 8 October.
Interestingly, many birds migrate through Sikkim. Thus, at times we have a glimpse of a few species of geese and duck which otherwise is a part of Sikkim’s avifauna. As if this was not enough, a friend told me he had sighted a Blue whistling thrush in Chandigarh - far away from its Himalayan range. We went through many books on ornithology. At last, we found out that the Blue whistling thrush, though a non-migratory bird, flies out during winters to places a couple of kilometres away. Such occurrences though, are extremely rare.
In the context of migratory birds I came across another interesting Lepcha belief. According to it, when Mayel Pho (Divine birds- Lepcha term for migratory birds), first arrived from Mayel (Heaven), Mother Goddess Nazong Nyo decided to ensure a comfortable stay for them. She chose a few lakes for their visit. To ensure the cleanliness and sanctity of these lakes she commanded Chamung Pho (Whistling thrush) to keep the lake clean and sacred by removing dead leaves and twigs from the same. Lepchas believe Chamung Pho can still be seen cleaning the lake religiously and the Chamung Tea estate in Darjeeling district derives its name from this bird. This Lepcha belief throws up interesting possibilities for ecologists. Do migratory and non-migratory birds share a symbiotic relationship? Do non-migratory birds in any way help migratory birds? There must be some truth in such a hypothesis. Offhand, it may be said that migratory birds such as various Cuckoos are brood parasites, which depend on non-migratory birds such as thrushes to hatch their eggs and nurture their young ones by laying eggs in their nests.
I am sure this is not all. There must be many more nuances of bird migrations that I am yet to discover. Perhaps that is why we find the world of birds so supremely enchanting!
Class XII, Holy Cross School, Gangtok