The Fauna of the Northeast India

Thursday, July 3, 2008

The Fauna of the Northeast India
An Article by Mohan Pai

The Northeast India represents the transitional zone between the Indian, Indo-Malayan and Indo-Chinese biogeographic regions and is the geographical ‘gateway’ for much of India’s flora and fauna. As a consequence, the area is one of the richest in biological values, high in endemism and holds a large number of rare species that are now under serious threat.Hotspots are areas that are extremely rich in species, have high endemism and are under constant threat due to human pressure (having lost 70% of their original habitat). The Northeast is among the 34 Hot Spots of the world, identified in India, the other being the Western Ghats.

Northeast India
One of the richest biomes of the world, high in endemism and rare species which is now under constant threat.
The Northeast India, (22-30 degree N and 89-97 degree E) spread over 2,62,379 sq.km., represents the transition zone between the Indian, Indo-Malayan and Indo-Chinese biogeographic regions and a meeting place of the Himalayan Mountains and Peninsular India. It was the part of the northward moving ‘Deccan Peninsula’ that first touched the Asian landmass after the break up of Gondwanaland in the early Tertiary Period. Northeast India is thus the geographical ‘gateway’ for much of India’s flora and fauna. It is in this lowland-highland transition zone that the highest diversity of biomes or ecological communities can be found, and species diversities within these communities are also extremely high.

Hoollock Gibbon - Pic by Ritu Raj Konwar

The region is made up of eight states: Arunachal Pradesh, Assam, Meghalaya, Manipur, Mizoram, Nagaland, Sikkim and Tripura and is endowed with a wide range of physiography and eco-climatic conditions. The State of Assam has extensive flood plains, while Khangchendzonga in Sikkim stands 8586 m. tall. Cherrapunjee in the State of Meghalaya holds the record for the highest rainfall in a single month (9,300 mm) as well as the most in a year (26,461 mm) in India, while the nearby Mawsynram has the world’s highest average rainfall (11,873 mm). The forests in the region are extremely diverse in structure and composition and combine tropical and temperate forest types, alpine meadows and cold deserts. There are regions, for example, in the State of Sikkim, where the faunal assemblages also change rapidly from tropical to subtropical, temperate, alpine and finally to cold desert forms.

Northeast India forms one of the major regions of tropical forests in India, especially the species-rich tropical rain forests. The tropical semi-evergreen and moist deciduous forests in the lowlands of this region extend south and west into the subcontinent, and east into Southern China and Southeast Asia. The subtropical forests of the region follow the foothills of the Himalaya to the west; also extend into Southeast China in the east. Himalayan temperate and subalpine zone forests extend from northern Pakistan and adjacent Afghanistan through Northeast India to Southwest China. This region represents an important part of the Indo-Myanmar biodiversity hotspot, one of the 34 global biodiversity hotspots recognized currently (2005). Golden langur - Pic by Arunchs
Global Biodiversity Hotspots
Norman Myers, a conservation biologist, in 1988 first identified ten tropical forest ‘hotspots’ characterised by exceptional levels of plant endemism and by serious levels of habitat loss. In 1990, Myers added another 8 spots to his list. Conservation International adopted Myer’s hotspots as its institutional blue print in 1989, and in1996.To qualify as a hotspot, a region must meet two strict criteria: it must contain at least 1,500 species of vascular plants as endemic and it has to have lost at least 70% of its original habitat. These are the areas which are under constant threat due to human pressure. In the 1999 analysis, in all 25 hotspots were identified. A second major analysis was undertaken and the number or global hotspots stood at 34 in 2005.Overall, the 34 hots pots once covered 15.7% of the Earth’s land surface. In all 86% of the hots pots’ habitat has already been destroyed. The intact remnants of the hotspots now cover only 2.3% of the Earth’s land surface. Over 50% of the world’s plant species and 42% of all terrestrial vertebrate species are endemic to these 34 biodiversity hotspots.Among the 34 hotspots of the world, two have been identified in India - The Eastern Himalayas and the Western Ghats. These are particularly rich in floral wealth and endemism, not only in flowering plants but also reptiles, amphibians, butterflies and mammals.

The Fauna

Mammals
There appears to be a dearth of exploration and research concerning the fauna of Northeast India. The remoteness of the region, difficult terrain as well as the severe hunting pressures exerted by the people around their immediate surroundings in many parts of the region make it extremely difficult to document the fauna of the region. Primates India sustains eleven species of primates, if we follow the recent revisions in primate taxonomy.

Red Panda

It is but unfortunate that except three species, which could be considered common in Assam, they face an uncertain future in this region.
The Hoolock (Hoolock hoolock) is the only ape in India. The eastern limit for this lesser ape is Salween River in Myanmar and its range extends to Southern China. It occurs in Assam, Arunachal Pradesh, Manipur, Meghalaya, Tripura and Mizoram in Northeast India, and its continued existence in the State of Nagaland is uncertain. Despite the wide area in which the animal occurs, it has become a rare animal, all over its range. Monogamy, frugivory and adaptation to brachiation make the species highly susceptible to habitat fragmentation and degradation.

Slow Loris
Most of the tropical forests that harbour this species are subjected to slash and burn or shifting cultivation and therefore, the ape’s habitat is highly degraded and fragmented. It is hunted for the pot and the belief that its flesh and blood have medicinal properties has made it a highly prized commodity. It is also highly prized in the pet trade.
The Golden Langur (Trachypithecus geei) is one of the most localized species, between Manas and Sankosh Rivers in the Himalayan foothills along the Assam - Bhutan border areas. In Tripura, one can count seven species of primates. The Phayeri’s Langur (Trachypithecus phayeri) assumes high conservation significance, as this species is restricted in distribution to the State with reported existence of a few troops in North Cachar Hills of Assam, adjacent to the northern boundary of Tripura. Yet another species of particular interest is the newly designated primate species, Semnopethicus schistaceus (Nepal Langur), which is endemic to the higher elevations in Sikkim and Nepal. The Capped Langur (Trachypithecus pileatus) is also a rare animal with limited distribution in Northeast India.The Stump-tailed Macaque (Macaca arctoides) and the Northern Pigtailed Macaque (M. leonina) have sympatric distributions in Northeast India and both have become endangered. The Slow Loris (Nycticebus bengalensis) is an inhabitant of tropical forests south of the Brahmaputra River in Northeast India.

Carnivores

India harbours six largest cats of the world and the State of Arunachal Pradesh prides itself for sustaining four large cats of Asia – the Tiger (Panthera tigris), Leopard (Panthera pardus), Snow Leopard (Uncia uncia) and the Clouded Leopard (Neofelis nebulosa). Of these, the Indian population of the Clouded Leopard is restricted to the Northeastern region. With a very long tail for balance and large paws for climbing, the Clouded Leopard is well suited for life in the canopy. It also has the longest upper canines proportional to its skull size of any cat, reminiscent of the saber-toothed cat. Despite the presence of this elusive animal in all the eight states of the region, its habitat is shrinking at an alarming rate. Vast tracts of forests, especially in the State of Arunachal Pradesh, where the animal reigns free, could remain safe for this magnificent animal, provided such forests are kept away from developmental activities, including the construction of roads. Tiger has become a very rare animal in the entire region and perhaps Assam provides the safest asylum for this large cat. The more adaptable Leopard has managed to survive in greater numbers. Little is known about the status of Snow Leopard, which ekes out a living in the high altitudinal zones of Arunachal Pradesh and Sikkim.Northeast India sustains diverse assemblages of small carnivores, and this region is perhaps the richest region for small carnivores in the entire planet.
Fishing Cat - Pic by Atin Dutt
The tiny State of Manipur, with an area of 22327 sq.km., apart from sustaining three large cats, harbours the Marbled Cat (Pardofelis marmorata), Golden Cat (Catopuma temmincki), Leopard Cat (Prionailurus bengalensis), Fishing Cat (Prionailurus viverrinus) and the Jungle Cat (Felis chaus). It also has 3 Mustelids and 7 Viverrids: Yellow-throated Marten (Martes flavigula), Ferret Badger (Melogale sp.), Hog badger (Arctonyx collaris), Eurasian Otter (Lutra lutra); and among the Viverrids, Small Indian Civet (Viverricula indica), Large Indian Civet (Viverra zibetha), Common Palm Civet (Paradoxurus hermaphroditus), Himalayan Palm Civet (Paguma larvata), Binturong (Arctictis binturong) and Spotted Linshang (Prionodon pardicolor). Binturong
Two other species of Otter, namely Smooth-coated Otter (Lutrogale perspicillata) and Small-clawed Otter (Amblonyx cinereus), known from elsewhere in India, may also occur in Manipur State, while Arunachal Pradesh and Sikkim, may have even more species of small carnivores than Manipur

The high biodiversity of small carnivores and other biota in the Northeastern States could be attributed to the wide ranging altitudinal variations that one comes across in the region and also to the heavy rainfall and humidity that triggers luxurious plant growth especially in the lower elevations. All these rare animals occupy narrow bands of forests in the hills and valleys of the region, and, living in small populations, they are extremely susceptible to habitat degradation and hunting pressures. Many of the species in lowland forests are already on the verge of extinction as these forests were the first to be occupied, altered and degraded by man. Of the Mustelids, the Ferret Badger and the Hog Badger found in the Northeastern India take the pride of place not only because of their rarity but also because of their uniqueness. The Red Panda (Ailurus fulgens) is yet another flagship species of this region, restricted to the higher altitudes.

All the bear species that occur in India are recorded from the northeastern region. Besides, Northeast India forms the western end of the range for Malayan Sun Bear (Helarctos malayanus). Bears of the lower elevations are under especially serious threats owing to habitat degradation as well as persecution by man, as the bile of the animal is considered highly medicinal.
Wild Dog or Dhole, is yet another rarity in the wilderness of Northeast India. Wild Dog found in Sikkim (and in Kumaon, Nepal and Bhutan) is considered Cuon alpinus primaevus. The Cuon alpinus adjustus found in eastern Arunachal Pradesh is considered to be the same subspecies found in northern Myanmar.

Bats and rodents
Inventories, especially for bats and rodents, are wanting from Northeast India. Though, with about 65 species, bats dominate the mammalian fauna of Northeast India, reliable information available on them is sparse. The Wroughton’s Free-tailed Bat (Otomops wroughtonii), recorded from the Barapede cave in North Kanara district of Karnataka was believed to be a narrow endemic. However, now it has now been reported from Siju Cave in South Garo Hills of Meghalaya in Northeast India, and also from Cambodia. The Government of India has listed the Wroughton’s Free-tailed Bat in Schedule I of Wildlife (Protection) Act, 1972. The Namdapha Flying Squirrel (Biswamayopterus biswas) is a little known narrow endemic found in the State of Arunachal Pradesh. The Namdapha National Park, one of the largest parks in the country Holds a number of other squirrels - Hairyfooted Flying Squirrel (Belomys pearsoni) and Particoloured Flying Squirrel (Hylopetes Alboniger), Orange-bellied Himalayan Squirrel (Dremomys lokriah), Malayan Giant Squirrel (Ratufa bicolor), Hoary- bellied Squirrel (Callosciurus pygerythrus) and Himalayan Striped Squirrel (Callosciurus macclellandi) could all be seen in this park.
The Hispid Hare (Caprolagus hispidus) is yet another habitat Specialist that is facing the threat of elimination from the region.

Ungulates
Of the 25000 wild elephants in India, about 33% are found in Northeast India. In fact, Assam alone accounts for more elephants than Myanmar, Thailand, Indonesia or any other country in Asia. However, elephant population is dwindling sharply in Northeast India. There has been a very serious decline in the elephant population in central Assam whereas those in the southern parts have virtually vanished. The population has seriously declined in Tripura and there are only a few elephants left in Manipur and Mizoram and probably none in Nagaland. Heavy loss of prime elephant habitat is an issue of great concern as loss of elephant habitats heralds doom for smaller creatures as well.Great Indian Rhinoceros (Rhinoceros unicornis) is the largest of all the rhinos now inhabiting the world. In Northeast India this species is now restricted to Kaziranga, Pabitora and Orang in Assam. The population at Manas in Assam is believed to have been decimated in recent years. Historical records suggest that both the One-horned Javan Rhinoceros (Rhinoceros sondaicus) and the Two-horned Sumatran Rhinoceros (Didermocerus sumatrensis) were once found in parts of Northeast India. Both the species are now extinct from the region.The Water Buffalo (Bubalus bubalis) found in Northeastern India is faced with a genetic problem. A large number of domestic buffalo, most of them genetically a ‘cocktail species’ bred by man, are grazed in the habitats of the wild buffalo and the interbreeding revitalizes the domestic strain but has the opposite effect on the wild strains. The Banteng (Bos javanicus) occurred in the hills of Manipur as late as 1990s, but is now not reported from the State.

Sangai

The Brow-antlered Deer (Cervus eldi eldi) is endemic to the State of Manipur. Sangai, as the deer is locally known, is one of the rarest and the most localized subspecies of deer in the world. Reported to be extinct in 1951, this deer was subsequently discovered in a small pocket on the floating mats of vegetation, called ‘phumdi’ in the Loktak Lake. Though just fourteen heads were counted in the first aerial census in 1974, their number has steadily increased since then. Loktak Lake is now a RAMSAR site and there are now about 150 individuals in this undoubtedly the most fragile habitat of the region. The Swamp Deer (Cervus duvauceli) found in Assam is yet another Cervid of great conservation significance. The Serow (Capricornis sumatraensis), Goral (Naemorhedus goral) and Red Goral (Naemorhedus baileyi) are three other species that are of great conservation significance in the region. The Pygmy Hog (Sus salvanius) is the smallest and the rarest wild suid in the world, and only a few isolated wild populations survive in Northeast India.

Other Mammals

In the State of Sikkim, at the heights above 3600 m. where the tree line ends, the alpine Scrub and grasslands support some of the most unique fauna of the planet, the Yak (Bos grunniens), The Tibetan Wild Ass (Equus hemionus kiang), Markhor (Capra falconeri), Ibex (Capra ibex), Great Tibetan Sheep (Ovis ammon hodgsoni), Blue Sheep (Pseudois nayaur), are only to name a few.It is recorded that the Chinese Pangolin (Manis pentadactyla) ranges westwards through Assam and the Eastern Himalaya to Nepal, Myanmar and South China. However, the Indian Pangolin (Manis crassicaudata) is also reported from the Indo-Myanmar border areas and this confirms that both species exist in Northeast India.
Ganges River Dolphin (Platanista gangetica) is yet another mammal of great conservation importance that can still be found in the Brahmaputra River in Northeast India.

Birds
Northeast India supports some of the rarest, least known and most sought-after birds of the Oriental Region. This region perhaps supports the highest diversity of bird species in the Orient. More than 400 species of birds are recorded from Kaziranga National Park alone in Assam and although not thoroughly explored, the State of Arunachal Pradesh has a record of 665 species of birds.

Crested Serpent Eagle
Though birds are one of the most studied organisms, there is acute paucity of information concerning the avian fauna of the region and at the same time, new species are continuously being added to the region’s list. Poor dispersers such as babblers and laughing thrushes are important forest understorey passerines in the rainforests and they have diversified locally and contribute significantly to the diversity of the avifauna of Northeast India (they constitute about 10% of the Eastern Himalayan avifauna). The Brown-capped Laughing Thrush (Garrulax austeni) is only known from the hills south of the Brahmaputra in the North Cachar Hills (Assam), Nagaland, Manipur and Mizoram. The bird’s habitat consists of oak and rhododendron forest, secondary growth and bamboo from 1200 m. to 2700 m.The Elliot’s Laughing Thrush (Garrulax elliotii) and Brown-cheeked Laughing Thrush (G. henrici) are two species that have been recently added to the region’s list, from Arunachal Pradesh. Both these species had previously been recorded only in China. The Assam Plains and the Eastern Himalaya have been identified as Endemic Bird Areas by Bird Life International. The Assam Plains holds Blackbreasted Parrotbill (Paradoxornis flavirostris) and the Marsh Babbler (Pellorneum palustre) and in this region one can always hope to rediscover the Manipur Bush Quail (Perdicula manipurensis). The Eastern Himalayan part of Northeast India supports 22 restricted-range bird species (those that have a total world range of less than 50,000 square kilometres); of these 19 are endemics Perhaps, with the exception of Manipur Bush Quail (Perdicula manipurensis), which is considered to be extinct, one could perhaps hope to see all the other 21 bird species in Northeast India, which holds one of the largest concentrations of globally threatened birds in Asia. The relatively high species richness of birds at high altitude zones in the region, compared with other taxa, is also notable.
White-winged Wood Duck (Cairina scutulata) is perhaps the rarest duck in the world today and this bird occupies the pride of place among the avifauna of the region. However, extensive destruction of its natural habitat ranging from Assam and Arunachal Pradesh to Java has pushed this species into isolated groups of small populations. Greater Adjutant (Leptoptilos dubius) is a globally threatened bird with the majority of the world’s population now found in Assam. Spot-billed Pelican (Pelicanus philippensis), Blacknecked Stork (Ephippiorhyncus asiaticus), Lesser Adjutant (Leptotilos javanicus), and Pale-capped Pigeon (Columba punicea), are only to name a few of the globally threatened birds found in the region. Swamp Francolin (Francolinus gularis), found in Northeast India, is endemic to the Indian subcontinent. The Bengal Florican (Houbaropsis bengalensis) is one of the rarest bustards in the world. Manas National Park has the largest population of this bird in the world. Hornbills, too, exhibit high species richness in northeast India, found in few places elsewhere in the world.Lesser Fish Eagle (Icthyophaga humilis) is the rarest of the fish and sea eagles, and there are reports of its sightings in Namdapha in Arunachal Pradesh. Jerdon’s (Blyth’s) Baza (Aviceda jerdoni) is a very rare resident bird of India, and the chances of sighting this globally endangered bird are bright in evergreen forests of Northeast India. Burmese Hobby (Falco severus severus) is an uncommon breeding resident of Northeast India, south of Brahmaputra River. Pied Falconet (Microhierax melanoleucos) is also one of the rarest Indian raptors found in Northeast India. The Sclater‘s Monal (Lophophorus sclateri) and Blyth‘s Tragopan (Tragopan blythii) are among the rare and beautiful pheasants that live in a limited range of the eastern Himalaya. With the exception of a status survey conducted on the Blyth’s Tragopan in Blue Mountain National Park in Mizoram, which is recorded to harbour 38 birds, no detailed study has been carried out to date on these two species in any part of their range. It is even now a custom in certain hill areas of the region to present a Tragopan or Mrs. Hume’s Pheasant (Syrmaticus humiae) to a visiting dignitary (to be slaughtered and eaten). All the pheasant species that occur in this region are to be considered endangered. Ward’s Trogon (Harpactes wardi) is yet another beautiful resident bird reported from Arunachal Pradesh and Sikkim. The bird is sighted in the State of Manipur also.Buff-throated Partridge (Tetraophasis szechenyii) is a rare resident of rocky ravines and Rhododendron thickets in the subalpine zone of central Arunachal Pradesh. At higher altitudes in Sikkim, birds include Snow Partridge (Lerwa lerwa), Blood Pheasant (Ithaginis cruentus), Himalayan Monal (Lophophorus impejanus) and Ibisbill (Ibidorhyncha struthersii). The highly endangered Rufous-vented Prinia of the eastern population, regarded as a separate species ‘Swamp Prinia’ (Prinia cinerascens), is reported from the Pobitora Wildlife Sanctuary in Assam. Beautiful Nuthatch (Sitta formosa) is a resident of primary forests of Northeast India. The Khasi Hills Swift (Apus acuticauda) is one of the world’s rarest and least known Apus species, and is known only at its breeding cliff near Cherrapunjee in Meghalaya from late February to the end of April. The movements of this endemic bird outside the breeding period are largely undocumented. Pink-headed Duck (Rhodonessa caryophyllacea), as its local name ‘nganu koknganbi’ suggests that it was once a common bird in Manipur and elsewhere in Northeast India. It is now extinct. India’s only Buff-throated Warbler was collected from Meghalaya in 1953, and no further records exist in India. Rufous-bellied Eagle (Hieraetus kienerii) found in this region is also probably extinct. Burmese Peafowl (Pavo muticus), found in the Indo-Myanmar border areas, is also seldom sighted in the region.Though there is less information about the migration routes of birds in Northeast India, the Brahmaputra River and her tributaries are thought to form a flyway for birds from Northeast Asia.

Lower Vertebrates
The reptilian fauna of northeast India has the greatest affinity to the Oriental, Indo – Malayan and Indo-Chinese regions. According to existing records, there are 137 species of reptiles in Northeast India, but in reality there could be many more species that are yet to be identified. Python

With better sampling and studies on the herpeto-fauna, the number of species is expected to change considerably for each of the states and for the region as a whole.Among the component of reptilian fauna, the Gharial (Gavialis gangeticus) found in Brahmaputra River is of great conservation significance. Northeast India has the highest diversity of turtles. Of the 26 species of non-marine chelonians reported from India, 19 are found in this region. However, the information on this group of reptiles is also quite inadequate as most of the available records concerning the known species available are from the Brahmaputra Plain and adjoining areas in lower Eastern Himalaya. The hill states, especially south of Brahmaputra basin, viz., Nagaland, Manipur, Tripura, Meghalaya and Mizoram, remain poorly studied. As recently as 2000, a chelonian species -Amyda cartilaginaea, was reported from Mizoram as a first record for India. Asian Roofed Turtle (Kachuga sylhetensis) is endemic to the region. The Elongated Tortoise (Indotestudo elongata), Asian Brown Tortoise (Manouria emys), Narrowheaded Softshell Turtle (Chitra indica) and Indian Flapshell Turtle (Lissemys punctata) are very rare among the recorded species.

The lizard fauna of Northeast India is profoundly influenced by the Indo-Chinese connection. Published records indicate 20 lizard species from the State of Assam, and 18 species from the tiny state of Manipur. Of the three species of Monitor Lizards found in the region, Varanus flavescens is listed in Schedule I under Wildlife (Protection) Act, 1972. The Tokay Gecko (Gekko gekko) is the largest gecko alive today and is found in northeast India.
The Burmese Glass Snake (Ophisaurus gracilis) is yet another interesting reptile of Northeast India.Fifty eight species of snakes have been recorded in Assam and 34 from Manipur. Python reticulatus, the largest snake in India, is found in northeast India and Python molurus bivittatus is known from a single specimen from the Arunachal Pradesh, which was a first record for India. One can expect to sight both the snakes in ‘Mouling National Park’ in the Upper Siang District of Arunachal Pradesh. King Cobra (Ophiophagus hannah) is the most awe-inspiring reptile of the region. Typhlops jerdoni, T. tenuicollis, Stoliczkaia khasiensis, Elaphe mandarina, Oligodon melazonotus, Xenochrophis punctulatus, Bungarus bungaroides, Trimeresurus jerdoni are just a few examples of very elusive and rare snakes of Northeast India.

Amphibians
Existing records indicate the presence of 64 species of amphibians in the Northeast India but this figure again could be a gross underestimate as they are a poorly studied group in Northeast India. A survey of amphibians conducted in the State of Nagaland from 1998 to 2002 has resulted in 19 species as new records for the State and 5 species (Megophrys wuliangshanensis, M. glandulosa, Amolops viridimaculatus, Rana humeralis and Rhacophorus gongshanensis) as new records for India. Only four species of caecilians, Ichthyophis garoensis, Ichthyophis hussaini, Ichthyophis sikkimensis and Gegeneophis fulleri are known from Northeast India. The Himalayan Newt (Tylototriton verrucosus) deserves a special mention, as it is the only species of Salamander known from India, occurring in Manipur, Khasi Hills and Sikkim. Hitherto, they were little affected by man, but use of the pesticides in paddy cultivation is posing a threat to the species.

Fish Fauna
Fishes are the most ancient and numerous of vertebrates. Over 24,000 species of fishes are known in the world, and – a majority of these are from warm tropical waters. Northeast India is exceptionally rich in freshwater fishes, and it is heartening to note that the region has been extensively surveyed, and accounts for 236 species. From the State of Manipur alone, 167 species of freshwater species belonging to 11 orders, 31 families and 84 genera are recorded. The fish fauna of Loktak Lake in Manipur comprises 64 species. Two of these species, Monopterus albus and Osteobrama belangeri are restricted in their distribution to the Yunan State of China, Myanmar, and in India only to the State of Manipur. The Loktak Lake also serves as the breeding ground for several species of migratory fishes eg. Labeo dero, L. bata and Cirrhinus reba.

Sone Lake (12.5 km long and 3.0 km. wide), is one of the biggest tectonic lakes in Assam. It sustains 75 species of fishes under 24 families and 49 genera and of which, 20 species are widely distributed while 8 species are native to Northeast India. Despite a very high diversity of fresh-water fishes, Northeast India does not have many endemic species (the fish fauna of India contains 2 endemic families, both of which are absent from the region).

Invertebrates
The Biodiversity Strategy and Action Plan for Northeast Ecoregion states that 3,624 species of insects and 50 molluscs are recorded from the region. Butterflies and moths are by far the best-studied invertebrate organisms in Northeast India, and the region contributes the maximum number of species for the group in the country. A decade ago, 689 species of butterflies were recorded from the State of Sikkim. An ecological study on Mammals, Birds, Herpeto-fauna and Butterflies carried out in Teesta Basin, Sikkim, revealed nearly 350 species of butterflies in altitudes less than 900 m. (In the study area the family Nymphalidae is recorded to be the most species rich forming 50% of the observed species, followed by Lycaenidae and Pieridae (17.2% each). Papilionidae and Hesperiidae have relatively low species richness, forming only 8.6% and 7.0% of the species, respectively).

Atlas Moth
As species richness in the study area was found to be far greater than that reported earlier, especially at higher altitudes, this particular study highlights the importance of altitudinal gradients in the distribution of butterflies, and in their conservation. One of the largest known tropical Lepidoptera is the Atlas Moth (Attacus atlas), is not uncommon in many parts of Northeast India. Princeps polyctor ganesa, which occurs in Northeast India, is one of the most beautiful butterflies in the country, while, -Erysmia pulchella and Nyctalemon patroclus are very beautiful moths that occur in the region. It is pertinent to add that sericulture is an age-old occupation for some people in states like Assam and Manipur, especially in the ‘Loi’ community in Manipur who have rendered the skill of silkworm rearing and silk weaving to art form.Honey bees, render very valuable ecological services like pollinating wild and cultivated plant species apart from producing honey, and their advanced eusocial behaviour has always been a source of fascination for man. Four indigenous species of honey bees are recognized from India: Apis cerana, A. dorsata, A. florae and A. andreniformes. Of these, Apis andreniformis is only known from a few specimens collected from Northeast India where the species is exceedingly uncommon. It is an unfortunate practice that people in certain parts of Northeast India not only consume the honey and larvae of this insect, but also fry and eat the honey bees themselves.

Fast disappearing forests
& species of the Northeast India

The primary vegetation in extensive areas of the Northeast India has been disturbed and modified and in some places destroyed by seismic activities, frequent landslides and resultant soil erosion. While these natural causes have contributed only marginally to the change in vegetation type, it is the activity of Man that has led to the irreversible transformation in the landscapes and has resulted in colossal loss of biodiversity in the entire region. Human influences have pushed many species to the brink of extinction and have caused havoc to natural fragile ecosystems. Such devastations to natural ecosystems are witnessed almost everywhere in the region and is a cause of great concern.Northeast India has 64% of the total geographical area under forest cover and it is often quoted that it continues to be a forest surplus region. However, the forest cover is rapidly disappearing from the entire region. There has been a decrease of about 1800 sq.km. in the forest cover between 1991 and 1999 (F.S.I., 2000). More worrisome still is the fact that the quality of the forest is also deteriorating, with the dense forests (canopy closure of 40% or more) becoming degraded into open forest or scrub. Though there is a succession of several edaphic formations, a vast area of land has already been transformed into barren and unproductive wastelands. This being the case, the statistics of ‘more than 64 % of the total geographic area in this region under forest cover’ could be misleading. For example, though the forest cover in Manipur extends to 78% of the total geographic area, only 22% of forest area is under dense forest cover and the rest has been converted to open forests. Except in the Brahmaputra and Barak valleys of Assam where substantial areas are under agriculture, little of the land is available for settled cultivation. Hence, shifting agriculture or slash-and-burn agriculture is the major land use in Northeast India and extends over 1.73 million ha (F S I, 1999). Different agencies have come up with different figures concerning the total area under shifting cultivation (jhum) in the region. What is not disputable is that with an ever shortening jhum cycle, the other human influences have caused environmental degradation with disastrous consequences.Though Northeast India is predominantly mountainous, the region is very rich in aquatic ecosystem diversity. A large number of bheels, ponds and marshlands in the lowlying and floodplain areas of Assam, Arunachal Pradesh and Tripura represent the diversity in lentic ecosystems. However, deforestation and the resultant loss of soil, especially in the hill areas, are leading to increased siltation of rivers and streams. The deep pools that are the favoured habitats of many species, are rapidly becoming shallow and choked with silt, leading to a decline in habitat. At the same time, swamps, marshes, and other wetlands are increasingly being reclaimed for urban and agricultural expansion.The forests of Assam once acted as a sponge, absorbing the tremendous impact of the monsoons. The natural drainage of the vast northeastern Himalaya is channelled through Assam and with the loss of thick forest cover, Brahmaputra, one of the largest and fastest flowing rivers of the subcontinent is creating havoc in the State. Floods that have devastating effects are now common to Northeast India and protecting the forests is a difficult problem.
A vast majority of the indigenous inhabitants of this region are meat-eating in their food habits and almost all communities have expert hunters, trappers and fishermen. One can find bones, skulls and hides of large and small mammals in tribal huts. It should be noted that though the traditional practices of trapping, snaring etc of animals are carried out in very remote areas, in most parts of Northeast India shooting wild animals with guns is prevalent, giving very little chance for the denizens of the forests to recoup from such pressures. Besides, certain meat is valued as medicinal and such animals are persecuted as great efforts are made by a few individuals to seek such animals and bring back home their body parts. In the past, the hunting/trapping was done with considerable prudence with many taboos and restrictions. For example, the Anaal Naga in Manipur did not consume turtle or tortoise meat. The Maram Naga did not eat pork and the Thangkhul Naga did not eat any member of the cat family. Unfortunately, such taboos no more hold any sway among the people now. It is a great tragedy that in many parts of Northeast India some people poison the rivers, streams and other water bodies to get good catches of fish. Apart from using plant poisons, lime, DDT, copper sulphate (Cu SO4) and, other synthetic chemicals are being used for fishing. Some are even using dynamite and gelatine sticks for the same purpose. This has serious ill effects on the entire aquatic ecosystems. Fish stocks are being entirely wiped out; several species of amphibians, birds and other fish predators are also being affected in the process; and nothing is known as to what happens to human beings on consuming such poisoned fishes.Northeastern India is often called India’s forgotten corner and it was perceived that the remoteness of the place has helped preserve its biodiversity. However, the penetration of roads into interior areas has already exposed the local populace to market economy, unscrupulous urban traders and middlemen in most parts of the region. A series of proposed dams in the Northeastern region may lead to submergence of vast tracts of rainforests. Comprehensive environmental impact assessments, which are mandatory as per the law of the land, reveal the possible danger that these projects pose to the biodiversity of the region. The impregnability of certain forests in Northeast India is a source of only some protection, as this factor itself offers some hope for the survival of many species.
Source: “Biodiversity of Northeast India - An Overview”
by V. Ramakantha, A. K. Gupta and Ajith Kumar