Andaman And Nicobar Islands: Fauna
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FAUNA
This tropical rain forest despite its isolation from adjacent land masses is surprisingly enriched with many animals.
Nature bestowed the Bay islands with some unique and fascinating Wildlife, which eke out their livelihood in the luxuriant tropical rain forests. The emerald islands and the turquoise ocean around comprise variety of Eco-systems providing shelter to wide variety of flora and fauna.
Though, biological investigations , 2200 species of flowering plants have been identified so far. Among animals, 58 species of mammals, 242 species of birds, 83 species of reptiles, 10 species of amphibians, 750 species of fishes, 326 species of coelenterates (corals & sponges etc.), 941 species of molluscs, (oyster, clams etc.) and 1500 sp. of insects besides other creatures, have been identified.
Andaman and Nicobar Islands are one of the 221 priority areas concerning conservation of global bio-diversity.
Botanical Survey of India and Zoological Survey of India, Port Blair surveyed floral diversity and faunal diversity respectively and as per their study the results are as follows:
Faunal diversity of the Islands:
Over 5100 animals have been described which include 100 fresh water, 2100 terrestrial and 2900 marine animals.
Marine life comprises more than 1200 spp of fish, 350 spp of echinoderms, 179 spp of corals, 1000 spp of molluscs, and many other lower forms of life.
ECO-SYSTEMS, FLORA AND FAUNA
The Island territory comprising 1962kms of coastline, about 6 lakh sq. kilometers of marine water zone and 7171 sq. kilometers of tropical rain forests, constitute two major types of Eco-systems with several microhabitats.
1) Island Eco-system: Comprises forests and the coastline, including mangrove and littoral forests, beaches and other intertidal zones.
2) Marine Eco-system: comprising the open sea and coral reef.
Besides 179 species of Corals, including Plate corals, Brain corals, Taghorn corals, Finger corals and Mushroom corals etc. 147 species of Coelentrates, 100 species of Molluscs and 70 species of Sponges are also found in this region.
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BIRDS
Some species
Birds – 284 species and sub species reported (99 spp endemic)
Andaman grey Teal (Anas gibberfrons)
Andaman Tree Pie (Dendrocitta beyleyi)
Andaman wood Pigeon (Columba palumboides) The State Bird
Cotton Teal (Nettapus coromondalica)
Crested Serpent Eagle (Spilornis cheela)
Emerald Dove (Chalcophaps indica)
Green imperial Pigeon (Ducula aenia)
Hill Myna (Gracula religiosa)
Lesser Whistling Teal (Dendrocygna javanica)
Swiftlets (Collocalia fuciphaga)
White Bellied Sea Eagle (Haliatus leucogaster)
A backgrounder
IN his book Song of the Dodo, biologist David Quammen talks about how geographical isolation triggers speciation. The dodo of Mauritius is the best example of this development. With no predator to worry about, the dodo flourished for millennia in the Indian Ocean island till man landed there in the 18th Century. However Quammen points out that geographical isolation does not always result in appearance of a new species. But when new species evolve, they do so only in isolation. Of all the life forms it is the bird species that reflect this feature. It was the finches of Galapagos Island that led Darwin to his theory of evolution. This was brought home to us dramatically when we spent a few hours in the Andaman-Nicobar archipelago recently.
Primeval splendour Havelock Island is about two hours by boat from Port Blair. Surrounded by emerald lagoons, much of the mountainous island is covered with tropical evergreen forests. In some stretches, mangrove swamps line the shores. It was a landscape of primeval splendour. On the first day, wading in the lagoon, I saw two birds on a mangrove tree. One look and I knew it was a "lifer" for me — a bird species you see for the first time in your life. They were white-headed mynas. Within minutes, a woodpecker with a white-barred black mantle and red crown landed on the same tree. Another "lifer" — the fulvous-breasted woodpecker. Both birds are exclusive to the Andamans
The 324 islands of the Andaman-Nicobar archipelago are the tops of the submerged mountain chain, a continuation of the Arakan Yomas of Myanmar. But they have been separated long enough from the mainland to develop avifauna of their own. The islands are home to about 242 birds of which 39 are unique to the islands. Ornithologists describe them as endemic, birds that have evolved into distinctive species because of the insularity of their habitats. Soon we saw more endemic species like the olive-backed sunbird and Andaman swallow. These islands are a birdwatcher's paradise.
After the 1857 rising, the British government turned its attention to Andaman Islands to explore the possibility of setting up a penal colony. Soon a few amateur ornithologists from the civil services visited the islands and collected specimens.
One such was A.O. Hume, the founder of the Indian National Congress. Based on his collections, he wrote a series of articles between 1874 and 1876 in Stray Feathers, a journal of natural history. At least one bird in the islands is named after Hume — the white collared kingfisher (Todiramphus chloris humii), easily spotted in the jetty area of Port Blair. Hume was also the first to get a specimen of the Narcondam hornbill, another endemic bird. The entire population of 300 hornbills is confined to a single forested island, Narcondam. Another endemic bird easily spotted in Port Blair is the Andaman crow pheasant.
After taxonomist Humayun Abdulali of the Bombay Natural History Society carried out a series of surverys in the 1980s and published his observations, ornithologists realised the unrivalled nature of the birds in the islands. The megapode, which has come to symbolise the endemic birds of Andamans, inhabits the Nicobar Islands. Another distinct bird is the Nicobar pigeon with its metallic green hackles and sheen on its plumage.
Sighting the shama For the last three days of our holiday, we stayed in the cottages of the Andaman Nicobar Ecology Team (ANET) in a forest in Wandoor. Every morning at daybreak we would hear hauntingly long-drawn fluid birdcalls. Peeping out, we could see the shama singing and pirouetting in a bamboo clump. The plumage was a little different from the shama in the mainland.
A quick look at the book revealed that this was indeed a sub-species exclusive to the Andamans — the white-rumped shama (cpyschus malabricus albiventris). Arguably the best songbird, the shama is a forest dweller and difficult to spot. For a birder, the sight of this bird announcing the arrival of a new day is a consummation devoutly to be wished for.
BUTTERFLIES AND MOTHS
With about 225 species, the A&N Islands house some of the larger and most spectacular butterflies of the world. Ten species are endemic to these Islands. Mount Harriet National Park is one of the richest areas of butterfly and moth diversity on these Islands.
CORALS
Corals belong to a large group of animals known as Coelenterata (stinging animals) or Cnidaria (thread animals). Corals grow slow, they have type wise site specific growth rates. The massive forms may grow upto 2 cm. in diameter and upto 1 cm in height a year, whereas, delicate branching forms grow between 5 to 10 cm. per annum. A true reef building stony coral may be unisexual or bisexual. They breed together once in a year at a pre-determined time after dusk. This process, at places is so intense that the water stays pinkish till next morning. A large number of baby corals are released in the open ocean this way. After sometime these baby corals settle over a suitable substratum and start forming new colonies through asexual reproduction. Their morphological features change with the environment in which they settle. Due to this peculiar character they are often called 'Plastic animals'. Stony corals could be broadly divided into reef builders and non-reef builders, the reef builders are called hermatypic whereas others are known as ahermatypic corals. The reef builders possess hard calcareous skeleton and need sunlight like plants to survive. On the other hand, the non-reef builders are devoid of a true stony framework and can live well without sunlight. A few among them are capable of making protein based solidified skeleton
MAMMALS
62 species – 55 terrestrial and 7 marine species (32 spp endemic)
About 55 varieties of forest mammals are found to occur in A&N Islands, most of them are understood to be brought in from outside and are now considered endemic due to their prolonged insular adaptation.
Rat is the largest group having 26 species followed by 14 species of bat.
Among the larger mammals there are two endemic varieties of wild pig namely Sus Scrofa andamanensis from Andaman and S.S.nicobaricus from Nicobar.
The spotted deer Axis axis, Barking deer and Sambar are found in Andaman District.
Interview island in Middle Andaman holds a fairly good stock of feral elephants. These elephants were brought in for forest work by a private contractor who subsequently left them loose.
Andaman Spiny Shrew (Crocidura hispida)
Andaman Wild pig (Sus scrofa andamanensis)
Barking Deer (Muntiacus muntjak)
Blue Whale (Balenoptera muscules)
Sperm Whale (Physeter catodon)
Chital (Axis axis)
Common Dolphin (Delphinus delphis)
Dugong (Seacow) (Dugong dugon): -The State Animal
Palm Civet (Paguma larvata)
REPTILES
Reptiles – 88 species 76 terrestrial and 12 marine spp (24 endemic)
Andaman Banded Krait (Bungarus andamanensis)
Green Sea Turtle (Chelonia mydas)
Hawksbill Turtle (Eretmochelys imbricata)
Leather back Turtle (Dermochelys coreacea)
Olive Ridley Turtle (Lepido chelys olivacea)
Salt Water Crocodile (Crocodylus porosus)
Water Monitor Lizard (Varanus salvator)
SHELLS
Shells are perhaps the most colourful and fascinating objects known to man other than Gems since time immemorial. They served as money, ornaments, musical instruments, drinking cups, in magic and in the making of fine porcelains. They were also the symbols in rituals and religious observances, and the returning pilgrims wore them as a token of divine pardon. These islands are traditionally known for their shell wealth specially Turbo,Trochus, Murex and Nautilus. Earliest recorded commercial exploitation began during 1929. Shells are important to these islands because some like Turbo, Trochus & Nautilus etc. are being used as novelties supporting many cottage industries producing a wide range of decorative items & ornaments. Shells such as Giant clam, Green mussel and Oyster support edible shellfishery, a few like Scallop, Clam and Cockle are burnt in kiln to produce edible lime. The Univalve or one shell group belongs to the class Gastropoda having more than 80,000 species. Sacred Chank belongs to this group. Their body, in the course of development, go through a complicated process, 'torsion' i.e. the visceral mass is twisted though 90 degree together with the shell that covers it. Under mysterious circumstances many a time this process proceeds in the reverse direction thus creating an abnormal shell which otherwise lives like a normal shell. A classic example is the most wanted left-handed chank. The Bivalve or Pelecypoda has about 20,000 living species. Majority of then burrows in sand or mud such as Pearl Oyster, Wing oyster, Giant clam etc. A third group, which is comparatively smaller, is called Cephalopoda, which includes Octopus, Squid, Nautilus etc. The soft body animal, which lives inside the shell, is covered with a thick layer of specialised epithelium cells known as rnantle, which in turn secretes a two tier shell material making the shell. The outer layer having a different colour pattern is organic in constitution, technically called 'periostracum'. Calcium ions from the environment are absorbed into the blood and deposited evenly under this layer. The next inner layer is called 'nacre' or 'mother of pearl' responsible for the pearly lustre common to many shells.
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Details
Andaman And Nicobar Islands Administration
Acridotheres tristis (Linnaeus) Indian Myna
Indian Myna It was introduced by Col. Tytler at Ross Island in 1867.It is very common and abundant through out South Andaman in cultivations and in the neighborhood of homesteads, villages and town. A confirmed associate of man, following wherever he opens up new habitations. Omnivorous. Eats fruits, insects, kitchen scraps. Follows the plough for earthworms, etc., and attends on grazing cattle for the grasshoppers.
Birgus latro (Robber Crab)
Birgus latro It is the world’s largest land crab and is found in plenty in South Sentinel and Great Nicobar Island. There is a popular belief that this crab can easily pluck the coconut from the tree, peel off the husk and break open its shell.
Cassis cornuta (Helmet Shell or King Shell)
King Shell The Helmet Shells are solid with large body whorls and short spires, usually with blunt knobs. The animals live in sandy areas in the tropics and temperate zone, in shallow and deep water. They prey on sea urchins and other echinoids. The males tend to be smaller than the females with a slightly less expanded shield.
Charonia tritonis (Triton’s trumpets)
Triton’s trumpets It is one of the world’s larger gastropods (the name implies that an animal of this class crawls on its stomach). They live in sandy and rocky areas in deep and shallow waters in the tropics worldwide. They are carnivorous, living on echinoderms and mollusks. They have a long free swimming stage, after they are hatched and before developing into the final form.
Crocodiles, saltwater
Conflict/ 2019
Ishita Mishra, Authorities at odds over Andamans crocs, March 13, 2019: The Times of India
Wildlife scientists and the Andaman & Nicobar residents are at odds over the culling of saltwater crocodiles, which the latter say are harming the islands’ tourism prospects due to the increase in instances of human-crocodile conflicts.
Citing the growing number of attacks on tourists, the islands had last year requested the central government to delist salt water crocodiles (or ‘salties’) from Schedule 1 of the Wildlife Protection Act, 1972. This was followed by a proposal to cull the animals. The environment ministry roped in Dehradunbased Wildlife Institute of India (WII) to check the feasibly of the request. After conducting an over six-monthlong survey, WII observed that the situation did not warrant de-notification of the salties and neither was culling a solution.
Shiva Kumar, senior scientist at WII, told TOI that crocodiles in the island were not so many that they could pose a “significant threat” to humans. WII’s study has evoked a mixed response from the island. The forest department which had forwarded the culling proposal to the Union environment ministry was guarded in its response. Tarun Coomar, principal chief conservator of forests, A&N Islands, said he “welcomes the suggestions given by WII but the institute must now come up with concrete solutions”.
WII has outlined a 5-yearplan at a cost of Rs 56 crore to tackle the problem. VB Mathur, director, WII, said, “We’ve divided the islands into three zones. The first is only for crocodiles, second for humans and the third is a co-existence zone for both. If a crocodile crosses its boundaries, it should be captured and kept in a rehabilitation and research centre.” He also called for patrolling with drones and underwater cameras.
However, the WII report has been returned twice with objections raised by the local administration and tourism body. The third and final draft of the report, according to Shiva Kumar, is to be submitted shortly.
Dugong
Popularly known as sea cow, the dugong once enjoyed a wide distribution in the Indo-pacific region. It is a seal-like marine mammal, bluish-grey in colour and grows to a length of 2.3 m. It is sluggish and herbivorous, feeding on marine grasses and algae. The cow gives birth to only one calf at a time. It was largely hunted for its delicious meat, fat, oil and skin. With the result, its population has completely disappeared from many places, making it the most threatened marine mammal in the Indian Ocean. It is rarely encountered in a few pockets in these islands. The dugong is now decidedly a diminishing species deserving prompt protection.
Francolinus pondicerianus (Gmelin)(Grey Partridge)
Gmelin This bird was introduced in Port Blair in 1890. It is popularly known as ‘Safed Teetar’. A plump, stub-tailed grayish brown game bird with chestnut blotching above and fine wavy black and buff vermiculations, and chestnut tail. Throat rufous-buff circumscribed by a broken blackish line. Sexes alike. Avoids heavy forest and humid tracts.
Green humphead parrotfish
Aathira Perinchery, Protected areas matter to bumphead parrotfish, March 23, 2019: The Hindu
Photo Credit: Vardhan Patankar
From: Aathira Perinchery, Protected areas matter to bumphead parrotfish, March 23, 2019: The Hindu
Bumpheads are the world’s largest parrotfish. Ramming its enormous green head against corals to dislodge them, a single bumphead can nibble up to five tonnes of coral every year. Though seemingly destructive, this activity promotes coral growth and keeps reef ecosystems healthy. However, numbers of bumphead parrotfish have decreased worldwide.
2019/ low density
Aathira Perinchery, Protected areas matter to bumphead parrotfish, March 23, 2019: The Hindu
Study finds low densities of the fish in the Andaman and Nicobar Islands
The survival of the threatened bumphead parrotfish in the Andaman and Nicobar Islands hinges on the persistence of coral reefs and presence of marine protected areas. Implementing fishing regulations could help its population bounce back, say researchers.
Overfishing is a concern, for the fish are highly prized catches. But how are India’s bumpheads in the Andaman and Nicobar Islands doing?
In an effort to generate baseline data, a team comprising Vardhan Patankar (Wildlife Conservation Society-India) surveyed 75 coral reef sites off 51 islands to obtain information on the distribution of bumpheads. Diving underwater, they counted the numbers of bumpheads and quantified benthic cover (such as live coral, algae, sand and rubble) there. Their results, published in Oryx, reveal that the fish occurred only patchily in these waters at densities of just 0.0032 per hectare. The team spotted no juveniles, only 59 adults at merely nine islands.
“The low densities are shocking, very similar to those of bumphead populations in southeast Asia where they are legally protected,” said Dr. Patankar.
Live coral cover and the presence of marine protected areas – where fishing is banned – emerged as crucial factors for bumphead presence. To supplement this information with local knowledge, the team also conducted 99 interviews with fishermen in the South and Middle Andaman islands and Central Nicobar. Most fishers were aware of the presence of bumpheads in their waters; and all fishermen in Central Nicobar and Middle Andaman had seen the fish feeding and aggregating (bumpheads tend to aggregate in numbers larger than 10). Most fishers had hunted the fish all their lives, using hand-held wooden spears or harpoons.
Currently, this hunting is only opportunistic. However, if this changes to targeted fishing it could endanger bumpheads which could be easily conserved as a ‘flagship species’, says Dr. Patankar. “Bumpheads are not legally protected in India though the IUCN categorises them as Vulnerable,” he says. “Now would be a good time to protect them legally and implement some fishing restrictions so their numbers can improve. Natural catastrophes such as bleaching may have already affected these large fish.”
Laticauda laticauda (Andaman blind sea snake - an Amphibious sea Snake)
Andaman blind sea snake The Amphibious Sea Snake, like other Sea Kraits, spends its time mainly at sea in shallow tropical reefs and it frequently comes ashore to lay their eggs on land. The attractive silver and black banding covers the entire body from the neck area to the tip of the tail. The tail is laterally compressed and rudder-like, making the snake an efficient underwater swimmer. They are venomous which are ten times as strong as rattlesnake venom. The venom is composed of powerful neurotoxins (affect nervous system).
Lepidochelys olivacae (Olive Ridley turtle)
Olive ridley turtle This is a small marine turtle measuring less than 1.0 metre in length and weighing upto 60kg. The head is large and triangular. Carapace is olive-grey in colour. The turtle occurs in coastal waters as well as in open sea. Although the species is widely distributed in tropical seas around the world, due to excessive killing of adult and collection of eggs, it is being rarely encountered in these islands.
Macaca fascicularis umbrosa (Crab eating Monkey)
Crab eating Monkey This is a small marine turtle measuring less than 1.0 metre in length and weighing upto 60kg. The head is large and triangular. Carapace is olive-grey in colour. The turtle occurs in coastal waters as well as in open sea. Although the species is widely distributed in tropical seas around the world, due to excessive killing of adult and collection of eggs, it is being rarely encountered in these islands.
Megapodius freycinet (Megapode)
Megapode This is a fowl like bird confined to the dense forests along seashores of Nicobar Islands. It is dull in colour, with long legs and toes. Both the sexes are alike. The megapode is omnivorous, feeding on insects, worms, snails, seeds, tubers etc. The bird incubates its eggs in a huge earthen mound of vegetable matter. The decomposing leaves of the mound release the heat necessary for the incubation of eggs. As this bird is not a good flier, it is easily caught and killed. Over-exploitation for flesh and eggs has reduced the species to an endangered position. Needs effective protection and conservation.
Nautilus pompilius
Nautilus pompilius Nautilus is the sole survivor of an extensive group of varied forms, which have become extinct. It has a calcareous chambered shell. The chambers are in a series of plane spiral. As the animal grows, fresh chambers are secreted and the old ones are separated by partitions. The soft body having numerous slender tentacles in places of arms occupies the outermost chamber in the spiral.
Passer domesticus (Linnaeus)(House Sparrow)
House SparrowIt is undoubtedly our most familiar bird, which was introduced at Ross Island during the second half of the 19th century. Male with grey crown, black lores and around eye. Female ashy grey-brown above streaked with blackish and rufous. Omnivorous, eats grains, insects fruit buds, flower nectar and kitchen scraps.
Phelsuma andamanensis (Andaman Islands day gecko)
Phelsuma andamanensis It is native to the Andaman Islands. They are diurnal (active during the day) and they have a clear plate covering their eyes and do not have eyelids. Day geckos are capable of climbing up glasswalls and across ceilings, making them great escape artist. In the wild day geckos feed on invertebrates, nectar and pollen.
Rhyticeros norcondami (Narcondom hornbill)
Narcondom hornbillThis is a medium-sized, black- bodied and white-tailed resident bird, endemic to the volcanic Narcondom Island. It is quite noisy and fearless of man. The bird moves in small groups and perches on tall trees. It feeds on wild figs of the jungle. Because of its restricted distribution to this tiny island, its present status is considered as quite vulnerable. It is no doubt a rare bird requiring effective protection.
Inhabited Islands
2018/ no need for Restricted Area Permit
Access to Andamans eased, August 8, 2018: The Hindu
From: Access to Andamans eased, August 8, 2018: The Hindu
Foreigners can visit 29 inhabited islands without Restricted Areas Permit
Foreigners no longer need a Restricted Areas Permit to visit 29 inhabited islands in the Andaman and Nicobar chain. The Union Home Ministry decided on Tuesday to lift restrictions as the government intends to boost tourism.
An official said 11 other uninhabited islands will also be thrown open to foreigners.
Area permits The 29 inhabited islands have been excluded from the restricted area permit (RAP) notified under the Foreigners (Restricted Areas) Order, 1963, till December 31, 2022, subject to certain conditions.
However, citizens of Afghanistan, China and Pakistan and foreign nationals having their origin in these countries would continue to require RAP to visit the Union Territory, the official said.
For visiting Mayabunder and Diglipur, citizens of Myanmar will continue to require RAP, which shall be issued only with the prior approval of the ministry.
“To ensure preservation of natural and marine resources, including marine parks and environment, of the Union Territory without affecting tourism and business at large, it should be ensured by the Andaman and Nicobar Islands administration that the guidelines issued by the Environment and Forests Ministry are strictly adhered to,” said the official.
Separate approvals of the competent authority would be required for visiting reserved forests, wildlife sanctuaries and tribal reserves, the official said.
Invasive species in Andaman & Nicobar Islands
Bull frog
Mohit M Rao, Indian bull frog: the Andamans’ new colonisers, August 11, 2018: The Hindu
From: Mohit M Rao, Indian bull frog: the Andamans’ new colonisers, August 11, 2018: The Hindu
The Indian bull frog, a recent arrival from the mainland, is steadily occupying the islands’ ecosystem and threatening the local economy. Mohit M. Rao reports on the bizarre man-frog conflict brewing in the islands
A narrow road bifurcates the hyper-green paddy fields of Webi village in Middle Andaman, in the Andaman and Nicobar Islands. A clear stream flows around the Webi, home to the Karen community, brought to these shores from Myanmar 93 years ago.
At dusk, as fading sunlight paints the surrounding hills in silhouette, the calls of cicadas, crickets and frogs rise in crescendo. In the cacophonic stillness, a centipede winds its way across the empty weathered road. And then, in the blink of an eye, it’s gone, swallowed whole by a recent migrant to the island — the Indian bullfrog (Hoplobatrachus tigerinus). Barely 10 cm long, this particular specimen is small. But the larger ones weigh at least half a kilo. The golden stripe on their backs and the glitter around their throats shine in the diffused light of a mobile phone. Less than two feet from the centipede-eater sits another frog. Next to that, one more, and another, and another... scores of frogs in varied sizes, basking in the warmth of the asphalt. Every now and then, one of them leaps toward the murky waters of the paddy fields. There is nothing frog-like about the deep, guttural croaks of these prolific breeders. Rather, they sound more like a bull with a sore throat.
“It wasn’t here even five years ago. Now they’ve taken over the village,” says Nau Thaw Raytoo, a mother of four, who lives in a concrete-bamboo house with her children, their wives, and her six grandchildren. Her broken Hindi shifts to fluent, high-pitched Karen when instructing raucous kids.
Webi is just among the scores of villages in the islands where the amphibian has arrived in hordes. An unusual man-frog conflict is brewing. The voracious animal gulps down anything that would fit in its jaws: centipedes, leeches, native frogs, lizards, small snakes, and even chicks and ducklings, which are an important source of food for the islanders.
“I’ve seen them eat chicks, swallowing the head whole,” says Raytoo, adding that of the 15 chicks hatched in the family’s chicken coop this year, only three have survived. Balakishore, whose father is Ranchi (an overarching term for Jharkhand tribals who were settled here to clear the forests decades ago) and mother is Karen, has lost 50 ducklings to the frogs. When grown, each duck would have fetched at least ₹300 in the local market.
One invader, many names
In the villages carved out of the virgin Andaman forests, the amphibian invader has evoked both surprise (“where did they come from?”) — and anxiety (“when will they go away?”). The bullfrog, found widely in mainland India and protected under Schedule IV of the Indian Wildlife Act 1972, is making the most of a free run that it’s enjoying in the erstwhile penal colony.
In the Andaman Islands, it can rain eight months of the year. The first rains in May are the signal for the bullfrogs to come out of the streams and agricultural ponds that have become their shelters. They breed by the hundreds, with each female able to lay between 3,500 and 20,000 eggs. Not all survive, but enough live to breed again, ensuring that the horde extends their range. With an average life span of seven years, and time to sexual maturity of 10-12 months, their population can dramatically shoot up in a very short time, which is precisely what happened once they landed in the islands.
“This is an invasion,” says Nitya Mohanty, a doctoral student at the Centre for Invasion Biology at Stellenbosch University (South Africa). His research, done with the Andaman and Nicobar Environment Team, has been on invasive species — first on the chitals (spotted deer) that have established their herds in the Andamans, and now on the bullfrog invasion.
So far, the bullfrog has been found in six out of the eight major inhabited islands. In 2017, it was even found in Little Andaman, which is separated from the Greater Andaman Islands by more than 55 km of sea. “This kind of incursion into remote islands is not naturally possible in such a short time,” says Mohanty.
The frog has acquired many names in the course of its journey through multi-cultural settlements of the island: shona beng (‘Golden frog’, for the prominent golden stripe) among the Bengali settlers; haramendak (‘Green frog’, for its olive-green skin) in Ranchi villages, where you could hear Oraon, Sadri or Munda being spoken; and dey-phala (‘Green frog”) in villages where the 2,500-odd Karen community stays. Whatever the name or language, the narrative of economic loss and ecological threat is a constant.
How they spread
Mohanty’s team sought to define the contours of this “invasion” through interviews with locals. As early as 2001, the bullfrog had already established breeding populations in one village. By 2009, it had spread to seven villages. Since then, at least 53 villages have reported the bullfrog in worrying densities.
Like most contemporary tales in the archipelago, the bullfrog story may also have to do with the earthquake and the tsunami that devastated large parts of Andaman and Nicobar islands in 2004. Following the decline of natural fish stock, the local administration encouraged integrated farming, with aquaculture in agricultural ponds. There are now over 2,500 such ponds in the islands, most of them filled with stocks of exotic, fast-growing fish imported from the mainland.
The fishling stocks (mostly from Kolkata) released into some of these ponds were contaminated with bullfrog eggs and tadpoles. All fingers point at the local fisheries department, which has, however, dismissed these claims and accused private traders of having brought the invader to the islands.
Most villagers believe that the bullfrog’s first hop into the islands was in Diglipur, in the northern tip of the Andamans, where its prolific spread first became a talking point. By 2011, it was spotted at Mayabunder in Middle Andaman, and by 2013, it was found in Wandoor, near the southern tip of the Andamans, around 300 km from Diglipur. While many were accidental releases, in some areas, it had been released by villagers as a fast-breeding cheap food.
Researchers Harikrishnan Surendran and Karthikeyan Vasudevan had been working in Wandoor since 2008, and were the first to report the presence of the bullfrog as an invasive in a scientific journal. “[The spread] is not surprising at all, given the high reproductive output of Indian bullfrogs and their association with agricultural areas... it was only a matter of time before they got introduced to other islands,” says Surendran.
Nearly two years ago, while engaged in construction and repairs at a resort near Wandoor in South Andaman, M. Alazhagan, 35, saw a multitude of frogs thronging the swimming pool. Some, he says, had turned yellow, with blue globules on their throat — males decked up for the breeding season. He approached one, and it froze. He decided to take a selfie: him grinning in the foreground, with the frog posing meditatively in the background. “It looked so strange! So much bigger than the frogs we were used to seeing and so colourful,” he recalls. But fascination soon gave way to frustration. In North Wandoor village, located at the edge of the Lohabarrack Salt Water Crocodile Sanctuary, it isn’t the crocs that villagers keep an eye on.
The tsunami had created salty channels in the area and rendered large tracts infertile. So, many had turned to creating agricultural ponds — to rear fish and also because they would serve as sources of freshwater when the rains filled it up. Shushil Mondal found that his pond had been taken over by frogs. “Earlier I could get 20 kg of fish whenever I spread the net. Now, I get only shona beng. There is no fish left now. It has eaten everything,” he says.
The frogs pose a threat particularly to the livelihoods of landless labourers, such as Parimal Das and his family of eight. They had migrated to the Andamans from Kolkata nearly 20 years ago, and are now nomads, leasing land wherever it is available to grow vegetables. Agriculture in a rain-heavy, saline-rich soil is difficult, and free-range chickens are an important and steady source of income, with each fetching up to ₹600. “I’ve lost six chicks this year already. We had to build a murghi ghar [wooden makeshift cage on stilts] to lock the chickens at night, but even then the frogs manage to squeeze through,” he says.
On the other side of the Greater Andaman islands, the Andaman Trunk Road snakes its way through dense forests. Trees form a seemingly impenetrable canopy, creepers drape branches in a gown of broad leaves, and undergrowth form layers upon layers above the damp soil. Amidst the shades of green, the Andaman Crape Myrtle, a deciduous tree, bursts in bouquets of small lilac flowers.
Five kilometres of these forests separate Gannatabla village — a settlement of Jharkhand tribals — from the nearest village in North Andaman. The village is a clump of 50 houses and a series of rectangular paddy fields. There is no pond here where fish is cultured. The bullfrog, however, lurks in these fields and drinking water wells. “We don’t know how it has come here. Three years ago, we spotted it in the streams that come through the forests when we went fishing for kala macchi (black fish). Now the fish is hardly seen but the frog is everywhere,” says 29-year-old Johnson Kirketa, suggesting that the bullfrog had crossed the forests through channels and streams.
Colonisers among the natives
Bullfrogs are found all over mainland India, but it is in the unique ecosystem of the islands that it becomes a major threat. Unlike the mainland, resources on the islands are scarce for big animals, while natural calamities are more frequent. The wildlife here has evolved in a miniature setting: there are no large herbivores (the largest is the Andaman wild pig) or large carnivores.
“Islands have fewer species, but their nature make them irreplaceable. They are found no where else in the world... This makes the entire food web in the islands very different from that of the mainland,” says Vasudevan, senior principal scientist at the Centre for Cellular and Molecular Biology, Hyderabad.
The Zoological Survey of India has found that out of the 9,130 marine and terrestrial species discovered so far in the islands, 1,032 species (or 11.30%) are endemic (found only in the Andamans). In the constraints of land, this endemicity increases to nearly 25%, or 816 out of the 3,271 land species. These creatures had evolved to cope with natural disaster, but have little capacity to withstand rapid, human-induced impacts. “There is not much room for redundancy and refuges in these islands,” says Vasudevan.
But the bullfrog is only the latest entrant in the Andamans’ 150-year-old history of invasives, with alien species introduced in waves by the British, Japanese, and ‘mainland’ Indians having gradually colonised many parts of the island territory. These include the elephant(introduced for logging and later abandoned), chital, hog deer, and barking deer (all three for game meat).
In 2013, using satellite imagery, Rauf Ali from the Puducherry-based Foundation for Ecological Research, Advocacy and Learning found that forests with elephants and chitals had suffered significant degradation (Interview Island) compared to places where they were absent (Little Andaman). It’s a one-two punch: elephants knock down trees and strip barks, while chitals prevent regeneration of forests by grazing on seedlings. Invasives have come in all forms to the Andamans. The Japanese introduced the Giant African Snail, one of the 100 worst invasive species as described by the International Union for Conservation of Nature (IUCN), in the 1940s during their three-year occupation. It has now established itself as a major agricultural pest. Meanwhile, about 90% of the fish being bred in ponds are carps and other exotic fish which have even established natural breeding sites outside human-created ponds. Similarly, the islands are home to at least 592 introduced alien plant species, some indirectly pushing endemic plants to the fringe. Away from the obvious economic impact, it is in the sounds of the night that one can perhaps gauge the ecological impact of the invasive bullfrog. Across infested villages, residents say sightings of native species of frogs have reduced. Full grown natives pale in size to even a young bullfrog. Water snakes, a common accompaniment for the paddy farmer, and centipedes are in decline.
But even more worrying signs were found in the gut of the frog. For months, Mohanty and his associates captured and “stomach flushed” contents out of 798 individuals belonging to two native species and the invasive bullfrog. From the gut of the bullfrog came out native frogs, the endemic Andaman blind snake, the endemic emerald gecko, skinks and others. “Adult bullfrogs pose a threat to small endemic vertebrates [from frogs to birds]. Within frog species, it can have a two-pronged impact on the Limnonectes genus of frogs. Bullfrogs not only eat the native frogs, even their diets overlap, indicating a possibility of competition,” he says. It isn’t just their size that works to their advantage. It’s their appetite for meat, even at the tadpole stage. Bullfrog tadpoles are highly carnivorous, preying on other tadpoles (even native tadpoles) heavily.
Controlling invasives
In a few villages, the explosion in population from May onward sees a feast of bullfrogs: skin fried to a crisp, their legs boiled or fried. Here, a kilo (roughly three medium-sized frogs) is sold for ₹60 — the cheapest source of protein in the market. In other places, it is anger that has humans killing the frog. “Whenever I find it on the road, I beat it with a stick. If it jumps, I’ll jump into the paddy field and chase it. One dead frog means one lesser mother laying thousands of eggs,” says a villager in North Andaman, whose name has been withheld as killing bullfrogs is a criminal act under wildlife laws. In Wandoor, a family claims to have killed nearly 50 frogs in July.
However, these are mere dents in a burgeoning population. “It is difficult...I don’t see a way to stop it. The government should think of something. Else, in five years, poora basti bhar jayega [the village will be filled with frogs],” says Krishna Singh at Mohanpur village in North Andaman. He claims to have lost 30 chicks to the frog.
Murmurs of the conflict have started, with the issue being raised by local political representatives. “It really is a big menace. But we have to see how the population stabilises,” says S. Dam Roy, Principal Scientist at the Central Island Agricultural Research Institute, Port Blair, which operates the local agriculture helpline.
Stung by the inflow of invasives, and with the fear that more could come, it was in the serene, undulating plantations that form the CIARI headquarters that a plan was hatched five years ago to start a ₹40-crore bio-security laboratory for quarantine and research. The plan did not materialise.
Globally, invasive species, particularly in islands, are becoming the focus of numerous organisations. The Convention on Biological Diversity has said that invasives have contributed to 40% of all animal extinctions since the 17th century. The IUCN has formulated guidelines for managing invasives specifically in islands, largely involving data collection, community engagement, policy measures and management plans.
Far away from the concerns of scientific papers and environmentalists, in the government offices at Port Blair, there is little panic about invasives. “They are just animals, and nature will find a way to live in harmony,” says Tarun Coomar, Principal Chief Conservator of Forests, who also holds the post of Environment Secretary in the relatively small administration governing the islands.
This confidence is not reflected among the villagers. While many are resigned to the invasion, some suggest commercial harvest for export to South-East Asia, for history has shown that animal populations crash when they have an economic value attached to them.
But for now, it is an unchecked invasion. “Bullfrogs have reached little Andaman, the next frontier is Nicobar. There are other islands they are yet to invade, and we must do everything to stop that. Signs at jetties about the adverse economic impact of bullfrogs and the need to check contamination of fish stocks could be useful,” says Mohanty.
For millenia, the islands, now a Union Territory, were largely disconnected, literally and figuratively, from the mainland. In more ways than one, the landscape here resembles those in Myanmar, Thailand and Indonesia than mainland India.
In ethos too, the disconnect remains. In government offices, officials caution outsiders (whose annual numbers touch 6.5 lakh, as compared to 3.9 lakh residents) to take it slow in the islands: “Ye mainland nahi, yeh Andaman hai [This is not the mainland, this is Andaman].” But it may not stay that way for long. As the croaks of the bullfrog reverberate through the islands, their clamour assumes the urgency of a clarion call — to act before it is too late.
See also
Andaman And Nicobar Islands: Fauna
Andaman And Nicobar Islands: Flora
Andaman And Nicobar Islands: Natural calamities
Andaman and Nicobar Islands: Parliamentary elections
Andaman and Nicobar Islands: Tribes
Census India 1931: The Population Problem in Andaman and Nicobar Islands
