Saturday, September 19, 2009

Vanishing Species: Indian Otters

Sunday article by Mohan Pai

Indian Otters
Mustelids


Photo: courtesy: K. Pichumani

Playful creatures, a group of Otters is called ‘romp’, being descriptive of their playful nature.

Otters are semi-aquatic, fish-eating mammals. The otter subfamily Lutrinae forms part of the family Mustelidae, which also includes weasels, polecats, badgers, as well as others. With thirteen species in seven genera, otters have an almost worldwide distribution. They mainly eat aquatic animals, predominantly fish and shellfish, but also other invertebrates, amphibians, birds and small mammals.An otter's den is called a holt or couch. A male otter is a dog (otter), a female a bitch (otter), and a baby a whelp or pup. The collective nouns for otters are bevy, family, lodge or romp, being descriptive of their often playful nature, or when in water raft.

India is home to three species of otters: the Eurasian otter (Lutra lutra), the smooth-coated otter (Lutra perspicillata) and the small-clawed otter (Amblonyx cinerous). Just 50 years ago, the smooth coated otter, also referred to as the smooth Indian otter, was widespread in the country while both Eurasian and the small clawed otter (earlier called the clawless otter) were absent from central India, but found in broad bands in the Himalayas and the ghats in the south. It is essentially an otter of cold hill and moutain streams and lakes. Today, these elegant creatures are confined only to protected areas and zoos. If there are any unknown pockets outside, they are unlikely to survive.What happened to otters was quite simple. Found in rivers, lakes and other wetlands, they competed with human beings for fish, their main diet, and lost. Pollution poisoned their food and habitat. Lakes and wetlands were drained for agriculture. In fact the trade of otter skins has been going on for hundreds of years in South East Asia. According to a wildlife trade survey done in Thailand, an otter skin can be sold for $90-$100 to leather factories and considered the best leather to make jackets. It is also believed that otter fat was good for rheumatism, and dried otter penis can fetch up to $50 per inch in Mandalay, and in Myitkyina in the Kachin state. A researcher from the Centre for Ecological Sciences, Bangalore, V. Meena, found nomadic tribal herb collectors from Haryana trapping otters in the Palani hills of Tamil Nadu to sell the oil and skin and of course, eat the flesh, while they were at it.

Characteristics
Otters have long, slim bodies and relatively short limbs, with webbed paws. Most have sharp claws on their feet, and all except the sea otter have long muscular tails.They have a very soft, insulated underfur which is protected by their outer layer of long guard hair. This traps a layer of air, and keeps them dry and warm under water.Many otters live in cold waters and have very high metabolic rates to help keep them warm. In summer, in the Himalayas many otters go up the streams and torrents ascending to altitudes of 12,000 ft or more. Their upward movement probably coincides with the upward migration of carp and other fish for purposes of spawning. With the advent of winter they come down to the lower streams.For most otters, fish is the primary staple of their diet. This is often supplemented by frogs, crayfish and crabs. Some otters are expert at opening shellfish, and others will feed on available small mammals or birds. Prey-dependence leaves otters very vulnerable to prey depletion.Otters are very active, chasing prey in the water or searching the beds of rivers, lakes or the seas. Most species live beside water, entering it mainly to hunt or travel, otherwise spending much of their time on land to avoid their fur becoming waterlogged. The sea otter does live in the sea for most of its life.Otters are playful animals and appear to engage in various behaviors for sheer enjoyment. Different species vary in their social structure, with some being largely solitary, while others live in groups – in a few species these groups may be fairly large.

Range map of Otters (IUCN)

Major Threat(s): The aquatic habitats of otters are extremely vulnerable to man-made changes. Canalisation of rivers, removal of bank side vegetation, dam construction, draining of wetlands, aquaculture activities and associated man-made impacts on aquatic systems are all unfavourable to otter populations (Reuther and Hilton-Taylor 2004). In South and South East Asia, the decrease in prey species from wetlands and water ways had reduced the population to an unsustainable threshold leading to local extinctions. The poaching is one of the main cause of its decline from South and South East Asia, and possibly also from the North Asia. (IUCN Red List)

References: Wikipedia, IUCN Red List, S. H. Prater (the book of Indian Animals), Aniruddha Mookerjee in the Hindu.

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