OTTERS IN ASIA: SPECIES, CHARACTERISTICS, BEHAVIOR AND REPRODUCTION

OTTERS

Eurasian otter

Otters are expert swimmers and one of the few animals that can catch fish underwater. They are also famous for their playfulness. There are two kinds of otters — land otters and sea otters. Land otters of various kinds are found in small numbers, scattered around the globe, in lakes, streams and swamps. Sea otters are found in north Pacific along the coast of California, British Columbia, Alaska and eastern Russia.

The discovery of a species that lived 6.6 million years ago in southwestern China suggests that ancient otters had "wolf-like" proportions, and weighed roughly 45 kilograms (100 pounds). The creature — whose skull was excavated in Yunnan province — was twice the size of today's largest otters. [Source: Ashley Strickland, CNN, May 2, 2018]

Otters have disappeared from many places they were once plentiful. They have been hurt by hunting, deforestation and erosion, draining of swamps. water pollution and competition from other animals. The surviving number of Eurasian otters is unknown. They are largely gone from many countries but are making a comeback in some places. Their decline is attributed to habitat loss, pollution, depletion of fish and other food sources. DDT is blamed on the disappearance of otters from some parts of Europe. Some otters have been trapped for fur or killed because they have been blamed for taking away fish from fishermen.

Otter Characteristics

Otters have stream-lined bodies that reach lengths of one and half meters (4½ feet), including their powerful, tapered 60-centimeter (two-foot) -long tail. They have short legs with webbed feet and a small head with a cute whiskered face. Their fur is dark-brown, glossy and thick and features ling, silky guard hairs. David Attenborough wrote: “Otters, anatomically, are very like large weasels. Their sharp spiky canine teeth and shearing carnassials that served them so well on land are equally well suited to dealing with slippery fish. They have dealt with he problems of chilling...by developing a very fine fur. Its outer layer is relatively coarse, being made of long guard hairs. Beneath that, however, the fur is thick and so woolly that it traps air and forms very effective insulation indeed.

“Swimmer, needless to say, use their limbs in a very different way from runners. The otters have converted their feet into paddles simply by growing webs f skin between their toes. They have also developed strong muscles at the base of the tail so that they are able too use it like a rudder. The need to breath air, however, is still a major problem for them and they usually have to snatch a breath every half minute or so when they are in the water. Nevertheless, the are much skilled swimmers, so athletic and so bursting with energy, that even with this handicap, they can pursue and out-swim fish.”

Although they have these very effective adaptions, most species of otter spend most of their lives out of water. During the day they are usually asleep in their dens beside a river bank. Even at night, when they do much of their fishing, they tend to rest on he bank for a few hours around midnight, Nor have they lost their skills or taste for hunting.” In Scotland they hunt rabbits and mark land territories with droppings on particularly rocks. They also sometimes hunt in the sea.

Otters are wide ranging animals. They sometimes venture up to 80 kilometers (50 miles) from their den in search of food or a mate. They do no hibernate. Otters are one of the few animals that seems to get a lot of joy out of playing as an adult. Its favorite activity seems to be sliding down muddy river banks.

Otter Behavior

range of the Eurasian otter

Otters generally feed on fish and other water creatures such as frogs, shellfish, crabs and mollusks. Sometime they also eat land creatures such as snakes and mice. Otters prefer to build their dens in river banks. Many dens have their entrance in the water and 25 to 30 foot tunnel that slants upwards to a place above the water level. Sometimes there is also a land exit.

The marking behavior of otters on vegetation and rocks is called sprainting. In areas where the smooth-coated otter, European otter, and small-clawed otter occur together, sprainting occurrs in different areas by each species. Sprainting sites in small-clawed otters are usually high on the bank on flat rocks. Sites for smooth-coated otters are more prominent than those of small-clawed otters. Sprainting sites of European otters are lower on the bank and less frequent than that of other otters. [Source: Timothy White, Animal Diversity Web (ADW) /=]

A study published in British Wildlife in August 2000 reported disturbing evidence of otter cannibalism and infanticide. Post-mortem examinations on 200 otters between 1998 and 2000 showed that 33 of them — almost 17 per cent — had bite wounds inflicted by other otters. These were the result not just of fights between rival territorial males, but also involved cannibalism and even suspected infanticide, according to the Vic Simpson, a veterinary pathologist, and Karen Coxon, a fellow scientist. They found that many of the otters had wounds on face, feet, anus and genitals. Eight of the animals had died directly as a result of the bites. The stomach of one dog otter contained the remains of a four-week old cub.

Simpson said: "We do not know whether these injuries are symptomatic of new and worrying behaviour or just that our population levels have recovered enough for them to become apparent again. But there is no reported evidence of this sort of behaviour happening elsewhere, such as Germany, where the species is also doing well. "What is new is that there is now clear evidence that aggressive behaviour does not just involve males fighting for territories - females are being badly bitten and dying too. It even applies to cubs." One theory is that a Vitamin A deficiency, caused by ingesting pollutants, has caused increased aggression. Mr Simpson, however, was sceptical and suggested that the aggressive behavior could be linked to the gradual recovery of the otter population in Britain prompting fierce competition for territory.

Otters in Asia

Asia is home to three species of otter: Smooth-coated otter (Lutrogale perspicillata), Asian small-clawed otter (Aonyx cinereus) and the Eurasian otter (Lutra lutra)/ The smooth coated otter (Lutrogale perspicillata).

Eurasians otters are found in and around rivers, lakes, marshes and seacoast in Europe, Asia and North Africa. They have a head and body length of 60 to 80 centimeters (inches), with a 30 to 45 (inches) centimeter tail, and weigh six to 12 kilograms. They can be elusive, are largely nocturnal and often live in inaccessible places. In some places they are rarely seen; in other places they are less shy. Females raise one to three cubs alone. The cubs remain with their mother for about a year. Their mothers teaches them fishing skills and provides other tips for survival. Otters generally only mate once a year, in the early spring. The young are raised inside a nest or burrow.

The genus Aonyx is composed of three species known by the the common name “clawless otters.” These species can be found in Africa and Southeast Asia nearly anywhere there is a source of freshwater. The genus is semi-aquatic and hunts in freshwater for crabs, fish, and molluscs. Their weight ranges from less than 3.5 kilograms up to 34 kilograms. All species in Aonyx have reduced or no claws on the front feet — hence their name. Two species are near-threatened and one species is vulnerable on the International Union for Conservation of Nature (IUCN) Red List. [Source: Katie Badwey, Animal Diversity Web (ADW) /=]

The three species of clawless otters are the African clawless otter (Aonyx capensis), the Congo clawless otter (Aonyx congicus), and the Asian small-clawed otter (Aonyx cinereus). The genus Aonyx is a monophyletic grouping, though species and lower level classifications are not fully agreed upon. Asian small-clawed otters have been considered to be in a separate Amblonyx genus. In Bangladesh domesticated otters are used to catch fish.

Asian Small-Clawed Otters

Asian small-clawed otter

Asian small-clawed otters (Aonyx cinerea) are smallest otter species. Also known as Oriental small-clawed otters and small-clawed otters, they are found in rivers and marshland in India, southern China and Southeast Asia and live in family units and eat small aquatic creatures such as crabs and fish. In some places they are kept as pets. They come when called and are playful creatures but keeping them as pets overall is not a good idea/

Asian small-clawed otters are commonly seen in the shallows of freshwater streams and rivers as well as coastal regions. There is often dense foliage nearby, which they use as defensive cover, and which restricts behavioral studies in the wild. Nesting burrows are dug into the muddy banks where they live. They are sometimes seen in rice paddies and found in some coastal areas. Their lifespan in captivity is up to 16 years. [Source: David Hamman, Animal Diversity Web (ADW) /=]

On the International Union for Conservation of Nature (IUCN) Red List, Asian small-clawed otters are listed as Vulnerable. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status. Threats include habitat loss and degradation of the water in their habitats. They are sometimes captured as pets and regarded as pest for eating fish and damaging rice paddies. Natural predators may include crocodiles and snakes

Asian Small-Clawed Otter Characteristics and Diet

Asian small-clawed otters range in weight from 2.7 to 5.4 kilograms (5.9 to 11.9 pounds). Their head and body length ranges from 40.6 to centimeters (16 to 25 inches), with a tail that is of 24.6 to 30.4 centimeters (9.7 to 12 inches) in length. Sexual Dimorphism (differences between males and females) is not present: Both sexes are roughly equal in size and look similar. [Source: David Hamman, Animal Diversity Web (ADW) /=]

Asian small-clawed otters have dark, greyish-brown fur covering most of their body, and a lighter cream coloration on their face and neck. Their claws are extremely reduced, and rarely extend past the digit. The paws are only partially webbed, which allows for more dexterity than otters with full webbing. /=\

Asian small-clawed otters are primarily carnivores (mainly eat meat or animal parts) and mostly eat shellfish and molluscs as well as amphibians and fish. Unlike most otters, they use their forepaws to locate and capture prey, rather than their mouth. The incomplete webbing on their forpaws helps give them the manual dexterity they need to do this. Shellfish, clams, mussels and crabs are snagged by digging in sand and mud at the shoreline. To extract the meat they either crush the shell or let heat from the sun open the shells. Their teeth are broad and strong and adapted for such crushing duties.

Asian Small-Clawed Otter Behavior and Reproduction

Asian small-clawed otter range

Asian small-clawed otters are natatorial (equipped for swimming), diurnal (active during the daytime), motile (move around as opposed to being stationary), sedentary (remain in the same area), and social (associates with others of its species; forms social groups). They live in extended family groups with about twelve individuals and are often seen playing on mud banks and in the water, and on slides.In captivity they have been observed juggling pebbles and other small objects. [Source: David Hamman, Animal Diversity Web (ADW) /=]

Asian small-clawed otters sense and communicate with vision, touch, sound and chemicals usually detected by smelling. They are social and vocal animals. Twelve different vocalizations have been identified in this species, not counting simple alarm vocalizations. Communication also takes places with tactile and chemical cues and body language such as social grooming, hormonal changes, and posturing.

Asian clawless otters form monogamous pairs for life. The estrous cycle is 28 days with a three day period of estrus. They engage in year-round breeding and may produce two litters annually. The average gestation period is 60 days, the average number of offspring is two but litters up six occur, and the average weaning age is 80 days.

Parental care is provided by both females and males. Males assist with nest building before birth and food procurement after birth. Newborn young are relatively undeveloped. At birth, they weigh around 50 grams and have closed eyes. Their weigh increases to around 600 grams when they are two months old. Eyes open at around 40 days, and pups can be seen outside the den after ten weeks. Young begin eating solid food after 80 days, and start swimming after three months. /=\

Smooth-Coated Otters

Smooth-coated otters (Lutrogale perspicillata) are found throughout much of southern Asia, south of Himalayass, from India in the west to Vietnam in the east and southward as far as Sumatra and Java. There is a a small isolated population in the marshes of Iraq. They typically live four to 10 years years. One lived in captivity for 20 years and four months.[Source: Timothy White, Animal Diversity Web (ADW) /=]

Smooth-coated otters live in tropical and temperate, freshwater environments in lowlands, forests and aquatic biomes such as lakes, ponds, rivers, streams. temporary pools, wetlands, swamps and areas adjacent to rivers and other water bodies. They prefer coastal mangrove forests, peat swamp forests, freshwater wetlands, large forested rivers, and rice paddies. Although they adapted for water, smooth-coated otters are comfortable on land and can travel long distances overland in search of suitable habitat. They shelter in shallow burrows and piles of rocks or driftwood. Some build permanent burrows near water with an underwater entrance and a tunnel that leads to a chamber above the high-water line, much like American beaver. In Malaysia smooth-coated otters are more abundant in mangrove forests than in river systems. /=\

smooth-coated otters

On the International Union for Conservation of Nature (IUCN) Red List smooth-coated otters they are listed as Vulnerable; US Federal List: classifies them as Threatened. In CITES (Convention on International Trade in Endangered Species of Wild) they are in Appendix II, which lists species not necessarily threatened with extinction now but that may become so unless trade is closely controlled.

These otters are threatened by loss of wetland habitats to large-scale hydroelectric projects, settlements, agriculture, poaching, and contamination of waterways by pesticides. They are protected in India under the Wildlife (Protection) Act, 1972, and are listed as endangered. There is evidence that the range and population of these animals are shrinking due to loss of habitat and intensive trapping. Although no conclusive studies have been conducted it has been hypothesized that the mortality rate of smooth-coated otters is correlated with the abundance of fish. Natural predators include various species of crocodiles. Medium-sized cat species and large birds of prey may feed on young otters.

Smooth-Coated Otter Characteristics and Diet

Smooth-coated otters are the largest otters in southeast Asia. They range in weight from seven to 11 kilograms (15.4 to 24.2 pounds) and have a head and body length that ranges from one to 1.3 meters (3.3 to 4.3 feet). Their tail is with a 37 to 43 centimeters (15 to 17 inches) long. Sexual Dimorphism (differences between males and females) is present: Males are larger than females. [Source: Timothy White, Animal Diversity Web (ADW) /=]

The fur of Smooth-coated otters is shorter and smoother than other otters, and looks shiny and velvety. They have short tightly packed under fur and longer water repellant guard hairs. The under fur measures 6 to 8 millimeters; the guard hairs are 12-14 millimeters long. The fur is light to dark brown on the back and light brown to almost gray on their undersides. Smooth-coated otters are distinguished from other otters by their rounder heads, prominent naked noses, and flattened tails. Their noses resemble an upside down v, or a distorted diamond. Like other otters, they have webbed feet and strong dexterous paws that are armed with sharp claws. /=\

smooth-coated otter range

Smooth-coated otters are carnivores (mainly eat meat or animal parts) and primarily piscivores (eat mainly fish). Their food includes birds, mammals, amphibians, reptiles, fish, eggs, mollusks terrestrial worms, aquatic worms, insects, earthworms, crustaceans, frogs, water rats, turtles, large birds, and fish. Fish make up 75 to 100 percent of the diet. These otters often hunt in groups, driving schools of fish together for easy capture.

Fishermen in India and Bangladesh use this group hunting behavior to train them to herd fish into nets. A single adult consumes about one kilogram of food per day in captivity. A group of otters in the wild have a feeding territory of seven to 12 square kilometers. In the Terai region of southern Nepal, during the monsoon season, they migrate into flooded swamp areas to take advantage of fish population booms there. The otters breed there. When the swamps shrink and the fish return to the permanent rivers the otters so also.

Smooth-Coated Otter Behavior and Reproduction

Smooth-coated otters are terricolous (live on the ground), fossorial (engaged in a burrowing life-style or behavior, and good at digging or burrowing), natatorial (equipped for swimming), motile (move around as opposed to being stationary), sedentary (remain in the same area), territorial (defend an area within the home range) and social (associates with others of its species; forms social groups). They frequently hunt in groups (See Above) and have a feeding territory of 7-12 square kilometers. [Source: Timothy White, Animal Diversity Web (ADW) /=]

Smooth-coated otters sense and communicate with vision, touch, sound and chemicals usually detected by smelling. They use visual cues, such as body postures to communicate and leave scent marks placed so others can smell and taste them. They have a pair of scent glands at the base of the tail, which they use to mark vegetation, flat rocks, or shorelines near feeding areas.

Smooth-coated otters form strong monogamous pairs. Although males are larger, it is females that dominate the pair. These otters engage in seasonal breeding once a year, from occurs from August to December. The number of offspring ranges from two to five. The gestation period ranges from 61 to 65 days. The average weaning age is 130 days. The cubs disperse at about one year of age. On average males and females reach sexual or reproductive maturity at two years.

Smooth-coated otters are altricial. This means that young are born relatively underdeveloped and are unable to feed or care for themselves or move independently for a period of time after birth. Two to five cubs are born in a litter, blind and helpless. At thirty days, the cub's eyes open, and by sixty days, they can swim. Smooth-coated otters give birth to and raise their young in a burrow or shelter near water, which they excavate themselves or , or they assume an abandoned one. Sexual maturity is reached at two years. /=\

During the pre-weaning stage provisioning and protecting are done by females. During the pre-independence stage provisioning and protecting are done by males and females. The post-independence period is characterized by the association of offspring with their parents. Unlike other otters, smooth-coated otters form small family groups consisting of a mated pair with up to four offspring from previous seasons. The male is allowed to join the group after the cubs are weaned, and he helps provide the cubs with food. /=\

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated January 2025