Smooth-coated otter

Appearance

The smooth-coated otter is a relatively large otter, from 7 to 11 kg in weight and 59 to 64 cm in head-body length, with a tail 37 to 43 cm long. It is distinguished from other otter species by its more rounded head and a hairless nose in the shape of a distorted diamond. Its tail is flattened, in contrast to the more rounded tails of other otters. Its legs are short and strong, with large webbed feet bearing strong claws. As its name suggests, it has unusually short and sleek fur; this is dark to reddish brown along the back, while the underside is light brown to almost grey in color. Females have two pairs of teats.

Distribution

The smooth-coated otter has been recorded in Pakistan, India, Nepal, Bhutan, Bangladesh, southwest China, Myanmar, Thailand, Vietnam, Malaysia, Singapore, Indonesian islands of Borneo, Sumatra and Java, and Brunei. An isolated population is also found in the marshes of Iraq.

Behavior

Smooth-coated otters are social and hunt in groups. They are mainly diurnal, and have a short lull in activity during midday.

They spend the night in dens dug in dense vegetation, under tree roots, or among boulders. They use scent to communicate both within the otter species, and with other animals. Each otter possesses a pair of scent glands at the base of the tail which are used to mark land or objects, such as rocks or vegetation, near feeding areas in a behavior called sprainting. They also communicate through vocalisations such as whistles, chirps, and wails.

Some may construct permanent holts near water, in a layout similar to that of a beaver dam, with an underwater entrance and a tunnel that leads to a nest above the water.

Habitat

It occurs in areas where fresh water is plentiful — wetlands and seasonal swamps, rivers, lakes, and rice paddies. Where it is the only occurring otter species, it lives in almost any suitable habitat. But where it is sympatric with other otter species, it avoids smaller streams and canals in favour of larger water bodies.
Although it is often found in saltwater near the coast, especially on smaller islands, it requires a nearby source of fresh water.

Reproduction

Smooth-coated otters form small family groups of a mated pair with up to four offspring from previous seasons. Copulation occurs in water and lasts less than one minute.

So long as the food supply is sufficient, they breed throughout the year, but where otters are dependent on monsoons for precipitation, breeding occurs between October and February. A litter of up to five pups is born after a gestation period of 60 to 63 days. However, on 14 June 2014, a smooth-coated otter called Ping at Wingham Wildlife Park in the UK gave birth to a litter of seven young. The mothers give birth to and raise their young in a burrow near water. They may either construct such a burrow themselves, or they may take over an abandoned one. At birth, the pups are blind and helpless, but after 10 days, their eyes open, and they are weaned at about three to five months. They reach adult size at about a year of age, and sexual maturity at two or three years.

In Singapore, it was discovered that female Asian small-clawed otters interbred with male smooth-coated otters, resulting in the first documented case of hybridization between otter species in the wild. The resulting offspring and their descendants bred back into the smooth-coated otter population, but maintained many of the genes found in their small-clawed otter ancestors. Today, a population of at least 60 of these hybrid otters exists in Singapore, but the question remains as to how widespread the hybridization is between these two species actually is, and the resulting effects it has.

Food

Fish comprise over 70% of their diet, but they also eat reptiles, frogs, insects, crustaceans, and small mammals. Especially in areas where other species of otter are also found, they prefer larger fish, typically between 5 and 30 cm in length. They sometimes hunt in groups of up to 11 individuals.

In the Kuala Selangor Nature Park, an otter group was observed hunting. They formed an undulating, slightly V-shaped line, pointing in the direction of movement and nearly as wide as the creek. The largest individuals occupied the middle section. In this formation, they undulated wildly through the creek, causing panic‑stricken fish to jump out of the water a few metres ahead. They suddenly dived and grasped the fish with their snouts. Then they moved ashore, tossed the fish up a little on the muddy part of the bank, and swallowed it head‑first in one piece.

A group of otters can have a feeding range of 7 to 12 km2. A single adult consumes about 1 kg of food per day in captivity.