Our Post-Release Monitoring (PRM) team met a small mammal residing in the river of Kehje Sewen Forest. Who could it have been? Any guesses? If you said the Asian small-clawed otter (Aonyx cinereus), you are right!

In Indonesian, this adorable river resident is commonly referred to as sero ambrang. They are known for their cute faces and exceptional swimming skills. While found throughout Southeast Asia, in Borneo, these otters are specifically called dengen. Some distinguishing features of the sero ambrang compared to other members of its family are its small body size and short claws, making it the smallest otter.

They are carnivores that prefer to eat fish, crabs, shrimp, clams, snails, and even amphibians. Their short legs and partially webbed toes make it easy for them to swim and hunt in the water and use their forepaws to catch prey, in contrast to other otters which use their mouths to catch prey. They also use their forepaws to dig into mud and sand in search of shellfish. Their agility and manoeuvrability not only help them catch prey, but also evade predators such as crocodiles and snakes.

READ MORE: RARE SERO AMBRANG FOUND AT JUQ KEHJE SWEN

Sero ambrang is a vocal animal, using various sounds to communicate and coordinate with other individuals, especially when feeding or when a threat is present. Their calls often sound like a whistling “Nyitt Nyitt Nyitt” noise. They are known as crepuscular animals, meaning they are most active during dusk, dawn, and bright moonlit nights. Its frequent hunting and movement are due to its high metabolism, requiring it to consume over 20% of its body weight in food per day. Interestingly, they often like to wash their food before eating.

Unlike many animals that live in groups, the sero ambrang is a social, but monogamous creature. Pairs may stay together for life and will both help with raising their young. When the female is ready to mate, she will rub her body more frequently, releasing scent excretions from glands at the base of her tail and marking her territory on nearby wood or vegetation. This body-rubbing behaviour is also common after eating.

READ MORE: JELARANG BILALANG: THE SHY SQUIRREL

The distribution of the sero ambrang is extensive, including China, India, and Southeast Asia. For Indonesia in particular, it is found in Java, Sumatra, and Kalimantan. However, its population is declining across its range due to habitat destruction and exploitation, river pollution from pesticides, and reduced food availability. 

In our rapidly changing world, most mammals are facing challenges finding food and raising their offspring. We hope the population of sero ambrang in Kehje Sewen continues to thrive as they are an integral part of the forest ecosystem.

Text by: PRM Team at Camp Lesik, Kehje Sewen Forest, East Kalimantan