'It's detective work': Finding and counting Singapore's otters
More than 20 otter watchers trawled parks and waterways over two months, photographing the animals for the third population census in Singapore.
Otters from the Four Points family. (Photo: Ang Chiah Sin)
SINGAPORE: Since 2017, Ms Marjorie Chong has loved watching otters. She’s an active member of the Otter Working Group, and usually goes to watch the semiaquatic animals two to three times a week.
But there can be too much of a good thing – she once spent about 400 hours looking for otters over two months.
“The two months felt very long,” Ms Chong said with a laugh. “But we believed in it.”
She and 20 other otter watchers were helping to collect data for Singapore’s third population census of smooth-coated otters, photographing them and noting down relevant information.
That data was then verified by Ms Michelle Tan, who was working on the census for her final-year project as a life sciences student at the National University of Singapore (NUS). She submitted the project in April 2025.
The census is undergoing scientific review and will be published later this year.
WHERE THE WILD THINGS ARE
Ms Tan was new to otter watching when she embarked on her final-year project, so the first step was to receive an orientation from those who were more experienced.
They are familiar with where the otters might be, but even then, the creatures could prove elusive.
“A refrain that you hear often is, oh the otters, they are everywhere … but when you actually count them, (they are) not that easy to find,” said Ms Chong.
A sighting can lead to many posts on social media, but that may really just be one group of otters. The animals often move around within their so-called home range, which can be quite large.
“I urge you, one day, to just go and look out for otters when you don’t know where they are, and see whether you can find them,” she said.
Despite a few watchers tracking an otter family at Bishan-Ang Mo Kio park for two days before CNA’s interview, they were nowhere to be found on the day itself.
“We had no luck today … I was checking the drains and the holts, the places that we know they have lived before,” said Ms Tan.
That day, she could only find otter spraint, or faeces, near one of the holts. Otters use faeces to mark their territory.
It was “relatively fresh” at the time, with flies buzzing around and a discernible smell, but no otters were around.
“That’s the only thing I saw,” she said. “It’s detective work.”
Ms Tan used those skills to find the elusive otter family at Changi Bay Point during the census, when she realised there was a “strong smell of spraint” in the air.
Using her binoculars to look into a small, narrow space under a road, she found the otters that were just waking from their afternoon nap.
NO PICTURE, NO COUNT
Just spotting otters was not enough for them to be added to the count, however, especially if they were spotted swimming in a canal.
“You have to wait for the otters to come up on land first, because when they are in the water, you can’t tell how many there are, maybe one is underwater,” said Ms Tan.
There must also be clear photo or video evidence, so that someone who sees the image or clip can count and verify the number of otters.
Ms Chong recounted an incident where she was following an otter family near Lower Seletar. She knew there was a drain that the otters would need to hop over one by one, and thought a video of that would be perfect for the census.
“There I am counting … as I'm filming number 10, one of them hops over the other way, and then they start doing this (back and forth) over the drain,” she said.
“So that footage is no count – it’s zero.”
When submitting a photo or video, the date, time and location of the group should be reported, along with the total number as well as the breakdown between adults and pups.
Such information helps to determine whether it was the same family that was spotted. This prevents double-counting.
Unique identifiers such as injuries, scars or chipped teeth also help to identify an otter and its family.
Multiple sightings of a group would need to be verified before it can be included in the census.
“If there are some otter families that cannot be differentiated even with all these robust criteria, then from these remaining families … we just take the largest family, we include it in the census,” said Ms Tan.
WHY IS A CENSUS NEEDED?
While there are dozens of resident otters now, it is thought that otters disappeared from Singapore by the 1970s because of habitat loss, degradation and pollution as the country quickly urbanised.
After significant efforts to improve the cleanliness of Singapore’s waterways and waterbodies, the otters returned in the 1990s and found enough food and places to rest.
Naturally, the population has increased, and so has human-otter interaction.
“We realised that people aren’t used to wildlife in their midst,” said Mr N Sivasothi, a senior lecturer at NUS' Department of Biological Sciences.
“Getting an idea of how many, where they are, what kind of spaces they're using, what's the average litter size – these are all basic questions which need to be answered, when we want to appreciate how to coexist with them in a city,” he said.
The first census was conducted in 2017 to find out more about the otters. As the population continued to increase, a second one was conducted in 2021, before another in 2024.
In recent years, there have been media reports of otters biting humans or eating fish in ponds.
Last month, after an otter entered some homes in the Lentor and Mayflower neighbourhoods, the National Parks Board told CNA it is exploring measures to reduce conflict, including translocation and population control measures such as sterilisation.
CNA understands that such wildlife birth control methods could include surgery and contraceptives.
Mr Sivasothi said sterilisation has been a topic of ongoing discussion since 2023.
“If there are cases where (a group is) persistent in a space, and the personality of the group is one which is going to heighten conflict, then will there be a time when we run out of options?” he said.
For example, otters tend to be more protective when there are pups in the family.
But sterilisation is not something that NParks would embark on lightly, said Mr Sivasothi, adding that there needs to be an understanding of the ecology and the specific instance when sterilisation might be helpful.
“You can't just respond emotionally, and then we have other problems you create, long term,” he said.
“BE KIND AND LEARN MORE”
He added that it is natural to have a diversity of responses from humans when it comes to coexisting with wildlife. Some might find otters cute, while others think they are a nuisance.
“You can’t ignore human attitudes,” he said. But education and outreach can help to address or overcome fears and concerns.
To those who feel that otters are encroaching on their space, he asked them to show some kindness.
“I think we all profit from (having a) city in nature. It’s definitely quite critical for health and wellness, our feeling of happiness in the city,” he said.
Wildlife is part and parcel of that. “Be kind and learn more,” he said.
There should be some give and take. Humans prevent wildlife from accessing some spaces, and can make adjustments for them in other areas.
“We are not indifferent to the needs of people. In fact, that's quite uppermost in our mind,” said Mr Sivasothi.
“But if we work together, we can work out situations where they have a much more enriched life with nature around them, and give some space for these creatures to exist.”
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