SINGAPORE, Feb. 18 -- Singapore has completed its third national census of smooth-coated otters, a painstaking effort that volunteers describe as "detective work," involving hundreds of hours spent tracking the elusive animals to build a clearer picture of their population.

The census, which is currently undergoing scientific review, relies on a network of dedicated otter watchers who help collect data by photographing the animals and noting down their location and family size.

But as volunteer Marjorie Chong explains, it's not as simple as it sounds, CNA reported.

"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," she said, recounting one census p...