SingaporeOn a grassy strip along the highway, a blur of brown fur moves quickly, a small head popping up every so often to check for danger. It’s a family of seven otters, likely on their way to their den at the Singapore Botanic Gardens. Commuters sitting in evening traffic appear oblivious, likely already accustomed to seeing the charismatic mammals traipsing about this Southeast Asian metropolis of 5.7 million.

It's a far cry from 50 years ago, when Singapore’s rivers were choked with rotting animal carcasses, garbage, and sewage. Smooth-coated otters, native to the area, had disappeared and were in danger of being locally extinct. In 1977, the Singaporean government launched its Clean River Campaign, and in 1998, otters