National parks board establishes Cryptic Painted frog population on Pulau Ubin

The National Parks Board (NParks) moved adult frogs and tadpoles from mainland reserves to Pulau Ubin in Singapore to establish a new breeding population for the Cryptic Painted Frog.

This move aims to protect the vulnerable species from habitat loss, disease, and extreme weather by diversifying its locations.

Because the frogs require water-filled tree cavities to breed, which are rare in the secondary forests of Pulau Ubin, NParks installed 21 artificial phytotelmata, which are water-filled plastic containers equipped with PVC pipes and sticks. Student volunteers from the Youth Stewards for Nature program worked with NParks conservation manager Leroy Alphonso to monitor the frogs over six months. The team used non-invasive bioacoustics, placing four sound recorders and motion-detection cameras across the site to track the frogs' nocturnal calling activity.

They also performed weekly physical checks on the artificial breeding containers to count eggs and identify tadpoles. The researchers found that the frogs' calling activity correlated strongly with egg counts and was more influenced by rainfall and humidity than by air temperature. The team used specialized software to identify the frogs' specific high-pitched chirps, which typically fall between 2 to 4 kHz.

The project successfully demonstrated that sound tracking is an effective way to monitor breeding patterns for shy, elusive species without disturbing them.