‘Explosive breeding’ of invasive species found on Malaysia island for first time
As night settled across a large island in Southeast Asia, several golden creatures gathered near a puddle and began “calling very loudly” as part of an “explosive breeding” event. The sound caught the attention of nearby scientists — and for good reason.
The animals turned out to be the area’s first record of an invasive species.
A team of researchers visited Borneo island in April as part of a project “to expand the Kinabalu area of UNESCO Global Geopark” in Sabah, Malaysia, according to a study published Sept. 11 in the peer-reviewed journal Check List.
During some nighttime fieldwork, researchers heard a “series of high-pitched ‘kriiiiick’ calls” and tracked the sound to some frogs near a shallow grassy puddle, the study said. The team caught a few frogs and quickly identified them as dark-sided chorus frogs.
Dark-sided chorus frogs, or Microhyla heymonsi, are an “easily” recognized species of “tiny, stocky, tear-shaped frog with a small, flattened head,” researchers said. The species has “wide range across the Asian mainland” but had not been found on Borneo island — until now.
The dark-sided chorus frogs in Sabah “were very common but challenging to collect because they were hidden in the tall grasses” and relatively small, the study said. Photos show a few of the frogs after being caught.
“Given this new population was recorded from a highly disturbed agricultural area, we believe that the frogs were accidentally introduced into Borneo through anthropogenic activities, possibly through the import of farming materials,” researchers said.
The dark-sided chorus frogs appeared “to be well established and not a recent introduction into the area as the frogs were abundant and explosive breeding was taking place after the rains,” the study said.
Researchers don’t know what impact the invasive species will have on the local ecosystem.
“Other herpetologists working in Borneo should keep a lookout when conducting field surveys to monitor the presence of this species to keep track of their spread,” the study said. “Based on what is known regarding the ecology of the species and its adaptability to human-modified landscapes, its spread across Borneo appears inevitable and can be expected in the near-future.”
Borneo is an island shared between Brunei, Indonesia and Malaysia and known for its biodiversity.
The research team included Evan Quah, Aderina Dukit, Alvinus Joseph and Paul Imbun.
This story was originally published September 12, 2025 at 3:10 PM with the headline "‘Explosive breeding’ of invasive species found on Malaysia island for first time."
