Borneo amphibians

Meet Borneo’s organic barometers

Leaping their way through Borneo’s dense rainforest vegetation, frogs are the ‘forest’s barometers’. Abundant and easy to observe, their sensitivity to ecological and climate changes makes them excellent indicators for assessing forest condition.
	© WWF/David Bickford
Caption: In 2008 scientists found out that the up to 7cm long Bornean flat-headed frog (Barbourula kalimantanensis) is the world?s first lungless frog. Instead of lungs, this unique species breathes entirely through its skin. Other organs can be found in the place lungs would normally be, which makes the overall appearance of the frog flatter. As well as a larger surface area with which to absorb more oxygen, scientists believe this flatter and more aerodynamic shape allow the frogs to maneouvre more capably in the fast flowing streams the species inhabits in the Kalimantan rainforest, in the Heart of Borneo. The species was first discovered in 1978 and is currently listed as Endangered on the IUCN Red List of Threatened Species. It is known only from two locations in the middle of the Kapuas River Basin, where the species is threatened by pollution from mining activities.
© WWF/David Bickford

Amphibian distribution on Borneo

While amphibians are found all over Borneo, their distribution on the island is far from uniform. Around 2/3 of all known Borneo amphibian species are found in Gunung Mulu National Park (Sarawak, Malaysia), including the visually striking Wallace’s flying frog (Rhacophorus nigropalmatus). This large species has black, green and yellow patterns, and characteristic webbed feet that allow it to glide from one tree to another. The only time it’s found on the ground is during mating, when it constructs a bubble nest.

Some species show very restricted ranges, such as Philautus saueri, which is only found in around 5 locations in Sabah, Malaysia. This species has the unique habit of placing its eggs and larvae in the receptacles of pitcher plants (Nephentes species).

Creative solutions for survival

Some frog species lay their eggs along rivers, or store them in tree cavities where rainwater has accumulated, sometimes –up to 4 metres from the ground. Such is a technique developed by the lowland tree frog (Rhacophorus harrissoni), found below 250 m in altitude.

Much less conspicuous than its giant relative, the Malayan horned frog or horned toad (Megophrys nasuta) blends with the surrounding vegetation.

By changing its colour, it mimics the colour of leaves on the forest floor. This frog’s physical characteristics help it to hide - sharply pointed ‘horns’ above each eye reinforce its camouflage.

Amphibians in all sizes

The sheer variety of forms and adaptations seen in this wildlife group are impressive. For example, amphibians range in size from the tiny sharp-snouted bush frog (Philautus ingeri) - about 3.6 cm in length for males - to the giant river toad (Bufo juxtasper) – which grows up to 30 cm.

On average, 3 new species are discovered each month in the Heart of Borneo

Between 1995 and 2010 more than 600 species have been discovered - that is 3 species each and every month.


	© Alexander Haas
Newly discovered Borneo tree frog (Rhacophorus gadingensis).
© Alexander Haas

Amphibian discoveries in the Heart of Borneo

  • Kalophrynus eok, a new frog species found in the Kelabit Highlands of Sarawak (North Central Borneo). These ground dwelling animals are also called ‘sticky frogs’ as they secrete a sticky, poisonous mucus when attacked.

  • Philautus erythrophthalmus, the dwarf red-eyed tree frog from Sabah, discovered at 1,550 m above sea level in a montane oak forest. Species of this genus are unusual as tadpoles don’tdevelop in water.

  • Ansonia anotis, a species of the Ansonia toad group found in the highlands of Sabah. In contrast to other Ansonia toad, this new species doesn’t have a hearing organ and the tadpole stage has a distinct abdominal sucker, which it may use for climbing.

  • The discovery of the Bornean flat-headed frog in the middle of the Kapuas River basin some years ago was quite spectacular, since this species represented a family of frogs previously unknown in Borneo. But this species may be lost before we get a chance to get to know it asthe area where it occurs is highly disturbed due to illegal gold mining.

  • A colour-changing flying frog was found 1,650m above sea level in Gunung Mulu National Park, Sarawak. The species is known only from the Tapin Valley near a small stream in the area, making it highly endemic. Tiny, with males growing to just 3.5cm, the Mulu Flying Frog, as it is commonly known, has a small pointed snout. The species has bright green skin at night but changes colour to display a brown hue during the day.
	© Stefan Hertwig
This Mulu Flying Frog was found 1,650m above sea level in Gunung Mulu National Park, Sarawak, in the Heart of Borneo. The species is known only from the Tapin Valley near a small stream in the area, making it highly endemic.
© Stefan Hertwig
Bongon whipping frog. East Sabah. Borneo. Malaysia. 
	© WWF / Gerald S. CUBITT
Bongon whipping frog. East Sabah. Borneo. Malaysia.
© WWF / Gerald S. CUBITT
	© © Dr Indraneil Das
This tree frog, Polypedates chlorophthalmus, is one of the species new to science in Borneo.
© © Dr Indraneil Das

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