Borneo is a big island in South-east Asia, nestled amongst the islands of Indonesia, Malaysia and the Philippines. It’s separated from Australia’s biogeographic region by the ‘Wallace line’ – reflecting a very different evolutionary history. In terms of frog assemblages, without delving into the murky waters of frog systematics, this means that while there are some frogs in Borneo that are similar to ours taxonomically, many others are quite unrelated.
For example, the microhylid family is well represented in both regions while the rhacophorid family is diverse in Asia but is not found at all Australia. So, being fairly familiar with what Australia has to offer, we were now heading into a region filled with animals completely new to us. We were looking forward to being clueless as to what we were seeing. That, and the fact that it’s a big island covered in hot, wet rainforest filled with animals and so what’s not to love?
Within hours of landing on the island we were in the rainforest after nightfall following tracks and streams and loving every minute, our dreams coming true. This was more-or-less how we would spend the next month. We rushed around in frenzy, looking at each new animal, admiring its novelty, taking some photos, pondering its identity, then rushing only a few steps further before some new fascinating subject was caught in the beam of a torch. It soon became overwhelming. Without being overwhelming myself, I’ll try to condense a few highlights of the frog fauna that we saw.
There’s the tree-hole frog (Metaphrynella sundana), a microhylid that breeds in small hollows in tree trunks that collect a little water. The tadpoles of another microhylid (Microhyla nepenthicola) live in the digestive fluids of carnivorous pitcher-plants. There’s the file-eared frog (Polypedates otilophus), with its beautiful tiger-striped legs and flanks, named for the sharp, serrated bony projections above the tympana (we discovered that this frog had a peculiar, strong stink when handled). We saw charming little Black-spotted rock frogs (Staurois guttatus) and their congeners the rock-skippers (S. latopalmatus) – frogs that live on and around waterfalls and signal to each other with waves of the back feet.
The giant river frogs (Limnonectes leporinus) which can grow to 15 cm long, eat anything they can fit in their mouths, and in turn and can be bought at village markets as a delicacy. Tree toads (Pedostibes hosii) that, despite their ordinary appearance, climb many metres up trees to call for mates. Also adept climbers are the slender toads (Ansonia spp.) with their long graceful arms and legs. The jade frog (Rhacophorus dulitensis) – a carved jewel. The guardian frogs (Limnonectes finchi and palavanensis); the male of which carries a mass of squirming tadpoles on his back. I could go on.
If, like me, you ever pored over a book on frogs of the world as a child there’s little doubt that you’ve seen photos of two particular iconic frogs found in Borneo. The first we came across on only our second night – the Bornean Horned Frog (Megophrys nasuta). The legendary camouflage of this frog doesn’t help it stay hidden at night, when its eye-shine stands out like a beacon. Stumbling across three individuals easily was very lucky, as finding the frog by its call is frustrating in the extreme – it only makes its honking call once every few minutes. We were surprised to find that the ‘nose’ and other sharp-looking projections on this frog’s head are soft and fleshy!
Continue reading (Incl. Pics) at: Borneo – A Frogger’s Dream.