Borneo – A Frogger’s Dream

The following is an article I wrote for the Frog and Tadpole Group's (FATS) annual colour edition of the newsletter Frogcall for December 2012. The draft title of "Borneo - A Frogger's Wet Dream" was deemed inappropriate for the family audience of FATS.

The articles I’ve written in the past for Frogcall have a common theme: travelling somewhere interesting and looking for frogs, often along with fellow FATS member George Madani. In April 2012, hungering for new adventure, we took this strange obsession to a new extreme, choosing to spend a month together in Borneo. To many of the frog-mad readers of this publication, this decision needs no further explanation. Why not? But for those not so well acquainted with the island in question, allow me to briefly explain our choice. 

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.  

The Black-spotted rock frog (Staurois latopalmatus) waves with its back feet to communicate.

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. 

A male Rough Guardian Frog (Limnonectes finchii) carrying a mass of tadpoles on his back.

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! 

Needing no further introduction: the Bornean Horned Frog, Megophrys nasuta

The second ‘icon’ was Wallace’s flying frog (Rhacophorus nigropalmatus). Borneo is overrun with ‘flying’ animals: species of geckos, dragons, squirrels, snakes, and of course frogs. There’s also a very strange mammal called the Colugo or Flying Lemur – though it’s no lemur, occupying its very own order (Dermoptera). These animals all use flaps of skin, supported by fingers or limbs or, in the case of the reptiles, ribs, to slow and control a glide from a tree. In the case of frogs, there are several species in the rhacophorid family that have extensive webbing between the fingers to a greater or lesser degree. In the case of Wallace’s flying frog, this webbing is immense. Eventually, we found this spectacular species above a small muddy pool used by pigs as a wallow – and also by the frogs as a breeding site.

Wallace’s Flying frog (Rhacophorus nigropalmatus) showing off its webbing 

While space permits only a brief mention of the other animals we spotted, suffice to say we were very very lucky and equally pleased. We got good looks at all those other types of flying animals. Plenty of snakes. Macaques, leaf-monkeys, proboscis monkeys, gibbons. The 70 cm long giant squirrel and the mouse-sized pygmy squirrel and several other types in-between. Tarsiers galore, Slow loris, even a Pangolin. Hornbills of several varieties. Large and beautiful insects, snails, millipedes. Shrews and otters and mouse-deer and civets, including the vegetarian binturong. Even an orang-utan and a bull elephant. 

Truly, Borneo is a paradise for the keen naturalist. Altogether we saw more than 50 species of frog alone, representing a vast variety of shapes, sizes, colours and life-history strategies. Though the conditions can be challenging, the reward in observing the myriad forms of life is unquestionably worth the effort.

In the shadow of Mt Kinabalu, the tallest peak in south-east Asia, we found the spectacular Mossy Treefrog (Philautus macroscelis)

If you’re interested in browsing many more photos of the bizarre and beautiful animals from David and George’s trip, head to the photo gallery here