Sarawak: Around the Frog Pond

The frog pond in Kubah National Park deserves its name about as well as any other landmark on the planet.  At night, it positively drips with frogs, of a variety of species, all looking for mates.  It's a great place even for rank amateur frog-finders like me, and to prove it here are some images of five species that I found (admittedly with help) over the course of two nights during our birding guide training workshop in October 2012.

First up is the most startling-looking of the lot, the File-eared Tree Frog (Polypedates otilophus).  Its large size, the tiger-like striping on its legs and sides, and the pronounced ridges behind its eyes make it unmistakeable (and more than a bit awe-inspiring).

The File-eared Tree Frog is a member of the largely Asian family Rhacophoridae, and is confined to Sumatra and Borneo.  Apparently its preferred activity is loitering around the margins of stagnant forest ponds, a few metres off the ground - pretty much exactly what these individuals were doing.

Anyway, they make ideal photographic subjects.  The upper individual is sitting right on the guardrail of the boardwalk that runs around the pond, and you can't get more cooperative than that.

The Four-lined Tree Frog (Polypedates leucomystax), a less spectacular (but still attractive) cousin of the File-Eared, is, according to the excellent website Frogs of Borneo, "closely follows human activities: it is found around villages, artificial forest edges, and along roads where it breeds in ditches and puddles."

It apparently stays out of primary forest, so it may have reached the frog pond along the road edge into the park.

The most remarkable of the rhacophorids may well be the "flying" frogs of the genus Rhacophorus, famed for their ability to glide on the parachute-like webbing between their outstretched toes.  This is the commonest of them, the Harlequin Flying Frog (Rhacophorus pardalis), easily identified by its red gliding webs.

These frogs lay their eggs in a foam nest hanging over the water; this is probably a male, keeping an eye on his brood.  When the tadpoles hatch, they will drop into the pond to continue their development.

Away from the breeding pond, these frogs spend their lives high in the trees, and like so many canopy animals - even common ones like these - we know little about their daily lives.

That's the nice thing about the frog pond - it gives you a chance to get up close and personal with creatures that othewise might remain well out of sight.

The attractive White-lipped Frog (Hylarana raniceps) is not a rhacophorid, but a member of the "true" frog family Ranidae.  Recently the Ranidae have been broken up into a number of smaller families, but Hylarana has yet to be moved elsewhere.  

To a North American this may seem odd, as the expanded toe pads make it look more like one of the "typical" tree frogs of the Hylidae (a family missing in Borneo) than a ranid; our ranids are pond frogs that, by and large, wouldn't be caught dead in a tree.  It just goes to show how diverse frogs are.

Not all the frogs around the pond are tree-dwellers.  The Giant River Frog (Limnonectes leporinus) prefers the vicinity of forest streams.  Males can get quite large - up to 175 cm. - and are sought by locals as food.  This frog is now placed in the family Dicroglossidae, one of the shards of the breakup of the Ranidae.

Litter frogs, as the name implies, are very much animals of the forest floor.  They belong to the family Megophryidae, another split from the Ranidae.  They may not look it, but that makes them cousins of the obese Horned Frog (Megophrys nasuta).  This strikingly un-obese little animal is a Sarawak Slender Litter Frog (Leptolalax gracilis).  Even its tadpoles are skinny-looking.