Streams of Borneo – A photographic essay

The mountainous countryside of western Sabah, Borneo condenses the hot, warm air from the sea in immense clouds that drench the mountains in rain most of the year. This water begins its journey back to the sea in the cloud forests of the mid-altitudes…

Bryophytes just love the moisture.

Water is not permanent up here, so many of the frogs do not use it. This is a mossy bush frog (Philautus macroscelis). Most frogs from this group lay eggs in ferns growing in the trees or in the leaf litter to hatch into frogs directly, but this is possibly unique among bush frogs in laying eggs into the small streams that do exist.

Often heard calling but rarely seen is the green bush frog (Philautus bunitus). Males call from broad leaves well above the ground.

Like so many frogs of Borneo, little is known of the Hose’s bush frog (Philautus hosii) but it is very often found along streams. It is thought that they may lay their eggs in the mud of stream banks rather than in the water.

A barely audible chirp gives away the presence of this medium to high altitude frog – the sharp nosed tree frog (Rhacophorus angulirostris). It calls above the streams in loose clusters and is easily overlooked.

Probably the most intimidating and intense looking frog is the montane horned frog (Megophrys kobayashii) The textured pattern of the back and sides hides it beautifully in the leaf litter along the stream banks. In fact the only clue that one is even there are the eyes.

This is presumably the Kinabalu horned frog (Xenophrys baluensis) If so, it is a female as it is large and bulky at about 70mm. This little known frog is apparently rarely seen.

Like so many frogs of Borneo, little is known of the Hose’s bush frog (Philautus hosii) but it is very often found along streams. It is thought that they may lay their eggs in the mud of stream banks rather than in the water.

A barely audible chirp gives away the presence of this medium to high altitude frog – the sharp nosed tree frog (Rhacophorus angulirostris). It calls above the streams in loose clusters and is easily overlooked.

Sharing the habitat of the montane horned frog is the montane litter frog (Leptobrachium montanum). It too is wonderfully camouflaged, usually given away by its loud call.

The smallest of the litter frogs are the dwarf litter frogs. This is Leptobrachella baluensis - an incredible ventriloquist, the short, sharp grating call is unbelievably hard to trace and sounds as if it is coming from all around.

Inger’s dwarf frog (Ingerana baluensis) is rarely seen and literally nothing is known about it. The call, breeding habits and so on are all unknown. It lives in mid altitude streams.

Fish are very rare in the cloud forests, though this little loach-like species is found in tiny, crystal clear pools that are generally only 2-10cm deep. Very secretive, they seem to be nocturnal.

Information on many of Borneo’s fishes is very scarce.

Insects are the most obvious life forms in these nearly sterile streams. This mayfly nymph is gleaning whatever it can from the surface of this rock. It will spend most of its life scraping at scum, to become a beautiful adult with wings and a shiny body – but only for a few hours as adults must breed quickly before the energy they gained while young runs out. Adults cannot feed, they are only breeding machines.

Moving down the mountains to about 700m above sea level the streams widen and there is more diversity.

This is a very odd tadpole indeed. With a long, slender body and a strange funnel-shaped mouth you may wonder how it feeds…

..And this is what it does. This tadpole feeds on pollen, bacteria and yeasts that float on the surface of the water, funneling them into the strange shaped mouth…

It morphs into a strange frog, the common horned frog. The leaf like projections over the eyes, the pointed nose and brown colouration make this frog blend in very well, much like its montane cousin.

This is the adult. Males call late in the afternoon during heavy rains. The call is an extremely loud honking sound.

The cavity-eared frog has deeply sunken eardrums. The reason for this is unknown but they are usually found along the stream sides in the leaf litter.

Tree frogs are oddly scarce. The short-nosed tree frog (Rhacophorus gauni) is found along the stream banks in the vegetation.

Snakes cash in on the abundance of frogs in the upper lowlands. This keelback (Rhabdophis conspicillata) is a common snake of the stream banks.

The torrent frogs from the Meristogenys group are extremely common, making up for over 80% of all frogs in some areas. Their call s a short sharp chirp.

Typically over the small tributaries, this small toad – the long fingered toad (Ansonia longidigita) calls from leaves. Like so many Bornean frogs and toads, these have no adaptations for climbing yet are very good at it.

The tiny dwarf toad (Ansonia minuta) is also found in these mid and low level streams. It is incredibly hard to find yet abundant.

Moving closer to sea level, the larger streams are home to this frog, the rock skipper (Staurois latopalmatus). It is active by day and if disturbed will skip along the surface of the water to another rock.

Like its close cousin the rock-skipper, this signal frog Staurois natator has a cool trick to combat the noise of rushing water…

…They display with their feet! Males signal for territorial rights and to attract females using bright blue feet!

These eggs, firmly glued to this rock may belong to a Meristogenys torrent frog

The exquisite spotted stream frog is found around log and debris jams.

This rather inoffensive looking frog is highly toxic. The poison rock frog (Odorrana hosii) is common in fast jungle streams. Touching it then touching your eyes or mouth is not recommended.

Fish are far more common in the lower altitudes due to greater nutrient loads and warmer water. This Nematobramid is an insect eater.

The Bornean spotted barb (Systomus seali) is found in practically any flowing water, right down to trickles 10cm wide and 10cm deep.

The shallow waters of the larger streams offer sanctuary for the juvenile Bornean mahseer (Tor douronensis). These fish grow to several kilograms and are predators of smaller fish as well as almost anything else that crosses their path in a river. Adults prefer deeper water.

This other unidentified fish (possibly Lobocheilus bo) was also collected in a lowland stream.

Various forms of suckerfish are also working their way over the rocks. This one is known as the “flying fox” in the aquarium trade but so far eludes identification.

This is another unidentified suckerfish, it gets its nourishment from scraping algae off the rocks.

The better feeding grounds are also home to freshwater shrimps…

…And crabs which scavenge along the bottom among the rocks.

But a predator of all of them is the snakehead (Ophicephalus melanosoma) which eats anything it can catch.

Above the streams, this unidentified dragon lizard sleeps by night…

This male shows beautiful coloration.

The smaller animals of the stream had better look out for the oriental dwarf kingfisher. One of the most colorful members of its family it is normally only seen as a multicolored streak shooting through the trees.

The white-nosed water snake (Amphiesma flavifrons) is a common frog-eater of the lowlands and totally harmless to humans.

 

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