Mon, Oct 19, 2009 page4

• FEATURE: Rain forests of Brunei hold secrets for biologists

  • DPA
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  If you ever thought that finding a needle in a haystack was difficult, try looking for a microchipped frog in a rainforest.

  This is what German biologist Ulmar Grafe is attempting in one of the world’s few remaining untouched rainforests in the oil-rich sultanate of Brunei.

  Situated on the north-eastern coast of the island of Borneo, more than half of Brunei’s 5,700km² are covered in rainforests, with one-third of the territory under protection.

  Setting out at dusk from a research station on the Belalong river in the middle of mangrove forests and jungle, undeterred by pouring rain, waist-deep water, biting insects, snakes and other creeping forest dwellers, Grafe and a colleague started their search for some of the region’s 66 known species of frog.

  The scientists were looking for one particular frog. Grafe had previously implanted several of the tiny creatures with microchips, hoping the telemetric data received can help broaden knowledge about their range of movement.

  The researchers unfolded a huge antenna among the towering trees. A signal showed that one of them, a Borneo river frog, must be close by. However, the signal did not necessarily mean the animal was still alive.

  “The chip keeps sending signals, even when it is inside a snake,” Grafe said.

  The frog expert was not unduly worried by the fact that Borneo is home to some of the world’s most dangerous snakes.

  “You just have to keep your distance,” he said.

  Besides, the biggest danger in a rainforest is being hit by a falling tree, he said to the sound of crashing wood.

  Stumbling through the pitch-dark night, the researchers closed in on the chipped frog, the antennae readouts leading them to a steep slope. They found the frog hiding under fallen leaves. Fortunately, it had not become a snake’s dinner.

  Grafe marked the site with a satellite navigation unit, the information to be entered later into his computer program mapping the amphibians’ movements.

  The variations among Borneo’s frogs seem endless. A tiny specimen sitting on a leaf next to a stream turned out to be a foot-flagging frog.

  The male of the species has developed a special way to attract females over the noise of running water — it waves its legs, which sport bright white webbing.

  Grafe also found out that in many species only males are attacked by bloodsucking flies, which are attracted by the frogs’ croaking.

  Experiments with loudspeakers blasting the animals’ courtship croaks into the rainforest showed that species emitting sounds in the high-frequency spectrum were ignored by the flies.

  This research led to other scientists looking into the hearing abilities of flies, which may help in the development of hearing aids.

  Borneo’s rainforests lack large animals: a few species of deer, wild boar, cats, some lizards and that’s it.

  “There is too much competition for resources,” Grafe said.

  The soil is poor and lacks nutrients to support large species other than huge trees, he said.

  The forest is a complex ecosystem that can become unbalanced even by the smallest changes — like a road cutting through it.

  One such swathe near Temburong led to the introduction of the rough-sided frog, a species distinguished by its bark-like croak. It prefers open spaces and small ponds.

  “Is their arrival good or bad? Do other species vanish or does the number of them increase. We just don’t know,” Grafe said. “Do we have to look into that? Well, the answer simply is: You never know what it’s good for.”

  Changes to the ecosystem may, for example, lead to the disappearance of frogs whose skin secretions could help cure cancer.

  The rainforests have to stay intact to keep those possibilities alive.

  “The rainforests provide all those free gifts — clean water and clean air,” Grafe said.

  If the primary forests are cut down, the animals vanish.

  Rainforests also help keep down pests like mosquitoes, which transmit diseases such as dengue fever.
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