Terrestial Life Forms of Sipadan Island

(Nature Watch April-June 1996)

Photos: Billy Kon & Dr Chua Ee Kiam

 

Sipadan island, off Sabah, has in recent years become synonymous with scuba diving
but Dr Chua Ee Kiam and Billy Kon took time out to beach-comb
and trek the dwindling patch of rainforest, discovering not only gigantic Robber Grabs
but a Green Turtle nesting and the elusive Megapode bird

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A frenzied cry coming from the direction of the beach drowned the soft splash of water lapping on the shore and stirred the normally laid back divers and snorkellers on the verandah of Sipadan Divers (resort). The turtles have hatched! Everyone dashed out, making tracks for the beach, but carefully enough to avoid stamping out the life of these tiny creatures. Armed with torches, plastic bags and pails, the excited crowd combed the grounds to pick up the vulnerable hatchlings of Sipadan's famous Green Turtles. These newly-hatched reptiles are particularly vulnerable to attacks by predatory rats, fish, monitor lizards and sea birds.

We noted with concern that instead of heading for the sea, these young reptiles were being drawn to the chalets by its bright lights. With so much commotion all around, the hatchlings appeared shell-shocked. Not surprisingly, when they were picked up and released on the beach, they still appeared disoriented and continued heading for the chalets, though the lights were now some distance away.Finally, gentle hands had to put them nearer the waterline and coax them into the sea. If not for the sandflies that were biting viciously that night, I felt good shepherding these baby turtles into the sea.

Cycle of life
Getting the hatchlings in to the relative safety of the sea completes the birth process that had begun when the Green Turtles (Chelonia mydas) had come ashore. Weighing up to 400 lbs (about 160 kilos), the gravid females come ashore when the tide is high. Heavy with eggs, it's a struggle for the turtle to hoist and drag her body forward on the powdery soft sand. She searches for a suitable site. It should not be too dry or too wet. If too dry the eggs can get dehydrated, that is, all dried up. If too wet, the eggs may get washed out to sea when the tide is high. Finally she finds the right spot for her nest and, when it is time, she strains away, shedding copious tears to flush the sand out of her eyes. When all her eggs have been laid, she uses her flippers to cover them with sand to protect them from the elements and also from human and other predators like monitor lizards, crabs and rats. That done, the Green Turtle heads back to sea. The hatching period is usually 5060 days.

Billy and I were lucky to see a Green Turtle nesting. Lucky because security measures forbade visitors to walk on the beach at night and night rambles through the forest were also strictly forbidden. But, thanks to the goodwill of the Wildlife Department, we managed to see the ponderous Green Turtle in her nest. The next morning we saw from the trails made by the turtles that at least 10 managed to come ashore, but not all the turtles laid their eggs. This could have been due to either human interference or the unsuitability of sites on this beach.

Observing an elusive bird

It was also a distinctive cry that drew our attention to another of Sipadan's terrestrial life form. This time it was the maniacal cat-like cry of the Megapode bird (Megapodius cummingii) which occurred in the morning. When tracked to its source, we found this large brown bird scratching the ground, churning up the leaves and even the earth. Its large claws, much like a chicken's claws, were effective excavators. These birds rummage the forest floor looking for fallen fruits, snails and worms. The male of the Megapode plays a most useful role in ensuring that the eggs laid by the females are kept at the right temperature. First of all, the male uses his beak to detect the temperature of the egg chamber, then he makes the necessary adjustments. If more warmth is needed, he adds more decaying vegetation, if the temperature needs to be lowered, he adds sand. We were most pleasantly surprised to see this bird as it had been so elusive when we tried to see it on an earlier trip to Pulau Tiga, off the west coast of Sabah.

Birds galore
Besides the Megapode, the cackle of the White-collared Kingfisher often filled the air as we trekked through the remnants of the rainforests. Then, following the coos of the Pied Imperial Pigeon (Ducula bicolor), we were led to a flock of about six birds. Although a bland black and white, the Pied Imperial Pigeon's creamy white is conspicuos as it rests on the island's tall trees.

A common sight were the Nicobar Pigeons which could be seen feeding in the undergrowth and by the shore at low tide. In flight its short white tail is unmistakable. Roosting on the forest trees were migrant birds like the Blackcrowned Night heron. Other birds we encountered were the Green Imperial Pigeon, Olive-backed Sunbird and the Philippines Glossy Starling.

Coconut-feeding crustaceans

But a main attraction for its on Sipadan were the Robber Crabs, also known as Coconut Crab (Birgus latro). This largest of terrestrial anthropods has been so named because they are widely believed to feed only on coconuts; however they will also scavenge for anything organic on the ground. Incidentally no one has reported seeing these Coconut Crabs pry open the coconuts but certainly their huge claws would be capable of tearing the husk open. Robber crabs are awesome creatures. Bluish or coppery brown, these gigantic crabs are endemic to oceanic soils. They behave like typical hermit crabs. Protected by law, and by the sea shells they use as their "home", they grow until they are too large for the shell, which they shed. After this shedding they continue to grow until they reach gigantic proportions.

Besides these huge Robber crabs we also encountered a Box-crab (possibly a Calappa hepatica). Gently turning it over we saw a wing-like expansion of the carapace which allows its legs to be concealed when withdrawn. This means it is totally protected when upright.

Rare finds
The other land creatures we encountered include two distinctively colored snails (belonging to the F. Camacnidae family) and skinks, with their blue tails. Sensing our presence, the skinks scurried through the undergrowth and up the coconut trees. Skinks have conical heads, somewhat similar to a snake's head, cylindrical bodies and long tails. They are often seen basking in the sun. Not without good reason. The sun's rays help to thermo-regulate them, maintaining a body temperature that is suited for activity to begin. We could not identify the species we saw but surmised that it was probably a juvenile as some of the slightly larger skinks do not have blue tails.

We also knew that we could come across pangolins. These scaly creatures, also known as ant-eaters, had been introduced because the islanders found too many ants for their comfort. Most memorable, it was not the dwindling forest, it was our walk on the firm oceanic floor when the tide was out. The tide went far out to sea.

Beach combing bonanza
In the shallow tidal pools we spotted sea cucumbers, star fish, brittle stars and even moray eels, a giant clam and a puffer fish about a foot long. This fish got stranded in the shallows when the tide receded. We also saw seasnakes among the sea grass and more crabs. If it were not for the steady drizzle we would have walked right to the edge of the drop-off!. We had not imagined that beachcombing could be such a fruitful and thrilling experience.

More thrills were in stock when we donned borrowed flippers and snorkels and went snorkeling off the jetty. Immediately we were mesmerized by the verdant liquid universe we encountered. I was a tremendous experience swimming with a pack of 300-400 jacks. One could actually feel the tails of these fish, each fish measuring more than a foot in length, flapping against our sides.

Then, near the drop-off, a barracuda swam close and eyed us. I could never forget this experience. It was on my mind as our launch chugged across the plateau, back to Semporna on mainland Sabah. We counted more than 10 Green Turtles finning in the shallows. They were probably cruising around, waiting to come ashore to lay their eggs, later in the night. Then, the azure waters surrounding Sipadan slowly faded as we put more distance between us. But the beauty of the island was partly masked by the diesel fumes exuded bv our launch!

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