Don’t Wake the Dragon Princess

Gabrielle Basa

Once upon a time, a beautiful Chinese princess fell desperately in love with a Singaporean prince. Determined to spend the rest of her life at his side, she departed her homeland and magically flew over great oceans to reach his kingdom. Growing exhausted on her journey, the princess scouted below for a shallow yet tranquil grove of ocean to lay down to rest. Upon waking, however, she found herself inundated with a myriad of creatures who had made their homes on her. It was at this moment that the beloved princess chose to give her life to the earth and become one with nature. And so, just 20 miles off the eastern coast of Malaysia, the magical island of Pulau Tioman was born. Well, as believed by some groups among the island’s native peoples. Others purport that she was a dragon on a forbidden quest to find her sister. Furious, the gods struck her from above and hardened her scales to stone, and she fell—a great boulder—into the welcoming sea. The island’s unique topography is reminiscent of the fallen dragon’s body. 


For centuries unknown, Pulau Tioman has breathed life into hundreds of land and marine species, each free to flourish in its vast jungles and intricate reef systems. Some, like the strangling fig plant christened “Mother Willow,” are now hallowed by local tribes and utilized in traditional medicine and religious ceremonies. Unfortunately, international praise of the island in the 1980s brought unforeseen attention to the mythic paradise. Since then, the Malaysian government has strongly pushed for tourism on the island and ignored possible long-term consequences of anthropogenic disturbance. Anthropogenic disturbance, which encompasses anything from noise pollution to forest removal, threatens ecological structure and biodiversity. Each year, thousands of tourists flock like seagulls to scuba dive in her crystalline waters, hike up the lush Gunung Kajang mountain, or take to her rough jungles in rougher automobiles. All of these invasive activities, combined with the slow burn of urbanization, deepen our human footprint on Tioman as we nudge and poke her in her sleep. With new plans circulating to construct an international airport on the island, its biodiversity is more precious than ever. Under the guidance of Dr. Chan Kin Onn and Movin Nyanasengeran, undergraduate researcher Sally Guan set off for Tioman in hopes of uncovering more about anthropogenic disturbance.


Based on previous studies done on Tioman, Guan and her team hypothesized that there would be a difference in bird species diversity between the island’s forested and urban habitats. They generally expected the forested habitat to contain higher diversity. While there is little to no research on Tioman’s bird communities, studies done in similar locations have reported a lower number of bird species in urbanized areas compared to surrounding forested areas. These findings correlate with worldwide deforestation and ongoing destruction of natural habitats. One might ask, with the abundance of endemic species on Tioman, why choose birds? Well, the island boasts 128 separate species of birds whose individual and collective abundance make them important bioindicators, or living organisms that reflect the health of an ecosystem. Guan’s team also focused their study on the presence of generalists versus specialists in each habitat to infer the evolutionary effects of anthropogenic disturbance. Generalist species are typically adapted to survive in a wide range of environments and off of a varied diet. Specialists, just like their name suggests, are more selective about their living conditions and sustenance options, leaving them more vulnerable to endangerment if their ecosystem breaks down. An overwhelming presence of generalists or specialists in a certain habitat may indicate the availability of resources and the overall quality of life. 


Over the span of four days, two groups of four observers would each survey an urban or forested habitat for birds from 7 to 11 in the morning. To evenly distribute the locations of their findings, the teams maintained a transect of 500 meters into each habitat. Think of a transect like the straight and scaly spine of a dragon. By establishing a locational baseline off of which their observational points stemmed, Guan and her team roughly quantified the distribution of various bird species they encountered throughout each habitat. To identify birds on the fly, they noted visible features and audible bird calls, citing The Birds Southeast Asia for reference. Collectively, they logged 22 bird species in each transect. What an observational coincidence! However, the team suggests that their overall sampling constraints may have produced an underestimate of Tioman’s forest bird diversity. For example, the urban transect’s sparse vegetation on ground and aerial levels allowed for greater visibility over a larger distance. Additionally, dense canopy cover over the forest transect could have reduced their ability to spot flyovers, or birds who did not make a visible landing during the observational period. 


The most frequently observed species in both habitats was the common hill myna, a Southeast Asian non-migratory bird known for its bright orange-yellow beak. Hill mynas are often found in and at the edge of humid forests, but they sometimes visit cultivated areas like plantations. They are known for their varied repertoire of up to 13 distinct bird calls and mimicry skills that rival those of the infamous Grey parrot. In fact, the common hill myna scientific name Gracula religiosa originates from the practice of teaching these birds to recite prayers. “Myna” is derived from the Hindu word “maina,” meaning “messenger of God.” Like parrots, mynas are vocal learners who can associate a set of sounds with a certain situation or set of actions. Driven by a need to fit in with their human “flock”, mynas will insert themselves in human conversation and imitate what they hear. The most fascinating aspect of this species is their ability to form dialects between different locations/communities. Birdwatchers in the past have recorded hill mynas with distinct dialects a mere 9-13 miles apart. 


To test her hypothesis on species diversity, Guan used the Shannon-Wiener Index, a longstanding diversity indicator used to measure species richness and evenness. Richness refers to the number of distinct species present in the dataset, while evenness refers to the abundance of each species compared to the others. By these metrics, a high index indicates high diversity, while an index of 0 indicates none. In practice, the highest possible value for a Shannon diversity index (SDI) for a sample of 100 species would be 4.605. Guan’s team calculated a mean SDI of 1.31 for the forested habitat and a mean SDI of 1.55 for the urban habitat. These values show that there is an overall higher species richness and evenness in the urban habitat than in the forested habitat. Then, using the SDI values of the 5 points off each transect, they performed a statistical test known as a t-test to analyze the variability of the two habitats. A t-test produces a p-value, and if this p-value is 0.05 or less, this generally means that the differences observed are statistically significant, or not due to chance. Guan’s team calculated a p-value of 0.5787, showing that there was no significant difference between Tioman’s forested and urban habitats at large. 


Although they did not observe higher bird diversity in forested habitats on Tioman, the team made several resounding discoveries concerning functional traits. Of the species that Guan’s team observed in the forested habitat, they identified 72.7% specialists and 27.3% generalists. In the urban transect, they observed the virtual opposite: 81.8% generalist and 18.2% specialist.

Recalling the local legends, a dragon’s functional traits may be the girth of its wings or its lung capacity. Both traits would directly correlate to its ability to survive and thrive in various habitats. Prior studies performed in biodiverse regions like Tioman island have shown a larger number of generalist species than specialist in urban areas. In the dense forests of Tioman, there are numerous niches for specialist bird species to fill; urban habitats might not offer the same security for as many species. Light and noise pollution combined with the absence of various prey species in urban areas contribute to the gradual emptying of specialists. Additionally, Guan and her team further categorized each species into feeding guilds or diets. There were roughly double the number of insectivore species living in the forest transect than in the urban transect, an observation that supports past studies. Guan cites high air pollution levels as a possible deterrent to invertebrate populations in urbanized areas, necessitating the increase of predatory birds and scavengers. These findings, although supplemental to the question of their hypothesis, prove most relevant to tackling the main issue of species and habitat conservation. 


In summary, although Guan and her team did not find evidence to support their original hypothesis, they did observe important findings relating to their overarching view of conservation. They arrived on Tioman expecting to find a significant difference in bird species biodiversity between its forested and urban habitats. Instead, they observed differing ratios of functional traits that denoted two separately evolving bird populations. Guan recommends for interested researchers going forward to focus their studies and/or conservation efforts on Tioman’s specialist species, as they will be most vulnerable to drastic environmental changes. By preserving biodiversity one habitat at a time, Tioman and its inhabitants can brace for anthropogenic impact and still be able to thrive.