Today was the HSS’ first Herp Walk held on Pulau Ubin! Previously, night walks had been held in collaboration with the Vertebrate Study Group (VSG) branch of the Nature Society as part of Pesta Ubin 2016, and HSS members also helped survey for herptiles during BioBlitz Ubin in December last year. Given the rich herpetofauna that we observed during those events, it was a no-brainer to have our first Herp Walk of 2017 at everyone’s favourite kampong getaway. However, we were also heartbroken to learn that the recent oil spill had now affected the mangroves of Ubin; more about this towards the end of the post.
As we started off on the walk, we were greeted by two of Ubin’s iconic Oriental Pied Hornbills (Anthracoceros albirostris) just next to the jetty! These charismatic birds were once extinct from Singapore, before making a return through natural dispersal from Johor; Ubin was their first foothold. It was good to see them still doing well.
Our first herp of the day proved to be a male Sumatran Flying Dragon (Draco sumatranus)! This amazing gliding lizard was high up a coconut tree, flashing its yellow dewlap to ward off rival males. As we scanned the trunks of the neighbouring trees, we spotted a Green Crested Lizard (Bronchocela cristatella) and two more Flying Dragons, basking in the bright sunshine. The Green Crested Lizard, like its introduced competitor the Changeable Lizard, is able to change colour; depending on its mood or need for camouflage, it can switch between black and green.
It wasn’t long before one of our participants spotted the first snake of the day: an adult Oriental Whip Snake (Ahaetulla prasina), probably the most commonly sighted snake in Singapore. A minute later, a juvenile Oriental Whip was discovered in a bush just next to the adult! Instead of being neon green, young Oriental Whips are a dull brown, perhaps so that their very slender bodies can better resemble small twigs.
As we moved on to the mangroves, the fiddler crabs (Uca sp.) were out in force, with dozens of males flashing their bright orange claws to defend their territories and attract females. Mangroves are important habitat for lots of animals including reptiles, such as monitor lizards, snakes, and crocodiles. The Restore Ubin Mangroves project, which aims to promote natural regrowth of the mangrove forests by making the hydrography more favourable for new seedlings to grow, will thus hopefully also create more habitat for these herps to flourish!
Many birds made an appearance throughout the walk, including these two bright balls of energy: an Orange-bellied Flowerpecker (Dicaeum trigonostigma), and a Crimson Sunbird (Aethopyga siparaja)! The former was feeding on the berries of the Singapore Rhododendron (Melastoma malabathricum), also known as Sendudok, while the latter flitted about looking for flowers to suck nectar from. These birds are important to forest ecosystems as they disperse the seeds of plants and help pollinate their flowers.
We ended off the walk with a sighting of the introduced Changeable Lizard (Calotes versicolor), and another Green Crested Lizard (Bronchocela cristatella). Both these species have similar niches, though the more aggressive Changeable Lizard seems to have pushed the Green Crested out of parkland and urban areas. Ubin however seems to be one of the few places where both can be easily spotted, possibly due to the unique mix of secondary forest and kampong habitat found throughout the island.
After the walk ended, most of the guides headed over to Chek Jawa to take a look at the impact of the oil spill. Many of the mangrove roots were covered in sticky black oil, though most of the mudflat seemed clean. There were many workers deployed to clean up the oil that had evaded the absorbent booms just offshore, as well as some volunteers, all wearing protective body suits, boots and gloves. We also received word from our friends at NUS Toddycats that were helping with the cleanup, that a nationally Critically Endangered Keel-bellied Whip Snake (Dryophiops rubescens) had been found coated with oil. Gently retrieving the snake, we rushed it back to the NParks office on Ubin where it was slowly cleaned by staff and left to recover before release. Note: snakes should not be handled except by trained experts, and only where it is necessary and does not harm the snake’s welfare. Do not try this at home!
As the example of the Keel-Bellied Whip Snake demonstrates, oil spills can affect a very wide variety of wildlife; even an arboreal snake like this one may accidentally stumble into oil that has been washed up onto mangrove trees. If we are to protect our biodiversity and herptiles from such threats, we need to be well-prepared to ensure that the oil never reaches the shore, or even better, doesn’t spill into the sea in the first place. Given the large role that oil has in our economy, this will almost certainly not be the last such disaster. Hopefully going forward, this tragic incident will teach us the lessons needed to better handle future incidents and minimise the impact on our precious wildlife.