Surveying Snakes in Singapore
Phil Vogrinc, a master’s student in the Department of Biological Sciences, is in East Asia this summer to assess how rising sea levels affect coastal semi-aquatic snakes.
The latest Climate Assessment Report issued by the Intergovernmental Panel on Climate Change projects that under the worst-case scenario, increased ocean warming and melting glaciers and ice sheets could lead to a global sea-level rise of up to 1 meter by the year 2100.
These changes are expected to detrimentally impact mangrove and coastal wetland habitats that are home to diverse species populations. Of particular concern is in Singapore, where Phil is doing most of his research. On average, Singapore lies only 15 meters above sea level and has lost much of its native mangrove habitat.
“Many water snakes rely on this imperiled habitat and changes in sea-level could cause species extirpations,” Phil said. “Many of these poorly understood snakes are found nowhere else. As regulating predators in coastal ecosystems, snake losses could result in unnatural levels of some prey species, such as fish and crustaceans, and the disappearance of others – directly impacting fisheries and other economically important coastal recreational activities.”
(Earlier this summer, Phil made an appearance in a Research Frontiers Field Notes story and video.)
Since the snakes he studies are nocturnal, Phil traverses mangrove forests at night. It’s dirty and dangerous – and sometimes frightening – work, which he describes in an e-mail:
Searching for snakes in this environment is difficult. I often walk in knee- to waste-deep water or mud that likes to fight my every step. The mud is what makes studying these snakes special however. Water snakes have evolved for millions of years in mud so many of them have very tiny eyes that are located on the tops of their heads, which allow them to view the surface of the mud/water. They also have valve-like nostrils and the ability to extend their glottis into their nasal cavity to prevent salt water from entering. Most of he snakes are relatively slow and sluggish which allows for me to more easily view and identify them in the mud.
Mud is not the only difficulty encountered while walking through mangroves. Each mangrove tree has a complex system of above-ground roots that form “natural” obstacle courses. The mangrove pit viper likes to hunt on the root tangles and low-lying branches so I can’t put my hands on any vegetation to stabilize myself without looking very carefully. I have also encountered crocodiles in northern Singapore, which slightly terrifies me so I avoid walking through turbid water.
An added danger is that many mangroves are littered with trash and debris because there is a serious problem of using the ocean as a landfill in Southeast Asia and the fact that mangrove roots trap trash. I ended up impaling my foot one night resulting in stitches. Finally, it is common to startle 40- to 80-pound-plus monitor lizards that sleep on tree limbs. When startled, the lizard drops straight out of the trees and onto the mud and makes a very loud sound. I almost died of fright when a huge lizard fell out of the sky within 10 feet of me. So you can imagine that most of the surveys are conducted quite slowly, not only looking for snakes, but also dangers of the mangroves.
I also search for snakes in urban areas such as canals, sewers and public beaches and natural areas like coral reefs and rocky shorelines in order to better understand how these snakes use habitat/ecosystems.
Phil is funded by a National Science Foundation grant that supports research for U.S. graduate students studying in East Asia and Pacific summer institutes (EAPSI). His adviser at the U of A is J.D. Willson, an assistant professor of biological sciences. Vogrinc is collaborating with David Bickford at the National University of Singapore, an expert in oriental tropical evolutionary ecology and conservation.
Here are some significant snakes Phil has documented this summer, with his descriptions:
Mangrove pit vipers. This species looks purple, a very unique color for a snake. They feed on lizards and mammals and are usually found one or two meters off the ground. They range from Myanmar, Thailand, Peninsular Malaysia, to Singapore and Sumatra.
Dog-faced water snake a.k.a. Asian Bockadam or Schneider’s Bockadam. This snake is one of my target species and probably the most abundant water snake in Southeast Asia. Mildly venomous but you can still handle them safely. This is probably the strangest snake I have ever captured as it is often slow and lethargic and looks very similar to thin mangrove roots. They eat fish stranded in tidal pools and creeks.
Crab-eating water snake. Another target species. These snakes live in the giant mounds of dirt created by mud lobsters. At night they exit the mounds and forage about the floor of the mangrove forest searching for crabs to eat. If the snake seizes a small hard-shelled crab, it will consume it whole. If the crab is too large to swallow, this snake pins the crab against the mud and tears a leg off one by one and consumes each leg. This is one of three species on Earth that I am aware of that does not swallow prey whole. It’s incredible.