snakes on Koh Chang Island, Thailand

[dendrelaphis]

I visited Koh Chand Island, Thailand, for 2,5 weeks with my family. Although I predominantly did family-things (a lot of swimming with my kids), I managed to spend 1,5 hours in the rainforest each day searching intensively for snakes. Getting into the rainforest of Koh Chang turned out be be difficult. When I entered a trail to Kong Plu waterfall in the evening I was stopped by personell, I wasn’t allowed to enter. When I subsequently entered a small stream into the forest somewhere else, someone (I saw a silhouette moving though the forest as it wasn’t completely dark yet) shot a rifle twice and I decided to turn around. But in the end I found some wonderfull trails (a trail used for elephant trekking, some river beds and a beautiful trail to Kai Bae waterfall). In total, I spent 25 hours in the forest and in that time I found 25 snakes representing 9 species. Obviously, that’s just scratching the surface: the species accumulation curve is still climbing steeply. On Borneo, where I invested a huge amount of time (Santubong Peninsula), I found roughly 1 snake every 2 hours. Using the same “Visual Encounter Survey” strategy on Koh Chang I found 1 snake every 1 hour. I’ll have to do some statistical tests but it appears that the snake density on Koh chang is significantly higher. In that sense, Koh Chang reminded me of Pulau Tioman (Malaysia) which was snake paradise. Rest assured, I will be back on Koh Chang next year.

Some shots of the rainforest to start with:




Then some shots of how snakes are found:





And here we go:

Trimeresurus cardamomensis (tentative id)








Dryacolamus davisoni






Oligodon cyclurus (still tenative id)



Lycodon laoensis


Ahaetulla prasina


Ptyas korros

Xenochrophis flavipunctulatus






Gonyosoma oxycephalum


Chrysopelea ornata

[Jeroen Speybroeck]

Nice! I'm jealous of having missed the 2 final ones last month...

[dendrelaphis]

Yeah, Gonyosoma is often considered a common snake but in my experience it isn't. Although it's a rather slow snake and should be easy to spot at night, this is the second I have seen!

[Tom charlton]

Very nice, you certainly did well! I'd like to return to the island at some point, especially after reading reports of Daboia siamensis being found on the there (however unlikely it is!).

[dendrelaphis]

Yeah, I heard from a Dutch biologist who lives on Koh Chang that Daboia siamensis indeed occurs on Koh Chang. It is possible, this species has a weird, patchy, distribution. Unfortunately I missed it. So you have surveyed Koh chang as well? Did you find species that I missed?

[Ruxs]

Yeah, Gonyosoma is often considered a common snake but in my experience it isn't. Although it's a rather slow snake and should be easy to spot at night, this is the second I have seen!

Agreed, I've only ever seen 2 as I recall (not including several DOR specimens), but I put that down to not looking in the best places. I found both of mine (one day and one night), around smallish streams, but I know people who have found several in one day hanging out in trees above slower flowing bodies of water like large rivers and mangrove estuaries.

[jonathan]

Yeah, Gonyosoma is often considered a common snake but in my experience it isn't. Although it's a rather slow snake and should be easy to spot at night, this is the second I have seen!

Agreed, I've only ever seen 2 as I recall (not including several DOR specimens), but I put that down to not looking in the best places. I found both of mine (one day and one night), around smallish streams, but I know people who have found several in one day hanging out in trees above slower flowing bodies of water like large rivers and mangrove estuaries.

I wonder how much their behavior changes based on range. This February I was in the Philippines and saw two live and one dead in just a few nights of herping. Neither of the live ones were anywhere near water.

[dendrelaphis]

That's a lot indeed, on Santubong, Borneo, I found one specimen in nearly 100 days (4 hours per day). I guess differences between populations and ecosystemens can be great.

Example from my experience: Oligodon purpurascens from Tioman Island are fairly friendly snakes (although they will still provide you with a nasty bite) whereas the specimen I encountered on Borneo was fast and very agressive. Furthermore, I frequently found them on Tioman while I found only a single specimen on Santubong in those 100 days…. So they appear to occur in higher densities on Tioman and appear to display different behaviour.

I guess in many cases one might even wonder whether we are really talking about the same species. Genetically (geographically) isolated populations --> diverging lineages etc. Back to the example: the O. pupupurascnes from Borneo turned out to exhibit fairly strong genetic divergence in comparison with the Tioman population, besides differences in coloration. Does it still represent the same species?

All the best,
Johan