Yes, There Are Two Vipers Here - Observation of the Week, 3/14/23

Our Observation of the Week is this pair of Wagler's Pit Vipers (Tropidolaemus wagleri), seen in Singapore by @limhongyao!

Like many of us, the seeds of Lim Hong Yao’s interest in nature were planted in his childhood, when he watched documentaries on TV. “However,” he says,

it was only years later, during my undergraduate studies, when I realised that nature was all around me and not just those far away places on TV (Africa, Madagascar, the deep sea, etc.). I started out with birdwatching and bird photography and subsequently grew into a general naturalist, finding beauty in all sorts of animals. Currently I am still heavily invested in bird watching, but am also very keen to seek out butterflies, odonates, herpetofauna and mammals (in no order of interest).

So when Hong Yao heard about a pair of Wagler’s pit vipers seen in the area of a planned night hike, he had to stop by and take some shots. “I had not expected to see them though, as I heard that they were first seen over a week ago,” he says.

I wasn’t able to find any information on the reproductive behavior of these venomous snakes (if you know anything, please share in the comments!) but it’s pretty cool that the snakes look to have stayed together for at least a week. What’s really amazing is the sexual dimorphism here. The female in this photo is quite large and has black, yellow and white coloration, while the male is much smaller, pale green and white, and has a stripe over each eye. 

Like many arboreal snakes, individuals of this species don’t move much and rely on ambush to capture prey. They range throughout much of southeast Asia, both on islands and the mainland.

Hong Yao (above, eating a meal after birdwatching), joined iNat in 2018 and says

I mainly use iNaturalist to look for existing observations of animals I am interested to seek out, to share my sightings in general, as well as to get help with identifying subjects that I am not familiar with. I believe that using iNaturalist has led me to gain a better appreciation of the distribution of many animals, and the importance of habitats and microhabitats. Being able to look at the spatial distribution of a species on a map serves as a great starting point for learning more about a species and its ecology.

(Photo of Hong Yao by Goh Cheng Teng.)

Check out the beauty and diversity of temple vipers on iNat!

- A different temple viper species was Observation of the Week waaaay back in 2017!

Posted on March 14, 2023 10:33 PM by tiwane tiwane


Amazing! I would never have guessed they were the same species.

Posted by vireyajacquard 7 months ago

Wow. It took me a few seconds to find the second viper and they look so different. Nature is both beautiful but shocking at the same time.

Posted by yayemaster 7 months ago

Great photo of an interesting species!

Posted by bit 7 months ago

Stunning! So much to wonder about!

Posted by schizoform 7 months ago

That is an incredible shot! I don't know much about their reproductive habits, but one thing that blows my mind is the complex nature of the thermal pit organs of pit vipers such as Wagler's. These pits transduce infrared radiation (heat) into electrical impulses, which are interpreted by the optic tectum in the brain (according to leading theory) to make an image much like our brains do using the information obtained by our eyes. In essence, Wagler's pit viper can "see" heat. You can read all about it in this technical article ( or in this simpler article ( -- scroll down to "Heat Sensors").

Your picture reminds me of the words of Agur written over 2500 years ago when he said that "the way of a serpent on a rock" was "too wonderful" for him to comprehend (Proverbs 30:18-19). The sheer beauty and intricate design of the pit viper is stunning and impossible to fully understand.

Posted by seakrait 7 months ago

Wonderful stuff -- thank you Lim Hong Yao!

Posted by susanhewitt 7 months ago

Amazing photo!

Posted by huttonia 7 months ago

Double amazing seeing a pair. So, in the past, I only been seeing females and never see a male. Wow, I have gained new knowledge from your encounter. Thank so much.

Posted by leewm66 7 months ago

A jaw dropping observation, congratulations!

Posted by nelson_wisnik 7 months ago

Absolutely incredible! Such a great observation. I can only imagine how cool it was to see in real life!

Posted by lisa_bennett 7 months ago

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Posted by delphiawilson 6 months ago

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