Natural History





Newborn from Borneo (Kalimantan), about 19 cm long


About 2.5 years old and 50 cm long. Note that some white markings and the red band running crossing the eye are still present.


8 months later, the female is gravid for first time. The white markings have disappeared, the red band of the head has turned blue, the eyes have darkened, and some more of the green scales on the back have turned yellow or blue.


More than 5 years old and about 80 cm long. Yellow and blue coloration is further pronouced.






Captive-bred Thai juvenile female, 1 month old and about 19-20 cm long . Note the somewhat flat head, which becomes more voluminous when it grows.


Same female 7 month old.


15 month old (color appears different, because of flashlight)


Thai female, 2 years old and about 40 cm long. The typical juvenile coloration is still dominant, but labial scales already show yellow and blue elements.


32 month old. Change to the adult pattern starts in that red bars turn black in the middle and posterior part of the body. The head has become broader and bulkier. Like its siblings, this female has become increasingly aggressive, day and night, snapping at everything that appears to be prey and moves.


Here, the Thai female is 3 years and 3 months old, about 50 cm long. The hind body already shows the typical adult pattern (yellow and black intensify, green scales become fringed with black), whereas the neck and anterior parts still feature reddish bars. Again, the width of the juvenile red bars does not indicate the width of the yellow bars that appear later on.

Thai females appear to develop slower than Sumatran females (see Table below), which can reach this stage already at 2 years of age. It also appears that adult Sumatran females can become longer and heavier than their Thai counterparts. However whatever geographical origin, when females are 2-3 years old, they are not mature enough for breeding. I never found gravid females of this stage in the wild. Gravid females in the wild are usually 60-100 cm long and appear quite bulky.

The same applies to captivity: there is certainly a minimum weight at which breeding could start. However, that has not been determined yet for the various Thai, Sumatran, or Western Malaysian populations. To be on the safe side, the best choice is an adult female in the size range mentioned above. If Bornean females are to be an indicator, breeding could start in the 4th or 5th year (see above).


The table shows a comparison of increase of body weight between southern Thailand and northern Sumatran individuals born and raised in captivity. Interestingly, the divergence in growth rates between males and females can set on after one year already in the case of Sumatran vipers, whereas Thai individuals show this split after 3 years. After 3 years, Sumatran females are much heavier (at around 50 cm body length) than their Thai counterparts.

Similar to Thai populations, Western Malaysian temple pit vipers also appear to develop slower. In the following example, transition to adult coloration was not complete after 3 years.




Juvenile female from Malaysia (about 40 cm) with early indications (black spots on head) of an approaching change in coloration.


Same animal as above 7 months later. The red markings on the back and head have turned black. Dorsal scales gradually become fringed with black.


Another 7 months later, yellow elements have become stronger and more scales on the head have turned black.


Another 12 months later; the animal is now more than 3 years old.



This image of a juvenile female from Penang illustrates that the juvenile red-white markings do not necessarily indicate the full length (or even position) of the transversal bands that appear later on. Instead, the adult pattern is indicated by the yellowish coloration. This is why juvenile females with 'male markings' may develop a perfectly normal banding pattern in adulthood.