© 2004-2021 Thomas Jäkel
Breeding
Breeding of Wagler's Vipers in captivity is possible
and not too difficult once the animals are healthy
and stress (induced by cagemates or otherwise) is
avoided. The image below depicts an adult
Sumatran female copulating with an adult male.
This behavior can be stimulated in captivity by
simulating heavy rainfall during certain months of
the year, for instance during October to December
in the case of southern Thai or western Malaysian
animals.
Mating can occur at any time of the year if male
and females are kept together in a container.
However, keeping several snakes permanently
together can only be recommended in a large
container, providing enough resting and hiding
places for each individual snake. These vipers are
solitary animals. Especially females do not tolerate
each other very well, and they do not tolerate
males during certain periods. This may be become
obvious by an inferior animal losing appetite in
presence of a superior, but can also result in open
aggression involving bites.
If cages are small (e.g. 60x90x40, LxHxD[cm]),
males are kept solitary and separate from females
for most of the time. In case of Thai and western
Malaysian animals, August to February is suitable
period to try breeding. A male that has been kept
solitary for a while usually mounts a female
immediately once placed into a container together
with her. It starts to make jerky movements and
tries to get a grip of the female's tail in order to
position its cloaca close to hers (see photo above).
The copula may last many hours, and can be
repeated various times in the weeks to follow.
Females are usually quite lethargic and tolerate all
of the male's attempts. Should there be signs,
however, that the female rejects the male, the
latter should be removed immediately.
Here are some climate charts (temperature and
rainfall) of various locations in Southeast Asia
that could be helpful for designing the right
climatic conditions in a container throughout the
year (move over the image to zoom in).
The length of the gestation period is difficult to
determine exactly, because not every copulation
will result in fertilization. Furthermore, a single
insemination by a male viper may be sufficient to
induce offspring for two consecutive years. We
have observed this especially with females from
the Philippines. Usually the gestation period of
Thai, Western Malaysian and Bornean females
lasts 6 to 8 months.
The table below summarizes our experiences with
breeding of temple pit vipers in captivity as well as
some of our observations in the wild.
If
one assumes a 6-months gestation period, and
compares the data in the table with the
corresponding climate charts above, it is probable
that mating in Thai and western Malaysian
populations occurs around October to November,
during the rainy season. However, I also observed
gravid females on Penang island in July, meaning
that mating in the wild may take place also during
other periods of the year. Northern Philippine
populations (Luzon) may mate during the dry
season, provided that the Manila chart is some
kind of representative for other locations in the
northern Philippines.
Gravid females usually give birth during the night.
The tiny newborn vipers (around 20 cm) are quite
agile and can climb vertically sticking to the wall of
the container after spraying with water. Young
Wagleris look very similar, regardless of their
geographic origin. I have developed some kind of
sense to distinguish them, however, coloration can
be misleading. The juveniles displayed in the
'Biology' section are typical for populations in
Thailand and western Malaysia. Sumatran
newborn tend to show a stronger uniform green,
with a green or yellow venter and strongly
contrasting red-white marks on the back. However,
blue forms also exist (See the blue and green
newborns from Narathiwat province of Southern
Thailand below). Usually, all of them are quite
docile and do not readily accept baby-mice.
Philippine newborns have a fairly different temper.
They are similar in size like young of the other
populations, although the parents are relatively
smaller (females, 60-90 g, 40-50 cm; males around
30 g, 40-45 cm) than their Sumatran or Malaysian
counterparts. They are quite agressive and
immediately accept newborn mice, dead or alive.
This holds true also for young of some populations
from Borneo.