Egg incubation of the Boomslang (Dispholidus typus)

The Boomslang Dispholidus typus is a unique species of snake belonging to the Family Colubridae, and is found throughout Southern and Sub-Saharan Africa. It is arguably the most potently venomous snake on the African continent when it's venom is compared on a drop-for-drop basis. It has "rear fangs" or rather fangs below the eyes, and has relatively small venom output. The venom is strongly haemotoxic, and is life-threatening to humans. Fortunately there are very few bites from this species as they are shy and spend most of their time in trees, hence the name, boom- tree, slang- snake. They are one of the few species of snake showing sexual dimorphism, with females usually a dull olive colour with a lighter belly, and males being much brighter, depending on locality they can be bright green, green with black between the scales, or yellow and black. They are a diurnal species, and are aided in their day time activities by very large, sensitive eyes, which are lobed at the front to assist with binocular vision. Adults can be between 1 to 2 m, and they have strongly keeled dorsal scales.

Females usually lay between 8 and 27 eggs in hollow logs during late spring. In 2009 I was lucky enough to attempt for the first time incubating Boomslang eggs in captivity. On the 7th of September 2009 a recently captive female laid 21 eggs, all healthy looking. The eggs were set up in an ordinary plastic tub with potting mix as a substrate. No extra moisture was added as it was wet enough. The tub had 2 small holes in the lid for ventilation, and the tub was placed in a room that naturally stayed at 30 to 32 deg. C in the Southern African sun. This incubation method was very rudimentary compared to the well measured and weighed methods i was used to in Australia, but as my colleague pointed out, this is how the eggs would have been out in nature. As it turned out this method proved to be just as successful, if not more so, with the many different species' eggs I incubated that season.

After 95 days of incubation the first slit appeared, with the only maintenance being my morning ritual of keenly observing the eggs through an open lid, seeing they were all ok, and then closing the lid. I did this also to allow a bit of air exchange as well. The eggs took care of themselves more or less, and on the 11th of December the first slits appeared.

On the 12th of Decemeber the first baby emerged.

As you can see the neonates are very brightly coloured. They are very different from the mature adults, and are in my opinion, one of the most beatiful little snakes around. Juvenile Boomslang have a bright coloured thoat for threat displays, they puff it out to look big and threatening. Adults also do this but the colour displayed (often blue) is between the scales and only visible during the puffing up display.

On the 13th we had the second hatchling emerge, on the 14th we had twelve emerge, and finally on the 15th the final three came out. That left four eggs that didn't hatch, but there were no surprises there, as they had shrivelled up early on in incubation. But I consider this a pretty good hatch rate, 17 out of 21.

After two weeks, all 17 hatchlings had shed, although I might add that 12 out of 17 had retained spectacles. This required very delicate removal of the eye caps with tweezers and manual handling. Their weights were between 25 and 32 grams- so tiny! So pinning and holding them behind the head felt like surgery. During a slight lapse in concentration I felt a prick in my thumb, and it quickly registered what was happening. I looked down and the little snake had simply stretched his jaw sideways to reach a fang to my skin. Luckily it did not pierce the skin, but having seen that I'm convinced that every one of those hatchlings could have touched fang to skin if they had so desired! A scarey thought! All of them ate a pinky mouse after they'd sloughed, and a week after that we released them in the bush near wher the mother had come from. A happy ending.