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Does food play a role in birth rate of puff adders?

- Wits University

French postdoctoral research fellow, Dr Xavier Glaudas, is on a mission to find out.

He catches snakes for a living. Literally.

As a behavioural ecologist, Glaudas specialises in studying factors that affect animals in nature. And his favourite creatures of all are snakes – vipers, to be more specific.

“There are about 300 to 350 species of Viperidae in the wild and their common feature is that they are all venomous,” says Glaudas.

He completed his PhD in Biology at the University of Nevada in Las Vegas and was appointed as a postdoctoral research fellow in the School of Animal, Plant and Environmental Sciences under Professor Graham Alexander.

Glaudas is nearing the end of his three-year research project to determine whether the availability of food plays a role in the birth rates of puff adders.

Puff adders are ambush predators that rely on their natural camouflage and lie in wait for their prey.

The males usually move only 10 to 20 metres per day. However, in mating season, males go in search of mates, travelling up to 1.5km per night in search of a female.

“They travel significant distances for a heavy-bodied snake,” says Glaudas. “The distances differ year-on-year but the greatest distance travelled that I’ve found was 18km in three months.”

For the past three years during the puff adder mating season, which runs from March to June in Gauteng, Glaudas has tracked over 40 snakes – each tagged with a radio transmitter – at a time without rest, at ten hours a day.

“I track them by foot, using telemetry (radio receivers) to tell me where they are,” he says.

Two months before the mating season, Glaudas catches the snakes and separates them into two groups. He then feeds half of them with dead rats to up to 15% of their body weight and releases them.

In 2013, the first year of the project, Glaudas found that the fed group travelled about twice as far as the control group. However, in the two subsequent years the fed group and control group travelled equal distances.

“We don’t know why. It might be that the first year was very dry and there was less prey in the natural environment but it can be because of other factors,” explains Glaudas. “It just shows that you cannot rely on one year’s data alone.”

Glaudas plans to identify the fathers of specific babies via their DNA to try and establish whether the feeding patterns play a role in the snakes’ reproduction patterns.