July 8, 2002
By Lucille Davie
THE Johannesburg Zoo is taking part in a unique international programme to study and preserve one of Africa's pythons.
The programme is called Flagship Species and involves animals around the world listed by the Convention on International Trade in Endangered Species (Cites). Traditionally, a single high-profile animal is chosen for conservation. This new approach involves the preservation of diverse ecosystems but also strives to connect political, social and cultural interests to the preservation of a species and its ecosystem.
The African rock python, Africa's largest snake, has been chosen by the Zoo as its Flagship Species for several reasons.
Firstly, very little research on African snakes has been done. The Zoo has recently joined the Python Study Group, a collaboration of Wits University, The Zoo, various nature reserves and farmers. Through captive and field research, this is one of the first in-depth studies of an African snake.
Secondly, the aim is to eventually release these pythons back into their natural habitat in the Eastern Cape, where they have become extinct. The more knowledge and understanding of their habits, diet and breeding patterns, the more successful the re-introduction is likely to be.
A field station has been set up in the Hammanskraal area in Gauteng, where a group of farmers is catching snakes, which then have transmitters implanted in order to track them for research purposes. After about two years these transmitters are replaced with microchips for long-term tracking.
The next stage in the pilot study is to introduce captive-bred snakes to the recently-expanded Vernon Croockes Nature Reserve on the KwaZulu-Natal south coast, where they will be carefully monitored to ascertain where they best survive and reproduce.
From here the pythons will be re-introduced into the Eastern Cape, around the Addo Elephant Park area, in about two years' time. "We have historical proof of their existence here in the form of skins," says Andrew Pringle, keeper of small carnivores and reptiles at the Zoo.
It is believed that pythons became extinct in the Cape because of human pressure and climate changes. In South Africa they appear mostly in bushveld areas, along the KwaZulu-Natal coast, north of Pretoria right up to Botswana.
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It has been established that the pythons' breeding patterns are related to the weather patterns. For example, they lay their eggs in burrows and when it is particularly wet, the eggs are washed out of the burrows and lost.
"Over a three-to-five-year period the eggs were not hatching. When we looked at the climate records they coincided with these unproductive years," explains Pringle.
This year the Zoo has had four hatchlings, now several months old, but very little is known about how the mother keeps the eggs warm.
"Closely-related Burmese pythons keep their eggs warm by shuddering their bodies which heats up their muscles, thus warming their eggs," says Pringle. It is unknown whether African pythons follow the same practice.
Research so far reveals that a single female will mate with several males, and store the sperm. It is not known at this stage what mechanisms determine which male or males eventually father the offspring. In time DNA tests will be done to establish which male is the father of the babies.
Generally a female of three metres will produce 20-30 eggs, and a python of two metres will produce 10-20 eggs. About a third of those will hatch.
Ancient snakes
Pythons are the most ancient of all snakes and all species have two small claws about 15cm up from the end of their tails, a remnant of legs. It is believed that males use these claws to displace other males from approaching a female, although at present there are two males curled snugly around a female python in the Zoo's snake enclosure.
The Australian male pythons use their claws when fighting, leaving marks on their opponents.
The Zoo has six females and three males in their snake display enclosure, with several young pythons behind the scenes. The intention is to get the young snakes used to being handled so that they can be used for educational purposes, with members of the public able to handle them, says Pringle.
The pythons have around 250 teeth and catch their prey by biting, grabbing, then wrapping themselves around the prey and constricting it. In the Zoo the large snakes are fed guinea pigs and rabbits, while the smaller snakes are given mice and rats. In the wild they eat ground squirrels and spring hares, normally pests to farmers, and hence the willingness of the farmers to participate in the study.
Metabolic research
The present research will also explore how the pythons' digestive systems work.
Once pythons have eaten a large meal - an adult python can eat an impala - their digestive systems will shut down, in cases of large adults, for up to two years.
"Overseas research with Burmese pythons has revealed that the python's heart, kidneys, and liver can double in size shortly after it has eaten a meal," says Pringle. This is measured by means of ultrasound and electro-magnetic mechanisms. An indirect measurement of this is the amount of oxygen the snake consumes, and this is measured by placing the snake in a chamber before and after a meal, for up to two days.
"It's important to emphasise that we don't do any invasive surgery in this research," says Pringle.
The reason for the expansion of the snake's vital organs is that the snake moves from a state of shut-down to one of getting its large gut up and running, so the heart in particular needs a massive boost to generate energy to digest what the snake has eaten.
Although this sounds stressful for the snake, adds Pringle, the enlargement of the organs is an adaptation to its normal conditions and does not adversely affect the snake.
"This is cutting-edge research - two to three years old. Further research along the same lines is being done in birds, to explain how they manage to use huge amounts of energy to spend hours flying to the opposite hemisphere," says Pringle.
This research has relevance for humans - it will lead to an understanding of how humans survive in extreme conditions. A person moving from South Africa to Sweden will undergo seasonal changes, says Pringle. "That person's gut will enlarge as an adaptation to the cold, to keep the body warm."
This study is to be a showcase project for the World Summit on Sustainable Development. The enclosure is to be spruced up, and will be carefully labelled in time for the Summit.
Pringle says the Zoo is in desperate need of new enclosures for the pythons. So, dig deep for Africa's largest snake - it could tell you something more about yourself.
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