JOHANNESBURG – Shedding their cold-blooded image, snakes emerge from a recent study as more caring creatures that protect their nests and remain with their young for a brief period after hatching.
The study of the nesting behavior of the southern African python, published this month in the London-based Journal of Zoology, is the first-ever report of maternal care of babies in an egg-laying snake.
Based on seven years fieldwork, Graham Alexander of Johannesburg’s University of the Witwatersrand found female pythons went around seven months without eating, from the time they mated until after the hatching of their clutch.
Being reptiles, snakes are “ectothermic” in biological parlance — “cold-blooded” in layman’s terms — meaning their bodies rely on external heating. Unlike mammals, which have an internal furnace that requires constant fuel, reptiles can go long periods without eating.
“There must be an evolutionary advantage, because if the mother is forgoing feeding all that time it’s obviously a big cost to her, so there must be some benefit that outweighs that cost,” Alexander said. The females can lose 40 percent of their body weight during this period.
Still, there are limits: the females spend only two weeks with the young, which typically number in the dozens, after they hatch, and they don’t provide them with food or instruct them in the ways of the wild.
But during that time the babies are wrapped at night in the protective embrace of their mother’s coils, which Alexander said helped to keep the hatchlings warm — and presumably bolster their chances of surviving.
“Because the mother is so much bigger than the young, she takes a longer time to cool down at night. So while the babies are in the mother’s coils it stands to reason that they cool down more slowly as well,” he said.
Similar behavior has been observed in rattlesnakes, but they give live birth. And other pythons are known to stay with their eggs for most of the incubation period, but no other python species has been observed spending time with the young.
Among egg-laying reptiles, crocodiles also stay on their nests and spend time with their hatchlings.
The fieldwork was conducted in the Dinokeng Game Reserve near Pretoria. Radio transmitters that were inserted into snakes captured using old-fashioned methods.
“You run up and grab it by the tail,” Alexander said. A second person clamps a grab stick behind its head. Brought to the lab, the snake is anesthetized and the transmitter inserted in its body cavity.
The pythons were then tracked to their nest chambers in aardvark burrows, where they were observed with infrared video cameras gingerly lowered inside.