TikTok has nothing on these researchers who captured on video for the first time a giant tortoise, long thought to be a vegetarian, grabbing a meaty snack.
Giant tortoises are massive animals; males can weigh more than 700 pounds. They devour a lot of greens, primarily grasses and leaves, and can eat up to 11% of the vegetation in their home turf, so to speak.
But Anna Zora, a conservation manager at the private Frégate Island in the Seychelles Islands, was observing birds in July 2020 and happened upon a tortoise stalking a tern chick on a log and decided to record the incident.
“What attracted my attention was this tortoise was not just roaming around,” she said in a video presentation published in Current Biology, dated Aug. 23. “It was looking at this chick. … We stopped and started recording because I thought maybe something interesting is going to happen.”
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Captured on video: Giant tortoise on hunt
In a video on YouTube, you can see the tortoise approach the bird, which at first looks away as if to say, “Nothing to see here.” Then as the tortoise gets nearer, the bird turns to look at it, perhaps accepting its fate. The tortoise then attacked the chick and ultimately devoured it.
“The giant tortoise pursued the tern chick along a log, finally killing the chick and eating it,” said Justin Gerlach, director of studies for biology at Peterhouse, part of the University of Cambridge and an affiliate researcher for the university’s Museum of Biology. “It was a very slow encounter, with the tortoise moving at its normal, slow walking pace – the whole interaction took seven minutes and was quite horrifying,” said Gerlach, who co-authored the research with Zora, in a statement issued Monday about the findings.
What Zora and her team captured on video is “a remarkable observation,” because no tortoise has been recorded actively pursuing prey, Gerhach said in Current Biology.
All tortoises were thought to be vegetarians, but some feed on dead animals, bones and snail shells. Still, others have witnessed tortoises killing or eating other animals before. But “this is the first time that this surprising event has been recorded on video,” Gerlach said.
“And it’s been impossible to tell if this was a deliberate hunting or just the animal opportunistically taking advantage of a piece of extra protein,” he said. “What we report is clearly hunting.”
New ‘hunting’ behavior for tortoises
Giant tortoises can live to be more than 150 years old and up to 6 feet in length, according to National Geographic. Widespread in prehistoric times, the tortoises even lived in what is now the southern and southeastern U.S. and the Caribbean. But they are now only known to survive in the Seychelles and the Galapagos islands.
Turtles may be on your mind lately because of the two-headed sea turtle discovered recently in North Carolina. But tortoises and turtles – both are reptiles – have differences. Tortoises are turtles that live on the land and aren’t equipped for water (turtles’ feet are webbed), National Geographic says.
About 3,000 tortoises live on the island, which is managed for ecotourism. This “entirely new hunting behaviour” is likely driven by the growth of a tree-nesting tern colony of about 265,000 noddy terns, which often have chicks fall from their nests, Gerlach said.
“These days Frégate island’s combination of tree-nesting terns and giant tortoise populations is unusual, but our observation highlights that when ecosystems are restored, totally unexpected interactions between species may appear,” Gerlach said. “Things that probably happened commonly in the past but we’ve never seen before.”
For other chicks on the island there is some good news. Tortoises not only move slow, but also digest food very slowly and can survive up to a year without drinking or eating.
Follow Mike Snider on Twitter: @MikeSnider.