Scientists filmed the moment a Seychelles giant tortoise – once believed to be vegetarian – attacked and ate a tern chick in what they say was the first documentation of deliberate hunting in a species of wild turtle.
“This is completely unexpected behavior and never seen before in wild turtles,” Justin Gerlach, director of studies at Peterhouse, Cambridge and affiliate researcher at the University of Cambridge Museum of Zoology, said in a statement.
“The giant tortoise chased the tern chick along a log, ultimately killing and eating it,” said Gerlach, who led the study, published Monday in the journal Current Biology.
“It was a very slow encounter, with the turtle moving at its normal, slow walking pace – the whole interaction lasted seven minutes and was pretty awful. “
“When I saw the turtle move in a weird way, I sat and watched, and when I realized what she was doing, I started filming,” Zora said in the communicated.
Gerlach told CNN that the way the turtle moved towards the chick suggested she was “experienced.”
“He’s moving very deliberately – it’s not just wandering around, he’s looking at that tern, and he’s walking right over it, with a clear intention to do something.” This suggests to me that he is doing it with intention. He knows what he’s doing, he’s already done that, ”he said.
Although turtles are considered vegetarians, they have been spotted eating carrion, as well as bones and snail shells for calcium.
“It’s pretty common for herbivores to eat a little bit of dead animal as a free source of protein, basically. But this is the first video evidence that they deliberately kill to eat, ”he said.
Still, the team can’t say for sure how common such behavior is among turtles and plan to study them further.
Giant tortoises are the largest herbivores in the Galapagos Islands and the Seychelles and eat up to 11% of the vegetation, researchers say. Gerlach added that the turtle’s behavior was unlikely to significantly affect tern populations.
Experts said the new hunting behavior was due to the ‘unusual’ combination of a tree-nesting tern colony and a resident giant tortoise population on Frégate Island in the Seychelles, which is home to around 3 000 turtles.
This is not the first time that unusual deadly attacks between animal species have been observed in the wild – chimpanzees were observed killing gorillas in the wild for the first time in 2019.
“It’s probably not uncommon for animals to surprise our expectations by eating unexpected things that can be unique,” explained Gerlach.
“We should try to avoid having too many assumptions about what the animals are going to do, or what they are doing. And it really shows the value of observation. Just by watching and recording what the animals are doing, you can find things that are really totally unexpected, things that we weren’t able to discover on purpose – it must have been by chance, ”he said.