A Seychelles giant tortoise apparently defied its historically plant-based diet when it was spotted snacking on a baby bird — a “horrifying” moment, scientists said.
Ecological researchers at the University of Cambridge’s Museum of Zoology caught the disturbing incident on video, which occurred in July 2020 on Frégate Island in the Indian Ocean.
“This is completely unexpected behavior and has never been seen before in wild tortoises,” said lead researcher Justin Gerlach, director of studies at Peterhouse Cambridge college, in a statement on Monday, according to CNN.
“The giant tortoise pursued the tern chick along a log, finally killing the chick and eating it,” recalled Gerlach, whose recent work was published in the journal Current 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.”
Frégate Island conservation manager and study co-author Anna Zora said that she was alerted to keep her camera’s lens pointed towards the tortoise when she “saw [it] moving in a strange way.”
The slow-moving reptile was stalking its prey — a tern chick — Zora realized.
“It’s moving very deliberately — it’s not just wandering about, it’s looking at this tern, and it’s walking straight at it, clearly intending to do something. That suggests to me that it’s doing it with intent. It knows what it’s doing, it’s done this before,” said Gerlach, who added that the tortoise looked “experienced” at hunting.
Tortoises are most typically herbivorous, although they are considered “opportunistic” eaters that will snag a leftover meaty morsel for a boost of protein.
“It’s quite common for herbivores to eat a bit of dead animal as a free protein source, essentially,” Gerlach told CNN. “But this is the first video evidence of them deliberately killing in order to eat.”
Researchers plan to continue their study of the Seychelles tortoise’s diet to determine how widespread omnivorous behavior has become across the species.
They also added that the tortoise’s unexpected craving is unlikely to have an impact on the island’s tern population.
“It’s probably not uncommon for animals to surprise our expectations by eating unexpected things that may just be a one-off,” Gerlach explained.
“Just by watching and recording what animals are doing you can find really totally unexpected things, things that we couldn’t discover deliberately — it has to be by chance,” he added.