Justin Gerlach thought there must be some sort of misunderstanding — because tortoises don’t hunt. These gentle herbivores spend their days munching on plants. They don’t stalk prey. So his colleague’s report must be wrong.
Except the video was indisputable.
One summer evening in 2020, a female Seychelles giant tortoise cornered a noddy tern chick. This was on Frégate Island. It’s part of the Seychelles, an archipelago off of East Africa. The young noddy tern (Anous tenuirostris) had fallen from its nest. Slowly but surely, the tortoise (Aldabrachelys gigantea) forced the chick to retreat down a log, like a pirate walking the plank.
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Eventually, the bird had nowhere to go. Several slow, deliberate lunges later, the tortoise chomped down on the bird. The bite crushed the chick’s head. Then the tortoise swallowed her prize whole.
This is the first recorded instance of a tortoise hunting. The footage was captured by Anna Zora. She’s a conservation and sustainability manager at Frégate Island Sanctuary. That’s the island’s nature reserve. Zora and her colleagues shared their discovery August 23 in Current Biology.
“This was totally unexpected,” says Gerlach. “It’s just amazing and slightly horrifying.”
Gerlach is a biologist at the University of Cambridge in England. He’s a coauthor on the new study.
Many herbivores are known to scarf down dead animals for protein, Gerlach says. And there have been some reports of tortoises crushing and eating small birds. “But it’s unclear whether these are deliberate [actions],” he says. These tortoises may have just stepped on birds by accident. After all, tortoises don’t look like natural hunters. Most prey can outrun them.
But the noddy tern chick in the new video proved easy pickings. It was too young to fly. Once the tortoise had it cornered on a log, the chick had nowhere to run. That’s because the chick, which nests in trees, may have been too afraid to jump off the log, Gerlach says.
He suspects this tortoise has hunted before. Its deliberate movements suggest it was experienced. Gerlach now plans to investigate whether tortoises hunt regularly. But even if they don’t, this one video has changed his view of the reptiles.
“[People] don’t think of tortoises as having very interesting behaviors,” he says. “This shows there’s an awful lot more to them.”