Giant tortoises have a reputation as slow-moving vegetarians that snack on grasses and fruits. Video captured by researchers is changing the way we think about these heavy land animals. Still slow? Pretty much. Vegetarian? Not always.
The video comes from Fregate Island in the Indian Ocean. The island in the Seychelles is privately owned and hosts ecotourists who come for the beaches and to view the birds and wildlife, including a population of over 3,000 free-roaming giant tortoises. Some of those tortoises are into hunting and eating birds, an unusual dining choice for an animal thought to be an herbivore.
If you saw the title of this article and clicked on it anyway, you know what you’re in for: footage of a giant tortoise eating a seabird chick. If you don’t want to see that, don’t hit play on the video. Fregate Island deputy conservation manager Anna Zora filmed the encounter in July 2020.
The video features a shortened version of the hunt and shows a giant tortoise biting a tern chick that had fallen from its nest. It leaves out the inevitable conclusion of the attack. The University of Cambridge in the UK described the event as “the first documentation of deliberate hunting in any wild tortoise species” in a statement on Monday.
“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 biologist Justin Gerlach, co-author along with Zora of a paper on the tortoise published in the journal Current Biology on Monday.
Researchers have seen other tortoises making similar attacks, but didn’t capture full video evidence of those events. Giant tortoises have been known to eat carrion when convenient, but the tortoise in the footage is displaying hunting behaviors in pursuing the chick, which it eventually swallowed whole.
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This likely wasn’t the tortoise’s first bird-eating rodeo. Said Gerlach in a Cell Press statement, “It looked to me like that individual had hunted successfully before; it seemed to know what it was doing.”
The wildlife conservation efforts on Fregate Island have fostered healthy tortoise and seabird populations, creating what might be a perfect storm for tortoise-bird interactions.
Gerlach thinks there’s an element of enjoyment to eating terns that motivates the tortoises to put the effort into hunting. “Compared to the ease of eating plants,” Gerlack said, “they’re going to quite a lot of trouble.”