“Vegetarian” Giant Tortoise Attacks and Eats Seabird As Horrified Researchers Film

Credit: Anna Zora

Researchers have captured on film the moment when a Seychelles giant tortoise, Aldabrachelys gigantea, attacked and ate a tern chick. This is the first documentation of deliberate hunting in any wild tortoise species.

The hunting tortoise was seen in July 2020 on Frégate Island, a privately owned island in the Seychelles group managed for ecotourism, where around 3,000 tortoises live. Other tortoises in the same area have been seen making similar attacks.

“The whole interaction took seven minutes and was quite horrifying.” — Justin Gerlach

“This is completely unexpected behavior and has never been seen before in wild tortoises,” said Dr. Justin Gerlach, Director of Studies at Peterhouse, Cambridge and Affiliated Researcher at the University of Cambridge’s Museum of Zoology, who led the study.

He added: “The giant tortoise pursued the tern chick along a log, finally killing the chick and eating it. 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.”

The interaction was filmed by Anna Zora, conservation manager on Frégate Island and co-author of the study.

“When I saw the tortoise moving in a strange way I sat and watched, and when I realized what it was doing I started filming,” said Zora.

The finding was published recently in the journal Current Biology.

All tortoises were previously thought to be vegetarian — although they have been spotted feeding opportunistically on carrion, and they eat bones and snail shells for calcium. But no tortoise species has been seen actively pursuing prey in the wild before.

Credit: Anna Zora

The researchers think that this entirely new hunting behavior was driven by the unusual combination of a tree-nesting tern colony and a resident giant tortoise population on the Seychelles’ Frégate island.

Extensive habitat restoration on the island has enabled sea-birds to recolonize, and there is a colony of 265,000 noddy terns, Anous tenuirostris. The ground under the colony is littered with dropped fish and chicks that have fallen from their nests.

In most places, potential prey are too fast or agile to be caught by giant tortoises. The researchers say that the way the tortoise approached the chick on the log suggests this type of interaction happens frequently.

On the Galapagos and Seychelles islands, giant tortoises are the largest herbivores and eat up to 11% of the vegetation. They also play an important role in dispersing seeds, breaking vegetation, and eroding rocks.

“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; things that probably happened commonly in the past but we’ve never seen before,” said Gerlach.

For more on this study, see Slow but Deadly: Watch This Tortoise Hunt a Baby Bird.

Reference “Giant tortoises hunt and consume birds” by Anna Zora and Justin Gerlach, 23 August 2021, Current Biology.
DOI: 10.1016/j.cub.2021.06.088

This research was supported by Fregate Island Foundation.

TortoiseUniversity of Cambridge
Comments ( 18 )
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  • Charles Farish

    has the turtle been tagged and maybe given and camera that can transmit live video following its eating habits. Maybe a small camera with a solar power system attached to the shell. Or would that be illegal with a protected species. A camera that can swivel to see its surroundings, logging temperature, time,and potentially catching poachers.

  • Sigurther

    Everyone’s a vegan until food starts getting scarce. 😂

  • Jdub

    Turtles are not vegetarian they eat minnows small fish worms and fruit to eat all kinds of s***

  • Puddin

    Why didnt it fly away lol

  • ArrantPrac

    Om’s finally getting his revenge on avian kind!

  • Chris M

    I once saw a Squirrel eat a bird… was told animals Know when they are lacking vitamins, minerals etc and they know/sense where to get it.

  • Jack

    It isn’t a turtle. My smart*** wife made sure to point that out when I told her the story. I said it looks like a turtle it’s a turtle.

  • Joseph

    It seems like there may be some kind of war between the two

  • Rick

    “The whole interaction took seven minutes and was quite horrifying.”
    Are even natural scientists now editorializing instead of reporting?
    Evidently these creatures are not vegan and there is nothing good, bad or “horrifying” about it.

  • Eric

    If a wildlife researcher thinks something like this is “horrifying” then maybe they should go into another career field. It’s nature. It’s the way it’s supposed to be.

  • Jenee

    Angry birds 3 plot?

  • Chris

    I had a couple tortoises that I kept in the backyard when I lived in Las Vegas, and they killed and ate a few birds over the years. Never actually saw them do it, but the circumstantial evidence was clear.

  • Joso

    My box turtle only eats meat. I leave mouse traps in the back yard so he always has fresh meat.

  • Biggolegee

    Sounds like a good idea for a commercial. I can see it now… the tortoise walks in to Popeye’s looks at the menu… and the impatient rabbit cashier says… “I know, you want the spicy chicken sandwich.”

  • Herb

    Serial killer maybe?

  • RampagerRadio

    Humans cam eat a 50% of a mermaid before being labeled a cannibal

  • Bobabooey

    The ‘horrified researchers’, need to find a new line of work.

  • Frank

    Your sure the chick didn’t climb in it’s mouth?