Unbelievable! See How A Giant Tortoise Stalks, Kills And Eats Its Prey In Seychelles
This is the first time that deliberate hunting by a tortoise has been documented. Video referenced in a paper published in Current Biology magazine.
New Delhi: Tortoises are assumed to be gentle, harmless herbivores that mostly consume small plants, and are not expected to hunt prey. However, a recent video of a giant tortoise hunting, killing and consuming a bird, proves otherwise.
This is the first time that deliberate hunting by a chelonian species (a reptile of the order, Testudines that includes reptiles like turtles and tortoises) has been documented.
The video referenced in a paper published in Current Biology magazine was captured by Anna Zora, co-author of the study and conservation manager of Frégate Island, a privately owned island in the Seychelles group managed for conservation and ecotourism.
Zora and her team had visited a noisy tern colony in Frégate Island, on July 30, 2020, when they observed a female Seychelles giant tortoise (Aldabrachelys gigantea) and a lesser noddy (Anous tenuirostris) sitting on a log. Zora noticed the behaviour of the tortoise to be strange, and saw it advancing towards the young tern. She at once decided to film the seemingly unusual event.
They observed the tortoise at 'Anse Parc', a restored woodland, which harbours a dense population of tortoises.
In another video referenced in the paper, Zora mentioned that the carapace (tortoise shell) length of the adult female tortoise was 50 cm. At its usual speed, the reptile was moving towards the tern chick with its mouth wide open. The chick was trying to escape the tortoise by retreating along the log and was fluttering its wings, to defend itself, but as the bird reached the end of the log, it stopped moving, and eventually fell prey to the tortoise, which closed its jaws on the head of the chick, resulting in its instant death.
As the chick fell off the log, the tortoise moved to the ground to devour the bird, swallowing it whole. The whole event occured over seven minutes, from the tortoise approaching the chick to swallowing it. The hunt for the bird on the log lasted for 92 seconds.
Why Is This Video Surprising?
Justin Gerlach, Director of Studies for Biology at Peterhouse, Cambridge, mentioned in the video that though several accounts of tortoises hunting prey have been witnessed in the island, there has been no documented evidence to support the claim. He said this is the first time an unexpected event like this has been recorded on video.
He also said that tortoises were widespread in ancient times but today they were associated with only a few places like the Galapagos and the Seychelles Islands, where they are the most significant herbivores effectively, and are the islands' equivalent of elephants.
They play important roles in vegetation, dispersion of seeds, digging out mud wallows, and eroding rocks in these islands, one of them being Frégate Island, where 3,000 giant tortoises live in the forests.
Gerlach explained in the video that these giant tortoises had been absent in the islands' forests for many decades, as a result of which sea birds recently re-colonised the recovering forests. The lesser noddy (Anous tenuirostris) were the main species, with 10,000 pairs nesting in one colony.
In the video, the tortoise can be seen approaching the tern with its jaws wide open and tongue retracted, which is unusual feeding behaviour for chelonians living on ground, that keep their tongue protracted when they are about to eat, instead of demonstrating aggressive behaviour. Had it been some prey other than the grounded noddy tern check, the tortoise wouldn't have been able to successfully hunt the organism as it would outrun the tortoise, which is an inherently slow creature.
Noddy terns are afraid of being on the ground, as they may fall prey to perilous creatures like lizards and crabs, which is why the chick clung to the log.
According to Gerlach, the tortoise's movements suggest that he earlier hadn't had any hunting experience, stated a ScienceNews report. "[People] don't think of tortoises as having very interesting behaviours. This shows there's an awful lot more to them," the report quoted him as saying.
In the video, Gerlach also said it was difficult to tell whether this was a deliberate hunting or an opportunistically carrion (animal feeding on dead and rotting flesh) feeding event, because tortoises consume snail shells and bones. He explained that this new pattern of behaviour developed as the birds re-colonised the island and that the conservation and re-wilding work done in these islands resulted in the occurrence of unusual species interactions and behaviours, which may have existed long ago but had been impossible for hundreds of years.
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