THIS PHOTOGRAPH will surely shock those who think of tortoises as gentle consumers of lettuces. Though some aquatic testudines, such as terrapins, are well-known to have a taste for meat, terrestrial varieties of the group have a more herbivorous reputation. However, Justin Gerlach of Cambridge University and Anna Zora of the Fregate Island Foundation in the Seychelles, who are studying the giant tortoises of that island nation, have found an intriguing exception. As they write in Current Biology, and as the picture shows, they have seen one of the animals they are observing quite deliberately attack, kill and eat a noddy-tern chick.
Tortoises being slow-moving, the entire incident took seven minutes. But there was nothing accidental about it. The tortoise approached the chick with its jaws wide open and its tongue retracted. This is typical tortoise behaviour when they are being aggressive to one another, and contrasts with what they do when feeding on plants—namely sticking out their tongues out as they grab and chew leaves. Unable to fly, and apparently unwilling to flee the vicinity of its nest, the chick eventually became a protein-rich addition to the tortoise’s diet.