The Herbivorous Galapagos Tortoise sometimes hunts birds by drawing them under its shell. It then withdraws its limbs, crushing the bird beneath its weight.
The Galpagos tortoise has a mutually beneficial relationship with some species of Galpagos finch and mockingbirds. The tortoises let the birds feed on parasites stuck in spots on their body that they can't reach.
Small groups of finches initiate the process by hopping on the ground in an exaggerated fashion facing the tortoise.
The tortoise signals it is ready by rising up and extending its neck and legs, enabling the birds to reach otherwise inaccessible spots on the tortoise's body such as the neck, rear legs, cloacal opening, and skin between plastron and carapace.
The birds benefit from the food source and the tortoises get rid of irritating parasites.
The Galpagos tortoise is known as a herbivore, generally eating 70-80 pounds of plant life every single day. Their diets consist of cacti, grasses, leaves, lichens, and berries. But they don't always eat a vegetarian diet.
The tortoises will sometimes insidiously exploit its mutualistic relationship with birds. After rising and extending its limbs, the bird may go beneath the tortoise to investigate, whereupon suddenly the tortoise withdraws its limbs to drop flat and kill the bird. It then steps back to eat the bird, presumably to supplement its diet with protein.