How giant tortoise catch bird

So i just heard that tortoises, in this example is galapagos tortoise catch a bird for eat.
How can a slow galapagos tortoise catch a bird?
He stand high and not moving at all, when all the birds came to him, he just make a right moment when one of the birds came right under his plastron and he dropped his body. Gotcha! After that, he went backward and get his meal.

So what make me curious is aldabra, radiata, and several other tortoises, when given scratch will stand up high not moving,...

How giant tortoise catch bird