The greatest amount of energy released per gram of reactants occurs during a

It isn't only for the eating habits but also for building nests, hunting small insects, birds, other creatures including defence. Birds have a narrow small throat so the beak helps ripping off small peices of a big animal l(small bird) and for insects they crush and swallow it, they se their beak for feeding their children by grinding food in their beak and transferring it to the youngsters mouth