After dropping the large bones, the bearded vulture spirals or glides down to inspect them and may repeat the act if the bone is not sufficiently cracked. This learned skill requires extensive practice by immature birds and takes up to seven years to master. Its old name of "ossifrage" ("bone breaker") relates to this habit. Less frequently, these birds have been observed trying to break bones (usually of a medium size) by hammering them with their bill directly into rocks while perched. During the breeding season they feed mainly on carrion. They prefer limbs of sheep and other small mammals and they carry the food to the nest, unlike other vultures which feed their young by regurgitation.