The skeleton of the kakapo differs from other parrots in several features associated with flightlessness . Firstly , it have the smallest relative wing size of any parrot . Its wing feathers are shorter , more rounded , and less asymmetrical and have fewer distal barbules to lock the feathers together . The sternum is small and have a low , vestigial keel and a shortened spina externa . As in other flightless birds and some other flighted parrots , the furcula is not fused but consist of a pair of clavicles lying in contact with each coracoid . As in other flightless birds , the angle between the coracoid and sternum is enlarged . The kakapo have a larger pelvis than other parrots . The proximal bones of the leg and arm are disproportionately long and the distal elements are disproportionately short .