As the larger ground-feeding birds seldom take flight except to escape danger, it is probable that the nearly wingless condition of several birds, now inhabiting or which lately inhabited several oceanic islands, tenanted by no beasts of prey, has been caused by disuse.
Jatekoa lurrean bilatzen duen hegazti handiak arriskutik ihes egiteko izan ezik hegaz egiteari nekez ematen diotenez, badaiteke piztia ehiztaririk ez den irla ozeanikoetan gaur egun bizi diren edo oraintsu oraindik bizi ziren zenbait txorik hegorik ez edukitzea erabilerarik ezak eragina izatea.