Just as a woman experiences physical chances at menopause, the hen adopts masculine behavior when the levels of estrogen are disrupted. However there is no scientific evidence that these hens could insaminate another hen. There by , not really a true' sex change '.
http://www.backyardpoultrymag.com/spontaneous-sex-reversal-hen-just-become-rooster/
http://www.backyardpoultrymag.com/spontaneous-sex-reversal-hen-just-become-rooster/