The ibis of ancient Egypt was a protected species and Alexander had too much common sense to violate the traditional customs of Egypt just to bag a few birds ... ibis or otherwise.
Alexander defeated and ruled the known world with his military and diplomatic cunning but he was careful not to trample on the gods or customs of the nations he conquered ... Alexander never killed an ibis ... he never intentionally defiled a shrine or city BUT if you tried to double-cross him he would make you pay dearly ... and he didn’t accept foreign money, checks or credit cards ... he made you pay with blood, sweat and tears.
Alexander started out as Good but eventually he became Great ... if you want to know why, just ask anyone from Alexandria.