Caer Ibormeith From Wikipedia, the free encyclopedia Jump to: navigation, search For the Welsh reflex of Roman castrum, see caer. In Irish mythology, Caer Ibormeith was a daughter of Ethal and Prince Anubal of Connacht. Every alternate Samhain she would change into a swan, in which form she would remain for a year before becoming human again the following Samhain. She eventually married Aengus, but first he had to pick her out, in swan form, from a group of other swans at Loch Bel Dragon. He turned himself into a swan and they flew away, singing beautiful music that put all its listeners asleep for three days and nights. With Aengus, Caer was the mother of Diarmuid.