Whooper Swans (Cygnus cygnus) Eala Ghlórach (Gaelic).
They are a winter visitor to wetlands throughout Ireland from October to April.
They winter mostly on lowland open farmland around inland wetlands, and are regularly seen while feeding on grasslands and stubble.
The population wintering in Ireland breeds in Iceland.
Reference: http://www.birdwatchireland.ie/Default.aspx?tabid=151