Poultry have a long history in Ireland. By the time of St. Patrick in the 5th century AD, people would certainly have been keeping geese and swans, at least semi-domesticated. Both are migratory waterfowl that would have flown over Ireland and stopped for part of the year. Swans became semi-domesticated, living close to humans but continuing to migrate. Iron Age Britons revered the swan as supernatural. Swans continued to be held sacred throughout Europe through the Middle Ages, the 5th century to the 16th century.
Gray Geese such as these at the Frontier Culture Museum are the domesticated form of wild Graylag Geese. They were the common farmyard geese of colonial America. Geese are valued for their feathers and down as well as their meat and eggs. I took these pictures when I visited the museum as part of the Society of Environmental Journalists Healthy Food Shed Tour in 2008.
Ireland has an active poultry club today, the Irish Poultry Society, http://irishpoultrysociety.com/. They champion many rare and historic breeds.