Part of a flock of 19 Canada Geese, Trabeg, 14th November 2013 (Michael O'Clery).
Although seemingly genuine Canada Geese have been seen in Kerry, they normally appear as singletons attached to wild geese flocks, such as the Barnacle Goose flock at Lough Gill or among the Whooper Swans and other geese at the Cashen (see eg, this post HERE). However there is always the spectre of some or all having 'escaped' from captivity and reverting to a wild state. Canada Geese are commonly kept in waterfowl collections throughout Europe and are often unpinioned, ie, perfectly capable of flying. Visit pretty much any park in London with a lake and you will see dozens flying about.
There are 11 races of Canada Goose currently recognised, ranging from the larger southern races such as maxima, which weighs in at an almost swan-sized 5030g, while the smallest minima, averaging a mere 1310 g, has almost duck-like proportions. Each race also has differently proportioned bills and wings, and some are overall much darker. It is usually the larger, paler breasted birds which are kept in captivity, so any small, dark races of the species are more likely to be the real thing.
This flock of 19 birds was in the field directly opposite the Seal and Wildlife Sanctuary at Trabeg, just outside Dingle. They are almost certainly derived from escaped birds from that centre when it was the 'Freshwater Experience' in 2004.
Four 'escapees' first appeared at Trabeg Estuary in autumn 2004, but by September 2006, nine birds were present with nine seen again in 2008. They were not always present around Trabeg however but were also found to be frequenting the estuary near Reenard, on the Ivearagh Peninsula, 25km to the south, and continue to move between those sites today. They are a lot more elusive in the spring and summer, but are surely breeding somewhere in Kerry.