Birds: Great Northern Diver (Lóma Mór), Gavia immer

A large seabird, around 85cm in length, the Great Northern Diver is a widespread winter visitor to the Irish coast. It is usually only to be found on the sea, though often not too far from the shore, and can sometimes be seen from piers and jetties.

In winter plumage, when we are most likely to encounter it, the Great Northern Diver is white below and dark grey above and can be distinguished from other diver species by its powerful bill. In breeding plumage, however, it looks very different, with a dark iridescent blackish-green head, barred collar and chequerboard-patterned back.

This species is a powerful swimmer, and can dive to great depths in search of fish. Its feet are set very far back on its body, the most efficient position for propulsion and steering; this is the same reason that the propeller and rudder are placed at the back of a boat. However, this means that they are extraordinarily ungainly and unbalanced on land, and unable to walk more than a few steps; on the rare occasions that they need to travel longer distances they are forced to rest their bellies on the ground and use their feet to shunt themselves along. They are good fliers, however, and can often be seen passing coastal headlands, low over the water.

Though a few remain in Ireland during the summer, this species does not breed here; all our visitors come to us from Iceland, Greenland and Arctic Canada. In fact, it is the national bird of Canada, where it is known as the Common Loon, most likely on account of its crazed song during the breeding season. It even appears on the Canadian one dollar coin, known to all Canadians as the "Loonie".

For more information on the Great Northern Divers or any of Ireland's other birds, or to join Birdwatch Ireland, visit www.birdwatchireland.ie, call 01 2819878, or email info@birdwatchireland.ie