A WINTER SIGHTING OF KILLER WHALES (ORCINUS-ORCA) IN ANTARCTIC SEA-ICE

A group of killer whales was sighted in open leads well inside Antarct ic sea ice during August 1995. This was the first winter sighting of k iller whales in Antarctic waters since 1955, and contradicts the view that all killer whales migrate north prior to the winter. A small calf was observed, providing the first evidence of a cetacean species bree ding in Antarctic waters. Several potential prey species were also pre sent. The sighting highlights the importance of lead and polynya syste ms to marine mammals, which probably use them to disperse within the w inter sea-ice zone.