Seal colony

Seal pups are born at a colony. Occasionally, pups are born at haul-out sites as well. To be classed as a colony, at least 15 pups have to be born at a site in one year. Australian Fur Seals mostly have their colonies on rocky islands. There are about 13 colonies of Australian Fur Seals. Most are in Bass Strait, between Victoria and Tasmania. The two largest colonies are Lady Julia Percy Island and Seal Rocks. One quarter of all pups are born at each of these colonies.

Why might seals have colonies on islands?