SummaryThe breeding population ofSula bassana serratoron Lawrence Rocks has apparently increased in recent years. In December 1961, 639 breeding pairs were counted.Banding has shown that juvenileS. b. serratorof the Australian breeding population, like otherS. bassanapopulations, leave their natal colonies and move long distances into areas with a warmer sea temperature. They apparently stay there for two to four years, after which they usually return to the natal area.