WHAT CAN THE BLACK ROBIN TELL US ABOUT POPULATION BOTTLENECKS?

The black robin (Petroica traversi) is resident in two of the Chatham Islands, a small cold and windswept cluster of islands several hundred kilometres off the east coast of New Zealand, with a limited ecosystem and, until recently, beset by introduced predators. Thirty years ago the black robin was known as the world's most endangered bird, with a surviving population of under ten individuals. Despite much crucial and creative work by the New Zealand Wildlife Service, survival of the species was uncertain for some years. While the population has now grown to over 400 birds, the entire present-day population is descended from just one male and one female who were alive in the 1978/1979 breeding season, and so is very inbred. The dedicated work of the Wildlife Service team has led to a great deal being known about the behaviour of each individual in the population during the most critical bottleneck phase. This information provides a detailed corpus of useful knowledge for ecologists involved in such rescue operations. It provides inter alia a complete genealogy of the population for the critical phase, a helpful corpus of knowledge for some genetic modelling and analysis of bottlenecks. We present an overview.