Common Noddies were first recorded breeding on Lancelin Island off south-western Australia in January 1992, when a colony of five pairs was discovered. This colony was 275 km south of the historical limits of its breeding range. A study of the population dynamics of this colony began in the 1994–95 breeding season and has now continued for 10 years. During that period the colony has expanded to more than 900 pairs. The demography of the colony was modelled using information on adult survivorship, age of first breeding and natal recruitment from the analysis of banding–recapture data and annual colony census data. During the establishment period, the Noddy colony went through a demographic transition. This involved an early phase of slow colony growth based on immigration, an intermediate phase of exponential growth driven by rapid immigration and a period of flattening growth characterised by declining immigration but increasing natal recruitment. Net immigration stopped by the 2003–04 season, 13 years after the colony was initiated. Future growth in the colony is predicted to be gradual and dependent on the natal recruitment rate.