Population dynamics, recruitment, individual quality and reproductive strategies in Common Terns Sterna hirundo marked with transponders

From 1992 to 1999, we used subcutaneously injected transponders, enabling r emote and automatic annual identification with the aim of performing an int egrated population study of a Common Tern sterna hirundo colony. Within a f ew years, population parameters and their inter-year variation could be cal culated with a high degree of accuracy (adult return rate 91%, subadult ret urn rate 35%, breeding success 1.3 fledglings pair(-1)y(-1), mean recruitme nt age 3y). Data on condition, fate, reproductive performance and output we re gathered year by year and contributed greatly towards the detailed study of many questions in behavioural and population ecology, such as individua ls' quality, prospecting and recruitment. The arrival time of prospectors a nd recruitment age were related to body condition. The high body mass of ad ults increased their reproductive performance and output. Divorce rate was low (18.9%) and increased with arrival asynchrony of mates. Divorced terns tended to change territories, whereas territory fidelity in general was hig h. The future focus of this ongoing study is reproductive value, senescence , lifetime reproductive success, fitness, and questions related to genealog y.