The early bird catches the worm: age-specific arrival time influences reproductive performance in the White Stork Ciconia ciconia

Abstract

<sec><title>Capsule</title>Age, arrival date and egg laying date are essentially closely related and determine reproductive performance in the White Stork Ciconia ciconia.</sec><sec><title>Aims</title>To describe the impact of age, arrival date and egg laying date on breeding success in the White Stork.</sec><sec><title>Methods</title>Ringing data from a White Stork breeding colony of 212 nests at Dréan, Algeria, were used to model the relationship between age, arrival date, laying date and reproductive performance. Seventy breeders that were individually colour-ringed as nestlings were monitored.</sec><sec><title>Results</title>Birds breeding on the periphery of the colony had significantly smaller nests and showed a tendency towards later laying dates, but they did not differ from centrally nesting birds in age or arrival date. First year birds did not breed and second year birds were significantly more likely than older age groups to occupy nests but fail to lay eggs. Older birds arrived earlier at the breeding colony and had a higher probability of initiating laying than younger birds. They also had a higher probability of nesting successfully and fledging a larger number of young.</sec><sec><title>Conclusion</title>Age determined arrival and laying dates and influenced breeding performance in the White Stork.</sec>