Breeding performance of very old Common Terns

摘要

We studied the breeding performance of very old Common Terns (Sterna birundo) at Bird Island, USA (41°40′N, 70°43′W), in 1999. We studied birds aged>=18 yr, comprising the oldest 5/100 of the birds breeding At this site. We located 24 of these old birds and measured their breeding performance, including laying dates, Clutch sizes, egg masses, hatching success, chick growth, chick survival, and overall productivity. We compared their Performance with that of several reference groups, including a date-matched group of young birds aged 6-9 yr and Date-matched birds of all ages.