Breeding performance of Common Terns (Sterna hirundo) does not decline among older age-classes

Declines in reproductive performance among older age-classes have been reported in many bird and mammal species, and are commonly presented as demonstrating reproductive senescence. However, no declines in performance could be demonstrated in studies of several bird species. We measured reproductive performance in Common Terns (Sterna hirundo) of known age (2–28 yr) during a 19-yr period at a site in Buzzards Bay, Massachusetts, USA. We measured 6 components of reproductive performance and used Generalized Additive Mixed Models (GAMMs) in a Bayesian framework to analyze dependence of each measure on parental age, while controlling for variations among years and indices of individual quality. Four measures of performance improved (earlier laying date, higher values of clutch size, fledging success and productivity) with age, most rapidly between ages 2–10 yr; egg mass and hatching success varied only slightly with age. No measure of performance showed reversals among the older age-classe...