No abstract

No abstract

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Survival from 1984 to 1985 was compared among known-aged California Gulls 4-23 yr old. Data supported a hypothesis of increasing reproductive effort with age. A flood during 1984 terminated breeding during the incubation phase of part of the colony, thus permitting an estimate of reproductive costs. Yearly survival of gulls whose nest flooded was 92% compared to 72% among gulls that carried out the reproductive cycle. Adult survival was inversely related to level of fledging success in 1984. Survival declined and fledging success increased with increasing age. However, gulls of differing ages within the same fledging success category had the same probability of survival. No evidence supported the hypothesis that fledging success increased with. age because disproportion!'ltely larger numbers of individuals with "good phenotypes" surviVed t

Comparisons of reproductive behaviors of three age classes of California gulls demonstrate that reproductive effort increases with age in this seabird. These findings contradict the assumption that increased reproductive success with age results from increased experience and social status and demonstrate that selection for increased reproductive effort can occur in long-lived species.