Citation: Sandvik, H., K. E. Erikstad, P. Fauchald, and T. Tveraa (2008) High survival of immatures in a long-lived seabird: insights from a long-term study of the Atlantic Puffin (Fratercula arctica). Auk, 125, 723–730.
Key words: Capture-mark-recapture, immature survival, juvenile survival, Fratercula arctica, philopatry, recruitment rate.
Abstract: Survival from fledging to maturity is an important life-history parameter in long-lived species such as seabirds. However, due to the long period of unobservability following fledging, few studies have reported reliable estimates of immature survival rates. In this study we estimate survival to maturity of two cohorts of Atlantic Puffin (Fratercula arctica) fledglings from Horn°ya in Northern Norway using capture–mark–recapture methodology. By only considering juveniles that actually left their nest burrows, we arrive at unbiased estimates of immature survival rates. Contrary to many previous studies, we find that annual immature survival is not depressed relative to adult survival. By the age of five years, more than two thirds of all fledglings are still estimated to be alive. Averaged over this period, annual immature survival is estimated as 0.933 (95% confidence interval: 0.806–0.993). This compares to an annual adult survival of 0.943 (0.909–0.965) during the same period. The survival estimates also imply that the cohorts studied are overwhelmingly philopatric. Dispersal of immatures must be extremely rare or absent. The annual estimates of re-sighting reveal a clear age-related pattern, including a peak at three years of age and a subsequent minimum at six years of age. Possible biological explanations for this behaviour are given.
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