Meeting Abstract

P2.134  Wednesday, Jan. 5  Poor foraging not breeding explains reproductive decline in a long-lived seabird. ALLEN, L*; GRACE, J; CHADWELL, B; WIKELSKI, M; ANDERSON, D; Salem College, Winston Salem, NC; Wake Forest University, Winston Salem, NC; Wake Forest University, Winston Salem, NC; Max Planck Institute for Ornithology, Germany; Wake Forest University, Winston Salem, NC louise.allen@salem.edu

We examined data on age-related foraging patterns in reproductively active adult Nazca boobies (Sula granti), a pelagic seabird nesting in the Galápagos Islands. We looked for evidence of declining foraging ability with age by pairing our long-term demographic data with animal mounted remote sensing technologies. Using miniature GPS and depth recording units we tracked two groups of middle-age (9-16yrs) and old (17+yrs) birds on foraging trips during incubation in a cross-sectional fashion. We provide preliminary evidence of declining foraging performance with age in this species. We show that older birds remain away from the colony for longer periods than middle-aged birds, and that older birds gained less weight per foraging night than middle-age birds. We found that older birds have longer inter-dive intervals than middle-age birds and that older birds make fewer deep dives per day. We also found that older birds traveled further and at slower flight speeds from the colony on their foraging trips than middle-age birds. Nazca boobies experience a peak in reproductive success between years 9 and 13 with declining success after 16 years of age. This decline is due to the failure to complete a reproductive attempt, rather than failure to attempt breeding, providing an important clue regarding the nature of the reproductive senescence. Our evidence of age-associated changes in foraging ability may explain much of the observed reproductive decline.