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Publication
Senescence effects in an extremely long-lived bird: The grey-headed albatross Thalassarche chrysostoma
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Advisor(s)
Abstract(s)
Studies attempting to document reproductive or other pre-lethal senescence effects in wild birds typically
face an array of problems, including flaws in statistical analyses, non-adaptive philopatry to deteriorating
environments, confounding effects arising from cohort heterogeneity and differential death rates of
phenotypes and the frequent pairing of old birds to younger mates. Furthermore, recent studies suggest
that birds could maintain a high level of physical fitness until old age, before being struck by a catastrophic
illness leading quickly to their demise. The presence of terminally ill individuals in most datasets (and their
greater incidence in older age categories) may therefore provide a false impression of progressive
senescence in cross-sectional analyses. This study was designed explicitly to avoid all the known pitfalls
linked to the demonstration of progressive senescence in wild populations, and involved one of the very
longest-lived bird species.We show that, during incubation, old (aged 35 years and over) male grey-headed
albatrosses Thalassarche chrysostoma make longer foraging trips, and have lower daily mass gains, than
experienced mid-aged individuals (aged up to 28 years). This is, to our knowledge, the first report
documenting reduced foraging performance with old age. Hatching and breeding success of pairs
composed of two old individuals were reduced in comparison to mid-aged pairs. Overall results were very
similar when analyses were repeated using only individuals known to have survived 1 or 2 years beyond
field measurements (hence probably not suffering from the effects of an advanced terminal illness). We
conclude that extremely long-lived individuals usually experience some degree of general physical
deterioration, leading to reduced foraging and breeding performance, long before their final demise.
Description
Keywords
Foraging performance Life histories Age Breeding performance
Citation
Proceedings of the Royal Society B: Biological Sciences, 273, 1625-1630