Data from: Age-related variation in non-breeding foraging behaviour and carry-over effects on fitness in an extremely long-lived bird

1. Senescence has been widely documented in wild vertebrate populations,
yet the proximate drivers of age-related declines in breeding success,
including allocation trade-offs and links with foraging performance, are
poorly understood. For long-lived, migratory species, the non-breeding
period represents a critical time for investment in self-maintenance and
restoration of body condition, which in many species is linked to fitness.
However, the relationships between age, non-breeding foraging behaviour
and fitness remain largely unexplored. 2. We performed a cross-sectional
study, investigating age-related variation in the foraging activity,
distribution and diet of an extremely long-lived seabird, the wandering
albatross Diomedea exulans during the non-breeding period, and its links
with subsequent reproductive performance. 3. We tracked the distributions
of 82 adults aged 8 – 33 years with geolocator-immersion loggers and found
an age-related decline in the number of landings (a proxy of foraging
effort) during daylight hours. There was a decrease in body feather δ13C
values in older males but not females, yet this did not accompany an
age-related shift in distributions. Males conducted fewer landings than
females, and the sexes were spatially segregated, with males foraging
further south, likely due to their differential utilization of winds. 4.
While younger (< 20 years) birds had higher foraging activity, all
individuals went on to breed successfully the following season. In
contrast, among older (20+ years) birds, individuals that landed more
often were more likely to defer breeding or fail during incubation,
suggesting they have lower foraging success. 5. As far as we are aware,
this is the first demonstration of an age-specific carry-over effect of
foraging behaviour in the non-breeding period on subsequent reproductive
performance. This link between foraging behaviour and fitness in late but
not early adulthood indicates that the ability of individuals to forage
efficiently outside the breeding period may be an important driver of
fitness differences in old age.