Identifying individual factors affecting life-span has long been of interest for biologists
and demographers: how do some individuals manage to dodge the forces of mortality
when the vast majority does not? Answering this question is not straightforward, partly
because of the arduous task of accurately estimating longevity in wild animals, and
of the statistical difficulties in correlating time-varying ecological covariables
with a single number (time-to-event). Here we investigated the relationship between
foraging strategy and life-span in an elusive and large marine predator: the Southern
Elephant Seal (
Mirounga leonina). Using teeth recovered from dead males on îles Kerguelen, Southern Ocean, we first
aged specimens. Then we used stable isotopic measurements of carbon (
) in dentin to study the effect of foraging location on individual life-span. Using
a joint change-point/survival modelling approach which enabled us to describe the
ontogenetic trajectory of foraging, we unveiled how a stable foraging strategy developed
early in life positively covaried with longevity in male Southern Elephant Seals.
Coupled with an appropriate statistical analysis, stable isotopes have the potential
to tackle ecological questions of long standing interest but whose answer has been
hampered by logistic constraints.