Raising offspring increases ageing: Differences in senescence among three populations of a long-lived seabird, the Atlantic puffin

1. Actuarial senescence, the decline of survival with age, is well
documented in the wild. Rates of senescence vary widely between taxa, to
some extent also between sexes, with the fastest life histories showing
the highest rates of senescence. Few studies have investigated differences
in senescence among populations of the same species, although such
variation is expected from population-level differences in environmental
conditions, leading to differences in vital rates and thus life histories.
2. We predict that, within species, populations differing in productivity
(suggesting different paces of life) should experience different rates of
senescence, but with little or no sexual difference in senescence within
populations of monogamous, monomorphic species where the sexes share
breeding duties. 3. We compared rates of actuarial senescence among three
contrasting populations of the Atlantic puffin Fratercula arctica. The
data set comprised 31 years (1990–2020) of parallel capture-mark-recapture
data from three breeding colonies, Isle of May (North Sea), Røst
(Norwegian Sea) and Hornøya (Barents Sea), showing contrasting
productivities (i.e. annual breeding success) and population trends. We
used time elapsed since first capture (TFC) as a proxy for bird age, and
productivity and the winter North Atlantic Oscillation Index (wNAO) as
proxies for the environmental conditions experienced by the populations
within and outside the breeding season, respectively. 4. In accordance
with our predictions, we found that senescence rates differed among the
study populations, with no evidence for sexual differences. There was no
evidence for an effect of wNAO, but the population with the lowest
productivity, Røst, showed the lowest rate of senescence. As a
consequence, the negative effect of senescence on the population growth
rate (λ) was up to 3–5 times smaller on Røst (Δλ = -0.009) than on the two
other colonies. 5. Our findings suggest that environmentally induced
differences in senescence rates among populations of a species should be
accounted for when predicting effects of climate variation and change on
species persistence. There is thus a need for more detailed information on
how both actuarial and reproductive senescence influence vital rates of
populations of the same species, calling for large-scale comparative
studies.