Data from: Local prey shortages drive foraging costs and breeding success in a declining seabird, the Atlantic puffin

As more and more species face anthropogenic threats, understanding causes
of population declines in vulnerable taxa is essential. However, long-term
datasets, ideal to identify lasting or indirect effects on fitness
measures such as those caused by environmental factors, are not always
available.  Here we use a single year but multi-population
approach on populations with contrasting demographic trends to identify
possible drivers and mechanisms of seabird population changes in the
north-east Atlantic, using the Atlantic puffin, a declining species, as a
model system.  We combine miniature GPS trackers with camera
traps and DNA metabarcoding techniques on four populations across the
puffins’ main breeding range to provide the most comprehensive study of
the species’ foraging ecology to date.  We find that puffins use
a dual foraging tactic combining short and long foraging trips in all four
populations, but declining populations in southern Iceland and north-west
Norway have much greater foraging ranges, which require more (costly)
flight, as well as lower chick-provisioning frequencies, and a more
diverse but likely less energy-dense diet, than stable populations in
northern Iceland and Wales.  Together, our findings suggest that
the poor productivity of declining puffin populations in the north-east
Atlantic is driven by breeding adults being forced to forage far from the
colony, presumably because of low prey availability near colonies,
possibly amplified by intraspecific competition. Our results provide
valuable information for the conservation of this and other important
North-Atlantic species and highlight the potential of multi-population
approaches to answer important questions about the ecological drivers of
population trends.