Data from: State-space modelling of geolocation data reveals sex differences in the use of management areas by breeding northern fulmars

Effective management and conservation of terrestrially breeding marine
predators requires information on connectivity between specific breeding
sites and at-sea foraging areas. In the north-east Atlantic, efforts to
monitor and manage the impacts of bycatch or pollution events within
different Convention for the Protection of the Marine Environment of the
North-East Atlantic (OSPAR) management regions are currently constrained
by uncertainty over the origins of seabirds occurring in each area. Whilst
Global Positioning System (GPS) loggers can now provide high resolution
data on seabird foraging characteristics, their use is largely restricted
to the chick-rearing period. Smaller light-based Global Location Sensors
(geolocators) could provide valuable data during earlier phases of the
breeding season, but additional information on their accuracy is required
to assess this potential. We used incubation trip tracking data from 11
double-tagged (GPS/geolocator) northern fulmars Fulmarus glacialis L.
within a state-space modelling (SSM) framework to estimate errors around
geolocator locations. The SSM was then fitted to a larger sample of
geolocator data from the pre-laying exodus using the mean of these error
estimates. Geolocator data were first used to compare the trip durations
of males and females during this critical pre-laying period. Outputs from
the SSM were then used to characterize their spatial distribution and
assess the extent of within-colony variation in the use of different OSPAR
management regions. During the pre-laying exodus, fulmars from a single
colony in the north-east of the United Kingdom foraged widely across
several biogeographical regions, up to 2900 km from the colony. Most (60%)
males remained within the North Sea region, whereas most (68%) females
flew north, foraging within the Norwegian and Barents Sea. A small subset
of birds (15%) travelled to the central North Atlantic. Foraging trips by
males appeared to be shorter (x = 18 days, n = 20) than by females (x = 25
days, n = 19). Policy implications. Our results of state-space modelling
of geolocation data collected from northern fulmars show that
within-colony variation in ranging behaviour during the breeding season
results in sex differences in exposure to threats such as fisheries
bycatch and marine plastics. Birds from a single colony dispersed over
several north-east Atlantic management areas. These patterns have
implications for interpreting trends in colony-based monitoring schemes,
and European Union Marine Strategy Framework programmes using these
seabirds as an indicator species for monitoring trends in marine litter
and prioritizing efforts to mitigate its impact.