Habitat availability is insufficient to explain regional variations in white stork breeding habitat preference

Understanding species-habitat associations is key for making predictions
of species distributions of relevance to ecology and conservation.
Regional differences in species habitat preferences can hinder the
transferability of habitat models in space and time, but our ability to
account for these differences will depend on the mechanisms underlying
them (differences in habitat availability, genetics, culture). Here, we
modelled the large-scale breeding distribution of an expanding species,
the white stork Ciconia ciconia in France, applying machine-learning
algorithms to an extensive dataset of the distribution of nests spanning
the whole country. Specifically, we assessed the transferability of the
models across different geographic zones and contrasted the modelled
nesting habitat preferences of the species across these zones. Finally, we
assessed whether local differences in model transferability were related
to habitat availability in each zone. Our models generally had good
calibration performances, but were not equally transferable to all zones.
Additionally, environmental variables did not have the same effects in the
different zones, with particularly striking differences between Alsace and
the rest of France. This included a certain preference for urban areas in
Alsace – absent from other zones - that was consistent with their tendency
to nesting on buildings in that zone. Differences in habitat availability
between Alsace and the rest of France, as well as connectivity within the
French white stork metapopulation appeared to be insufficient to explain
the lack of transferability of models to this zone, suggesting some
possible local historical and cultural effects on habitat selection.