The decline of ground-nesting birds in Europe: do we need to manage predation in addition to habitat?

Bird populations are declining globally with losses recorded in many
European breeding birds. Habitat management measures have not resulted in
a widespread reversal of these declines. We analysed national bird
population trends from ten European countries (France, Hungary, Ireland,
the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland, and the UK)
in relation to the species’ nesting strategy (‘ground-nesting' or
‘other’), Annex I designation (‘designated’ or ‘not designated’) and
association with agricultural habitats for breeding (‘associated’ or ‘not
associated’). For each country in our dataset, we also defined the
following factors: farming intensity; predator community complexity; and
predator control effort. Our results showed additive effects of nesting
strategy, designation, and breeding habitats on the likelihood of
population decline. Ground-nesting birds were 86% more likely to decline
than birds with other nesting strategies. Annex I designated species of
the Birds Directive were 50% less likely to decline than non-designated
birds. Birds breeding primarily in agricultural habitats were more likely
to decline than birds breeding in other habitats, interactively with
farming intensity. Homogenous trends across Europe (i.e., trends in two or
more countries that were either not declining in all countries or
declining in all countries) indicate that the probability of population
decline was related to nesting strategy and breeding habitat, with
ground-nesting birds being 15.6 times more likely than other birds to have
a declining trend across Europe, and birds nesting in agricultural habitat
being 17.8 times more likely than birds nesting in other habitats to have
a declining trend across Europe. Our results highlight a widespread
challenge, therefore widespread instruments (e.g. legislation, economic
policies, agri-environment schemes) will be required to reserve these
declines. Ground-nesting species requirements can be complex and multiple
strategies will be needed to restore populations including the development
of predation management tools.