Geographical generality of bird-habitat relationships depends on species traits
Résumé
Aim: The environmental filtering process is often considered as static in ecological
studies. However, growing evidence shows that species-environment
relationships
vary in space and time. In this study, we assessed to what extent bird responses to
landscape components can be geographically generalised and whether differences in
response generality can be explained by traits.
Location: France.
Methods: We collected a large bird data set (1968 point counts over two years) with
a standardised protocol in three agricultural regions with different levels of intensification
in France. We modelled the relationships between the distribution of 26 bird
species and three landscape components (percentage of woodland, hedgerow density
and landscape heterogeneity) and assessed whether differences between regions in
bird responses to landscape components (i.e., landscape-region
interactions) can be
explained by three species traits (habitat specialisation, diet and migration strategy).
We also examined the response of total species richness.
Results: We found that 16 species showed regional differences in their response at
least for one of the three landscape variables. Importance of landscape-region
interactions
was significantly correlated with two species traits. Responses of specialist species
to landscape components were geographically more constant than those of
generalists. The geographical variability of responses was higher for migrants than for
sedentary species. There were no significant relationships for the diet trait. Species
richness responded positively to the three landscape metrics in a similar way in the
three regions.
Main conclusions: The results underline the need to take into account the spatial differences
between species responses to habitats according to their traits when modelling
species-habitat
relationships at large scales. From a conservation point of view, we
suggest that conservation measures could be generalised at a large scale for specialist
species which are declining in agricultural landscapes.