The reliability of a composite biodiversity indicator in predicting bird species richness at different spatial scales

•We used species distribution modelling to implement a bird biodiversity indicator that we found highly predictive of bird species richness.•The biodiversity indicator was tested at three spatial scales: small, medium and large.•Testing results were used to infer about the reliability and usefulness of such an indicator in the broad context of biological monitoring and conservation planning.•We believe that the potential of our indicator is provided by the consolidated statistical and modelling techniques implemented and by its adaptability to different taxa and regions.