Do large‐scale associations in birds imply biotic interactions or environmental filtering?

Aim There has been a wide interest in the effect of biotic interactions on species' occurrences and abundances at large spatial scales, coupled with vast development statistical methods to study them. Still, evidence for whether effects within-trophic-level (e.g. competition heterospecific attraction) are discernible beyond local scales remains inconsistent. Here, we present novel hypothesis-testing framework based joint dynamic species distribution models functional trait similarity dissect between environmental filtering interactions. Location France Finland. Taxon Birds. Methods We estimated species-to-species associations within trophic level, independent main variables (mean temperature total precipitation) common scale (a multivariate spatiotemporal delta model) models. created hypotheses functionality (morphological and/or diet dissimilarity) habitat preferences about sign strength pairwise estimate extent which they result from (competition, filtering. Results Spatiotemporal were mostly positive (80%), followed by random (15%), only 5% negative. Where detected, negative different communities due few species. The relationship association dissimilarity among was negative, fulfils predictions both attraction. Main conclusions showed that processes leading aggregation (mixture seem dominate assembly rules, did not find competition. Altogether, our is beneficial ecological interpretation data covering several decades biogeographical regions.