Replacement drives native β‐diversity of British avifauna, while richness differences shape alien β‐diversity

Aim We explored the range shifts of alien and native birds, responses β-diversity to abiotic factors, effect diversity on in two time periods. Location Great Britain. Time period 1968–1972, 2007–2011. Taxa studied Breeding birds. Methods estimated species between periods 1968–1972 Following, communities was by Jaccard pairwise index (βtot) partitioned into richness difference replacement component for each period. built generalized dissimilarity models including factors βtot their components a biotic model aliens taxonomic functional as predictors. Results Most half expanded new regions during 40-year The did not exhibit clear pattern along longitudinal or latitudinal gradient, while tended move north-westwards. dominant β-diversity, contributed mostly β-diversity. Alien responded similarly but less strongly than gradients. Temperature-related variables, distance precipitation were most important drivers explained more deviance model. Main conclusions over 40 years, with driven gains. environmental filtering weaker compared slightly reinforced second first period, highlighting role change shaping patterns. Native played key driving through interactions or/and reflecting climatic suitability niche availability aliens.