Abstract
Aim Biodiversity patterns and the mechanisms driving these patterns are inherently scale dependent. Studies investigating biodiversity scaling have focused mostly on evaluating community turnover without taking into consideration its underlying processes of local extinction (hereafter, extinction) and colonization. Our goal was to evaluate the spatial scaling of change in avian assemblages through time and identify environmental drivers of community‐wide dynamics across a range of spatial scales, with a focus on extinction and colonization. Location New Y ork S tate. Methods We analysed community dissimilarity, temporal turnover, extinction and colonization as measures of temporal change in avian communities at five spatial resolutions (5 × 5, 10 × 10, 20 × 20, 40 × 40 and 80 km × 80 km). We evaluated the relationships between community change and change in climatic conditions, landscape fragmentation and elevation at each spatial grain using B ayesian spatially varying intercept models. Results We found that the decline in colonization with increasing spatial scale was less steep than the decline in community dissimilarity, temporal turnover or extinction. We also found that the importance of environmental drivers to community change was dependent on both scale and metric, though we did not find optimal spatial scales at which either landscape or climatic processes consistently drove patterns of community change. Landscape characteristics were the most important correlate of extinction at all spatial scales, while colonization was not predicted well by any of the environmental factors. Main conclusions The slower decline in colonization across spatial grains is probably a consequence of the high mobility and dispersal abilities of birds. We further conclude that the two processes underlying community change – extinction and colonization – are driven by different factors. Landscape characteristics strongly affect the rates of extinctions in avian communities. On the contrary, patterns of colonization are likely to be a result of intrinsic characteristics of birds – specifically, high dispersal ability – that allow them to colonize new sites, regardless of the environmental context.