Local avian assemblages as random draws from regional pools

It is becoming increasingly apparent that the ecological structure of local assemblages depends to some degree on the regional context within which they are embedded. Here. the structure of one such local assemblage the avifauna of Eastern Wood, southern England, is modelled as a random draw from the pool of British deciduous woodland species. The random draw model accurately predicts most (> 90%) of a suite of descriptive statistics calculated from the Eastern Wood avifauna, when the probability that a species is selected for inclusion in a random assemblage is weighted by its British geographic range size. Models for which a species selection is weighted by its British population size, or is unweighted, perform less well. This suggests that how a widespread a species is in a region affects the likelihood that it will occur at any given local site, and hence that large-scale patterns in the distribution of species can strongly influence the composition and structure of local assemblages.