ABUNDANCE-RANGE SIZE RELATIONSHIPS OF BREEDING AND WINTERING BIRDS INBRITAIN - A COMPARATIVE-ANALYSIS

Both breeding and wintering assemblages of birds in Britain exhibit po sitive interspecific relationships between population size and geograp hic range size, such that the average density of species is greater if they are more widely distributed. Species in common to both assemblag es, that is resident species, had greater population sizes, geographic range sizes, and densities in winter. In contrast, whilst winter migr ants had higher abundances than summer migrants, the range sizes of th e former were disproportionately larger still, resulting in a lower de nsity for species that only winter in Britain than for those that only breed. Such differences aside, the overall form of the abundance-rang e size relationship is remarkably similar between the two assemblages and their constituent subsets of species.