There has been debate as to whether the composition of avifaunas is determined primarily by responses of species to the floristic composition of habitats or to the structural features of habitats (viz. physiognomy). Some evidence suggests that the effects of geographic scale may be the source of this dispute. The present analysis demonstrated that the influence of both floristics and physiognomy could be detected at the regional level for avifaunas of south-eastern Australian woodlands. The impact of floristics often may be obscured by patchiness and relatively rapid rates of spatial change in the phytosociology of habitats relative to those of avian species, even at the local scale (say leqslant R: less-than-or-eq, slant 10 km). Such potential occlusion of the importance of floristics to avifaunas may be overcome by using floristic similarity indices that are based on plant taxonomic representations at both the specific and subfamilial levels. Both floristics and physiognomy are likely to affect avifaunal composition, although the perceived significance of each factor may vary with the scale of observation.