Does the response of bird assemblages to fire mosaic properties vary among spatial scales and foraging guilds?

CONTEXT: An increasing number of studies have investigated the impact of environmental heterogeneity on faunal assemblages when measured at multiple spatial scales. Few studies, however, have considered how the effects of heterogeneity on fauna vary with the spatial scale at which the response variable is characterised. OBJECTIVES: We investigated the relationship between landscape properties in a region characterised by diverse fire mosaics, and the structure and composition of avian assemblages measured at both the site- (1 ha) and landscape-scale (100 ha). METHODS: We surveyed birds and calculated spatial landscape properties in sub-tropical woodlands of central Queensland, Australia. RESULTS: Environmental heterogeneity, as measured by topographic complexity, was consistently important for bird species richness and composition. However, the explanatory power of topographic complexity varied depending on the spatial scale and the component of diversity under investigation. We found different correlates of richness within particular foraging guilds depending on the scale at which richness was measured. Extent of long-unburnt habitat (>10 years since fire) was the most important variable for the landscape-scale richness of frugivores, insectivores and canopy feeders, whereas environmental heterogeneity in the surrounding landscape was more important for site-scale richness of these foraging guilds. CONCLUSIONS: The response of species richness to landscape characteristics varies among scales, and among components of diversity. Thus, depending on the scale at which a biodiversity conservation goal is conceptualised—maximising richness at a site, or across a landscape—different landscape management approaches may be preferred.