Unburnt patches maintain bird abundance and species richness following large wildfires in an Australian semiarid woodland ecosystem

Large wildfires can cause widespread disruption to ecosystems and animal populations, but patches left unburnt within fire scars may play a key role in the persistence and post-fire recovery of communities, which may depend on habitat characteristics, patch size, or spatial configuration. To test this, we made use of a natural experiment in which a semi-arid landscape was burnt twice in the space of eight years. We surveyed bird assemblages at 130 sites, and tested the relative importance of time since fire, habitat features and landscape configuration of unburnt patches for post-fire species abundance, species richness and phylogenetic diversity. In the first three years after fire, abundance of 4/18 bird species were higher in unburnt patches than the surrounding burnt matrix, and after 8–10 years abundance of three species was still higher in unburnt patches. Short-term post-fire variation in species richness was associated with habitat differences between burnt and unburnt areas, but not with habitat differences among unburnt areas, nor with patch size or spatial configuration. Our results suggest that even small or isolated unburnt patches are important in maintaining bird abundance and species richness, and facilitating recovery of animal populations across large fire scars, especially in the first three years after a major fire event.