Refuges for birds in fire-prone landscapes

Submission note: A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy to the Department of Zoology, School of Life Sciences, Faculty of Science, Technology and Engineering, La Trobe University, Bundoora.

Unburnt patches within fire boundaries are considered to act as refuges for birds and other fauna; facilitating survival and persistence within fire-prone landscapes. Various processes (e.g. topography, planned burning) result in unburnt patches of varying habitat quality and value to avifauna. Unburnt patches may be especially important in the case of large, intense wildfire where there is a paucity of unburnt vegetation remaining within the fire boundary and large distances to unburnt habitat beyond the fire’s edge. Despite being regarded as important, the ecological value and nature of unburnt patches have rarely been examined. This study aimed to determine the importance of fire history, fire severity, topography, vegetation structure, floristic richness and landscape properties in predicting the persistence of birds in burnt landscapes. Surveys were conducted at 96 sites in mixed eucalypt foothill forest and gully vegetation of south-east Australia that had experienced a high intensity, landscape-scale wildfire ( greater than200,000 ha) in 2009. The study revealed that two to three years after this mega-fire i) unburnt, and to a lesser extent ground burnt, patches did act as refuges for birds; ii) underlying time-since-fire prior to the mega-fire was less relevant to bird communities than the severity at which a site was burnt; iii) no homogenising effect of the mega-fire upon bird assemblages occupying very different topographical positions in the landscape (i.e. gullies and slopes) was detected; iv) vegetation structure had a greater influence upon avian communities than floristic richness; v) the size, isolation and landscape context of unburnt or ground burnt patches had little to no influence on avian assemblages. This study contributes to a greater understanding of how avian communities persist in fire-affected landscapes and provides insights for the appropriate use of planned fire to achieve ecologically positive outcomes for birds.