Complex responses of birds to landscape‐level fire extent, fire severity and environmental drivers

Abstract

AbstractAimTo quantify bird responses to a large unplanned fire, taking into consideration landscape‐level fire severity and extent, pre‐fire site detection frequency and environmental gradients.LocationSouth‐easternAustralia.MethodsA major wildfire in 2009 coincided with a long‐term study of birds and provided a rare opportunity to quantify bird responses to wildfire. Using hierarchicalBayesian analysis, we modelled bird species richness and the detection frequency of individual species in response to a suite of explanatory variables, including (1) landscape‐level fire severity and extent (2) pre‐fire detection frequency, (3) site‐level vegetation density and (4) environmental variables (e.g. elevation and topography).ResultsLandscape‐level fire severity had strong effects on bird species richness and the detection frequency of the majority of bird species. These effects varied markedly between species; most responded negatively to amount of severely burned forest in the landscape, one negatively to the amount of moderately burned forest and one responded negatively to the total area of burned forest. Only one species – theFlameRobin – responded positively to the amount of burned forest. Relationships with landscape‐scale fire extent changed over time for one species – theBrownThornbill – with initially depressed rates of detection recovering after just 2 years. The majority of species were significantly more likely to be detected in burned areas if they have been recorded there prior to the fire.Main conclusionsBirds responded strongly to the severity and spatial extent of fire. They also exhibited strong site fidelity even after severe wildfire which causes profound changes in vegetation cover – a response likely influenced by environmental features such as elevation and topography.