Wildfire responses of a burrowing mammal were concentrated at burrows rather than nearby habitat

Abstract

Abstract Background Climate change is increasing the intensity and frequency of wildfires globally. Despite this, the effects of extreme wildfire events on animal species remain poorly understood. Animal responses to wildfire may be concentrated at fine-scale refuge features and therefore missed by broad-scale surveys. We measured the number of independent detection events (an index of relative abundance) and diel activity (activity patterns across the 24-h cycle) of common wombats ( Vombatus ursinus ) in response to the 2019–2020 wildfires in south-eastern Australia. We deployed unbaited wildlife cameras for 10 months at 56 sites across 28 sampling areas in Woomargama National Park and Woomargama State Forest, beginning 16 months after the wildfires. We paired each burrow site with a nearby non-burrow site in the same burnt or unburnt area in comparable habitat, with cameras at burrow sites positioned to sample burrow entrance use. Results Common wombat responses to fire differed between burrow and non-burrow sites. For diel activity, there was evidence that the effect of fire differed between burrow and non-burrow sites, with a greater fire-related reduction in hourly detection probability at burrow sites. Within burrow sites, hourly detection probability was lower in burnt than unburnt areas, whereas there was little evidence of a difference between burnt and unburnt non-burrow sites. Relative abundance showed a similar pattern, although evidence that the effect of fire differed between burrow and non-burrow sites was less conclusive. Within burrow sites, relative abundance was lower in burnt than unburnt areas, whereas there was little evidence of a difference between burnt and unburnt non-burrow sites. Conclusions Wildfire impacts can be overlooked when species responses to fire are measured at broader habitat scales, because responses may be concentrated at key refuge features such as burrows. Because common wombat burrows are known to provide shelter and other resources for multiple species following wildfire, reduced wombat detections at burnt burrow sites could have implications for how these refuge features function after fire. Our results suggest that post-fire monitoring should include fine-scale refuge features, such as burrows, to better detect species responses to wildfire and understand post-fire recovery.