Untangling the influences of fire, habitat and introduced predators on the endangered heath mouse.
Globally, species extinctions are driven by multiple interacting factors including altered fire regimes and introduced predators. In flammable ecosystems, there is great potential to use fire for animal conservation, however most fire-based conservation strategies do not explicitly consider interacting factors. In this study, we sought to understand the interrelationships between the endangered heath mouse Pseudomys shortridgei, fire, resource availability and the introduced fox Vulpes vulpes in southeast Australia. We predicted that heath-mouse relative abundance would respond indirectly to post-fire age class (recently burnt; 0-3 years since fire, early; 4-9 years, mid; 10-33 years and late; 34-79 years) via the mediating effects of resources (shrub cover and plant-group diversity) and fox relative abundance. We used structural equation modelling to determine the strength of hypothesized pathways between variables, and mediation analysis to detect indirect effects. Both the cover of shrubs (0-50 cm from the ground) and fox relative abundance were associated with post-fire age class. Shrub cover was highest 0-9 years after fire, while fox relative abundance was highest in recently burnt vegetation (0-3 years after fire). Heath mice were positively correlated with shrub cover and plant-group diversity, and negatively correlated with fox relative abundance. We did not detect a direct relationship between heath mice and post-fire age class, but they were indirectly associated with age class via its influence on both shrub cover and fox relative abundance. Our findings suggest that heath mice will benefit from a fire regime promoting dense shrub regeneration in combination with predator control. Understanding the indirect effects of fire on animals may help to identify complementary management practices that can be applied concurrently to benefit vulnerable species. Analytical and management frameworks that include multiple drivers of species abundance and explicitly recognize the indirect effects of fire regimes will assist animal conservation.