House mouse dynamics in a changing climate: The Grampians National Park long-term fire and climate experiment

Context and aims: To understand how future climatic changes, including increased fire, drought and flooding will affect ecosystems, it is important to develop long-term models of how species respond to these factors including introduced pest species such as the house mouse (Mus musculus). The aim of our research was therefore to determine the factors influencing house mouse dynamics in temperate ecosystems to investigate how the species may respond to climate change. Methods: We collected long-term data through small mammal surveys in the Grampians National Park during fire, drought and flooding events between 2008 and 2021. We developed models to test the influence of five categories on house mouse dynamics: fire, climate, competition, vegetation composition and underlying vegetation productivity. We took the best model from each influential category and developed new models to determine which variables combine to best describe house mouse dynamics in temperate ecosystems. Results and conclusions: Fire, climate and competition were the most important factors influencing the house mouse in the Grampians National Park, with time since fire and above average short-term rainfall the most influential. These two events are predicted to increase under climate change meaning we expect to see more frequent outbreaks of the house mouse. As a result, it is likely exotic predator populations will increase following early house mouse increases, potentially impacting the recovery of native small mammal populations. It is therefore recommended that exotic predator control be increased during periods of high rainfall after drought when house mouse numbers increase and provide a resource for predator populations to increase, to support the recovery of native mammals.