Mouse Ecology 2024-2029

GRDC has reinvested in a five-year project to expand our understanding of house mouse ecology and biology in Australian cropping systems. The farming systems in Australia have changed dramatically over the last 10-20 years, bringing in advances in conservation agriculture such as minimum tillage, stubble retention and diversified crop rotations. These practices increase profitability, break disease cycles and benefit soil properties (improving soil organics, soil structure, soil moisture and soil nutrients from crop residues and nitrogen from legumes). These changes have led to tremendous benefits to Australian grain growers and making their farming systems more resilient to a variable climate and more sustainable. One down-side is that these changes have inadvertently increased the problems of some pests, including the feral house mice (Mus musculus). House mice undergo periodic and irregular outbreaks and sometimes mouse plagues cause widespread damage. The new farming systems provide more cover (from retention of crop residues), more food (from increased cropping intensity) and less disturbance (from reduced tillage) meaning that mice are now living permanently in undisturbed mouse “warrens” in crops rather than retreating to crop margins as they did in the past under conventional systems when multiple ploughings were common. This has changed the face of management of mice in grain farms, as they appear to be more prevalent than in the past.

Using an understanding of mouse ecology and behaviour to direct crop protection management.

This 5-year project is designed to fill critical knowledge gaps and test a range of management practices with the aim of making some practical recommendations for growers and the grains industry to enable them to better manage mice. We will build on the significant body of work undertaken in the last 5 years (GRDC CSP 1806-015RTX) to further understand the importance of food (residual grain), and crop and stubble manipulations as the period from harvest to sowing is a key time for mouse management (Brown et al. 2020; Ruscoe et al. 2022; Ruscoe et al. 2023a; Robinson et al. 2023; Brown et al. 2024).

This new investment will complement the ongoing mouse management projects currently being undertaken by the CSIRO Rodent Management Team and ensure continued national capability and expertise in mouse ecology and management in grain-growing systems. This new body of work comprises studies of the behaviour and ecology of mice including how farming practices can be proactively used to make paddocks less attractive to mice, how to make baiting more efficient, and potential novel non-lethal methods to protect crops at critical times (Figure 1). We will examine the components of the cropping system that can be manipulated to minimise the impacts of pest mice including reducing food resources, reducing habitat quality, using seed predation deterrents, and baiting as effectively as possible when and where required.

**Figure 1**. Approximate effort directed at the three Themes proposed in this body of work (across near-term, mid-term and alternative future management solutions), and how they relate to previous and existing projects.

Our Research Questions

A range of research trials will be designed to answer several key questions around:

How can we reduce mouse food supply at critical times in their population cycles? Knowledge Gap: Do current farm practices (including strategic cultivation, use of harvest weed seed destroyers, and use of grazing) reduce the amount of residual grain on the ground (mouse food) following harvest?
How can we modify habitat quality to reduce breeding and/or survival of mice? Knowledge Gap: Can stubble and/ or windrow management be used to reduce vegetation cover, alter the breeding and survival of mice following harvest without compromising the benefits of conservation farming?
How to improve the effectiveness of mouse baiting? Knowledge Gap: How can we increase the effectiveness of ZnP baiting by increasing the encounter rate of toxic baits within the context of background food availability?
Can we protect high value sown seed from early mouse damage? Knowledge Gap: Can we use alternative methods of crop protection, for example protecting freshly sown seed from mice by using non-lethal deterrents?

CSIRO scientists from the Rodent Management Team will collaborate with academic researchers and postgraduate students from the University of Sydney to deliver innovative solutions to the mouse problem.