Reducing the environmental impact of controlling invasive rodent pests

Background

Rodents play important roles in many ecosystems, influencing habitat structure and plant diversity, and providing an important food source for many predators. However, a small number of species, such as brown and black rats (Rattus norvegicus, R. rattus), are major global pests. Such highly invasive rodents cause substantial change to ecosystems and directly contribute to the decline and extinction of other species (linked to 57% of all extinctions or species critically endangered1). They also carry important diseases that impact human and animal health, and cause substantial food losses through damage to crops and stored products. Control is thus essential, but currently relies on the use of highly toxic rodenticide baits that are non-specific and attract non-target species, particularly other rodents. In the UK, the main non-target rodents affected are field voles, bank voles and wood mice. Further, the persistence and bioaccumulation of these toxins also leads to significant secondary poisoning of predators2. The Predatory Bird Monitoring Scheme (https://pbms.ceh.ac.uk) has revealed, for example, that 95% of barn owls that died in 2015 had residues of anticoagulant rodenticides in their livers.

Objectives

This project will focus on using our understanding of the behavioural responses of brown rats and UK native rodents to novel bait technologies with the overall aim of reducing the impact of rodent control on non-target species. There will be opportunities to refine and field test some promising new approaches, such as the use of species-specific scent lures and push-pull strategies, and to contribute and test new ideas under both natural and semi-natural conditions.

Key objectives will be:
- Reduce exposure of non-target rodents to rodenticides deployed for rat control.
- Improve species-specific attraction of rats to control points, reducing the need for rodenticides.
- Demonstrate, through monitoring, the effectiveness of such approaches in real world situations

Novelty & Timeliness

The project addresses an urgent need to improve both the efficacy and humaneness of rodent pest control while reducing the environmental impact of control measures. Reliance on extremely toxic anticoagulant rodenticides persists despite widespread contamination of the natural environment because safe and more humane alternatives have not yet been developed.
1 Doherty TS et al. 2016 Invasive predators and global biodiversity loss. PNAS 113:11261-5.
2 Elliott JE et al. (2016) Bioscience 66:401-7.