Habitat preferences of Rattus rattus (ship rats) across composite urban landscapes
Predator Free Wellington is pioneering a world-first multispecies eradication in an urban environment, something which has previously only been achieved on offshore islands and fenced sanctuaries. There is no shortage of research about the behaviour of Ship rats in densely urban city centres. What makes Wellington unique is the combination of manmade and natural zones. We know from the mahi on Miramar Peninsula that Ship rats are more abundant in certain habitats, but their specific ecological preferences across varied peopled landscapes is largely unknown.
This research sought to address this knowledge gap by:
- Understanding ship rat preferences across six different habitat types in the case study area of Oruaiti, part of the Phase 1 project area. The six habitat types were Developed Urban, Coastal Scrub, Mid-regeneration Native, Capy Ivy, Mixed Vegetation, and Exotic Pine.
- Using these insights to help inform habitat-based elimination techniques.
Key findings from the research were that:
- Ship rats were detected across all of the assessed habitat types, but presence varied significantly depending on the type of habitat.
- Ship rats were most commonly detected in the Coastal Scrub habitat type, followed by Cape Ivy, i.e. these habitats presented the most favourable conditions.
- There was a moderate abundance of rats in the Mid-Regeneration native habitat, followed by the Mixed Vegetation habitat.
- Developed Urban and Exotic Pine habitats had an equally low presence of rats.
By assessing rat presence in these habitats, we concluded that:
- Dense vegetation creates a favourable habitat, with the availability of habitat-specific food sources and low levels of human disturbance also significant.
- Natural habitats were favoured more than manmade. However, the area studied was of a high socioeconomic level.
- This study was unable to find a habitat preference of native versus non-native vegetation.
We recommend elimination projects operating in composite urban envrironments assess the habitat before installing a habitat-based grid of devices. The network can then focus on favourable habitat.
For questions related to this research, please email us at hello@pfw.org.nz.
This research was conducted in 2023 by Eleanor Dewar, a postgraduate student researcher of Te Pūkenga Open Polytechnic, in collaboration with Predator Free Wellington Ltd.