A project undertaken at the Australian Wildlife Conservancy (AWC), and supervised by Dr Jennifer Anson.
Australian mammals have one of the highest extinction rates in the world, primarily due to the impact of introduced predators (foxes, cats). As a result, many species now persist only as remnant or reintroduced populations on feral predator-free islands or in fenced ‘mainland islands’.
Hopping Mouse investigating a habitat pod deployed at Mt Gibson, WA.
Native rodents are particularly vulnerable to introduced predators. The Plains Mouse (Pseudomys australis) and the Shark Bay Mouse (Pseudomys fieldi) are large native rodents (~50 g) once widespread throughout Australia. These species are now relegated to small areas of refugial habitat in SA and NT (Plains Mouse) and a handful of islands in WA (Shark Bay Mouse). Australian Wildlife Conservancy (AWC) has planned reintroductions for these species into fenced feral predator-free areas around Australia to establish additional populations and support their long-term survival and recovery.
Plains Mouse release into a habitat pod, as part of translocation to Pilliga Conservation Area, NSW
To date, reintroductions have been more successful for medium-sized mammals (e.g., bandicoots, bettongs) than small mammals (e.g., rodents). While factors driving this differential outcome are not well understood, contributory factors appear to be (i) hyperdispersal on release; (ii) higher rates of native predation on rodents compared to larger mammals; and (iii) the lower detectability of small mammals during monitoring.
Well-considered release strategies and effective monitoring of reintroduced populations are critical for optimising conservation outcomes, such as recruitment and establishment. This project aims to test the utility of artificial refuges, such as modular ‘habitat pods’, for improving reintroduction outcomes of threatened native rodents in feral predator-free fenced areas. Dr Alexandra Carthey conceptualised the habitat pods in response to the 2019 NSW bushfires and has worked with AWC to expand their conservation value following trials in NSW.
Habitat pods may assist in addressing constraints around reintroduction of small mammals. Habitat pods are lightweight, biodegradable artificial shelters that can be deployed easily in the environment. They may be deployed as a component of a soft release protocol, such that animals released from familiar pods they inhabited in captivity may be less likely to hyper-disperse upon release. Habitat pods have been designed to offer small mammals refuge from elevated levels of predation by acting as supplemental cover. Pods are ideal for use in the situation where native predation is problematic, as they do not impact on protected native predator species but can instead boost survival of small mammal prey by giving them more places to hide.
Habitat pods will be deployed as part of Plains Mouse and Shark Bay Mouse reintroductions in WA, NT and NSW. The main objective of this project is to assess whether translocation outcomes for these large (~50 g) native rodents can be improved via deployment of artificial refuges.
Our specific aims are to: i. Assess whether deployment of habitat pods increases site fidelity in native rodents following translocation. ii. Assess whether post-release survival of translocated native rodents is improved through the provision of additional refuge sites created by deployment of habitat pods, specifically whether habitat pods reduce the risk of predation following translocation. iii. Assess whether deployment of habitat pods enhances the ability to detect, and therefore to effectively monitor, native rodents following translocation. Translocation programs are critical for rebuilding small and fragmented populations through establishing self-sustaining, genetically diverse additional populations of species within their former range. The ultimate aim of this project is to improve translocation methodology and, in doing so, maximise conservation outcomes and ensure the long-term survival and recovery of threatened native rodent species.