Translocations of digging mammals and their potential for ecosystem restoration: a review of goals and monitoring programmes

Abstract

1. Globally, translocations are commonly used to improve the conservation status of threatened species. There is increasing recognition that translocations of ecosystem engineers also have the potential to restore ecological processes. Digging mammals are often considered to be ecosystem engineers, as their diggings provide shelter for other species and can significantly alter soil properties, with subsequent changes to vegetation. 2. Using Australian species as a case study, we reviewed published and grey literature on digging mammal translocations to determine how often these translocations are conducted to restore ecosystem processes. We documented ecosystem-level monitoring and research efforts, and assessed whether restoration was perceived to be occurring post-release. 3. At least 208 translocations of 24 digging mammal species have been conducted in Australia, with a further 38 planned for the near future. Prior to 2019, only 3% of translocations included a goal relating to the restoration of ecosystem processes associated with digging activities. Nearly a quarter of pre-2019 translocations have been the subject of some form of ecosystem-level monitoring or research, but long-term ecosystem-level monitoring was very rare. In contrast, 74% of the translocations planned for post-2018 include a goal relating to the restoration of ecological processes and most also include plans to conduct ecosystem-level monitoring. 4. Ecosystem restoration was perceived to be occurring for 26% of the pre-2019 translocations. None of the documents we reviewed indicated that ecological degradation had occurred post-translocation, even when declines in other taxa were recorded. 5. The restoration of ecosystem processes is increasingly being identified as a goal for translocation programmes. Where this is the case, we suggest that translocation practitioners include success criteria for the restoration of ecosystem processes, and commit to long-term monitoring designed to detect ecosystem-level effects of translocations.

Mapping Restoration Activities on Dirk Hartog Island Using Remotely Piloted Aircraft Imagery

“…Measuring vegetation in areas excluded from reintroduction can be compared to areas where fauna is permitted for the purpose of long-term ecosystem monitoring. Momentum for protecting native fauna in Australia is currently shifting towards the aim of ecosystem restoration, with 74% of post-2018 digging mammal translocations stating this as a goal [29]. Bioturbation by a digging mammal can reduce soil hydrophobicity [28]; increase soil nutrients [76]; improve soil density [77]; and influence seed germination [28].…”

“…Additional translocations are planned or underway with the aim of restoring the island's former fauna assemblage, which may result in beneficial conservation outcomes for some threatened species, e.g., the dibbler (Parantechinus apicalis). Other species, such as the boodie (Bettongia lesueur) and Shark Bay bandicoot (Perameles bougainville), may also help restore ecosystem services through their digging activities [28,29]. Identifying the flow-on effects that these changes may have on the island's biodiversity and ecosystem function requires a framework for repeat environmental monitoring.…”

Reconstructing lost ecosystems: A risk analysis framework for planning multispecies reintroductions under severe uncertainty

“…In Australia, multispecies reintroductions of mammal species within predator‐free fenced enclosures and islands have become an important conservation management tool (Legge et al., 2018). The core objectives of multispecies reintroductions are to prevent the extinction of threatened species (Armstrong & Seddon, 2008; Seddon et al., 2014), reconstruct historical faunal assemblages and restore ecosystem functioning (Palmer et al., 2020; Seddon et al., 2014).…”

Burrowing by translocated boodie (Bettongia lesueur) populations alters soils but has limited effects on vegetation

“…In an increasingly altered world, translocations are used to improve the conservation status of threatened species and to return species to areas from which they had become extirpated (IUCN/SSC, 2013; Seddon et al., 2014). Translocations are also more frequently being used to restore ecosystems by reinstating ecosystem processes regulated by lost species (Palmer et al., 2020). Ecosystem engineers, such as digging and burrowing mammals, may be particularly useful for this kind of translocation because of their ability to fundamentally restructure ecosystems (Seddon, 2010).…”

“…To redress their decline, boodies have been translocated to a number of additional islands and fenced, mainland reserves. Conservation concerns continue to drive translocation actions for boodies, but most future translocations are also aiming to restore the species’ historic ecosystem functions (Palmer et al., 2020). However, our understanding of their roles within ecosystems is largely based on the effects of their foraging diggings.…”