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Globally increasing rates of mine site discontinuations are resulting in the need for immediate implementation of effective conservation and management strategies. Surveying vegetation structure is a common method of assessing restoration success; however, responses of fauna to mine site restoration remain largely overlooked and understudied despite their importance within ecosystems as ecological engineers, pollinators, and restoration facilitators. Here we review the current state of the use of fauna in assessments of mine site restoration success globally, and address biases or shortcomings that indicate the assessment approach may undershoot closure and restoration success. We identified just 101 peer-reviewed publications or book chapters over a 49-year period that assess responses of fauna to mine site restoration globally. Most studies originate in Australia, with an emphasis on just one company. Assessments favour general species diversity and richness, with a particular focus on invertebrate responses to mine site restoration. Noteworthy issues included biases towards origin of study, study type, and target taxa. Further searches of the grey literature relating to fauna monitoring in mine site restoration, which was far more difficult to access, yielded six monitoring/guidance documents, three conference proceedings, two book chapters without empirical data, and a bulletin. As with peer-reviewed publications, grey literature focussed on invertebrate responses to restoration, or mentioned fauna only at the most basic level. We emphasise the need for global re-evaluation of regulatory standards to address these major limitations in assessing the capacity of the mining industry to comprehensively and representatively restore faunal communities after mining.

The project arose from knowledge gaps identified through a literature review of fauna responses to mine site restoration, and an interest in stimulating further discussion on this topic at a time where such discussion will contribute to the international debate of what constitutes effective restoration..Summary Despite the evidence that fauna play complex and critical roles in ecosystems (e.g. pollination and nutrient cycling) and the knowledge that they need to be considered in restoration, fauna often remain poorly represented in restoration goal setting, monitoring and assessments of restoration success. Fauna clearly are integral to the aspirations of achieving full ecosystem recovery. However, over-reaching assumptions about the unassisted return of fauna to restored sites, low investment in fauna monitoring, and minimal consideration of the requirements for fauna monitoring in regulatory guidance and standards appear to have led to the historically vegetation-centric approaches to rehabilitation and ecological restoration. We argue that ecological complexities render assumptions of unassisted fauna return inappropriate in many situations and may represent a missed opportunity to enhance ecological outcomes and improve restoration trajectories. We advocate for greater consideration of fauna as facilitators of ecological restoration and, particularly for well-funded projects, for monitoring to place greater emphasis on examining the behaviour and resilience of restored fauna communities. There is a clear need for both industry and regulators to recognise that fauna can be crucial facilitators of restoration and appreciate that the return and monitoring of functional faunal communities can be costly, challenging and may require detailed study across a wide range of taxonomic groups. Failure to advance from business as usual models may risk leaving a legacy of ostensibly functional, but biodiversity-depauperate, restored ecosystems.

The incorporation of conservation physiology into environmental management, particularly ecological restoration, is underutilized, despite the capacity of such approaches to discern how populations respond to the challenges of unpredictable and potentially inhospitable environments. We explore several examples where detailed mechanistic understanding of the physiological constraints of keystone and foundational species, ecological service providers such as insect pollinators, and species of conservation concern has been used to optimize the return of these species to landscapes following the cessation of mineral extraction. Using such data can optimize the rapid return of functioning ecosystems during restoration or increase the conservation value of restoration by returning insurance populations of threatened species. Integrating this level of mechanistic understanding with fine-resolution spatial data in the form of biophysical modeling can help plan recovery and identify targets that can subsequently be used in assessing restoration success, particularly in situations that require substantial investment over long periods, such as post-mining restoration. There is growing recognition of the valuable insights offered by conservation physiology to broader practice and policy development, and there have been substantial technical developments in conservation physiology leading up to and into the twenty-first century as a result. The global challenge facing restoration ecology has, however, also grown in that time. Rapidly and efficiently meeting ambitious global restoration objectives will require a targeted approach, and we suggest that the application of physiological data will be most strategic for rare species, keystone species, and ecosystem service providers more broadly.

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