![]() 2021), limiting their ability to estimate temporal variation in vital rates over the long term (e.g., Leech et al. However, many reintroduction studies span short timeframes (i.e., < 5 years, Parlato et al. This is particularly crucial when a population transitions through the three phases of reintroduction, from ‘establishment’ (where post-release effects drive population dynamics) to ‘growth’ (characterised by high rates of expansion) and, finally, to ‘regulation’ (where density dependence limits survival and recruitment, Sarrazin 2007). This uncertainty can be addressed using robust monitoring of demographic parameters including abundance, survival, and reproduction which can indicate population self-sustainability, density-dependence, carrying capacity, and threats to these processes (e.g., Manning et al. While reintroductions aim to establish a viable and self-sustaining population (IUCN 2013), management decisions must always be made in the face of imperfect knowledge about species and ecosystems (Armstrong and Seddon 2008). Reintroductions are a critical tool used to reverse defaunation and restore ecosystem function (Armstrong and Seddon 2008). These criteria enable managers to quantify the targets required to downlist (reclassify from higher risk to lower risk categories) or delist (remove from the IUCN Red List) a species, and encourages small-scale projects to be unified under long-term visions for species recovery. It provides a repository for information related to species range, population size, threats, and conservation actions, and compares these to broadly applicable and standardised criteria to categorise species from ‘Critically endangered’ to ‘Least concern’. The International Union for Conservation of Nature’s Red List of Threatened Species (IUCN 2021) provides a powerful tool used by conservationists and researchers to list declining species, and galvanise conservation action and policy change (Rodrigues et al. 2006), robust monitoring and species listings are paramount. Restoration presents a major challenge for the next century, but to avoid long-term goals being limited by short-term human memory of ecosystems (i.e., ‘shifting baseline syndrome’, Pauly 1995 Miller 2005 Manning et al. By taking advantage of a rapid life history and harvesting the ‘doomed surplus’, managers can achieve their stretch goals for species recovery in the long term.ĭefaunation in the Anthropocene, driven by human-induced environmental change and destruction, threatens biodiversity, ecosystem function, and human health worldwide (Dirzo et al. Due to the inherent difficulty in securing large areas for species recovery, we see these ambitious targets as a call to create coordinated and collaborative sanctuary networks where species can be managed as a metapopulation across multiple sites. Based on this model, a total harvest area of 413 km 2 and an occupancy area of 437 km 2 would be needed to recover the species within 10 years (i.e., 90 similar fenced reserves, not accounting for edge effects). Our demographic results indicated high mean apparent survival (90% ± 5), and PVAs revealed the probability of persistence over a 50-year time horizon was 50.5% with no interventions, 0% when the population was harvested of > 6 individuals, and 100% if harvests ≤ 54 juveniles were combined with an annual supplementation of ten maternal females (with ≤ 6 young each). After determining sustainable harvest rates, we then ‘back-cast’ the population size and occupancy area required to remove the species from the IUCN Red List within 10 years. We then incorporated the resulting demographic parameters into population viability analyses (PVAs) to estimate probabilities of persistence under several scenarios, including supplementations and harvests (removal of individuals for translocation to other locations). We calculated capture-mark-recapture population estimates for eastern quolls ( Dasyurus viverrinus) which had been reintroduced to a fenced reserve in the Australian Capital Territory. To address this, we investigated how demographic parameters from a reintroduced population can reveal threats to long-term persistence, inform thresholds for management interventions, and create targets for removing an endangered species from the IUCN Red List. It is therefore critical to maximise the number of individuals that are available to contribute to recovery efforts. ![]() Reintroductions are powerful tools for tackling biodiversity loss, but the resulting populations can be intrinsically small and vulnerable.
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