Reintroduced Population Research Articles

Reintroduction affects demographic rates but not their interannual correlations in an endangered shrub

Abstract Reintroducing endangered species constitutes an important conservation tool. The performance of reintroduced populations is commonly assessed through mean demographic rates (survival, growth, reproduction and fecundity), but rate correlations are less studied despite their role in extinction risk and trait evolution. In our study, we reintroduced the endangered shrub Vella pseudocytisus subsp. paui in two locations in Spain and compared its demographic performance to that of two natural populations to assess reintroduction success. In both natural and reintroduced sites, we selected sub‐locations with presumably more favourable (clay) vs. more stressful (gypsum) soil conditions. We monitored a total of 1269 individuals in natural (12 years) and reintroduced populations (6 years) and compared their mean demographic rates and the within‐individual rate correlations between years. In clay substrate, mean demographic rates of the natural and the reintroduced population were similar, suggesting a successful reintroduction. In contrast, the reintroduced population in gypsum showed higher reproduction and fecundity than the natural population, but lower survival and growth. Contrary to mean demographic performance, interannual correlations among demographic rates did not vary between natural and reintroduced populations. While reproduction in a given year was positively correlated with later growth and later reproduction, growth in a given year had some negative consequences in subsequent plant performance, especially in gypsum substrate. Synthesis and applications. Our study shows that stressful conditions may trigger individual‐level trade‐offs in resource allocation and population‐level compensation among demographic rates. Demographic shifts arising from reintroductions in different environmental conditions may be considered by managers as a potential mechanism of resilience against environmental change. Finally, the similarity in rate correlations among sites suggests that information about correlations, which can be relevant when focusing conservation efforts, may be extrapolated from natural to reintroduced populations. This might be particularly reliable for species where rate correlations are demographically influential, such as those living under generally stressful conditions, or lacking buffering mechanisms for demographic variation.

Leveraging how animals learn in conservation science: Behavioral responses of reintroduced bison to management interventions

AbstractReintroduction programs have increased amid unprecedented biodiversity loss, yet the success of these programs lag. A prominent reason for program failure is dispersal beyond the planned range of the population. Management techniques, such as hazing, can be used to prevent movement beyond set boundaries, but to be effective long‐term, the animals must learn to avoid the areas where they are hazed. Although concepts of animal learning have been used to improve reintroduction programs, learning is not often explicitly tested or used as an indicator of program success. We used a conservation behavior framework to evaluate how a range of management techniques influenced learning in a reintroduced population of bison in Banff National Park, Canada. We hypothesized exposure to stronger negative stimuli would enhance learning, leading to more pronounced behavioral responses. Specifically, we tested the degree to which management actions (i.e., drift fence encounters, foot, horseback, helicopter, and combined hazing) elicited behavioral responses and how they facilitated learning. Consistent with our predictions, drift fence interactions and foot and horseback hazing elicited fewer behavioral responses of a smaller magnitude than helicopter hazing or combined methods, suggesting these techniques cause less disturbance to the bison. Bison continually returned to locations where they encountered management actions that caused the least disturbance, demonstrating a lack of associative learning. Bison appeared to form negative associations with locations where they were hazed via helicopter or combined methods, however, and rarely returned to these locations. Evaluating management techniques is essential for improving conservation success. We demonstrate that by bridging the fields of conservation biology and animal learning, we can understand how management techniques influence learning and behavior thereby facilitating effective conservation plans that incorporate disruption levels of the animals, financial costs, and overall effectiveness. Effective conservation plans, in turn, improve our likelihood of successfully managing and recovering species.

Scale-dependence in elk habitat selection for a reintroduced population in Wisconsin, USA.

Habitat selection is a critical aspect of a species' ecology, requiring complex decision-making that is both hierarchical and scale-dependent, since factors that influence selection may be nested or unequal across scales. Elk (Cervus canadensis) ranged widely across diverse ecoregions in North America prior to European settlement and subsequent eastern extirpation. Most habitat selection studies have occurred within their contemporary western range, even after eastern reintroductions began. As habitat selection can vary by geographic location, available cover, season, and diel period, it is important to understand how a non-migratory, reintroduced population in northern Wisconsin, USA, is limited by the lack of variation in topography, elevation, and vegetation. We tested scale-dependent habitat selection on 79 adult elk from 2017 to 2020 using resource selection functions across temporal (i.e., seasonal) and spatial scales (i.e., landscape and home range). We found that selection varied both spatially and temporally, and elk selected areas with the greatest potential to influence fitness at larger scales, meaning elk selected areas closer to escape cover and further from "risky" features (e.g., annual wolf territory centers, county roads, and highways). We found stronger avoidance of annual wolf territory centers during spring, suggesting elk were selecting safer habitats during calving season. Elk selected habitats with less canopy cover across both spatial scales and all seasons, suggesting that elk selected areas with better access to forage as early seral stage stands have greater forage biomass than closed-canopy forests and direct solar radiation to provide warmth in the cooler seasons. This study provides insight into the complexity of hierarchical decision-making, such as how risky habitat features and land cover type influence habitat selection differently across seasons and spatial scales, influencing the decision-making of elk. Scale-dependent behavior is crucial to understand within specific geographic regions, as these decisions scale up to influence population dynamics.

Persistence of social structuring in an arid zone mammal following reintroduction

Animal social relationships affect animal survival, reproduction, and resource exploitation, and are important to translocation success, but little is known on how they are impacted in reintroduced populations. Here, we investigate the social genetic structure in a reintroduced population of boodies (Bettongia lesueur), one of few social burrowing marsupial species in Australia. Pairwise relatedness of male and female individuals located within seven warrens was determined using 12 microsatellite markers, while mitochondrial DNA was used to identify maternal ancestral lineage. Females were significantly more related within warrens than between warrens, while the difference among males was not significant. We also found evidence of fine-scale genetic structure up to distances of 2 km in females consistent with patterns found in natural populations. Although mean relatedness values were low, our results support the hypothesis that boodies exhibit a female social structure. Multiple maternal lineages were present within all warrens with one exception, suggesting boodies appear to be non-selective when living with individuals from different ancestral backgrounds. We found a significant positive relationship between female sex bias and the number of active entrances in each warren. Together, these results suggest that social structuring should be a key consideration in future reintroductions of boodies.

Is the Iberian lynx a hunters’ ally? a case study from a reintroduced population in Portugal

The Iberian lynx (Lynx pardinus) is one of the most endangered felids in the world, and a high proportion of its populations occur in hunting grounds managed for red-legged partridge (Alectoris rufa) and wild rabbit (Oryctolagus cuniculus), both game species of high socio-economic value and the latter a key prey species for the lynx. In this case study from south-eastern Portugal, we evaluated the game management practices, the abundance of partridges and rabbits (expressed as Kilometric Abundance Index), and the occurrence of mesocarnivores in four hunting grounds, two with and two without breeding lynx. In all grounds game management was conducted but in those where lynx occurred, full-time gamekeepers were employed and hunting was the major source of income. The results showed that grounds with breeding lynx had higher KAI values for partridges and rabbits, together with reduced mesocarnivores occurrence (particularly red fox Vulpes vulpes and stone marten Martes foina), compared to those without breeding lynx. Our results confirm that lynx occurrence fits within the management traits of those hunting grounds in Iberia aiming to increase partridges and rabbits for sustainable hunting, as they act as ‘natural’ gamekeepers. This could be considered as a ‘win-win’ situation; successful for lynx’s establishment and small game conservation.

Home range and dynamic space use reveals age‐related differences in risk exposure for reintroduced parrots

AbstractIndividual‐level differences in animal spatial behavior can lead to differential exposure to risk. We assessed the risk‐exposure of a reintroduced population of kākā (Nestor meridionalis) in a fenced reserve in New Zealand by GPS tracking 10 individuals and comparing the proportion of each individual's home range beyond the reserve's fence in relation to age, sex, and fledging origin. To estimate dynamic space use, we used a sweeping window framework to estimate occurrence distributions (ODs) from temporally overlapping snapshots. For each OD, we calculated the proportion outside the reserve's fence to assess temporal risk exposure, and the area, centroid, and overlap to represent the behavioral pattern of space use. Home range area declined significantly and consistently with age, and the space use of juvenile kākā was more dynamic, particularly in relation to locational changes of space use. The wider‐ranging and more dynamic behavior of younger kākā resulted in more time spent outside the reserve, which aligned with a higher number of incidental mortality observations. Quantifying both home range and dynamic space use is an effective approach to assess risk exposure, which can provide guidance for management interventions. We also emphasize the dynamic space use approach, which is flexible and can provide insights into a species' spatial ecology.

Detailed kinship estimation for detecting bias among breeding families in a reintroduced population of the endangered bagrid catfish Tachysurus ichikawai

AbstractIn the context of initiatives focused on captive breeding and reintroduction of endangered animal species, it is crucial to minimize any bias in reproductive success during the reintroduction phase in order to preserve genetic diversity. One population of Tachysurus ichikawai, a critically endangered bagrid catfish endemic to Japan, faces a threat from the construction of a dam. To address this, a captive breeding program followed by translocation is being implemented. Multiple breeding families are involved in this process; however, if there is a bias in reproductive success among them after release, it will result in a decline in genetic diversity. To ascertain potential biases of reproductive success among released individuals, we attempted to identify the familial lineage of individuals born at the release site. Due to the unavailability of samples from the released individuals themselves, we reconstructed the pedigree of three generations using distant kinship relationships, such as grandparent–grandchild and uncle–aunt–nephew–niece relationships, with data of 2230–5674 single‐nucleotide polymorphisms obtained from whole genome re‐sequence, and three different software. Our findings indicate no bias between lineages in the first year after reintroduction, but a significant bias in the second year, emphasizing the need for continuous management and monitoring of reintroduced populations. This study demonstrates that monitoring kinship after reintroduction can correct lineage bias, which is critical for the prompt restoration of genetic diversity.

Impact of Environmental Food Intake on the Gut Microbiota of Endangered Père David's Deer: Primary Evidence for Population Reintroduction.

Reintroduction has been successful in re-establishing several endangered wild animals in their historical habitats, including Père David's deer (Elaphurus davidianus). Continuous monitoring of reintroduced individuals is essential for improving the sustainability of ex situ conservation efforts. Despite an increased recognition of the significance of the gut microbiome for animal health, the correlation between diet and the gut microbiome in E. davidianus is unclear. In this study, 15 fresh fecal samples of E. davidianus were collected from Tianjin Qilihai Wetland and the association between dietary and gut microbiota composition was evaluated. Microscopic observations showed that Nymphoides peltata [relative density (RD = 0.3514), Phragmites australis (RD = 0.2662), Setaria viridis (RD = 0.1211), and Typha orientalis (RD = 0.1085) were the main dietary plants in the fecal samples. High-throughput 16S rRNA sequencing showed a predominance of the phyla Firmicutes and Proteobacteria and the genus Psychrobacillus (26.53%) in the gut microbiota. The RD of N. peltata was significantly positively correlated with the abundance of Firmicutes (p = 0.005) and the genus UCG-005 (p = 0.024). This study indicates a close association between food digestion and nutrient intake, providing basic monitoring data for the full reintroduction and recovery of wild E. davidianus.

Harem size should be measured by more than the sum of its parts: Phenology-based measurements reveal joint effects of intrinsic and extrinsic factors on a polygamous herbivore under non-stationary climatic conditions.

Social behaviour is thought to be a major component of survival, reproduction, and resilience of populations. Thus, it is a key component in management and conservation of wild populations. In polygynous breeding species, group size influences the reproductive success of males and females, and hence it is essential to understand the environmental and demographic factors that shape the phenology of group size within populations. Here, we investigate harem size and its determinants using a 15-year dataset of annual harem size phenology-based metrics from a reintroduced population of wild Przewalski horses in Hortobágy National Park, Hungary. From the initial reintroduction of 21 animals in 1997, the population grew to 174 animals in 2012. During that same period, the number of harems increased from three to 23. Despite the 8-fold increase in population size, harem sizes remained stable, and variability among harems within years decreased. The annual phenological cycle of harem size was not consistent over the 15-year period, and the associated annual phenology-based metrics varied differently over the years. The best predictors of our phenology-based harem size metrics were adult sex ratio, annual adult mortality and annual mean number of harems, with some evidence that mean age of harem stallions and drought severity were contributing factors. Our findings reveal that complex interactions between demography, climate, and harem size can emerge in social animals. Taken together, our results demonstrate that intrinsic population processes can regulate group size even in the presence of non-stationary climatic conditions during periods of growth in human-introduced, semi-free ranging animal populations.

Ontogeny of a threatened freshwater minnow: Implications for conservation

AbstractInvestigating the ontogeny of threatened freshwater fishes is vital for designing future conservation actions that will increase the potential of species' persistence. This study provides a detailed description of the early life stages of a threatened freshwater fish species, the Evrotas minnow Pelasgus laconicus, which occupies aquatic ecosystems with extreme seasonal hydrological variation. The study of the embryonic and juvenile stages was conducted in vivo using light microscopy from eggs obtained from acclimatized wild spawners at 20 ± 1°C. Fertilized eggs were spherical and transparent with a mean diameter of 1.24 ± 0.06 mm and the average length of free embryos at hatching was 3.85 mm NL (notochord length). The main morphological changes observed are related to the absorption of the yolk, the increase and distribution of the melanophores and the sequential development of the fins. In conclusion, the Evrotas minnow was identified as a multiple spawner, exhibiting a protracted reproductive period (March to August), a particularly short egg‐hatching period (5–6 days), a short free embryo stage and a rapid onset of exogenous feeding (2 days). The conservation implications of our study, such as safety stock creation, population reintroduction, conservation of fish refugia and breeding habitats and beaver dam analogues, are discussed.

Movement ecology of pre-adult Cinereous Vultures Aegypius monachus: insights from a reintroduced population

Summary Understanding the movement ecology of threatened species is fundamental to improving management and conservation actions for their protection, mainly during the pre-adult stage and particularly when a species is subject to population reinforcement or reintroduction projects. An example is the case of the Cinereous Vulture Aegypius monachus on the Iberian Peninsula, an endangered species that has been reintroduced in different regions during the last two decades. Here, we explore differences between the spatial ecology of reintroduced pre-adult Cinereous Vultures, according to age-class, sex, and season (breeding and non-breeding). We used GPS-tag data from 51 pre-adult individuals reintroduced into Catalonia (north-east Spain) to describe their use of space, i.e. home-range size, core area, and minimum convex polygon (MCP) and movement patterns, i.e. cumulative distance, maximum displacement, maximum daily dispersal, and maximum annual dispersal. Our study showed significant variation in the use of space and movement patterns among pre-adult birds and the influences of age, sex, and season. Age was the most influential factor, determining range areas and movement patterns. Similar to other vulture species, home range and core areas increase with age, with subadult vultures exhibiting larger ranges than young first year, juveniles, and immature birds, but the MCP measures were larger for juveniles. Movement patterns were also influenced by age-class, with juveniles making longer movements, followed by immatures and subadults (with similar values), and shorter movements for birds during their first year of life. Overall, males made shorter movements and explored smaller foraging areas than females. Season had an important effect on movement patterns, and the daily and dispersal movements were longer during the breeding period (February–August). Our findings fill a knowledge gap regarding the dispersal behaviours of Cinereous Vultures, information that will enable the improvement of management and conservation decisions.

Anthropogenic threats to the reintroduced population of Oriental storks in Japan: analysis of the causes of injury and death of 153 storks from 2005 to 2021.

After the native population of Oriental stork (Ciconia boyciana) in Japan disappeared, a reintroduction project was implemented in 2005. All released storks and most wild-fledged storks were individually identified using colored rings on their legs. The size of the reintroduced population reached 256 by the end of 2021. In this study, we investigated the causes of stork injury and death in wild populations to clarify important medical issues for successful reintroduction. During the survey, 153 of 412 (78 released and 334 fledged storks) storks were injured or died between 2005 and 2021. At least 49.7% of the injuries and deaths were directly caused by human activities. Entanglement with pest control measures (such as bird- and beast-proofing nets) and accident with electrical and telecommunication equipment are two major causes of injury and death of reintroduced Oriental storks in Japan. It is important to recognize that these anthropogenic threats have a significant impact on the establishment and maintenance of the reintroduced populations of Oriental storks in Japan. Therefore, it is necessary to implement countermeasures against these threats to establish human and Oriental storks coexistence, which is a major goal of reintroduction.

An assessment of potential herbivory impacts of a reintroduced marsupial in a predator‐free woodland sanctuary

SummaryFenced sanctuaries that exclude feral predators are critical for threatened species conservation. However, adaptive management of these sanctuaries requires careful consideration of the potential impact herbivore populations free from predation can have on the condition of native vegetation. The Mulligans Flat Woodland Sanctuary in the Australian Capital Territory comprises Critically Endangered box‐gum grassy woodland, threatened orchids, abundant macropods, and a reintroduced population of the Eastern Bettong (Bettongia gaimardi, hereafter “Ngaluda”). To understand how Ngaluda, along with other herbivores, may be potentially impacting vegetation across the sanctuary, we undertook an assessment of indicator plant species. We monitored 106 plots for 13 indicator species (10 species with tuberous roots that the burrowing Ngaluda would be preferentially targeting and three non‐tuberous species). We found that most floristic indicators we investigated – including richness of indicator species and the abundance of lilies – were higher in the Goorooyarroo area of the sanctuary (where Ngaluda are absent and wallabies are rare) compared to the Mulligans Flat area of the sanctuary (where Ngaluda are present and wallabies are abundant), suggesting a negative impact of the overall herbivore assemblage of Mulligans Flat. However, within just Mulligans Flat, some indicators, including the abundance of a common orchid, were significantly lower in areas associated with high Ngaluda activity irrespective of other herbivore densities. We found no instance of Ngaluda presence or higher activity being associated with higher values for any floristic indicator we investigated. These results are consistent with known impacts of abundant herbivores and reintroduced digging marsupials in other predator‐free sanctuaries in Australia. Our results highlight that Ngaluda herbivory may be outweighing any positive effect of their diggings on native vegetation and indicate the need for careful risk mitigation when deciding how critically endangered animals and vegetation communities are managed together in sanctuaries.

Recovery of cirl bunting, Emberiza cirlus, song diversity after translocation

AbstractIn order to improve conservation outcomes translocation or reintroduction of individuals may be necessary. When song learning birds are translocated, changes in the cultural diversity of song repertoires, or abnormal vocalizations, in the new population can be a problem. We monitored song production over 8 years in a reintroduced population of the cirl bunting (Emberiza cirlus). Chicks were removed from nests in Devon, UK, between 2006 and 2011, translocated at 6 days old to be hand‐reared and released in Cornwall, UK. Recordings at the release site in 2011 showed a significantly reduced population repertoire and individuals sang abnormal song types compared to the source populations in Devon. However, recordings in 2019, showed population song repertoire had reached the level of source populations of similar size, and song types were species typical. Our study shows that species can recover from a cultural bottleneck and suggests that, for some song learning birds, if translocation of nestlings is necessary it may not lead to long‐term problems for communication and thus population persistence. For future translocations of nestlings, we recommend that efforts are made to provide tutoring to enable song learning. This may be achieved by providing recordings, but may also include providing adult song tutors. In addition, playback of “normal” songs to translocated populations may aid in development of species typical song repertoires, although care must be taken that this is not disturbing the reintroduced birds.

Movement behavior and passive dispersal of a reintroduced population of alligator snapping turtles

AbstractMaladaptive movement behavior is a leading cause of failure for reptile reintroductions, thus characterizing movement for translocated populations is important to project success. From 2014–2016 we radio‐tracked 183 immature reintroduced alligator snapping turtles (Macrochelys temminckii) using very high frequency telemetry in a stream in southern Illinois, USA. We assessed environmental, temporal, morphometric, and microhabitat factors influencing movement, including post‐release dispersal from reintroduction sites, movement probability, and step length. We used directional statistics to investigate the effects of precipitation and age on directional movement in the stream. Numerous factors influenced active movement, including ambient temperatures, time since release, use of log jams, turtle size, and age. Precipitation had an age‐biased effect on movement. Directional analyses suggested that movement was largely passive as turtles were swept downstream with increased discharge. Overall, the behavior of reintroduced alligator snapping turtles was similar to that reported in wild populations. Passive downstream transport has implications for reintroduced and natural populations as a force for unintentional emigration in channelized streams under current conditions and future high flow regimes.

The assessment of Kunovat sanctuary natural complexes in the area of the Siberian white crane (<i>Leucogeranus leucogeranus</i>) reintroduction

The paper deals with the research of soils, vegetation, bird and mammal population composition and structure in the vicinity of the white crane field research station in the Kunovat sanctuary (Kunovat Zakaznik), northern taiga subzone, Shuryshkarsky District, Yamalo-Nenets Autonomous Okrug, Russia. The aim of this investigation is to assess the present state of natural complexes in the area of the critically endangered Leucogeranus leucogeranus Ob population reintroduction. It has been established that various components of the natural complexes under study are generally consistent with the zone-and-province landscape, climate and biotope peculiarities of the area, which is a sign of their good health and relative stability. At the same time, in small mammal communities (an indicator group) the resistant sustainability index has been higher than the resilient sustainability index for two years in a row, which is characteristic of disturbed habitats or of early ecological succession stages. Such imbalance may be accounted for by local wild fires and floods in the natural complex under study. Botaurus stellaris nests have been registered in different parts of the quaking (white crane) bog, whose breeding grounds used to lie further to the south. This is evidence that the species range moves to the high latitudes and that the global climate change influences the natural complexes in the historic breeding area of the West-Siberian white crane population.

The utility of coded very high frequency telemetry for monitoring reintroduced mammal populations.

Very high frequency (VHF) radio tracking technology deployed on terrestrial vertebrates has been well utilized in ecology without much evolution since the 1960s. With the advent of multi-species rewilding projects, and the new field of reintroduction biology, there has been an increase in requirements for telemetry systems to monitor survival and mortality for many animals simultaneously. Common, pulsed VHF can only monitor one individual on each radio frequency, and the number of individuals monitored is constrained by the amount of time spent on each frequency to facilitate a detection and the number of receivers. Coded VHF largely removes these constraints by using a digital code that can simultaneously monitor up to 512 individuals on a single frequency. Incorporated into an autonomous monitoring system, the coded VHF system also greatly reduces time in the field to confirm the status of individuals. Here we demonstrate the utility of coded VHF technologies applied to monitoring a reintroduced population of brush-tailed bettong (Bettongia penicillata) on the Southern Yorke Peninsula in southern Australia. A system of autonomous monitoring towers was able to monitor 28 different individuals simultaneously without having to change frequency on any of the towers. During a single 24-h period, one individual was recorded 24,078 times. Key benefits of the high detection rate and autonomous recording are, a timely response to mortalities or a predation event, the detection of nocturnal, cryptic, or burrowing species whenever they are active, and the reduced need for personnel to be in the field.

Isolation of Tulasnella spp. from Cultivated Paphiopedilum Orchids and Screening of Germination-Enhancing Fungi.

Ex situ conservation, an important way to increase the survival and sustainability of endangered species, is widely used in the conservation of endangered orchids. However, long-term ex situ conservation might affect the dominant group of orchid symbiotic fungi, which are crucial for orchid growth and reintroduction. This study investigated the culturable Tulasnella spp. associated with Paphiopedilum orchids after long-term greenhouse cultivation, and identified germination-enhancing isolates. A total of 44 Tulasnella isolates were obtained from the roots of 14 Paphiopedilum spp., and 29 of them were selected for phylogenetic analysis. They clustered mainly with Tulasnella deliquescens, Tulasnella calospora, Tulasnella bifrons, and Tulasnella irregularis, but included two potential new groups. Compared with published uncultured data, most of the isolates were grouped together with the reported types, and the dominant Tulasnella associated with P. armeniacum and P. micranthum could still be isolated after ten years of cultivation, most of which were the first isolation. In vitro symbiotic germination showed that certain root isolates could promote seed germination (e.g., parm152 isolated from P. armeniacum, Php12 from P. hirsutissimum, and prhi68 from P. rhizomatosum). These data indicated that the dominant Tulasnella types colonizing the roots of cultivated Paphiopedilum are stable over time, and germination-enhancing fungi colonizing the roots would benefit for seed reproduction after population reintroduction into the wild.

High survival promotes persistence in a reintroduced population of Common Crane (Grus grus)

Reintroductions are increasingly used for re‐establishing populations, though the documented success rates are variable. Success is typically measured by the survival and breeding success of released individuals and subsequent establishment and growth of the population. However, few studies quantify demographic rates of reintroduced populations of long‐lived species, with slower dynamics and lower reproductive rates, and the demographic rates of subsequent generations, which determine population growth and persistence, are often unknown. We document the success of the reintroduction of the Common Crane Grus grus to south‐west England in the UK, using survival analysis and population modelling to determine whether the overarching aim of establishing a self‐sustaining population is likely to be achieved. Between 2010 and 2014, 93 Common Cranes were hatched from wild eggs, custom‐reared and soft‐released into suitable habitat. Survival of all age‐classes was apparently higher than survival of healthy wild individuals, particularly in juvenile age‐classes, and was higher in females than in males. Productivity was relatively low, but increased with age. Assuming that the demographic rates of subsequent generations are at the levels estimated for the captive‐reared population, slow positive population growth is predicted over the next 30 years. Sensitivity analyses showed that the persistence of this population is sensitive to even a slight decrease in values of adult survival, and growth is impacted to a lesser extent by juvenile survival and levels of productivity. This study highlights the ability to achieve persistence in a reintroduced population despite low levels of productivity when survival is exceptionally high. It also illustrates the need for long‐term monitoring to establish reintroduction success in animals that have slow life histories: 9 years after initial releases, the Common Crane population remains dominated by first‐generation birds and productivity is skewed by transient age‐structure and the late onset of reproductive success.

Roadmap to recovery revealed through the reintroduction of an IUCN Red List species

Reintroductions are powerful tools for tackling biodiversity loss, but the resulting populations can be intrinsically small and vulnerable. It is therefore critical to maximise the number of individuals that are available to contribute to recovery efforts. 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. 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. 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). 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. 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). Based on this model, a total harvest area of 413 km2 and an occupancy area of 437 km2 would be needed to recover the species within 10 years (i.e., 90 similar fenced reserves, not accounting for edge effects). 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. 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.