Captive Breeding Does Not Alter Brain Volume in a Marsupial Over a Few Generations

Captive breeding followed by reintroduction to the wild is a common component of conservation management plans for various taxa. Although it is commonly used, captive breeding can result in morphological changes, including brain size decrease. Brain size reduction has been associated with behavioral changes in domestic animals, and such changes may negatively influence reintroduction success of captive‐bred animals. Many marsupials are currently bred in captivity for reintroduction, yet the impacts of captive breeding on brain size have never been studied in this taxa. We investigated the impacts of a few generations (2–7) of captive breeding on brain volume in the stripe‐faced dunnart (Sminthopsis macroura), and found that captive breeding in a relatively enriched environment did not cause any changes in brain volume. Nonetheless, we advocate that great care be taken to provide suitable husbandry conditions and to minimize the number of captive generations if marsupial reintroduction programs are to be successful. Zoo Biol 31:82;–86, 2012. © 2011 Wiley Periodicals, Inc.     

Assessing the Potential Threat Landscape of a Proposed Reintroduction Site for Carnivores

This study provides a framework to assess the feasibility of reintroducing carnivores into an area, using African wild dogs (Lycaon pictus) as an example. The Great Fish River Nature Reserve in the Eastern Cape Province, South Africa, has been identified as a potential reserve to reintroduce wild dogs, and we applied this framework to provide a threat assessment of the surrounding area to determine potential levels of human-wildlife conflict. Although 56% of neighbouring landowners and local communities were positive about a wild dog reintroduction, data collected from questionnaire surveys revealed that human-wild dog conflict is a potential threat to wild dog survival in the area. Additional potential threats include diseases, snaring, poaching and hunting wild dogs for the use of traditional medicine. A threat index was developed to establish which properties harboured the greatest threats to wild dogs. This index was significantly influenced by the respondent’s first language (isiXhosa had more positive indices), education level (poorer education was synonymous with more positive threat indices), land use (wildlife ranching being the most negative) and land tenure (community respondents had more positive indices than private landowners). Although threats are present, they can be effectively mitigated through strategies such as carnivore education programs, vaccination campaigns and anti-snare patrols to promote a successful reintroduction of this endangered canid.     

Translocations as experiments in the ecological resilience of an asocial mega-herbivore

Species translocations are remarkable experiments in evolutionary ecology, and increasingly critical to biodiversity conservation. Elaborate socio-ecological hypotheses for translocation success, based on theoretical fitness relationships, are untested and lead to complex uncertainty rather than parsimonious solutions. We used an extraordinary 89 reintroduction and 102 restocking events releasing 682 black rhinoceros (Diceros bicornis) to 81 reserves in southern Africa (1981-2005) to test the influence of interacting socio-ecological and individual characters on post-release survival. We predicted that the socio-ecological context should feature more prominently after restocking than reintroduction because released rhinoceros interact with resident conspecifics. Instead, an interaction between release cohort size and habitat quality explained reintroduction success but only individuals' ages explained restocking outcomes. Achieving translocation success for many species may not be as complicated as theory suggests. Black rhino, and similarly asocial generalist herbivores without substantial predators, are likely to be resilient to ecological challenges and robust candidates for crisis management in a changing world.     

Shifting threats faced by the San Clemente sage sparrow

Threats to a species' persistence are likely to change as conservation measures reduce some threats, while natural and anthropogenic changes increase others. Despite a variety of potential underlying mechanisms, extinction threats will be manifested through one of the 3 components of population dynamics: reducing population growth potential, increasing population variability, or lowering the population ceiling. Consequently, effective management can be guided by monitoring programs and population models that examine each of these components. We examined the potential for a coupled monitoring and modeling effort to guide management of species-at-risk while accounting for evolving risks using the case study of the threatened San Clemente sage sparrow (Amphispiza belli clementeae). Originally listed due to a low population ceiling imposed by severe habitat loss, we found that the major threat to San Clemente sage sparrow persistence has shifted to low population growth potential driven by high juvenile mortality. We further found that successful mitigation of high juvenile mortality will shift the primary threat to drought frequency, which is predicted to increase on San Clemente Island as a consequence of global climate change. The latter shift is a consequence of the boom-bust ecology exhibited by San Clemente sage sparrows in response to rainfall—likely a common characteristic of short-lived terrestrial vertebrates in arid environments. Our ability to successfully recover this species hinges on a comprehensive monitoring and modeling program incorporating all 3 components of population dynamics informing changes in management priorities to reflect shifting threats. Our study indicates that the next critical step to recovering sage sparrows is to understand and mitigate the causes of high juvenile mortality. In response to these predictions, the United States Navy has funded a radio-telemetry study to determine the cause(s) of juvenile mortalities. © 2011 The Wildlife Society.     

Out of the frying pan: Reintroduction of toad‐smart northern quolls to southern Kakadu National Park

Invasive species are a leading cause of native biodiversity loss. In Australia, the toxic, invasive cane toad Rhinella marina has caused massive and widespread declines of northern quolls Dasyurus hallucatus. Quolls are fatally poisoned if they mistakenly prey on adult toads. To prevent the extinction of this native dasyurid from the Top End, an insurance population was set up in 2003 on two toad‐free islands in Arnhem Land. In 2015, quolls were collected from one of these islands (Astell) for reintroduction. We used conditioned taste aversion to render 22 of these toad‐naïve quolls toad averse. Seven quolls received no taste aversion training. The source island was also predator‐free, so all quolls received very basic predator‐aversion training. In an attempt to re‐establish the mainland population, we reintroduced these 29 northern quolls into Kakadu National Park in northern Australia where cane toads have been established for 13 years. The difference in survival between toad‐averse and toad‐naive quolls was immediately apparent. Toad‐naive quolls were almost all killed by toads within 3 days. Toad‐averse quolls, on the other hand, not only survived longer but also were recorded mating. Our predator training, however, was far less effective. Dingo predation accounted for a significant proportion of toad‐smart quoll mortality. In Kakadu, dingoes have been responsible for high levels of quoll predation in the past and reintroduced animals are often vulnerable to predation‐mediated population extinction. Dingoes may also be more effective predators in fire degraded landscapes. Together, these factors could explain the extreme predation mortality that we witnessed. In addition, predator aversion may have been lost from the predator‐free island populations. These possibilities are not mutually exclusive but need to be investigated because they have clear bearing on the long‐term recovery of the endangered northern quoll.     

Assortative mating among animals of captive and wild origin following experimental conservation releases

Captive breeding is a high profile management tool used for conserving threatened species. However, the inevitable consequence of generations in captivity is broad scale and often-rapid phenotypic divergence between captive and wild individuals, through environmental differences and genetic processes. Although poorly understood, mate choice preference is one of the changes that may occur in captivity that could have important implications for the reintroduction success of captive-bred animals. We bred wild-caught house mice for three generations to examine mating patterns and reproductive outcomes when these animals were simultaneously released into multiple outdoor enclosures with wild conspecifics. At release, there were significant differences in phenotypic (e.g. body mass) and genetic measures (e.g. G_st and F) between captive-bred and wild adult mice. Furthermore, 83% of offspring produced post-release were of same source parentage, inferring pronounced assortative mating. Our findings suggest that captive breeding may affect mating preferences, with potentially adverse implications for the success of threatened species reintroduction programmes.     

Ecological forecasts to inform near‐term management of threats to biodiversity

Ecosystems are being altered by rapid and interacting changes in natural processes and anthropogenic threats to biodiversity. Uncertainty in historical, current and future effectiveness of actions hampers decisions about how to mitigate changes to prevent biodiversity loss and species extinctions. Research in resource management, agriculture and health indicates that forecasts predicting the effects of near‐term or seasonal environmental conditions on management greatly improve outcomes. Such forecasts help resolve uncertainties about when and how to operationalize management. We reviewed the scientific literature on environmental management to investigate whether near‐term forecasts are developed to inform biodiversity decisions in Australia, a nation with one of the highest recent extinction rates across the globe. We found that forecasts focused on economic objectives (e.g. fisheries management) predict on significantly shorter timelines and answer a broader range of management questions than forecasts focused on biodiversity conservation. We then evaluated scientific literature on the effectiveness of 484 actions to manage seven major terrestrial threats in Australia, to identify opportunities for near‐term forecasts to inform operational conservation decisions. Depending on the action, between 30% and 80% threat management operations experienced near‐term weather impacts on outcomes before, during or after management. Disease control, species translocation/reintroduction and habitat restoration actions were most frequently impacted, and negative impacts such as increased species mortality and reduced recruitment were more likely than positive impacts. Drought or dry conditions, and rainfall, were the most frequently reported weather impacts, indicating that near‐term forecasts predicting the effects of low or excessive rainfall on management outcomes are likely to have the greatest benefits. Across the world, many regions are, like Australia, becoming warmer and drier, or experiencing more extreme rainfall events. Informing conservation decisions with near‐term and seasonal ecological forecasting will be critical to harness uncertainties and lower the risk of threat management failure under global change.     

Managing fire‐dependent vegetation in Byron Shire,Australia: Are we restoring the keystone ecological process of fire?

Fire is a keystone ecological process in many ecosystems. In such ecosystems, the exclusion of fire can lead to fundamental shifts in vegetation structure, composition and distribution and poses a major threat to the biodiversity dependent on these habitats. Programmes to manage and restore native vegetation have increased rapidly over recent decades, and while many such programmes have demonstrable success managing a range of environmental threats, their effectiveness in identifying and addressing the major threat of fire exclusion in fire‐dependent vegetation is questionable. This study sought to identify impediments to the management of fire‐excluded vegetation at the assessment and planning stage of ecological management programmes in Byron Shire in north‐east New South Wales. Sixty ecological management and restoration plans for sites known to be fire‐excluded in the shire were reviewed to determine the rate at which fire exclusion was identified and addressed in planning over the last decade. Document analysis found the majority of plans failed to accurately identify fire exclusion or to recommend the reintroduction of fire in fire‐excluded management sites. Absence of standardised guidelines that require comprehensive consideration of fire exclusion in ecological management and restoration plans is suggested as a key factor in the low response rates observed. Furthermore, it was found that existing implicit prompts to address inappropriate‐fire regimes generally, including government policies, project objectives and site‐assessment prompts had little effect on identification and response rates, further confirming the need for more‐explicit assessment prompts relating to fire‐frequency issues. Without improvements of the current ecological assessment and planning process to increase identification and management of fire exclusion in the study area, fire‐dependent biodiversity values will continue to decline wherever fire exclusion remains unmanaged. It is recommended that explicit assessment and planning templates are developed and implemented to effectively manage fire exclusion and conserve the fire‐dependent biodiversity of Byron Shire and the far north coast of NSW.     

Not such silly sausages: Evidence suggests northern quolls exhibit aversion to toads after training with toad sausages

The invasion of toxic cane toads (Rhinella marina) is a major threat to northern quolls (Dasyurus hallucatus) which are poisoned when they attack this novel prey item. Quolls are now endangered as a consequence of the toad invasion. Conditioned taste aversion can be used to train individual quolls to avoid toads, but we currently lack a training technique that can be used at a landscape scale to buffer entire populations from toad impact. Broad‐scale deployment requires a bait that can be used for training, but there is no guarantee that such a bait will ultimately elicit aversion to toads. Here, we test a manufactured bait – a ‘toad sausage’ – in a small captive trial, for its ability to elicit aversion to toads in northern quolls. To do this, we exposed one group of quolls to a toad sausage and another to a control sausage and compared the quolls' predatory responses when presented with a dead adult toad. Captive quolls that consumed a single toad sausage showed a reduced interest in cane toads, interacting with them for less than half the time of their untrained counterparts and showing reduced Attack behaviour. We also quantified bait uptake in the field, by both quolls and non‐target species. These field trials showed that wild quolls were the most frequent species attracted to the baits, and that approx. 61% of quolls consumed toad‐aversion baits when first encountered. Between 40% and 68% of these animals developed aversion to further bait consumption. Our results suggest that toad‐aversion sausages may be used to train wild quolls to avoid cane toads. This opens the possibility for broad‐scale quoll training with toad aversion sausages: a technique that may allow wildlife managers to prevent quoll extinctions at a landscape scale.     

Current threats faced by amphibian populations in the southern cone of South America

In this work, we update and increase knowledge on the severity and extent of threats affecting 57 populations of 46 amphibian species from Chile and Argentina in southern South America. We analyzed the intrinsic conservation problems that directly impact these populations. We shared a questionnaire among specialists on threats affecting target amphibian populations with information on i) range, ii) historical occurrence and abundance, iii) population trends, iv) local extinctions, v) threats, and vi) ongoing and necessary conservation/research. We assessed association patterns between reported threats and population trends using multiple correspondence analysis. Since 2010, 25 of 57 populations have declined, while 16 experienced local extinctions. These populations were affected by 81% of the threat categories analyzed, with those related to agricultural activities and/or habitat modifications being the most frequently reported. Invasive species, emerging diseases, and activities related to grazing, ranching, or farming were the threats most associated with population declines. Low connectivity was the most frequent intrinsic conservation problem affecting 68% of the target populations, followed by low population numbers, affecting 60%. Ongoing monitoring activity was conducted in 32 (56%) populations and was the most frequent research activity. Threat mitigation was reported in 27 (47%) populations and was the most frequent ongoing management activity. We found that habitat management is ongoing in 5 (9%) populations. At least 44% of the amphibian populations surveyed in Chile and Argentina are declining. More information related to the effect of management actions to restore habitats, recover populations, and eliminate threats such as invasive species is urgently needed to reverse the conservation crisis facing amphibians in this Neotropical region.     

Which species,how many,and from where: Integrating habitat suitability,population genomics,and abundance estimates into species reintroduction planning

Extirpated organisms are reintroduced into their former ranges worldwide to combat species declines and biodiversity losses. The growing field of reintroduction biology provides guiding principles for reestablishing populations, though criticisms remain regarding limited integration of initial planning, modeling frameworks, interdisciplinary collaborations, and multispecies approaches. We used an interdisciplinary, multispecies, quantitative framework to plan reintroductions of three fish species into Abrams Creek, Great Smoky Mountains National Park, USA. We first assessed the appropriateness of habitat at reintroduction sites for banded sculpin (Cottus carolinae), greenside darter (Etheostoma blennioides), and mottled sculpin (Cottus bairdii) using species distribution modeling. Next, we evaluated the relative suitability of nine potential source stock sites using population genomics, abundance estimates, and multiple‐criteria decision analysis (MCDA) based on known correlates of reintroduction success. Species distribution modeling identified mottled sculpin as a poor candidate, but banded sculpin and greenside darter as suitable candidates for reintroduction based on species‐habitat relationships and habitats available in Abrams Creek. Genotyping by sequencing revealed acceptable levels of genetic diversity at all candidate source stock sites, identified population clusters, and allowed for estimating the number of fish that should be included in translocations. Finally, MCDA highlighted priorities among candidate source stock sites that were most likely to yield successful reintroductions based on differential weightings of habitat assessment, population genomics, and the number of fish available for translocation. Our integrative approach represents a unification of multiple recent advancements in the field of reintroduction biology and highlights the benefit of shifting away from simply choosing nearby populations for translocation to an information‐based science with strong a priori planning coupled with several suggested posteriori monitoring objectives. Our framework can be applied to optimize reintroduction successes for a multitude of organisms and advances in the science of reintroduction biology by simultaneously addressing a variety of past criticisms of the field.     

Emergency relocation of a Purple Copper Butterfly colony during roadworks: Successes and lessons learned

Summary  In 2004, the Roads and Traffic Authority (RTA) undertook a road realignment project near Lidsdale in the Central Tablelands of New South Wales. However, the RTA had not detected a population of the threatened Purple Copper Butterfly within the footprint of the project. The RTA responded promptly when notified of the butterflies' presence by stopping works, and preparing and implementing a butterfly management programme. This programme included modifying the realignment (and reducing the development footprint), supplementary planting of habitat, habitat rehabilitation and translocation of individual caterpillars from within the final footprint area. These actions seem to have safeguarded the population at least in the short term; however, further active management of the site will be needed to ensure its long-term viability. The project reinforces the importance of thorough predisturbance assessment of a site at the early planning stages, and the results and observations could be particularly informative in planning for introduction, reintroduction and translocation proposals involving the Purple Copper Butterfly.     

Mapping tree species vulnerability to multiple threats as a guide to restoration and conservation of tropical dry forests

Understanding the vulnerability of tree species to anthropogenic threats is important for the efficient planning of restoration and conservation efforts. We quantified and compared the effects of future climate change and four current threats (fire, habitat conversion, overgrazing and overexploitation) on the 50 most common tree species of the tropical dry forests of northwestern Peru and southern Ecuador. We used an ensemble modelling approach to predict species distribution ranges, employed freely accessible spatial datasets to map threat exposures, and developed a trait‐based scoring approach to estimate species‐specific sensitivities, using differentiated trait weights in accordance with their expected importance in determining species sensitivities to specific threats. Species‐specific vulnerability maps were constructed from the product of the exposure maps and the sensitivity estimates. We found that all 50 species face considerable threats, with an average of 46% of species’ distribution ranges displaying high or very high vulnerability to at least one of the five threats. Our results suggest that current levels of habitat conversion, overexploitation and overgrazing pose larger threats to most of the studied species than climate change. We present a spatially explicit planning strategy for species‐specific restoration and conservation actions, proposing management interventions to focus on (a) in situ conservation of tree populations and seed collection for tree planting activities in areas with low vulnerability to climate change and current threats; (b) ex situ conservation or translocation of populations in areas with high climate change vulnerability; and (c) active planting or assisted regeneration in areas under high current threat vulnerability but low climate change vulnerability, provided that interventions are in place to lower threat pressure. We provide an online, user‐friendly tool to visualize both the vulnerability maps and the maps indicating priority restoration and conservation actions.     

Phylogeographical population structure of tiger quolls Dasyurus maculatus (Dasyuridae: Marsupialia), an endangered carnivorous marsupial

Tiger quolls, Dasyurus maculatus, are the largest carnivorous marsupials still extant on the mainland of Australia, and occupy an important ecological niche as top predators and scavengers. Two allopatric subspecies are recognized, D.m. gracilis in north Queensland, and D.m. maculatus in the southeast of the mainland and Tasmania. D.m. gracilis is considered endangered while D.m. maculatus is listed as vulnerable to extinction; both subspecies are still in decline. Phylogeographical subdivision was examined to determine evolutionarily significant units (ESUs) and management units (MUs) among populations of tiger quolls to assist in the conservation of these taxa. Ninety-three tiger quolls from nine representative populations were sampled from throughout the species range. Six nuclear microsatellite loci and the mitochondrial DNA (mtDNA) control region (471 bp) were used to examine ESUs and MUs in this species. We demonstrated that Tasmanian tiger quolls are reciprocally monophyletic to those from the mainland using mtDNA analysis, but D.m. gracilis was not monophyletic with respect to mainland D.m. maculatus. Analysis of microsatellite loci also revealed significant differences between the Tasmanian and mainland tiger quolls, and between D.m. gracilis and mainland D.m. maculatus. These results indicate that Tasmanian and mainland tiger quolls form two distinct evolutionary units but that D.m. gracilis and mainland D.m. maculatus are different MUs within the same ESU. The two marker types used in this study revealed different male and female dispersal patterns and indicate that the most appropriate units for short-term management are local populations. A revised classification and management plan are needed for tiger quolls, particularly in relation to conservation of the Tasmanian and Queensland populations.     

Migration patterns and survival of stocked Atlantic sturgeon (Acipenser oxyrinchus Mitchill, 1815) in Nemunas Basin,Baltic Sea

The restoration of the Atlantic sturgeon Acipenser oxyrinchus in Lithuania started in 2011. Two rivers (Neris and ?ventoji) were chosen for reintroduction in the Nemunas river basin based on historical data and ecological conditions. Since 2011, more than 116 thousand of sturgeon juveniles have been stocked in Lithuania. In order to achieve successful population restoration, it is vital to evaluate the efficiency of performed artificial stocking. Analysis of post‐stocking survival, migration patterns, predation pressure, fisheries‐related mortality and possible aggregation zones are all important to understand the main threats and prepare possible mitigation measures necessary for population establishment during the initial phase of restoration. Therefore, conventional and radio tagging studies were performed during the initial restoration phase in Lithuania. Atlantic sturgeon downstream migration was divergent in summer and appeared to have no significant associations with fish size, river quality or hydrophysical parameters, but in autumn migration speed and even survival in small rivers seemed to depend on flow velocity and water discharge. The distribution of recaptured tagged juveniles coincided with dominant currents in the Curonian Lagoon and Baltic Sea. Some tagged specimens migrated long distances, with two sturgeons from Lithuania being caught in Estonian and Finnish territorial waters at up to 800 km from their release site. Tag recapture analysis and mortality rate of tagged fish clearly indicate that annual fisheries‐related mortality exceeds the required threshold of 5% for population establishment. High survival in rivers indicates that the main threat for a successful sturgeon reintroduction program is commercial fishing in the Curonian Lagoon and Baltic Sea coastal zone.     

Optimizing the genetic management of reintroduction projects: genetic population structure of the captive Northern Bald Ibis population

Many threatened species are bred in captivity for conservation purposes and some of these programmes aim at future reintroduction. The Northern Bald Ibis, Geronticus eremita, is a Critically Endangered bird species, with recently only one population remaining in the wild (Morocco, Souss Massa region). During the last two decades, two breeding programs for reintroduction have been started (in Austria and Spain). As the genetic constitution of the founding population can have strong effects on reintroduction success, we studied the genetic diversity of the two source populations for reintroduction (‘Waldrappteam’ and ‘Proyecto eremita’) as well as the European zoo population (all individuals held ex situ) by genotyping 642 individuals at 15 microsatellite loci. To test the hypothesis that the wild population in Morocco and the extinct wild population in the Middle East belong to different evolutionary significant units, we sequenced two mitochondrial DNA fragments. Our results show that the European zoo population is genetically highly structured, reflecting separate breeding lines. Genetic diversity was highest in the historic samples from the wild eastern population. DNA sequencing revealed only a single substitution distinguishing the wild eastern and wild western population. Contrary to that, the microsatellite analysis showed a clear differentiation between them. This suggests that genetic differentiation between the two populations is recent and does not confirm the existence of two evolutionary significant units. The European zoo population appears to be vital and suitable for reintroduction, but the management of the European zoo population and the two source populations for reintroductions can be optimized to reach a higher level of admixture.     

Spatially explicit decision support for selecting translocation areas for Mojave desert tortoises

Spatially explicit decision support systems are assuming an increasing role in natural resource and conservation management. In order for these systems to be successful, however, they must address real-world management problems with input from both the scientific and management communities. The National Training Center at Fort Irwin, California, has expanded its training area, encroaching U.S. Fish and Wildlife Service critical habitat set aside for the Mojave desert tortoise (Gopherus agassizii), a federally threatened species. Of all the mitigation measures proposed to offset expansion, the most challenging to implement was the selection of areas most feasible for tortoise translocation. We developed an objective, open, scientifically defensible spatially explicit decision support system to evaluate translocation potential within the Western Mojave Recovery Unit for tortoise populations under imminent threat from military expansion. Using up to a total of 10 biological, anthropogenic, and/or logistical criteria, seven alternative translocation scenarios were developed. The final translocation model was a consensus model between the seven scenarios. Within the final model, six potential translocation areas were identified.     

What to do in the face of multiple threats? Incorporating dependencies within a return on investment framework for conservation

Aim Our study aimed to determine priority areas for conservation investment with explicit consideration of the impacts of multiple threatening processes, and the dependencies that exist between actions required to abate these threats. Location Australia. Methods We analysed the return on investment for two different management actions aimed at reducing the impact of invasive species on the native fauna and flora of Australia. We focussed on the management of the European red fox (Vulpes vulpes) and European rabbit (Oryctolagus cuniculus) at two spatial scales: across 72 biogeographic regions of Australia and within one high‐priority biogeographic region. We considered each action independently and also explicitly accounted for the option of an integrated fox and rabbit management action. We accounted for the spatial distributions of the threatened species within our analysis and determined how this refined spatial information influenced both the priority areas and the timing of this investment. Results Integrated fox and rabbit management was identified as a higher priority than singular threat abatement in most bioregions, whereas rabbit control alone was the most frequent priority if dependencies between actions were ignored. At the regional scale, funding was entirely directed to integrated action when seven or more species within the priority region were impacted by more than one threat. The total allocation of funding and timing of initial investment remained relatively insensitive to differences in the spatial overlap of species distributions. Main conclusions Our findings indicate that prioritizing conservation actions without explicit consideration of the impacts of multiple threats can reduce the cost‐effectiveness of investments. The benefits expected from investment in abating one threat alone may be overestimated where other processes continue to threaten species persistence. We conclude that future attention should be directed to refining our understanding of the cost‐efficiencies delivered through integrated actions and institutional mechanisms to achieve their delivery.     

Robust estimation of survival and contribution of captive‐bred Mallards Anas platyrhynchos to a wild population in a large‐scale release programme

The survival of captive‐bred individuals from release into the wild to their first breeding season is crucial to assess the success of reintroduction or translocation programmes, and to assess their potential impact of wild populations. However, assessing the survival of captive‐bred individuals following their release is often complicated by immediate dispersal once in the wild. Here, we apply Lindberg's robust design model, a method that incorporates emigration from the study site, to obtain true estimates of survival of captive‐bred Mallards Anas platyrhynchos, a common duck species released on a large scale in Europe since the 1970s. Overall survival rate from release in July until the onset of the next breeding season in April was low (0.18 ± 0.07 se) and equivalent to half the first‐year survival of local wild Mallards. Higher overall detectability and temporary emigration during the hunting period revealed movements in response to hunting pressure. Such low survival of released Mallards during their first year may help prevent large‐scale genetic mixing with the wild population. Nevertheless, by combining our results with regional waterfowl counts, we estimated that a minimum of 34% of the Mallards in the region were of captive origin at the onset of the breeding season. Although most released birds quickly die, restocking for hunting may be of sufficient magnitude to affect the wild population through genetic homogenization or loss of local adaptation. Robust design protocols allow for the estimation of true survival estimates by controlling for permanent and temporary emigration and may require only a moderate increase in fieldwork effort.