Search

The current extinction crisis requires effective assessment and monitoring tools. Genetic approaches are appealing given the relative ease of field sampling required to estimate genetic diversity characteristics assumed related to population size, evolutionary potential, and extinction risk, and to evaluate hybridization with non-native species simultaneously. However, linkages between population genetic metrics of diversity from survey-style field collections and demographic estimates of population size and extinction risk are still in need of empirical examples, especially for remotely distributed species of conservation concern where the approach might be most beneficial. We capitalized on an exceptional opportunity to evaluate congruence between genetic diversity metrics and demographic-based estimates of abundance and extinction risk from a comprehensive Multiple Population Viability Analysis (MPVA) in a threatened fish, the Lahontan cutthroat trout (LCT). We sequenced non-native trout reference samples and recently collected and archived tissue samples of most remaining populations of LCT (N=60) and estimated common genetic assessment metrics, predicting minimal hybridization with non-native trout, low diversity, and declining diversity over time. We further hypothesized genetic metrics would correlate positively with MPVA-estimated abundance and negatively with extinction probability. We uncovered several instances of hybridization that pointed to immediate management needs. After removing hybridized individuals, cautious interpretation of low effective population sizes (2-63) suggested reduced evolutionary potential for many LCT populations. Other genetic metrics did not decline over time nor correlate with MPVA-based estimates of harmonic mean abundance or 30-year extinction probability. Our results demonstrate benefits of genetic monitoring for efficiently detecting hybridization and, though genetic results were disconnected from demographic assessment of conservation status, they suggest reduced evolutionary potential and likely a higher conservation risk than currently recognized for this threatened fish. We emphasize that genetic information provides essential complementary insight, in addition to demographic information, for evaluating species status.

Ongoing environmental changes may reduce the population size and geographic distribution of many ecologically sensitive species. Predicting where populations will (or will not) be likely to resist these changes is crucial for planning their protection. The blond titi monkey (Callicebus barbarabrownae) is listed as Critically Endangered by the International Union for Conservation of Nature because of its small and declining population due to deforestation and hunting. The species is endemic to the Brazilian Caatinga dry forest, which has undergone extensive deforestation and climate-induced desertification. We address the extinction risk of this species in a spatially explicit context by predicting the geographic distribution of suitable areas that may permit the persistence of potentially viable populations over the next 50 years. We combined species distribution modeling with population viability analysis under more optimistic and pessimistic climate change scenarios and simulated forest loss, assessing how different populations will likely cope with these changes during the coming decades. Future models did not differ between the scenarios, but changes in the climatic suitability of the species’ habitat predicted a reduction of one-third of the currently suitable area. Viable populations in large forest remnants represent only a quarter of all known populations, and they also face a decline in climatic suitability. Smaller populations may be extirpated, regardless of the level of forest recovery. This species’ long-term persistence entails improving habitat quality and the connectivity of the large remnants to neighbor areas. Finally, the integration of spatial and temporal models is feasible and helpful to address threats and aid the conservation of primates.

Conceptual and methodological advances in population and evolutionary ecology are often pursued with the ambition that they will help identify demographic, ecological and genetic constraints on population growth rate (λ), and ultimately facilitate evidence-based conservation. However, such advances are often decoupled from conservation practice, impeding translation of scientific understanding into effective conservation, and of conservation-motivated research into wider conceptual understanding. We summarise key outcomes from long-term studies of a red-billed chough (Pyrrhorcorax pyrrhocorax) population of conservation concern, where we pro-actively aimed to achieve the dual and interacting objectives of advancing population and evolutionary ecology and advancing effective conservation. Estimation of means, variances and covariances in key vital rates from individual-based demographic data identified temporal and spatial variation in sub-adult survival as key constraints on λ, and simultaneously provided new insights into how vital rates can vary as functions of demographic structure, natal conditions and parental life-history. Targeted analyses showed that first-year survival increased with prey abundance, implying that food limitation may constrain λ. First-year survival then decreased dramatically, threatening population viability and prompting emergency supplementary feeding interventions. Detailed evaluations suggested that the interventions successfully increased first-year survival in some years, and additionally increased adult survival and successful reproduction, thereby feeding back to inform intervention refinements and understanding of complex ecological constraints on λ. Genetic analyses revealed novel evidence of expression of a lethal recessive allele, and demonstrated how critically small effective population size can arise, thereby increasing inbreeding and loss of genetic variation. Population viability analyses parameterised with all available demographic and genetic data showed how ecological and genetic constraints can interact to limit population viability, and identified ecological management as of primacy over genetic management to ensure short-term persistence of the focal population. This case study demonstrates a full iteration through the sequence of primary science, evidence-based intervention, quantitative evaluation and feedback that is advocated in conservation science but still infrequently achieved. It thereby illustrates how pure science advances informed conservation actions to ensure (short-term) stability of the target population, and how conservation-motivated analyses fed back to advance fundamental understanding of population processes.

Accurate status assessments of long-lived, widely distributed taxa depend on the availability of long-term monitoring data from multiple populations. However, monitoring populations across large temporal and spatial scales is often beyond the scope of any one researcher or research group. Consequently, wildlife managers may be tasked with utilizing limited information from different sources to detect range-wide evidence of population declines and their causes. When assessments need to be made under such constraints, the research and management communities must determine how to extrapolate from variable population data to species-level inferences. Here, using three different approaches, we integrate and analyze data from the peer-reviewed literature and government agency reports to inform conservation for northwestern pond turtles (NPT) Actinemys marmorata and southwestern pond turtles (SPT) Actinemys pallida. Both NPT and SPT are long-lived freshwater turtles distributed along the west coast of the United States and Mexico. Conservation concerns exist for both species; however, SPT may face more severe threats and are thought to exist at lower densities throughout their range than NPT. For each species, we ranked the impacts of 13 potential threats, estimated population sizes, and modeled population viability with and without long-term droughts. Our results suggest that predation of hatchlings by invasive predators, such as American bullfrogs Lithobates catesbeianus and Largemouth Bass Micropterus salmoides, is a high-ranking threat for NPT and SPT. Southwestern pond turtles may also face more severe impacts associated with natural disasters (droughts, wildfires, and floods) than do NPT. Population size estimates from trapping surveys indicate that SPT have smaller population sizes on average than do NPT (P = 0.0003), suggesting they may be at greater risk of local extirpation. Population viability analysis models revealed that long-term droughts are a key environmental parameter; as the frequency of severe droughts increases with climate change, the likelihood of population recovery decreases, especially when census sizes are low. Given current population trends and vulnerability to natural disasters throughout their range, we suggest that conservation and recovery actions first focus on SPT to prevent further population declines.

As an endemic bird to the Fynbos biome, prominently featured in literature and marketing material for the avifauna of the continent, the Cape Rockjumper Chaetops frenatus is an iconic species of So...

OBJECTIVES Infanticide in white-faced capuchins (Cebus capucinus imitator) typically occurs in association with alpha male replacements (AMRs). Although infanticide is likely adaptive for males, it imposes costs on females that are difficult to quantify without long-term demographic data. Here we investigate effects of AMRs and infanticide on female reproductive success and how these costs affect capuchin groups. We investigate (1) effects of AMR frequency on the production of surviving infants; (2) energetic and (3) temporal "opportunity costs" of infant loss; and (4) how AMR frequency impacts capuchin group sizes. MATERIALS AND METHODS We censused six groups (7-33 years/group, 74 adult females). We modeled surviving infant production in relation to AMR. We estimated a female's energy requirements for lost infants and the temporal cost relative to the median reproductive window. We simulated how varying AMR rates would affect future capuchin group sizes. RESULTS Females exposed to more frequent AMR tended to produce fewer surviving offspring. We estimate the average lost infant requires approximately 33% additional energy intake for its mother and represents 10% of the average reproductive opportunity window available to females. Simulated populations remain viable at the observed rate of AMR occurrence but decrease in size at even slightly higher rates. DISCUSSION While infanticide is adaptive for males, for females it affects lifetime reproductive success and imposes energetic and opportunity costs. Although capuchin populations have evolved with AMRs and infanticide, small increases in AMR frequency may lead to population decline/extinction. Infanticide likely plays a large role in population maintenance for capuchins.

The Endangered Macadamia jansenii (C.L. Gross & P.H. Western, 1992) was known only from one small populationand a reintroduction program was implemented from 2009 to increase the number of populations. Recently, new subpopulations were discovered. However, in 2019, fire directly affected M. jansenii and the surrounding habitat. This study aimed to examine the abundance and distribution of M. jansenii in the wild pre- and post-fire, as well as to assess the success of the reintroduction program and species population viability. We undertook genetic analysis, population viability analysis (PVA) and updated the existing habitat models. The known wild M. jansenii population increased in abundance from 59 in a single population to 200 individuals (including seedlings), across three subpopulations. Results from the post-fire survey suggest that 83% of the wild plants have survived, with many plants resprouting. The newly discovered subpopulations were within predicted suitable habitat in the Bulburin National Park. These subpopulations are genetically similar to the original known population. Novel alleles suggest the potential for more plants to be located. The reintroduction program successfully established 20 individuals. PVA results indicate that even with the effects of fire, the species is unlikely to become extinct in the next 150 years.

Age‐based demography is fundamental to management of wild fish populations. Age estimates for individuals can determine rates of change in key life‐history parameters such as length, maturity, mortality and fecundity. These age‐based characteristics are critical for population viability analysis in endangered species and for developing sustainable harvest strategies. For teleost fish, age has traditionally been determined by counting increments formed in calcified structures such as otoliths. However, the collection of otoliths is lethal and therefore undesirable for threatened species. At a molecular level, age can be predicted by measuring DNA methylation. Here, we use previously identified age‐associated sites of DNA methylation in zebrafish (Danio rerio) to develop two epigenetic clocks for three threatened freshwater fish species. One epigenetic clock was developed for the Australian lungfish (Neoceratodus forsteri) and the second for the Murray cod (Maccullochella peelii) and Mary River cod (Maccullochella mariensis). Age estimation models were calibrated using either known‐age individuals, ages derived from otoliths or bomb radiocarbon dating of scales. We demonstrate a high Pearson's correlation between the chronological and predicted age in both the Lungfish clock (cor = .98) and Maccullochella clock (cor = .92). The median absolute error rate for both epigenetic clocks was also low (Lungfish = 0.86 years; Maccullochella = 0.34 years). This study demonstrates the transferability of DNA methylation sites for age prediction between highly phylogenetically divergent fish species. Given the method is nonlethal and suited to automation, age prediction by DNA methylation has the potential to improve fisheries and other wildlife management settings.

Across the Global South, wildlife is an important source of nutrition and income, particularly for rural communities. While wildlife consumption provides a valuable source of nutrition, high levels of hunting can endanger wildlife species. In the Makira region of north-eastern Madagascar, human health is threatened by food insecurity and malnutrition, and spiny tenrecs are a crucial source of subsistence bushmeat with 91% of households consuming tenrecs at least once per year. Moreover, Makira’s human populations are increasing, resulting in forest decline and degradation. In order to inform conservation and public health efforts, we investigated the influence of hunting, habitat loss and forest degradation on spiny tenrec population dynamics in the Makira region. We collected data on tenrec population densities as well as hunting and consumption by humans in 51 communities. We used these data to conduct a population viability analysis for the two most commonly hunted spiny tenrecs (Tenrec ecaudatus and Setifer setosus). We found that current harvest rates for these species are generally sustainable in the Makira region, largely due to tenrecs’ extraordinary fecundity. However, even assuming no change in current hunting rates, tenrec populations could become threatened if fecundity were to decline or background mortality to increase, both possible scenarios under future trajectories of habitat loss and degradation. We find that any future increase in hunting-induced mortality rates for tenrecs are similarly unsustainable – and likely to occur as human populations expand and hunting areas decline. We conclude that there is a vanishing window of opportunity to sustainably manage tenrec hunting in northeastern Madagascar in order to avoid negative conservation and human health outcomes.

The endangered Moorish tortoise Testudo graeca is the unique terrestrial chelonian species in Northwest Africa. In west-central Morocco, the endemic subspecies, the Souss valley tortoise T. g. soussensis, occupies semi-arid to arid low-quality habitats, and is subject to serious threats. A long-term mark-recapture programme from 2001 to 2012 allowed estimating population size and structure, sex ratio, and survivorship in one of the well-known populations in a degraded and overgrazed arid steppe-land of west-central Morocco. Spring population size considerably decreased to more than half in less than 10 years, with a mean density lower than 3 ind.ha-1 in 2012 compared to its last known density estimated in 2003. In spring 2012, the population structure exhibited an unbalanced male-biased sex ratio (61:39) and a scarcity of juveniles (

Although population viability analysis (PVA) is widely used in setting conservation policy, there is disagreement about the usefulness of this method. Objections have been raised concerning the precision of predictions in view of the short time series of data available and the sensitivity of estimates of extinction risk to estimated parameters (Hamilton & Moller 1995; Taylor 1995; Groom & Pascual 1998; Ludwig 1999). Beissinger and Westphal (1998) reviewed the use of demographic models for endangered-species management. They pointed out that poor data cause difficulties in parameter estimation, which in turn lead to unreliable estimates of extinction risk. There are additional

Context Species translocations are used in conservation globally. Although harvest for translocation may have negative impacts on source populations, translocation programs rarely explore ways of minimising those impacts. In fluctuating source populations, harvest timing may affect its impact because population size and trajectory vary among years. Aims We explored whether the timing and scale of harvest can be altered to reduce its impact on a fluctuating source population of Mallee Emu-wrens, Stipiturus mallee; an endangered passerine in south-eastern Australia. Mallee Emu-wren populations fluctuate with ~5–10-year drought–rain cycles. Methods We used population viability analysis (PVA) to compare the impact of five harvest scales (no harvest, 100, 200, 300 or 500 individuals) under three population trajectories (increasing, stable or decreasing) and two initial population sizes (our model-based estimate of the population size and the lower 95% confidence interval of that estimate). To generate a model-based estimate of the population size, we surveyed 540 sites (9 ha), stratified according to environmental variables known to affect Mallee Emu-wren occurrence. We used an information-theoretic approach with N-mixture models to estimate Mallee Emu-wren density, and extrapolated results over all potential habitat. Key Results We estimate that in spring 2019, the source population consisted of 6449 individuals, with a minimum of 1923 individuals (lower 95% confidence interval). Of 48 harvest scenarios, only seven showed no impact of harvest within 5 years (15%). Those seven all had increasing population trajectories and carrying capacity set to equal initial population size. Twenty-six populations showed no impact of harvest within 25 years (54%). These were either increasing populations that had reached carrying capacity or decreasing populations nearing extinction. Conclusions Initial population size, carrying capacity, harvest scale and population trajectory were all determinants of harvest impact. Given the importance of carrying capacity, further research is required to determine its role in the Mallee Emu-wren source population. Implications Harvesting Mallee Emu-wrens after high-rainfall years will have the least impact because source populations are likely to be large with increasing trajectories. For fluctuating source populations, flexibility in the timing of harvest can reduce its impact and should be considered during translocation planning.

Together climate and land-use change play a crucial role in determining species distribution and abundance, but measuring the simultaneous impacts of these processes on current and future population trajectories is challenging due to time lags, interactive effects and data limitations. Most approaches that relate multiple global change drivers to population changes have been based on occurrence or count data alone. We leveraged three long-term (1995-2019) datasets to develop a coupled integrated population model-Bayesian population viability analysis (IPM-BPVA) to project future survival and reproductive success for common loons Gavia immer in northern Wisconsin, USA, by explicitly linking vital rates to changes in climate and land use. The winter North Atlantic Oscillation (NAO), a broad-scale climate index, immediately preceding the breeding season and annual changes in developed land cover within breeding areas both had strongly negative influences on adult survival. Local summer rainfall was negatively related to fecundity, though this relationship was mediated by a lagged interaction with the winter NAO, suggesting a compensatory population-level response to climate variability. We compared population viability under 12 future scenarios of annual land-use change, precipitation and NAO conditions. Under all scenarios, the loon population was expected to decline, yet the steepest declines were projected under positive NAO trends, as anticipated with ongoing climate change. Thus, loons breeding in the northern United States are likely to remain affected by climatic processes occurring thousands of miles away in the North Atlantic during the non-breeding period of the annual cycle. Our results reveal that climate and land-use changes are differentially contributing to loon population declines along the southern edge of their breeding range and will continue to do so despite natural compensatory responses. We also demonstrate that concurrent analysis of multiple data types facilitates deeper understanding of the ecological implications of anthropogenic-induced change occurring at multiple spatial scales. Our modelling approach can be used to project demographic responses of populations to varying environmental conditions while accounting for multiple sources of uncertainty, an increasingly pressing need in the face of unprecedented global change.

The South China tiger (SCT) is close to extinction in the wild and the captive population may be the only hope of saving this species. Based on the international studbook of the SCT from 1956 to 2019, the life history and population parameters were summarized, and lethal equivalents (B) were estimated. Population viability analysis (PVA) was carried out to simulate the population dynamics and the effects of key factors influencing population dynamics were assessed on the basis of sensitivity analysis, including lethal equivalent, sex ratio, percentage of females breeding and percentage of males breeding. The average B value for the captive SCT population was estimated to be 4.24 at the population level. The captive population of SCT is currently growing up, with a positive growth rate of 0.093 (SD = 0.088) and a probability of extinction of 1% within the next 100 years. The current SCT population is sensitive to lethal equivalents (S = 2.30) and the percentage of females breeding (S = 1.94). We suggest a feasible breeding plan that can practically reduce the effect of inbreeding, and better husbandry practices to improve the percentage of females breeding.

Variation in individual demographic rates can have large consequences for populations. Female reproductive skew is an example of structured demographic heterogeneity where females have intrinsic qualities that make them more or less likely to breed. The consequences of reproductive skew for population dynamics are poorly understood in non-cooperatively breeding mammals, especially when coupled with other drivers such as poaching. We address this knowledge gap with population viability analyses using an age-specific, female-only, individual-based, stochastic population model built with long-term data for three Kenyan populations of the Critically Endangered eastern black rhino ( Diceros bicornis michaeli). There was substantial reproductive skew, with a high proportion of females not breeding or doing so at very low rates. This had a large impact on the projected population growth rate for the smaller population on Ol Jogi. Moreover, including female reproductive skew exacerbates the effects of poaching, increasing the probability of extinction by approximately 70% under a simulated poaching pressure of 5% offtake per year. Tackling the effects of reproductive skew depends on whether it is mediated by habitat or social factors, with potential strategies including habitat and biological management respectively. Investigating and tackling reproductive skew in other species requires long-term, individual-level data collection.

Predicting changes in the abundance of species over time is a central goal of conservation ecology. Typically, demographic data are used to parameterise models which describe population dynamics. Vital rates of plants vary across a species’ distribution, yet most demographic estimates are spatially constrained. Banksia ornata (Proteaceae), a widespread serotinous obligate-seeding shrub in southern Australia, has previously had a fire management model developed based on demographic data derived from a chronosequence in one part of the species’ range. We asked: are demographic data collected from a limited geographic range robust for developing population dynamic models that are applied across the broader species’ range? How much variation exists in the demography of species across their range and does this matter for estimating fire return intervals necessary for species persistence? We examine site-to-site variation in the pyrodemography of six populations of B. ornata encompassing its geographic range. We documented changes in population density, time to first reproduction and canopy seed bank accumulation in stands varying in age from 0.5 to 55 years. We model year of maximum seed production on demographic parameters such as population starting density and survival rate. Density, primary juvenile period, rates of mortality and seed bank accumulation varied across populations. Primary juvenile period varied across populations (from 6 to

The US Fish and Wildlife Service (USFWS) has initiated a re-envisioned approach for providing decision makers with the best available science and synthesis of that information, called the Species Status Assessment (SSA), for endangered species decision making. The SSA report is a descriptive document that provides decision makers with an assessment of the current and predicted future status of a species. These analyses support all manner of decisions under the US Endangered Species Act, such as listing, reclassification, and recovery planning. Novel scientific analysis and predictive modeling in SSAs could be an important part of rooting conservation decisions in current data and cutting edge analytical and modeling techniques. Here, we describe a novel analysis of available data to assess the current condition of eastern black rail Laterallus jamaicensis jamaicensis across its range in a dynamic occupancy analysis. We used the results of the analysis to develop a site occupancy projection model where the model parameters (initial occupancy, site persistence, colonization) were linked to environmental covariates, such as land management and land cover change (sea-level rise, development, etc.). We used the projection model to predict future status under multiple sea-level rise and habitat management scenarios. Occupancy probability and site colonization were low in all analysis units, and site persistence was also low, suggesting low resiliency and redundancy currently. Extinction probability was high for all analysis units in all simulated scenarios except one with significant effort to preserve existing habitat, suggesting low future resiliency and redundancy. With the results of these data analyses and predictive models, the USFWS concluded that protections of the Endangered Species Act were warranted for this subspecies.

Developers are often required by law to offset environmental impacts through targeted conservation actions. Most offset policies specify metrics for calculating offset requirements, usually by assessing vegetation condition. Despite widespread use, there is little evidence to support the effectiveness of vegetation-based metrics for ensuring biodiversity persistence. We compared long-term impacts of biodiversity offsetting based on area only; vegetation condition only; area × habitat suitability; and condition × habitat suitability in development and restoration simulations for the Hunter Region of New South Wales, Australia. We simulated development and subsequent offsetting through restoration within a virtual landscape, linking simulations to population viability models for 3 species. Habitat gains did not ensure species persistence. No net loss was achieved when performance of offsetting was assessed in terms of amount of habitat restored, but not when outcomes were assessed in terms of persistence. Maintenance of persistence occurred more often when impacts were avoided, giving further support to better enforce the avoidance stage of the mitigation hierarchy. When development affected areas of high habitat quality for species, persistence could not be guaranteed. Therefore, species must be more explicitly accounted for in offsets, rather than just vegetation or habitat alone. Declines due to a failure to account directly for species population dynamics and connectivity overshadowed the benefits delivered by producing large areas of high-quality habitat. Our modeling framework showed that the benefits delivered by offsets are species specific and that simple vegetation-based metrics can give misguided impressions on how well biodiversity offsets achieve no net loss.Cuantificación del Impacto de las Medidas Basadas en la Vegetación sobre la Persistencia de las Especies cuando se Eligen las Compensaciones por la Destrucción del Hábitat Resumen Con frecuencia se requiere por ley que los desarrolladores compensen los impactos ambientales por medio de acciones de conservación. La mayoría de las políticas de compensación especifican medidas para calcular los requerimientos de cada compensación, generalmente mediante la evaluación de las condiciones de la vegetación. A pesar del uso extenso de estas medidas basadas en la vegetación, existe muy poca evidencia que respalde su efectividad para asegurar la persistencia de la biodiversidad. Comparamos los impactos a largo plazo de las compensaciones de biodiversidad basadas solamente en el área; solamente en la condición de la vegetación; la idoneidad del área x hábitat; y la idoneidad condición x hábitat en las simulaciones de desarrollo y restauración para la Región Hunter de Nueva Gales del Sur, Australia. Simulamos el desarrollo y las compensaciones subsecuentes mediante la restauración dentro de un paisaje virtual, conectando las simulaciones con los modelos de viabilidad poblacional para tres especies. Las ganancias del hábitat no aseguraron la persistencia de las especies. No hubo pérdida neta cuando el desempeño de las compensaciones se evaluó en relación con la persistencia. El mantenimiento de la persistencia ocurrió más seguido cuando se evitaron los impactos, lo que proporciona un mayor respaldo para mejorar la aplicación de la fase de prevención de la jerarquía de mitigación. Cuando el desarrollo afectó a las áreas con una alta calidad de hábitat para las especies, no se pudo garantizar la persistencia. Por lo tanto, las especies deben considerarse más explícitamente en las compensaciones, en lugar de sólo considerar a la vegetación o al hábitat. Las declinaciones causadas por la falta de consideración directa de las dinámicas poblacionales de las especies y de la conectividad opacaron los beneficios producidos por las grandes áreas de hábitat de alta calidad. Nuestro marco de trabajo para el modelado demostró que los beneficios producidos por las compensaciones son específicos para cada especie y que las medidas simples basadas en la vegetación pueden brindar impresiones mal informadas sobre qué tanto influyen las compensaciones de biodiversidad en la no pérdida neta.法律经常要求开发商通过有针对性的保护行动来抵消对环境的影响。大多数生物多样补偿政策明确规定了计算补偿量需求的指标, 通常都是基于对植被条件的评估。这类基于植被的指标虽然已经得到广泛使用, 但其在确保生物多样性续存方面的有效性却几乎没有证据支持。本研究模拟了澳大利亚新南威尔士州猎人区的开发和恢复情况, 并分别从面积、植被条件、地区及生境的适宜性、植被条件及生境的适应性这几个方面比较了生物多样性补偿措施的长期影响。我们在一个虚拟景观中模拟了开发及随后通过恢复得到的补偿, 并将模拟情况与 3 个物种的种群生存模型进行整合。结果显示, 如果以恢复生境的数量来评价补偿效果, 则可以实现无净损失; 但如果以物种续存来进行评价, 则不能实现。在避免影响的情况下, 物种更有可能续存, 这一结果为更好地执行减缓影响层级结构中的避免影响阶段提供了进一步支持。当发展影响到物种高质量生境的区域时, 不能保证物种续存。因此, 必须更明确地将物种纳入补偿机制中, 而不仅仅是考虑植被或生境。因未能直接考虑物种种群动态和连接度而导致的种群数量下降的影响, 会超出制造大面积高质量生境带来的好处。我们的模型框架表明, 生物多样性补偿带来的好处是物种特异的, 而简单的基于植被的指标可能会误导人们, 使其对生物多样性补偿在多大程度上实现了无净损失产生错误印象。【翻译: 胡怡思; 审校: 聂永刚】.

Climate change affects population cycles of several species, threatening biodiversity. However, there are few long-term studies on species with conservation issues and restricted distributions. Huemul is a deer endemic to the southern Andes in South America and it is considered endangered mostly due to a 50% reduction of its distribution over the last 500 years. To assess environmental variables potentially affecting huemul population viability and the impact of climate change, we developed population dynamics models. We used a 14-year survey data from Bernardo O’Higgins National Park, coastal Chilean Patagonia. We used Ricker models considering winter and spring temperatures and precipitation as variables influencing huemul population dynamics. We used the Bayesian information criterion (BIC) to select models with the greatest predictive power. The two best models (ΔBIC

Small populations are at risk of extinction from deterministic and stochastic factors. Less than 250 Asian elephants (Elephas maximus) remain in China, and are distributed in a few isolated areas; yet, population viability analyses of this endangered population have not been conducted. Here, the current genetic status of the Pu'Er-Mengyang Asian elephant populations in China was analyzed, and the risk of extinction was predicted over the next 500 years. Factors affecting the viability of this population were determined through simulations. The genetic diversity of the population was very low (mean allele number: 3.1; expected heterozygosity: 0.463), even though a recent population bottleneck was not detected. The effective population size was approximately 24.1 adult elephants. Enough adult breeding individuals exist to maintain population viability. VORTEX simulation model showed that this population would not go extinct in the next 500 years. However, illegal poaching and harvesting could negatively affect population size. A sensitivity analysis showed that the mean stochastic growth rate of the study population is sensitive to sex ratio, number of breeding females, mortality of females of different age classes, carrying capacity, and lethal equivalents. Based on our results, we suggest that action should be taken to alleviate inbreeding and any further loss of genetic diversity, by connecting fragmented elephant habitat or by translocating individual elephants. In addition, human-elephant conflict should be mitigated using various modern approaches, including crop guarding techniques, and by encouraging farmers to switch to crops and income sources not vulnerable to elephant raids.

SummaryAfrican White-backed Vultures were recently uplisted to ‘Critically Endangered’ by IUCN due to declines across their range. Poisoning is widely accepted as the major reason for these declines. Botswana supports a high number of this species (breeding pairs > c.1,200), but as yet no published information exists on their breeding success in the country. However, mass poisonings within Botswana and neighbouring countries have killed thousands of White-backed Vultures in recent years. We therefore expected that nesting numbers may have declined in this region if these poisoning events killed local breeding birds. We used information from aerial surveys conducted between 2006 and 2017 in Khwai and Linyanti, two important breeding areas for this species in north-central Botswana, to determine if there was any change in nesting numbers and breeding success of White-backed Vultures. Results showed an overall 53.5% decline in nesting numbers, with a greater decline in Linyanti than in Khwai. In both areas, breeding success was significantly lower in 2017 than it was 10 ten years earlier. We recommend that similar repeat surveys are continued to provide greater confidence in the trends of both nesting numbers and breeding performance. Population viability analysis suggested that if the productivity levels detected in 2017 were a true indication of current productivity levels for this population, and if recent high poisoning rates continue, this population could be extirpated from the area in the next 13 years.

The southern African population of Bearded Vultures Gypaetus barbatus has declined rapidly and it is threatened with extinction. In response to this decline and the additional threats of wind farm ...

The Arabian Leopard Panthera pardus nimr, classified by IUCN as “Critically Endangered”, is Saudi Arabia’s flagship predator. The population of this species has declined to approximately 50 individ...

SummaryAlthough the population of Griffon VultureGyps fulvusis significantly increasing in Europe, in Italy the species is still on the Red List as ‘Critically Endangered’, with the last natural population persisting on the island of Sardinia. Several episodes of poisoning hampered the success of conservation actions implemented in the years 1987–1995. In 2005 there were estimated to be only 31–32 territorial pairs, with the population occupying the territories of Alghero and Bosa. We used a long-term dataset of reproductive records from the Sardinian Griffon Vulture populations to run a population viability analysis (PVA) to evaluate the extinction risk using the Vortex simulation software. The model estimated the probability of extinction over the next five generations (estimated generation time: 11 years, simulation time used: 55 years) as 96.4% for the Alghero population, and near-zero for the Bosa population. We used sensitivity analyses to understand how uncertainty about parameter values affect model outcomes. Population projections were evaluated under different management scenarios tackling the main threats (poisoning and human disturbance) and implementing conservation actions (supplementary feeding and restocking). Our results showed that population size is a critical factor in affecting the projections of population dynamics of Griffon Vultures. Sensitivity analyses highlighted the importance of poisoning events to population persistence and showed that juvenile and adult mortality rates had a secondary impact on population viability. The only conservation measure effective in significantly increasing stochastic growth rates in the Alghero population, whose initial population was set at five individuals, was the complete removal of poisoning events. When targeting the Bosa population (initial population size 94 individuals), supplementary feeding, mitigation of the risk of poisoning episodes, restocking, and mitigation of human disturbance in the reproductive sites significantly increased stochastic growth rate. A cost-effectiveness analysis should be performed to prioritise interventions.

Madagascar is home to 208 indigenous palm species, almost all of them endemic and >80% of which are endangered. We undertook complete population census and sampling for genetic analysis of a relatively recently discovered giant fan palm, the Critically Endangered Tahina spectablis in 2008 and 2016. Our 2016 study included newly discovered populations and added to our genetic study. We incorporated these new populations into species distribution niche model (SDM) and projected these onto maps of the region. We developed population matrix models based on observed demographic data to model population change and predict the species vulnerability to extinction by undertaking population viability analysis (PVA). We investigated the potential conservation value of reintroduced planted populations within the species potential suitable habitat. We found that the population studied in 2008 had grown in size due to seedling regeneration but had declined in the number of reproductively mature plants, and we were able to estimate that the species reproduces and dies after approximately 70 years. Our models suggest that if the habitat where it resides continues to be protected the species is unlikely to go extinct due to inherent population decline and that it will likely experience significant population growth after approximately 80 years due to the reproductive and life cycle attributes of the species. The newly discovered populations contain more genetic diversity than the first discovered southern population which is genetically depauperate. The species appears to demonstrate a pattern of dispersal leading to isolated founder plants which may eventually lead to population development depending on local establishment opportunities. The conservation efforts currently put in place including the reintroduction of plants within the species potential suitable habitat if maintained are thought likely to enable the species to sustain itself but it remains vulnerable to anthropogenic impacts., We studied the genetics, population ecology and suitable habitat for Tahina spectabilis a critically endangered palm from Madagascar to assess its long term viability. We found that current conservation measures may enable the species to persist. Its endangerment is not due to intrinsic population decline.

Most populations of giraffes have declined in recent decades, leading to the recent decision to upgrade the species to vulnerable status, and some subspecies to endangered. Translocations have been used as a conservation tool to re-introduce giraffes to previously occupied areas or establish new populations, but guidelines for founding populations are lacking. To provide general guidelines for translocation projects regarding feasibility, we simulated various scenarios of translocated giraffe populations to identify viable age and sex distributions of founding populations using Population Viability Analysis (PVA) implemented in Vortex software. We explored the parameter space for demography (population growth rates: λ = 1.001, 1.010, 1.024), and the genetic load (number of lethal equivalents: LE = 2.5, 6.29, 12.6), examining how variation in founding numbers (N = 5 to 80 females) and sex ratios (M:F = 0.1 to 0.5) affected 100-year probability of extinction and genetic diversity. We found that even very small numbers of founders (N ≤10 females) can appear to be successful in the first decades due to transient positive population growth, but with moderate population growth rate and moderate genetic load, long-term population viability (probability of extinction 95% genetic diversity of the source population in an isolated population, 50 females and 5 males are recommended to comprise the founding population. Sensitivity analyses revealed first-year survival and reproductive rate were the simulation parameters with the greatest proportional influence on probability of extinction and genetic diversity. These simulations highlight important considerations for translocation success, and data gaps including true genetic load in wild giraffe populations.

One of the most challenging tasks in wildlife conservation and management is to clarify how spatial variation in land cover due to anthropogenic disturbance influences wildlife demography and long‐term viability. To evaluate this, we compared rates of survival and population growth by woodland caribou (Rangifer tarandus caribou) from 2 study sites in northern Ontario, Canada that differed in the degree of anthropogenic disturbance because of commercial logging and road development, resulting in differences in predation risk due to gray wolves (Canis lupus). We used an individual‐based model for population viability analysis (PVA) that incorporated adaptive patterns of caribou movement in relation to predation risk and food availability to predict stochastic variation in rates of caribou survival. Field estimates of annual survival rates for adult female caribou in the unlogged ( x̄ = 0.90) and logged ( x̄ = 0.76) study sites recorded during 2010–2014 did not differ significantly (P > 0.05) from values predicted by the individual‐based PVA model (unlogged: x̄ = 0.87; logged: x̄ = 0.79). Outcomes from the individual‐based PVA model and a simpler stage‐structured matrix model suggest that substantial differences in adult survival largely due to wolf predation are likely to lead to long‐term decline of woodland caribou in the commercially logged landscape, whereas the unlogged landscape should be considerably more capable of sustaining caribou. Estimates of population growth rates (λ) for the 2010–2014 period differed little between the matrix model and the individual‐based PVA model for the unlogged (matrix model x̄ = 1.01; individual‐based model x̄ = 0.98) and logged landscape (matrix model x̄ = 0.88; individual‐based model x̄ = 0.89). We applied the spatially explicit PVA model to assess the viability of woodland caribou across 14 woodland caribou ranges in Ontario. Outcomes of these simulations suggest that woodland caribou ranges that have experienced significant levels of commercial forestry activities in the past had annual growth rates 0.96. These differences were strongly related to regional variation in wolf densities. Our results suggest that increased wolf predation risk due to anthropogenic disturbance is of sufficient magnitude to cause appreciable risk of population decline in woodland caribou in Ontario. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

We studied the population viability of two common marsupials, Didelphis marsupialis and Didelphis virginiana, based on field data and published ecological and genetic information. Using the VORTEX v. 10. 2.6 program, a 100-year simulation was performed with 1000 iterations for five populations of D. marsupialis and six of D. virginiana. A low probability of extinction was observed in both species, particularly for D. virginiana (0.000–0.007). Population size is higher considering a metapopulation dynamics approach versus individual populations for the two marsupials: 498.25 individuals for D. marsupialis and 367.41 individuals for D. virginiana. The estimated mean genetic diversity was high for both D. marsupialis (H e = 0.77–0.78) and D. virginiana (H e = 0.79–0.82). The survival of both species over time could be expected to increase if a metapopulation dynamics is favored over the coming decades, despite a 1.3% loss rate of forest cover. The monitoring of population size and genetic diversity is highly recommended to validate the trends suggested by the model; this is especially true for D. marsupialis, a species associated with conserved areas that are becoming progressively less abundant. This research provides information on the responses of common mammalian species to environmental changes such as deforestation.

The ongoing and often synergistic effects of habitat loss, invasive species, and climate change pose challenges for conservation and management as widespread species become greatly reduced, sometimes to a single small population. To address this problem, conservation biologists must consider using approaches like translocation to create new populations, reducing the probability of extinction by splitting a population into 2 or more populations in geographically distinct locales. The puaiohi Myadestes palmeri, an endangered Hawaiian forest bird, has a small population size (494; 95% CI: 414-580) and restricted range (~40 km2). One recovery plan objective involves translocating birds to higher elevation Hawaiian Islands. To evaluate translocation scenarios, we built upon previously developed population viability analysis models and considered how translocation regimes (initial harvest/population, number harvested/supplemented per event, harvest/supplementation interval, and length of harvest/supplementation) would affect both original and new populations. Furthermore, we modeled the puaiohi release population under 3 different conditions: a stable population, a predator-controlled environment, and a habitat improved in terms of resource availability. Our results indicated that while translocation offers hope of increasing puaiohi population size and decreasing extinction risk, success will depend on conditions at the release site. Furthermore, harvest and rearing of eggs to the juvenile stage or re-establishment of a captive breeding program may be necessary to provide enough birds to translocate, as the current wild population may not be productive enough to sustain levels of harvest necessary to successfully establish a new population.

Captive breeding is important for ex-situ conservation and the future reintroduction of bovids that become extinct in the wild. The age structure, development, and viability of captive-bred bantengs (Bos javanicus) are important to sustain the long-term reintroduction program in Salakphra Wildlife Sanctuary (SWF) and other areas. This research conducted a long-term population viability analysis (PVA) using height, weight, body condition scores (BSC), age structure, and development in captivity for a sustainable reintroduction program of bantengs in Thailand. Monthly development photographs of 23 founder individuals (12 males and 11 females) were assessed by three banteng experts, two researchers, and three members of the general public. The assessments of weight and BCS were not significantly different among the three groups, while height was underestimated by the general public. The PVA showed that the time to reach the maximum population in a captive banteng program is dependent on the carrying capacity of the habitat. The reduction of a small banteng founder group by the reintroduction of animals into the wild can negatively affect the population growth of the captive group. This information can be used to maintain the population viability of bantengs and sustain ex-situ conservation and the reintroduction program in Thailand and elsewhere.

Axis deer (Axis axis) are invasive species that threaten native ecosystems and agriculture on Maui Island. To mitigate negative effects, it is necessary to understand current abundance, population trajectory, and how to most effectively reduce the population. Our objectives were to examine the population history of Maui axis deer, estimate observed population growth, and use species-specific demographic parameters in a VORTEX population viability analysis to examine removal scenarios that would most effectively reduce the population. Only nine deer were introduced in 1959, but recent estimates of >10,000 deer suggest population growth rates (r) ranging between 0.147 and 0.160 even though >11,200 have been removed by hunters and resource managers. In VORTEX simulations, we evaluated an initial population size of 6,000 females and 4,000 males, reflecting the probable 3F:2M sex ratio, with annual removal rates of 10%, 20%, and 30% over a 10-year period. A removal rate of 10% resulted in a positive growth rate of 0.103 ± 0.001. A 20% removal rate resulted in only a slightly negative growth, while a 30% removal rate resulted in –0.130 ± 0.004. By increasing the ratio of females removed to 4F:1M in the 30% harvest scenario, the decline nearly doubled, resulting in –0.223 ± 0.004. Effectively reducing axis deer will most likely require an annual removal of approximately 20–30% of the population and with a greater proportion of females to increase the population decline. Selective removal of males may not only be inefficient, but also counterproductive to population reduction goals.

Several ground-nesting bird species living in European farmlands are experiencing a persistent decline. Poorer reproductive success is suspected to be the main demographic driver. We developed a model to quantify to what extent such recent change may impact the viability of their populations. We took the grey partridge Perdix perdix, a typical farmland species, as a well-documented case study, but the model can be adapted to other species. We built a model based on our in-depth demographic knowledge of this species and the large database compiled from our long-term population monitoring programme. We took into account environmental and demographic stochasticity as well as density-dependence processes. We investigated the impact of recent changes in reproductive success on the viability of (unharvested) populations. For this purpose, we considered two periods: 1979–2004 as ‘Past’ and 2005–2014 as ‘Present’ (we used data of subsequent years to test the model’s goodness of fit). During the ‘Past’ period, the simulated population was increasing with a mean stochastic growth rate λmean = 1.01 (25% of decreasing trajectories), whereas λmean = 0.89 during the ‘Present’ period (74% of decreasing trajectories). We provide detailed results and discuss the possible environmental causes, with a focus on extreme weather events. In a further step, we used our model as a tool to investigate the impact of four hunting bag management strategies on exploited populations. The hunting bag was assumed to be an additive cause of mortality. Hunting leads to a decrease in λmean but the amplitude (from minor to substantial) depends upon the strategy and the setting-up of parameters. We deliver our model as a tool to support decision-making for sustainable population management and provide the script (ULM software) as Supplementary information.

Since passage of the Endangered Species Act in 1973, over 1300 endangered and threatened species have been protected in the USA and its territories. Most species continue to face a significant risk of extinction, but the status of many species is improving. Here we present analyses of federal agency reports to the United States Congress (1988–2002) that describe differences in species status and show which variables are correlated with improving or declining status. We found that 52% of species showed repeated improvements or were not declining over this time. Species status improves over time, with only 35% still declining 13 years or more after protection. Taxonomy, funding by US Fish and Wildlife Service and National Oceanic and Atmospheric Administration, and agency assessment of risk of extinction and potential to recover were significantly correlated with status.

Increased variation in interannual weather due to climate change can exert a powerful influence on the population dynamics of a species. Understanding the influence of severe weather is important for managing weather‐sensitive species. While best management practices target vital rates that are affected by weather, focusing on a single vital rate may not be sufficient if other vital rates are secondarily limiting. A comprehensive modeling framework to forecast future population dynamics while incorporating weather scenarios and vital rate variation within observed ranges that can be affected by management actions are necessary. A potential approach is to combine an integrated population model (IPM) with a population viability analysis (PVA) to generate novel insights about population dynamics. We used the northern bobwhite (Colinus virginianus), a rapidly declining gamebird sensitive to snowfall along the northern extents of the species' range, to demonstrate the utility of a coupled IPM‐PVA framework for projecting the response of a population to weather, management, and changes in vital rates. We created an IPM using two sources of count data spanning seven years, five years of winter survival data, and two years of breeding season demographics for a declining bobwhite population in southwestern Ohio during 2007–2015. Quasi‐extinction probability at the end of the decadal projection during 2019–2029 was 0.384–0.410 for mild, average, and severe winter weather scenarios. Quasi‐extinction probability declined to 0.326 with 20% improvement in nest success and summer survival rates. A concurrent 20% increase in winter survival further reduced quasi‐extinction probability to 0.263, which is a ˜36% reduction in quasi‐extinction probability compared with the baseline scenario with no changes in vital rates. These results suggest that long‐term viability of this population may depend on extensive management of winter habitat to improve survival but will also require management actions to improve fecundity after severe winters. Our modeling approach demonstrated how IPMs can be used to project population responses to future weather conditions and overcome some of the pitfalls of traditional PVA. The coupled framework presented here can serve as a tool for managers to make climate‐informed management decisions.

Population viability analysis (PVA) is commonly used to assess future potential risks to threatened species. These models are typically based on mean vital rates, such as survival and fecundity, with some level of environmental stochasticity. However, the vital rates of wild populations, especially those already exhibiting declining trajectories, may be nonstationary, such that the mean or variance changes over time. In this study, we examined whether including observed temporal trends in vital rates affects the predictive accuracy of PVA, as well as the projected impact associated with a hypothetical threat. To achieve this, we ran a series of simulations using Leslie matrix PVA models that included different combinations of environmental stochasticity, temporal trends in vital rates, and threat. We apply our analysis to a long-lived colonial species of seabird, the black-legged kittiwake Rissa tridactyla, that is classified as globally Vulnerable and is potentially highly sensitive to offshore renewable energy development. We found that including observed temporal trends in vital rates was (i) crucial for the accurate reconstruction of observed population dynamics and (ii) had a dramatic effect on the projected impact from the hypothetical threat. In an era when many animal and plant populations are declining due to long-term trends in their vital rates, we identify that including this demographic structure is essential for robustly evaluating potential threats using PVA models. Omitting observed temporal trends in vital rates from impact assessments is highly likely to yield unreliable results that could misinform conservation and management decision making. This result has immediate application for conducting impact assessments on protected species and populations.

Background: China is paying more attention to ecological systems within the Yangtze River has provided great opportunities to the conservation of the Yangtze finless porpoise (YFP). The rapid population decline of YFP in the main steam appears to have slowed, but the infrequent movement of porpoises represents a considerable threat to the long-term viability of this species in this region. We studied the population viability of YFP in the Yangtze main steam, based on published ecological and genetic information.Methods: Vortex model was used to analyze the population viability of the YFP. The simulations were started from the year 2017 when the initial population size was 445 animals in baseline scenario. We examined the population viability for the species under demographic fluctuations and conservation scenarios.Result: Baseline model showed the probability of extinction was 0.245; deterministic growth rate was -0.023; stochastic growth rate was -0.036. Sensitivity analysis showed differences in population trends between the baseline and each alternative scenario and the most sensitive parameters were the percentage of females breeding and mortality rates. Under different conservation scenarios, the population of the YFP in the main stream will increase by 11.0%-181.2% in 100 years.