Knowledge of the life history traits, reproductive biology and demography of rare species is fundamental for their conservation, yet plant population monitoring is uncommon. The restricted ranges of the Limonium species endemic to the Mediterranean area, combined with the vulnerability of their specialized littoral habitats, indicate the need for appropriate conservation measures. We evaluate the conservation status and estimate the future extinction risk of three Limonium species endemic to Zakynthos Island in the Ionian Islands, Greece (Limonium korakonisicum, Limonium phitosianum and Limonium zacynthium) using 5 years of monitoring data. We compile information on their geographical distribution, population dynamics, reproductive biology and genetic diversity. Population sizes and survival rates of seedlings exhibited marked annual fluctuations, although fecundity and relative reproductive success remained high throughout the monitoring period. We observed a dominance of mature individuals in all three species, indicating their increased tolerance to salinity. Three subpopulations each of L. phitosianum and L. zacynthium were genotyped using five microsatellite loci. The observed number of alleles and the low gene flow value potentially indicate reduced genetic diversity, inbreeding, and limited gene flow within and among subpopulations of both species. Based on the IUCN categories and criteria, we assess L. korakonisicum as Critically Endangered, L. phitosianum as Near Threatened and L. zacynthium as Endangered. Population viability analyses predict that, among the three species, L. zacynthium will face the highest risk of extinction within the next 50 years. Knowledge of the biology of these species provides data essential for identifying critical factors for their survival and for proposing targeted conservation measures.

Spix’s Macaw Cyanopsitta spixii, extinct in the wild since 2000, was successfully reintroduced in Brazil in 2022, leading to significant progress, including the hatching of wild chicks. However, recent restrictions on further releases by the Brazilian government have put the reintroduction programme into jeopardy. This study updates our 2023 population viability analysis (PVA) to assess the impact of these delayed releases on the wild population. Using six modelled scenarios, we confirm that without annual supplementation of captive-bred birds, the probability of extinction in the wild remains at 100%. Even a one-time release is insufficient to secure population stability. Our results highlight that those annual releases of at least 20 individuals are necessary to ensure long-term viability, with reduced but still essential growth achievable with 10 birds per year. Supplementation of the wild population does not compromise the long-term viability of the well-established captive population. We urge immediate action to resume the release programme in 2024 to prevent the species from once again facing extinction in the wild.

Wind energy is a source of collision fatalities for birds and bats. To evaluate the risk that wind power development projects might pose to the conservation of protected species, it is essential to quantify the impact of collisions on the dynamics of wild populations. To address this challenge, two approaches are primarily employed: potential biological removal (PBR) and population projection analysis (PPA). PBR is a decision rule designed to calculate a sustainable fatality limit for a given population, whereas PPA relies on simulation-based modelling to forecast a population’s future trajectory under various scenarios. In the context of environmental impact assessments (EIAs), we argue that PPA offers a more suitable method than PBR for evaluating population-level impacts resulting from collisions with wind turbines. Unlike PBR, PPA can be focused on a single source of disturbance, aligning with the perspective of the EIA process. By contrast, PBR necessarily adopts a population-centred perspective and is therefore only relevant when considering all sources of mortality that jointly affect a population. Furthermore, robust utilization of the PBR approach requires the definition of quantitative conservation objectives and the implementation of a comprehensive management strategy evaluation, neither of which is ever undertaken within the context of an EIA.

The Tarim red deer Cervus hanglu has been recently recognized as a separate deer species with populations in China, Central Asia and Kashmir. These populations are few, isolated and at risk of extinction. The documented range of the Kashmir population of the hangul, now recognized as Cervus hanglu hanglu, is restricted to c. 808 km2 and comprises < 200 individuals, confined mainly to the 141 km2 Dachigam National Park. A few relict herds inhabit the surrounding landscape. Here we analyse the results of almost 20 years of population monitoring (January 2001–March 2020). We found that this population is unable to increase despite full protection within Dachigam National Park. We performed a population viability analysis using both deterministic and stochastic simulations and found that further population decrease is likely. We recommend the use of improved monitoring methods to investigate the population dynamics of the hangul and the implementation of measures to reduce the risk of extinction faced by this small population. Science-based conservation policies, including ex situ conservation and reintroduction programmes, will be required to increase the hangul population size and range.

Species reintroductions can be used in conservation management to increase biodiversity and aid in restoring ecosystem function. For reintroductions to be successful, it is important to identify the conditions required to establish a viable population. We developed a demographic model using Vortex10, an individual-based simulation software, to assess the long-term consequences of different management interventions on the success of the recent reintroduction of the white stork, Ciconia ciconia, to the UK. Demographic data obtained from this reintroduced population were supplemented with information from western European populations to build the models. The impact of incorporating different management actions (e.g. supplementing with captive-bred juveniles, provision of nesting platforms, and habitat improvement/supplementary feeding) on the stochastic population growth rate was assessed. Survival rates also differ depending on an individual’s migratory strategy, hence we tested the impact of having different proportions of the population as residents or migrants. Our models showed that if the British stork population adopts a fully migratory strategy, with its associated higher mortality rates, i.e. all individuals migrating to southern Europe or northern Africa, increasing the supplementation rate would not lead to a positive population growth rate. However, management actions which increased the number of fledglings per nest generated a slight positive growth rate that led to a 54.3% increase in population size after 50 years and, when combining all three management options, the population grew by 378.3%. Alternatively, if a minimum of 9% of individuals overwintered in Britain, which is likely based on field observations and tracking data, a positive growth rate can be achieved without additional management due to this behaviour’s lower mortality rates. We conclude that the British white stork population will likely be viable in the long term, but these models and projections should be updated as more demographic data on this novel population become available.

The northern bald ibis Geronticus eremita disappeared from Europe in the Middle Ages. Since 2003 a migratory population has been reintroduced in Central Europe. We conducted demographic analyses of the survival and reproduction of 384 northern bald ibises over a period of 12 years (2008–2019). These data also formed the basis for a population viability analysis simulating the possible future development of the northern bald ibis population under different scenarios. We analysed life stage-specific survival rates, rearing protocols and colonies, and the influence of stochastic catastrophic events and reinforcement translocations on population growth. Life stage-specific survival probabilities were 0.64–0.78. Forty-five per cent of the mature females reproduced, with a mean fecundity of 2.15 fledglings per nest. The complementary population viability analysis indicated that the Waldrappteam population is close to self-sustainability, with an estimated population growth rate of 0.95 and a 24% extinction probability within 50 years. Of the 326 future scenarios tested, 94% reached the criteria of extinction probabilities < 5% and population growth rates > 1. Stochastic catastrophic events had only a limited effect. Despite comparatively high survival and fecundity rates the population viability analysis indicated that to achieve self-sustainability the Waldrappteam population needs further translocations to support population growth and the implementation of effective measures against major mortality threats: illegal hunting in Italy and electrocution on unsecured power poles. The findings of this study are to be implemented as part of a second European LIFE project.

The blue-billed curassow Crax alberti is an endemic Colombian species categorized as Critically Endangered on the IUCN Red List because of the effects of hunting and habitat loss. Conservation and management actions are required to ensure its persistence in the forest remnants across its range. We conducted a population viability analysis for a population in the municipality of Yondó, Antioquia, based on data collected in the field and available information on the reproductive ecology of the species. We evaluate seven realistic conservation scenarios by comparing the effects that changes in mortality from hunting, carrying capacity and initial population size have on the survival probability of the population. Our results indicate that: (1) the studied population is not viable over a 100-year period under current conditions; (2) mortality as a result of hunting and the size of the initial population have the greatest impacts on the mean time to extinction; (3) a strategy based on eliminating hunting in the two sites with the largest forest remnants in the landscape could ensure the viability of the population over a 100-year period; and (4) other strategies (i.e. population supplementation with captive-bred individuals, reduction of deforestation in the landscape) do not guarantee the viability of the population if mortality from hunting remains constant, even at low levels. These results confirm the susceptibility of the blue-billed curassow to the threats it faces in this landscape, particularly hunting, and provide information on the conservation actions that could allow this remaining population to prevail in the long term.

Demographic modelling can reveal options for improved conservation management, especially for rare or long-lived species not amenable to experimentation. Sturgeon (Acipenseridae) include many such species, endangered by demand for caviar, their unfertilized roe, and by dams blocking their migrations. Restocking of sturgeon populations with farm-raised individuals has probably prevented extinctions and widespread extirpations of some species, but it has rarely led to true recovery in Eurasia, given ongoing harvest. We used modified Leslie matrix models to test whether restocking with year-old juveniles instead of weeks-old fry could recover the critically endangered Amur sturgeon (Acipenser schrenckii), endemic to the Amur River basin along the Russia–China border. Without restocking, or even releasing an expert-recommended annual volume of young fry (10 million), we project that three of four Amur sturgeon populations will be nearly extirpated within 30 years. However, restocking with 5% as many (500 000) year-old juveniles annually could grow three populations (currently 0–425 mature females) and slow declines in another so that each has over 6400 mature females within 30 years. Retooling stocking efforts to use fewer juveniles that survive at higher rates than do small fry could buy time to reduce harvesting pressure on Amur sturgeon and for other related sturgeon species.

Riverine cetaceans are threatened globally by increasing anthropogenic impacts, and the Yangtze river dolphin Lipotes vexillifer is already extinct. The Amazon river dolphin Inia geoffrensis is widely distributed, but is categorized as Endangered on the IUCN Red List. Drowning in gillnets and being hunted for fish bait are probably the main causes of its decline. A long-term (25-year) study of the biology and ecology of I. geoffrensis in and near the Mamirauá Reserve in Amazonas state, Brazil, has produced estimates of survival and reproductive rates based on the individual recognition of > 650 animals. Concurrently, monthly standardized counts of dolphins along a fixed transect in the Reserve over 22 years demonstrated a sustained, profound decline. In this study we tested whether the measured rate of population decline is consistent with population parameters estimated from independent data, using population viability analysis. With the known parameters as input, programme Vortex predicted population extinction in all scenarios and a 95% loss of dolphins within 50 years. With default parameters, the model predicted a 5.5% annual decline, which is consistent with that observed. We conclude that the Amazon river dolphin population is in severe decline because of human pressures, even in one of the better protected parts of its range. Unless the accidental and deliberate killing of this species is rapidly reduced, it is highly likely that the Amazon river dolphin will follow its Yangtze counterpart to extinction.

Although the population of Griffon Vulture Gyps fulvus is 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.

The sand-dune lizard Liolaemus multimaculatus is an Endangered species endemic to the Pampean coastal dunes of Argentina. To inform the development of a future Action Plan for this species, we investigated the demography and conservation status of all remaining populations, and we suggest management actions appropriate to local needs. We used population viability analysis to assess extinction risk in three inbreeding scenarios and estimate the minimum viable population and the minimum area requirement. To assess the current status of each local population, we used information related to population size, human pressure and connectivity. The results were then used to set and prioritize conservation management actions at local level. Our models indicated that populations of > 2,400 individuals would be viable in the long term and that inbreeding depression has a strong effect on extinction risk. The southern patches of coastal dune contain the largest populations of sand-dune lizards, and they are also better connected and less threatened. We suggest land protection as the priority management action for populations larger than the minimum viable population, whereas habitat recovery, when possible, should be the priority for patches of coastal dune smaller than the minimum area requirement. Supplementation with a small number of individuals could stabilize unviable populations but should be considered only in certain situations.

The long-term conservation of the sand-dune lizard will be feasible only if a conservation action plan is developed and implemented.

Many domestic breeds face challenges concerning genetic variability, because of their small population sizes along with a high risk of inbreeding. Therefore, it is important to obtain knowledge on their extinction risk, along with the possible benefits of certain breeding strategies. Since many domestic breeds face the same problems, results from such studies can be applied across breeds and species. Here a Population Viability Analysis (PVA) was implemented to simulate the future probability of extinction for a population of the endangered Danish Jutland cattle (Bos taurus), based on the software Vortex. A PVA evaluates the extinction risk of a population by including threats and demographic values. According to the results from the PVA the population will go extinct after 122 years with the current management. Four scenarios were created to investigate which changes in the breeding scheme would have the largest effect on the survival probabilities, including Scenario 1: More females in the breeding pool, scenario 2: More males in the breeding pool, scenario 3: Increased carrying capacity, and scenario 4: Supplementing males to the population through artificial insemination using semen from bulls used in the populations in past generations. All scenarios showed a positive effect on the population's probability of survival, and with a combination of the different scenarios, the population size seems to be stabilized.

Uruguayan Creole cattle are descended from animals brought by the Spanish conquerors. The population grew extensively without directional management and became semi-wild before the introduction of commercial breeds in the 19th century. Today only 575 animals remain, restricted to the San Miguel National Park. We performed a population viability analysis of this reserve using VORTEX v. 8.31 to study its demographic and genetic parameters, assess the environmental factors that affect its development, evaluate its future risk of extinction and test different management options. The probability of extinction in the next 100 years was always zero, even in the more pessimistic scenarios. The growth rate of the population was always positive and mostly affected by the mortality rate of calves. Population size increased rapidly up to carrying capacity, this being the only limiting factor for population growth. Retained heterozygosity was always above 90% and the inbreeding coefficient below 0.10. The analysis shows that the population is not at risk due to its genetic diversity and demographic structure, however all the individuals are concentrated in only one place. We suggest its subdivision into sub-populations located in different regions and connected by gene flow, decreasing the risk of extinction and accomplishing the conservation and self-sustainability goals.

The Mexican prairie dog Cynomys mexicanus is an endemic burrowing rodent with a restricted distribution. Up to 1996 the species experienced a loss of c. 60% of its historical range, and in the last few years a further loss of habitat has occurred, with the current range now covering only 36% of the historical range. In this study we examined the population dynamics of the Mexican prairie dog to determine the relative effects of habitat loss, isolation of remaining colonies, and decreasing habitat quality. We used data on prairie dog numbers in all colonies and demographic data for two colonies to carry out a stochastic population viability analysis. We found differing vital rates, which are presumed to result from differing habitat quality, at two colonies. As small variations of vital rates in the model strongly influenced the extinction risk for small populations, we conclude that habitat quality is important for the small populations. In the model the Los Angeles complex of colonies experienced a low risk of local extinction whereas at the Manantial complex local extinctions were frequent. Scenarios with changes in population sizes had the largest effect on extinction risk. Differing migration scenarios had little impact on extinction risk.

Breeding of the threatened long-tailed bat Chalinolobus tuberculatus was studied over seven summers, 1993–2000, in temperate rainforest, Fiordland, New Zealand. Reproductive history of 789 marked bats from three social groups was investigated. Seventy per cent of births occurred over a 10-day period in mid-December. Young began flying at 5–6 weeks and nipples of reproductive females were regressing 2 weeks later. Sex ratio at birth was equal. Lactation coincided with highest annual air temperatures and peak abundance of flying invertebrates. Date of first birth varied by 4 days annually, but date of first flight varied by 17 days. Males had distended cauda epididymides at 1 year old (mean±SE = 1.63±0.16 years) and epididymal distension peaked in early autumn. Females first gave birth at 2–3 years of age (2.33±0.08 years). The short, highly synchronous breeding season, birth of single young, early mating in autumn, and late age of female sexual maturity compared to similar-sized vespertilionids, may be related to low food availability and unpredictable cold-temperate weather conditions. Annual productivity did not differ among groups but probability of survival of juveniles varied from 0.26 to 0.88 and was inversely proportional to size of natal group. Variability in breeding parameters was unrelated to climate or body condition of bats. The group with highest survival rates contained reproductive females and juveniles with significantly higher body condition. Differences in roost site or food quality within the home range of each group, varying genetic quality of members of the groups, or density-dependent mechanisms, may explain differential survival, but these hypotheses require investigation. A population crash and poor productivity in 1996 coincided with an irruption in the numbers of stoats Mustela erminea implying that predation by introduced animals can cause periodic population crashes. These results should be used to examine implications of these hypotheses on the long-term viability of Chalinolobus populations.

An existing spatial population model, developed to assess the reintroduction of the European beaver Castor fiber to Scotland, was applied to predict the likely result of reintroducing beavers to Norfolk, England. A habitat analysis was conducted using the Land Cover Map (classified satellite imagery developed by the Institute of Terrestrial Ecology) to predict the location of areas suitable for beavers. The model was used to simulate population processes within these areas and dispersal between them following a range of reintroduction scenarios. To represent uncertainty regarding the probable behaviour of beavers in Norfolk, the habitat analysis and model were applied using three sets of parameter values (high, medium and low) derived from the literature. It was predicted that Norfolk could support between 18 and 40 beaver families. Using high or medium parameter values, beaver populations were predicted to expand following reintroduction and spread to new areas. Using low parameter values populations were predicted to decrease, risk extinction and not colonize new areas. This analysis is a preliminary investigation into the likely fate of beavers in Norfolk. Checking the estimates of habitat availability in the field would enable greater confidence to be placed in these predictions.