Annual Survival Research Articles

Survival of White-Tailed Eagles Tracked after Rehabilitation and Release

ABSTRACT There are many raptor rehabilitation centers around the world that receive and care for wild raptors. Wildlife rehabilitation is a labor- and cost-intensive part of addressing animal welfare. Apart from the compassionate aspect of taking responsibility for an injured animal, there remains an open question as to whether doing so contributes to animal conservation. The fates of such animals after their rehabilitation and release have rarely been studied. Long-term post-release monitoring is needed to assess survival and reproduction. Here, we investigate the post-release fates of 22 White-tailed Eagles (Haliaeetus albicilla), including juveniles, immature birds, and adults in Austria, the Czech Republic, Germany, and Slovakia. Using GPS tracking, we monitored the eagles for 2–2639 d (median = 340 d) between 2005 and 2023. The longest-surviving eagle was tracked for more than 7 yr. Release was followed by a short 6-d period of high mortality, followed in turn by a long-term annual adult survival rate of 74.6%. Anthropogenic factors contributed to 70% of the long-term mortality cases. Reason for admission, length of hospital stay, and use of flight aviaries had no statistically significant effect on long-term survival. Five eagles successfully bred and produced a total of 10 fledglings. Traveling as much as 1378 km, the released eagles dispersed throughout central, northern, and eastern Europe. Thus, it can be concluded that successful rehabilitation of White-tailed Eagles resulted in high survival rates; and in five cases, successful reproduction indicated effective reintegration into the wild population.

Survival estimates of GPS-tagged adult Golden Eagles (Aquila chrysaetos) breeding in Finland

Adult survival estimates are important for assessing population status and viability and for investigating the role of different anthropogenic effects on their variation. Currently, the rapidly increasing wind power poses a new and severe threat to survival of large raptors. Between 2011–2024, we monitored 26 Golden eagles (Aquila chrysaetos) using Global Positioning System tracking devices in Finland, on territories where wind-power plants are currently absent and eagles are not subject to increased mortality from wind power plant collisions. Using the accumulated tracking data, we constructed individual capture histories on a monthly basis and adult survival rates using known-fate models in program MARK. We also review published adult survival estimates of Golden Eagles reported throughout their range for relative comparison. Monthly adult survival in our study area was 0.9933 (0.9854–0.9970) which translates to annual survival of 0.924 (0.838–0.965). We found eight studies reporting survival estimates, which ranged from 0.860 to 0.975 with a mean of 0.928. Thus, adult survival rates of Golden Eagles breeding in northern Finland, that are not affected by wind power plants, are high as expected for a viable population and very close to the mean estimated from other Golden Eagle populations. Maintaining high adult survival rates will be key to Golden Eagle population stability with expanding wind energy development in Finland.

Variability and correlations among vital rates and their influence on population growth in mule and black‐tailed deer

AbstractTo reverse range‐wide population declines, managers of black‐tailed and mule deer (Odocoileus hemionus) require information on the vital rates and life stages most influential to population growth to target effective management actions. We extracted black‐tailed and mule deer vital rates from a range‐wide literature review and used hierarchical models to summarize vital rates, their variability, and how they correlate with one another. We then used matrix models and life‐stage simulation analysis to determine the individual vital rates that contributed most to annual population growth rate (i.e., lambda). Annual adult female survival explained the greatest amount of variation (62%) in lambda. Annual juvenile survival explained 44% of the variation in lambda, whereas summer or winter juvenile survival by themselves were far less informative. Winter fawn:doe ratios, a metric often collected by management agencies, explained only 10% of the variation in lambda. Given an adult female survival of 0.84, our simulations estimated a lambda of 1.0 (95% credible interval = 0.88–1.14), indicating equal probability that a population would increase or decrease. Simulations further indicated that given adult survival rates <70%, the population would always decline, but as survival increased lambda increased linearly. In contrast, estimates of lambda plateaued when annual juvenile survival reached approximately 0.5, indicating higher survival rates yielded diminishing returns to population stability. Using simulated values within the observed range of vital rate values across the species' geographical distribution, the mean lambda was 0.975 and in 61% of the simulations, lambda was <1. After 20 years, we estimated that this distribution of lambda values would cause populations to decrease in 92% of instances with a mean decrease of 44%. Our results align with observed declines in mule deer populations throughout their range over recent decades and indicate that these trends will continue until management can improve survival of adult females.

Medicaid Expansion and Overall Survival of Lower Gastrointestinal Cancer Patients After Cytoreductive Surgery and Heated Intraperitoneal Chemotherapy.

In the United States, often only tertiary centers offer cytoreductive surgery and heated intraperitoneal chemotherapy (CRS+HIPEC) for peritoneal metastases in advanced lower gastrointestinal malignancies. Growing evidence shows that Medicaid expansion under the Affordable Care Act (ACA) of 2010 enhanced healthcare access and outcomes. We sought to determine whether Medicaid expansion was associated with decreased all-cause mortality of lower gastrointestinal cancer patients following CRS+HIPEC. We analyzed data from the National Cancer Database (2010-2019) on lower gastrointestinal cancer patients who underwent CRS+HIPEC. Medicaid expansion, introduced under the ACA in 2010, extends health insurance to low-income adults. We categorized states by expansion timing: early (2010-2013), immediate (January 2014), late (after January 2014), or no expansion to assess the impact of Medicaid expansion on mortality using a multivariable Cox regression model. Of the 1001 study patients, 671 (67%) were diagnosed in Medicaid expansion states. Grade and Medicaid expansion status were the only factors independently associated with overall survival on multivariable analysis. On average, patients in Medicaid expansion states experienced a 4% increase in annual survival compared with those in non-expansion states who had a 1% decrease in annual survival over the study period. Patients from states that had an early expansion of Medicaid and patients with lower-grade tumors had significantly better overall survival. Our study findings suggest that improved access to healthcare through Medicaid expansion was associated with increased survival rates of lower gastrointestinal cancer patients who undergo CRS+HIPEC for the treatment of peritoneal metastases.

Generalizability of pharmaceutical randomized controlled trial eligibility criteria for progressive pulmonary fibrosis.

Progressive pulmonary fibrosis (PFF) is of substantial interest for novel pharmacotherapy discovery, but little is known about clinical trial eligibility criteria. We evaluated eligibility criteria of PPF randomized controlled trials (RCTs), their representativeness in registry patients, and forced vital capacity (FVC) changes and mortality according to trial eligibility. A systematic search was used to identify completed and in-progress phase II and III PPF RCTs. Common clinical trial eligibility criteria used in ≥60% of previous PPF RCTs were identified. The most common criteria for PPF used in RCTs ("trial-PPF criteria") and the clinical practice guideline definition of PPF ("guideline-PPF criteria") were both applied to patients enrolled in a prospective multicenter Canadian registry. Common trial eligibility criteria were tested for their frequency and association with health outcomes in registry patients who met trial-PPF and guideline-PPF criteria. Ten different definitions of PPF were used in 16 RCTs. At the time of meeting PPF definitions, 50% of 864 patients with trial-PPF and 44% of 408 patients with guideline-PPF met the common trial eligibility criteria. For both definitions, trial-eligible patients had more rapid 1-year FVC decline but better transplant-free survival than trial-ineligible patients. Patients with unclassifiable interstitial lung disease (ILD) had higher proportion of trial exclusion compared to those with connective tissue disease-associated ILD and fibrotic hypersensitivity pneumonitis. Annual FVC decline (trial-PPF: -67 to -21 mL; guideline-PPF: -116 to -41 mL) and 1-year transplant-free survival (trial-PPF: 90.5 to 97.5%; guideline-PPF: 87 to 96.2%) varied in trial-eligible patients across ILD subtypes. Existing RCTs use a variety of definitions for PPF with eligibility criteria that have limited representativeness. FVC decline and transplant-free survival vary according to trial eligibility and ILD subtypes.

Clinical Characteristics and Care Trajectories of Transgender and Gender Diverse Patients With Cancer Seen in a Pediatric Gender Clinic.

There is very little information on the experiences of transgender and gender diverse (TGD) youth with cancer. To examine clinical characteristics and care trajectories of TGD youth a history of cancer. This case series reviewed records of 2790 pediatric gender clinic patients seen between 2007 and 2022 to identify 14 with a history of cancer diagnosis. Demographics, clinical characteristics, disclosure of gender identity to oncology teams, oncology teams' use of correct names and pronouns, documented interprofessional communication between gender health and oncology teams, and course of medical gender affirmation were reviewed. Of 14 TGD youth with a history of cancer, 11 (78.6%) were diagnosed prior to presenting to the gender clinic (mean [SD]=8.2 [4.7] years), three following initial gender care (mean [SD]=1.1 [0.2] years). Six (42.9%) patients were engaged in annual survivorship care when presenting, and 8 (57.1%) were seen concurrently by both clinics. Nine (64.3%) patients had documented communication between teams. Three-quarters of patients who were seen concurrently by both clinics had documented interprofessional communication. Eight (57.1%) patients received gender affirming hormones, after cancer treatment concluded. TGD youth with cancer experiences present for gender affirming care and merit clinical attention. There was variability in (1) patients' and families' disclosure of TGD identities to oncology teams, (2) whether oncology documentation consistently used patients' correct name and pronouns, and (3) whether there was documented interprofessional consultation between teams. There is need for ongoing improvement in research and clinical protocols for TGD youth with cancer.

Habitat and density effects on the demography of an expanding wolf population in Central Europe

Demographic parameters are key to understanding population dynamics. Here, we analyse the survival and reproduction of the German wolf population in the 20 years following recolonization. Specifically, we analysed the effects of environmental, ecological and individual characteristics on 1) survival probability of the population; 2) annual survival rates of age classes; 3) reproduction probability; and 4) reproductive output, measured as the number of detected pups/juveniles. Using Cox proportional hazards model, we estimated a median survival time of circa three years for wolves. Annual survival probabilities were found to be 0.75 for juveniles, 0.75 for subadults and 0.88 for adults. Survival was lower for juveniles in winter and for subadult males in summer, probably associated with dispersal events. Low habitat suitability was clearly associated with lower survival in juveniles and subadults, but not in adults. Local territory density was related to increased survival. Reproduction probability within a territory was 0.88, but explanatory variables had no effect. Reproductive output was four pups/juveniles on average, positively related to habitat suitability and female experience, but negatively related to territory density. Survival values were very high for the species when compared to other regions. We hypothesize that carrying capacity has not been reached in the study area, thus the survival may decrease in the future if the landscape becomes saturated. Furthermore, our results highlight a spatial pattern in survival and reproduction, with area of better habitat suitability favouring faster population growth. Thus, targeting conservation measures to low habitat suitability areas will have a strong population effect on the short term by boosting survival and reproduction of the individuals, while long‐term viability should be carefully planned with high suitability areas in mind, as those contain the territories with higher survival and reproduction potential.

Using spaceborne LiDAR to reveal drivers of animal demography.

Remote sensing can provide continuous spatiotemporal information about vegetation to inform wildlife habitat estimates, but these methods are often limited in availability or lack adequate resolution to capture the three-dimensional vegetative details critical for understanding habitat. The Global Ecosystem Dynamics Investigation (GEDI) is a spaceborne light detection and ranging system (LiDAR) that has revolutionized the availability of high-quality three-dimensional vegetation measurements of the Earth's temperate and tropical forests. To date, wildlife-related applications of GEDI data or GEDI-fusion products have been limited to estimate species habitat use, distribution, and diversity. Here, our goal was to expand the use of GEDI-based applications to wildlife demography by evaluating if GEDI data fusions could aid in characterizing demographic parameters of wildlife. We leveraged a recently published dataset of GEDI-fusion forest structures and capture-mark-recapture data to estimate the density and survival of two small mammal species, Humboldt's flying squirrel (Glaucomys oregonensis) and Townsend's chipmunk (Neotamias townsendii), from three studies in western Oregon spanning 2014-2021. We used capture histories in Huggins robust design models to estimate apparent annual survival and density as a derived parameter. We found strong support that both flying squirrel and chipmunk density were associated with GEDI-fusion forest structures of foliage height diversity and plant area volume density in the 5-10 m strata for flying squirrels and proportionately higher plant area volume density in the 0-20 m strata for chipmunks, as well as other spatiotemporal factors such as elevation. We found weak support that apparent annual survival was associated with GEDI-fusion forest structures for flying squirrels but not for chipmunks. We demonstrate further utility of these methods by creating spatially explicit density maps of both species that could aid management and conservation policies. Our work represents a novel application of GEDI data to evaluate wildlife demography and produce continuous spatially explicit density predictions for these species. We conclude that aspects of small mammal demography can be explained by forest structure as characterized via GEDI data fusions.

Management considerations of moose life‐history characteristics in Colorado, USA

Wildlife management agencies are obliged to provide evidence‐based management recommendations to stakeholders. However, allocation of resources towards the management of species is rarely uniform. The consideration of life‐history characteristics of moose offers wildlife managers a more robust understanding of population ecology, while also providing insight into potential limiting factors for long‐term management. From 2014–2020 we simultaneously measured survival of adult female moose, as well as calf productivity, in relation to the nutritional condition of adult females, in Colorado. Mean annual adult survival was high (93% and 95% confidence interval: 91–95%). Human hunter harvest was the leading source of mortality and lowered annual adult survival to 88%. Malnutrition was the leading source of natural mortality. Mean annual pregnancy rates were relatively low (77%) and highly variable (95% confidence interval: 65–88%). However, low pregnancy rates were compensated for by high apparent calf survival. The best predictor of moose pregnancy was nutritional condition. Our data suggest that bottom‐up ecological processes were affecting moose population growth, but populations were likely increasing during our study, with a simulated population growth rate of 1.04 (95% confidence interval: 0.94–1.17).

Florida sandhill crane survival along a wildland‐to‐urban land use gradient

AbstractThe Florida sandhill crane (Antigone canadensis pratensis) is a state‐threatened non‐migratory subspecies. Our understanding of adult crane survival in Florida, USA, is unclear, as it relies on decades‐old unpublished data of birds residing in natural areas. Since that time, the loss of natural habitat precipitated cranes using urbanized areas such as suburban lawns and roadside verges for foraging and loafing. Contemporary studies are needed to properly guide crane management and conservation efforts. We addressed this knowledge gap by estimating the annual survival rate for sandhill cranes in 12 central Florida counties. We used a live‐dead capture‐recapture multistate model, monitoring 118 adult cranes from June 2017 to May 2023; 76 were color‐banded and 42 were tagged with Global System for Mobile Communications (GSM) transmitters. Fifteen cranes died during the study, with vehicle strikes (n = 9) being the most prevalent identified source of mortality. Overall, the annual survival probability was estimated at 0.79 (95% credibility interval = 0.75–0.84). Using the subset of GSM‐tagged cranes, we observed no influence of urbanization on annual survival rate (βurbanization gradient = 0.007, 95% credibility interval = −0.008, 0.022). The adult survival rates we observed are lower than reported for other populations of sandhill cranes in North America that are considered stable or growing.

Non-breeding conditions induce carry-over effects on survival of migratory birds

Identifying the processes that limit populations is a foundational objective of ecology and an urgent need forconservation. For migratory animals, researchers must study individuals throughout their annual cycles to determine how environmental conditions limit demographic rates within each period of the annual cycleand also between periods through carry-over effects and seasonal interactions.1,2,3,4,5,6 Our poor understanding of the rates and causes of avian migration mortality7 hinders the identification of limiting factors and the reversal of widespread avian population declines.8,9 Here, we implement new methods to estimate apparent survival (hereafter survival) during migration directly from automated telemetry data10 in Kirtland's Warblers (Setophaga kirtlandii) and indirectly from mark-recapture data in Black-throated Blue Warblers (S.caerulescens). Previous experimental and observational studies of our focal species and other migratory songbirds have shown strong effects of Caribbean precipitation and habitat quality on food availability,11,12,13,14 body condition,12,13,14,15,16,17,18,19 migration timing,11,12,15,16,20,21,22,23 natal dispersal,24,25 range dynamics,26 reproductive success,20,22,27 and annual survival.18,19,20,23,28,29,30,31 Building on this research, we test the hypotheses that environmental conditions during the non-breeding period affect subsequent survival during spring migration and breeding. We found that reduced precipitation and environmental productivity in the non-breeding period strongly influenced survival in both species, primarily by reducing survival during spring migration. Our results indicate that climate-driven environmental conditions can carry over to affect survival in subsequent periods and thus likely play an important role in year-round population dynamics. These lethal carry-over effects may be widespread and are likely magnified by intensifying climate change.

Nonstandardized High-Intensity Dialysis Dose Improves Survival in Patients With End-Stage Renal Disease.

Introduction One of the most important critical determinants of quality of life and adequacy of hemodialysis (HD) performed in patients is the recorded survival and mortality rates. Nowadays, as an adequately performed HD dialysis, we accept the one with reaching values for the index single pool Kt/V (spKt/V) higher than 1.2. In recent years, more intensive HD regimens with spKt/V≥1.5 have been increasingly discussed, which can significantly improve patient survival. However, their benefit has yet to be proven, as extremely high spKt/V values can be misleading as they may result from malnutrition leading to reduced survival and increased relative risk of death. The aim of this study is to present to the community the impact of nonstandardized high dialysis doses (spKt/V>1.5) on annual survival and mortality rates in the dialysis population and to explore new strategies for enhancing quality of life and survival, as well as to promote their regular implementation in clinical practice and personalized patient care. Material and methods The present retrospective study was conducted at the Clinic of Nephrology and Dialysis at University Hospital St. Marina in Varna, Bulgaria for a period of five years. It involved a survival analysis of 100 dialysis patients who met the inclusion and exclusion criteria. The dialysis dose delivered was the criterion for their allocation into three studied groups: Group 1 with adequate dose (standardized) - spKt/V = 1.2-1.49, Group 2 with high dose (nonstandardized) - spKt/V≥1.5, and Group 3 with inadequate dose (low) - spKt/V≤1.19. We recorded total annual mortality and survival rates, analyzing their relationship with the delivered dialysis dose and assessing the relative risk of death and expected survival. Results The analysis results indicated that high-intensity regimens with an spKt/V≥1.5 were linked to a better patient prognosis, with a significantly lower risk of death compared to standard regimens and increased survival expectancy. Data from the survival analysis suggested that the long-term impact of increasing the dialysis dose (spKt/V≥1.5) on survival becomes evident after the third year. Additionally, nutritional status parameters emerged as key risk factors for deterioration, along with the indicators of dialysis adequacy. Discussion Improved survival rates have been observed in patients undergoing nocturnal HD. In the latter, significantly higher spKt/V values have been achieved due to extended dialysis sessions, as well as in those performing dialysis at home. Despite concerns about possible misinterpretation of extremely high spKt/V values (>1.5) as a sign of malnutrition when urea volume of distribution is reduced, it is found that when only urea clearance (Kt) is used, without volume counts, the risk of death decreases by 2% for each liter increase in clearance. This demonstrates that the assessment of dialysis adequacy is a much broader concept than the values of generally accepted indicators and should be focused on individualized care and risk assessment tailored to each patient. Conclusions We believe that the modern nephrological community should strive to achieve a high dialysis dose (spKt/V≥1.5) to improve clinical outcomes and patient prognosis. Assessing dialysis adequacy is complex and goes beyond a simple numerical value such as spKt/V. It requires careful monitoring of nutritional status and the management of all HD-related complications.

Living on the edge: identifying demographic bottlenecks in an isolated sage‐grouse population

The greater sage‐grouse (Centrocercus urophasianus: hereafter sage‐grouse) population in Modoc County California is geographically isolated and contains a single lek (from 56 leks in the 1940s), despite significant efforts to increase the population through translocations and habitat improvement. Repeated wildfire within the landscape has led to an increase in invasive annual grasses and a decrease in sagebrush (Artemisia sp.) cover in important nesting and brood‐rearing habitat. We estimated survival for adult females, nests, and chicks and assessed biotic characteristics that may influence these survival estimates to identify factors that may be limiting population growth. We monitored 37 female sage‐grouse marked with GPS PTTS, 39 nests, and 8 broods for 3 years (2019–2021). We measured vegetation characteristics for nests at the microsite and landscape scale to evaluate effects on daily nest survival (DNS). We used survival rates from all life stages to parameterize matrix models and estimate population growth rate. Mean nest success over 3 years was 29% (95% CI: 17.1–44.8) across a 29‐day incubation period and DNS declined as the proportion of both medusahead Taeniatherum caput‐medusae and Japanese brome Bromus japonicus around the nest increased. Across all three years, mean chick survival across a 54‐day period was 44% (95% CI: 0.9–72.3) and mean annual survival for adult females was 29% (95% CI: 17.8–43.7). Our estimated vital rates were 45–55% lower than distribution‐wide estimates and the projected population growth rate was strongly declining (0.411, 95% CI: 0.30–0.52). Our results suggested recent cover changes associated with wildfire on the study area may have had a detrimental effect on this population across all life stages, and if attention is not given to preventing the transition from sagebrush communities into invasive grasslands, this population and others in degraded landscapes may not persist.

Migratory track from the United States breeding population of Cliff Swallows (Petrochelidon pyrrhonota) and effects of geolocators on annual survival

Migratory track from the United States breeding population of Cliff Swallows (Petrochelidon pyrrhonota) and effects of geolocators on annual survival

Post-release survival of loggerhead sea turtles (Caretta caretta) incidentally hooked in a North Atlantic pelagic longline fishery

Estimating mortality of sea turtles incidentally captured in fishing gear is essential to understanding fishery impacts on sea turtle populations. Loggerhead turtles (Caretta caretta) are a component of bycatch in pelagic longline fisheries, including those operating in Atlantic Canada. In this study, we used pop-up satellite archival tags (PSATs) attached to 62 loggerhead turtles incidentally hooked in Atlantic Canadian shallow-set pelagic longline gear (2012–2018) to estimate associated post-release survival. Consistent with conventional fishing practices, hooks were not removed from turtles prior to release. Analysis of diving behaviour, ocean temperature, and ambient light level was used to assign fates to turtles. Post-release survival was calculated using the Kaplan-Meier estimator with right censoring. Based on this method, the annual survival probability of an individual loggerhead post-release is 0.877 ± SE 0.052. While it is commonly assumed that hook location is an important variable in predicting fates of turtles after release, there was no difference in survival of deep-hooked (swallowed hook) versus shallow-hooked turtles. These results indicate higher survivorship among hooked loggerheads captured in shallow-set pelagic longline gear than prevailing wisdom and suggest that at least some of the population impacts on loggerhead turtles conventionally attributed to pelagic longline interactions may be linked to other threats.

Age truncation due to disease shrinks metapopulation viability for amphibians.

Metapopulations often exist in a fragile balance between local extinctions and (re)colonisations, in which case emerging threats that alter species vital rates may drastically increase metapopulation extinction risk. We combined empirical data with metapopulation simulations to examine how demographic shifts associated with amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) have altered metapopulation viability for threatened amphibians in Australia. Comparing the ages of museum specimens collected before Bd emerged in Australia with individuals from geographically matched remnant populations revealed significant truncation of age structures post-Bd, with a halving of annual adult survival probabilities. Spatially realistic metapopulation modelling demonstrated that reduced adult survival led to major reductions in the parameter space over which persistence was possible for the focal species, with contractions to landscapes with higher landscape connectivity, lower environmental stochasticity and considerably higher recruitment rates. Metapopulation persistence post-Bd required greater landscape connectivity than pre-Bd. This arises from a landscape-level analogue of compensatory recruitment at the population level, in which higher (re)colonisation rates can offset more frequent local extinctions, enabling persistence of amphibians susceptible to Bd. Interactions between recruitment rate, environmental stochasticity and landscape connectivity were also more important for metapopulation persistence post-Bd. Higher recruitment was required to mitigate the impacts of environmental stochasticity, and higher landscape connectivity was required to mitigate the impacts of environmental stochasticity and poor recruitment. Increased reliance on these interdependencies shrunk the parameter space over which metapopulations could persist post-Bd. Our study demonstrates that emerging threats that alter species vital rates can drastically reduce the capacity of certain environments to support metapopulations. For our focal species, reductions in adult survival rates due to Bd produced major reductions in the conditions under which persistence was possible, providing a mechanistic insight into the processes underpinning observed range and niche contractions of amphibians impacted by this pathogen. More broadly, our study illustrates how environmentally mediated host resilience can enable persistence following the emergence of novel pathogens. This pathway to persistence is worthy of greater attention on both conceptual and applied grounds.

Use of capture–recapture models to evaluate abundance and dynamics of a stocked Muskellunge population

AbstractTo evaluate the success of a stocking program in Fox Lake, Minnesota, adult (≥76 cm total length) Muskellunge were captured with large nearshore trap nets and individually marked with passive integrated transponder tags during the 2011–2013 and 2015–2017 spawning seasons; then, capture–recapture data were analyzed at two different time scales. Despite substantial sampling effort, daily capture histories within a single season only supported closed‐population abundance estimates for both sexes in half the years; estimates were imprecise, and there was evidence of trap shyness or violation of the short‐term closure assumption in some years. Jolly–Seber models over all years supported relatively precise abundance estimates for both sexes every year, as well as estimates of annual survival, recruitment, and population growth rate. Link–Barker Jolly–Seber models provided estimates of population growth rate λ ≈ 1 indicating that per‐capita annual recruitment rates of only about 0.15–0.20 were adequate to maintain the adult population given the high annual apparent survival rates of 0.80 for adult females and 0.89 for adult males. POPAN Jolly–Seber models revealed that about 80 adult females and 90–126 adult males were vulnerable to capture each year in the 385 ha lake, and about 16–18 fish of each sex recruited to the adult population annually. This study illustrates the importance of open‐population models with multiple years of data to evaluate the abundance and population dynamics of a low‐density, long‐lived species.

Moderate evidence for the sex‐dependent effect of poisoning on adult survival in a long‐lived raptor species

AbstractSurvival rate is usually the greatest contributor to population growth in long‐lived species, and its accurate estimation along with the evaluation of the factors influencing it is therefore essential for effective conservation. Here, we studied the survival of breeding eastern imperial eagles Aquila heliaca in Hungary between 2011 and 2022 and investigated the effect of poisoning, the leading known anthropogenic cause of mortality. We used the Cormack‐Jolly‐Seber mark‐recapture model to estimate annual apparent survival and encounter probabilities based on the capture histories of 208 males and 411 females. We obtained encounter data from the DNA profiles of shed feathers collected at the nest sites, which we also supplemented with presences inferred from parentage analysis. The most supported model estimated a constant 91.6% annual survival over the study period, but models including the effect of sex and poisoning rate on survival had similar support. Sex difference in survival was less than 1% on average, but the survival of males decreased more with poisoning rate than the survival of females. However, due to smaller encounter probabilities, the estimates for males were less precise compared to females. Males may be more at risk from poisoning than females not only due to their more active foraging behaviour during incubation and chick‐rearing but also due to their smaller body size. Apart from providing direct practical information for the conservation management of imperial eagles, our results also highlight the importance of long‐term studies for estimating population parameters of birds of prey.

RHDV2 outbreak reduces survival and juvenile recruitment, causing European rabbit population collapse

AbstractInfectious diseases can cause considerable mortality in vertebrate populations, especially when a new pathogen emerges. Quantifying the impact of diseases on wild populations and dissecting the underlying mechanisms requires longitudinal individual monitoring combining demographic and epidemiologic data. Such longitudinal population studies are rare. Rabbit hemorrhagic disease (RHD) is one of the main causes of the decline in European wild rabbit (Oryctolagus cuniculus) populations. A new genotype of RHD virus (RHDV), called RHDV2 or GI.2, emerged in 2010, posing a new threat to previously weakened populations, particularly as this virus can infect individuals already immune to classical RHDV strains. Taking advantage of intensive monitoring from 2009 to 2014 by physical captures and microchip detections of a semi‐captive population of rabbits, we finely assessed the demographic impact of an initial RHDV2 outbreak that occurred in the population and identified the most affected demographic parameters. A multi‐event modeling analysis revealed decreased survival in both juveniles and adults in 2011 and 2012, suggesting an RHDV2 outbreak for two consecutive years. The short‐term survival benefit of vaccination against classical RHDV strains only during these years, and the recovery of carcasses with RHDV2 detection, supported this hypothesis. Variations in population vaccination coverage also explain the difference in adult survival between the two years of the outbreak. And the transient protective effect of vaccination could explain the prolonged duration of the outbreak. A brief episode of myxomatosis in 2011 seems to have had only a limited impact on the population. During outbreak years, in individuals not recently vaccinated, monthly juvenile survival crashed (0.55), and annual adult survival was three times lower than in normal years (0.21 vs. 0.69). The combination of successive juvenile and adult survival estimates for unvaccinated rabbits during the outbreak years resulted in a very low recruitment rate in the breeding population. Finally, RHDV2 outbreaks appear to have caused mortalities comparable to those caused by older classical RHDV strains and may have a strong demographic impact on wild populations of European rabbit. This work highlights the importance of long‐term observational and experimental studies to better understand the impact of epidemics on animal populations.

Population viability analysis of Chihuahua Chub in the Mimbres River, New Mexico

AbstractObjectiveThe Chihuahua Chub Gila nigrescens is a species of conservation concern throughout its distribution. The species is threatened by habitat degradation, nonnative species, and stochastic events (e.g., wildfire and drought). Although conservation efforts are ongoing, it is unclear how Chihuahua Chub in the Mimbres River, New Mexico, respond to conservation actions and stochastic events.MethodsTo address these uncertainties, we collected population demographic and dynamics data on Chihuahua Chub in the Mimbres River and used the data to construct an age‐structured, female‐based population model. The model was used to evaluate the response of Chihuahua Chub to (1) habitat improvement, (2) conservation stocking, and (3) stochastic events. Habitat improvements were modeled as a 50% increase in current abundance. Conservation stocking was represented by two stocking regimes: annual “maintenance” stocking of 200 fish or “catastrophe” stocking of 400–1500 fish for two consecutive years after a stochastic event. The effects of stochastic events were represented by 20–95% reductions in annual survival. Each scenario was simulated for 5000 iterations over 25 years.ResultIn the absence of conservation actions, the Chihuahua Chub population was projected to decline due to stochastic events. However, stocking and habitat improvement decreased the risk of extirpation. When stochastic events resulted in a 95% decline in annual survival, catastrophe stocking reduced population declines in abundance by 47–58% relative to no conservation stocking. When stochastic events caused a 20% reduction in annual survival, habitat improvement increased the median population size after 25 years by almost 50% relative to no habitat improvements.ConclusionCollectively, our results suggest that an increase in habitat and conservation stocking efforts is likely the most effective approach for conserving Chihuahua Chub in the face of future stochastic events.