Capture-recapture Analysis Research Articles

Reinforcement of an endangered goose population: the effect of age and interspecific fostering on survival of released birds

The release of captive‐bred or translocated individuals is a strategy used worldwide to support threatened animal populations. By capture–recapture analysis, we examined the survival of released individuals when reinforcing a critically endangered Lesser White‐fronted Goose population. Our analysis includes data from 646 birds, released 1984–2017, including two different age classes, divided in two distinct periods when different techniques were used. Fledglings were released with foster parents of Barnacle Geese in the first period and by a soft release without support of foster parenting in the second period. Yearlings were released by soft release in both periods. We find that use of foster parents enhances survival rates, but these differences were detectable only in the first year of life. Fledglings supported by foster parents showed significantly higher survival compared to yearlings released by soft release, but this difference was not clear when soft release was applied to both groups. Resighting data suggest that most losses occurred during the acclimation period following the release. Foster parenting may enhance survival rates due to social learning enabling the transfer of crucial behaviors (e.g. feeding, anti‐predator, and migration) to released individuals. However, these conservation benefits need to be balanced against costs and potential inherent risks related to foster parenting, including the imprinting of undesired behaviors in released individuals, such as hybridization. Based on our results, we advise conservationists to carefully consider foster parenting as one method to improve survival probability, especially if capacity to produce individuals to be released is a limiting factor.

Estimating the Prevalence of Dementia in New Zealand Using Capture-Recapture Analysis on Routinely Collected Health Data.

Community based dementia prevalence studies are expensive and resource intensive. Aotearoa New Zealand (NZ) has never had a community based dementia prevalence study representing all major ethnic groups. In recent years, dementia prevalence estimates have been derived from routinely collected health data but issues of underdiagnosis and undercoding limit their utility. Capture-recapture techniques can estimate the number of dementia cases missing from health datasets by modelling the ascertained overlaps between linked data sources. Three routinely collected national health data sets-interRAI, Public hospital discharges, and Pharmaceuticals-were linked and all prevalent cases of dementia in NZ for the year 1 January 2021-31 December 2021 were identified. Capture-recapture analysis fitted eight loglinear models to the data, with the best fitting model used to estimate the number of prevalent cases missing from all three datasets. We estimated that almost half (47.8%) of dementia cases are not present in any of the three datasets. Dementia prevalence increased from 3.7% to 7.1% (95% CI 6.9%-7.4%) in the NZ 60+ population and from 4.9% to 9.2% (95% CI 8.9%-9.6%) in the NZ 65+ population when missing cases were included. Estimates of missing cases were significantly higher (p<0.001) in Māori (49.2%), Pacific peoples (50.6%) and Asian (59.6%) compared to Europeans (46.4%). This study provides updated estimates of dementia prevalence in NZ and the proportion of undiagnosed dementia in NZ, highlighting the need for better access to dementia assessment and diagnosis.

Semi-parametric Bayesian approach for population size estimation modelling the excess of singletons

Abstract The phenomenon of one-inflation has received increasing attention in the recent literature on capture–recapture analysis. When data consist of frequencies of number of captures, the phenomenon manifests as an excess of units captured exactly once. We distinguish two possible causes for modelling the excess of singletons, namely, the erroneous inclusion of out-of-scope units, and a behavioural effect preventing subsequent captures after the first one. Accordingly, we propose two families of semi-parametric one-inflated models to estimate the number of uncaptured units. We consider a Bayesian approach by fitting a Dirichlet process mixture model as the base model, and extend this class to include one-inflation. The proposed base model and its two one-inflated counterparts are used to estimate the number of criminals involved in prostitution exploitation activities in Italy. We further assess the performance of the proposed models on three datasets available in the literature, as well as on simulated data.

The importance of independence in unmarked spatial capture–recapture analysis

Wildlife populations can be unmarked, meaning individuals lack distinguishing features for individual identification. Populations may also exhibit non‐independent movements, meaning individuals move together. For populations of either unmarked or non‐independent individuals, models based on spatial capture–recapture (SCR) approaches can be used to estimate abundance, density, and other parameters critical for monitoring, management, and conservation. However, when individuals are both unmarked and non‐independent, few model options are available. One approach has been to apply unmarked models and not address the non‐independence despite unquantified impacts on bias, precision, and the ability to make robust ecological inferences. We conducted a simulation study to quantify the impact of non‐independence on the performance of spatial count (SC) and spatial partial identity models (SPIM) – two SCR‐based unmarked modeling approaches – and used the performance of fully marked and independent SCR as a reference. We varied the levels of non‐independence (aggregation and cohesion), detection probability, and the number of partial identity covariates used to resolve identities in SPIM estimation. We expected abundance estimates to be increasingly biased and precise as aggregation and cohesion increased. Results showed that models indeed became less robust to increasing non‐independence, but importantly suggested that only SPIM could be reliably applied under low levels of cohesion when sufficient partial identity covariates are available. SC yielded consistently biased estimates with poor precision. SCR was consistently robust across combinations of aggregation and cohesion, as expected. We therefore advise against the use of SC models for estimating population parameters when individuals are known to be non‐independent, caution that SPIM may be used under narrow ecological conditions, and encourage continued investigations into sampling design and methods development for estimating populations of unmarked and non‐independent individuals.

Intersectional inequities and longitudinal prevalence estimates of opioid use disorder in Massachusetts 2014–2020: a multi-sample capture-recapture analysis

As overdoses continue to increase worldwide, accurate estimates are needed to understand the size of the population at risk and address health disparities. Capture-recapture methods may be used in place of direct estimation at nearly any geographic level (e.g., city, state, country) to estimate the size of the population with opioid use disorder (OUD). We performed a multi-sample capture-recapture analysis with persons aged 18-64 years to estimate the prevalence of OUD in Massachusetts from 2014 to 2020, stratified by sex and race/ethnicity. We used seven statewide administrative data sources linked at the individual level. We developed log-linear models to estimate the unknown OUD-affected population. Uncertainty was characterized using 95% confidence intervals (95% CI) on the total counts and prevalence estimates. The estimated OUD prevalence increased from 5.47% (95% CI=4.89%, 5.98%) in 2014 to 5.79% (95% CI=5.34%, 6.19%) in 2020. Prevalence among Hispanic females doubled (2.46% in 2014 to 4.23% in 2020) and prevalence rose to nearly 10% among Black non-Hispanic males and Hispanic males from 2014 through 2019. Estimates for Black non-Hispanic females more than doubled from 2014 through 2019 (3.39% to 7.09%), and then decreased to 5.69% in2020. This study is the first to provide OUD prevalence trend estimates by binary sex and race/ethnicity at a state level using capture-recapture methods. Using these methods as the international overdose crisis worsens can allow jurisdictions to appropriately allocate resources and targeted interventions to marginalised populations. NIDA.

Outbreak of severe community-acquired bacterial infections among children in North Rhine-Westphalia (Germany), October to December 2022

PurposeIn late 2022, a surge of severe S. pyogenes infections was reported in several European countries. This study assessed hospitalizations and disease severity of community-acquired bacterial infections with S. pyogenes, S. pneumoniae, N. meningitidis, and H. influenzae among children in North Rhine-Westphalia (NRW), Germany, during the last quarter of 2022 compared to long-term incidences.MethodsHospital cases due to bacterial infections between October and December 2022 were collected in a multicenter study (MC) from 59/62 (95%) children's hospitals in NRW and combined with surveillance data (2016–2023) from the national reference laboratories for streptococci, N. meningitidis, and H. influenzae. Overall and pathogen-specific incidence rates (IR) from January 2016 to March 2023 were estimated via capture–recapture analyses. Expected annual deaths from the studied pathogens were calculated from national death cause statistics.ResultsIn the MC study, 153 cases with high overall disease severity were reported with pneumonia being most common (59%, n = 91). IRs of bacterial infections declined at the beginning of the COVID-19 pandemic and massively surged to unprecedented levels in late 2022 and early 2023 (overall hospitalizations 3.5-fold), with S. pyogenes and S. pneumoniae as main drivers (18-fold and threefold). Observed deaths during the study period exceeded the expected number for the entire year in NRW by far (7 vs. 0.9).DiscussionThe unprecedented peak of bacterial infections and deaths in late 2022 and early 2023 was caused mainly by S. pyogenes and S. pneumoniae. Improved precautionary measures are needed to attenuate future outbreaks.

Improving estimates of pertussis burden in Ontario, Canada 2010-2017 by combining validation and capture-recapture methodologies.

An underestimation of pertussis burden has impeded understanding of transmission and disallows effective policy and prevention to be prioritized and enacted. Capture-recapture analyses can improve burden estimates; however, uncertainty remains around incorporating health administrative data due to accuracy limitations. The aim of this study is to explore the impact of pertussis case definitions and data accuracy on capture-recapture estimates. We used a dataset from March 7, 2010 to December 31, 2017 comprised of pertussis case report, laboratory, and health administrative data. We compared Chao capture-recapture abundance estimates using prevalence, incidence, and adjusted false positive case definitions. The latter was developed by removing the proportion of false positive physician billing code-only case episodes after validation. We calculated sensitivity by dividing the number of observed cases by abundance. Abundance estimates demonstrated that a high proportion of cases were missed by all sources. Under the primary analysis, the highest sensitivity of 78.5% (95% CI 76.2-80.9%) for those less than one year of age was obtained using all sources after adjusting for false positives, which dropped to 43.1% (95% CI 42.4-43.8%) for those one year of age or older. Most code-only episodes were false positives (91.0%), leading to considerably lower abundance estimates and improvements in laboratory testing and case report sensitivity using this definition. Accuracy limitations can be accounted for in capture-recapture analyses using different case definitions and adjustment. The latter enhanced the validity of estimates, furthering the utility of capture-recapture methods to epidemiological research. Findings demonstrated that all sources consistently fail to detect pertussis cases. This is differential by age, suggesting ascertainment and testing bias. Results demonstrate the value of incorporating real time health administrative data into public health surveillance if accuracy limitations can be addressed.

Use of Capture-Recapture Analysis to Estimate the Number of Agricultural Fatalities and Severe Agricultural Injuries in Indiana

ABSTRACT Conducting surveillance of agricultural injuries and fatalities in the United States has been an ongoing challenge, with many cases falling outside the criteria of national and local surveillance systems. In this research, capture-recapture analysis was used to estimate the number of fatal agricultural injuries in Indiana between 2016 and 2020. A limited analysis of non-fatal injuries is also provided. This analysis was possible because of two publicly available datasets containing incident descriptions with sufficient detail for case matching. The first dataset consisted of summary lists of fatal and nonfatal agricultural injuries in Indiana published in annual agricultural fatality reports produced by the Purdue Extension. The second data source was AgInjuryNews, which gathers reports of agricultural injuries and fatalities published in news media and other publicly available sources. Results of the capture-recapture analysis estimate that, every year in Indiana, the Purdue Extension misses 18% of fatal incidents and AgInjuryNews misses approximately 60%. AgInjuryNews identifies approximately 3 fatal incidents per year that are missed by Purdue Extension. Analysis of nonfatal incidents was limited by the fact that both data sources only included nonfatal injuries that were extremely severe and/or connected to a fatality. The Purdue Extension is estimated to miss 22% and AgInjuryNews is estimated to miss 25% of nonfatal agricultural injuries meeting that narrow definition. While capture-recapture analysis only provides estimates of true injury rates, the results provide evidence that Purdue Extension’s surveillance captures most agricultural fatalities in the state. AgInjuryNews has been able to identify cases missed by Purdue, and this research takes an important step forward in quantifying how media reports found in this data source differ from extension surveillance. This research also highlights the continuing limitations in the surveillance non-fatal injuries and the ways in which publicly available data can aid researchers in filling gaps in surveillance.

Evaluating a Targeted Minimum Loss-Based Estimator for Capture-Recapture Analysis: An Application to HIV Surveillance in San Francisco, California.

The capture-recapture method is a common tool used in epidemiology to estimate the size of "hidden" populations and correct the underascertainment of cases, based on incomplete and overlapping lists of the target population. Log-linear models are often used to estimate the population size yet may produce implausible and unreliable estimates due to model misspecification and small cell sizes. A novel targeted minimum loss-based estimation (TMLE) model developed for capture-recapture makes several notable improvements to conventional modeling: "targeting" the parameter of interest, flexibly fitting the data to alternative functional forms, and limiting bias from small cell sizes. Using simulations and empirical data from the San Francisco, California, Department of Public Health's human immunodeficiency virus (HIV) surveillance registry, we evaluated the performance of the TMLE model and compared results with those of other common models. Based on 2,584 people observed on 3 lists reportable to the surveillance registry, the TMLE model estimated the number of San Francisco residents living with HIV as of December 31, 2019, to be 13,523 (95% confidence interval: 12,222, 14,824). This estimate, compared with a "ground truth" of 12,507, was the most accurate and precise of all models examined. The TMLE model is a significant advancement in capture-recapture studies, leveraging modern statistical methods to improve estimation of the sizes of hidden populations.

Prevalence of anti-neutrophil cytoplasmic antibody-associated vasculitis in the south of France, using the capture-recapture method.

This study aimed to estimate the prevalence of ANCA-associated vasculitis (AAV). That is, granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA), in Southern France in 2018, and evaluate differences among Europeans and non-Europeans. This population-based, cross-sectional study used four sources (hospitals, community-based physicians, laboratories, National Health Insurance) to identify adults ≥15 years diagnosed with GPA, MPA or EGPA, living in Hérault and Gard in 2018. Cases were defined using the ACR/EULAR classification criteria, and if necessary, the European Medicines Agency algorithm. Prevalence estimates were standardised to the world population and capture-recapture analysis was used to assess the comprehensiveness of the estimation. The influence of geographical origin was evaluated. A total of 202 patients were selected, with 86 cases of GPA (42.6%), 85 cases of MPA (42.1%) and 31 cases of EGPA (15.3%). The standardised prevalence estimates per million inhabitants for 2018 were: 103 (95%CI 84-125) for AAV, 48 (95%CI 35-64) for GPA, 39 (95%CI 28-53) for MPA and 16 (95%CI 9-26) for EGPA, 36 (95%CI 25-50) for anti-PR3 positive AAV, 46 (95%CI 34-61) for anti-MPO positive AAV, and 16 (95%CI 9-26) for ANCA-negative AAV. The global estimation of comprehensiveness by capture-recapture analysis was 80.5%. The number of AAV cases was higher for non-European residents (P = 0.001), particularly for MPA (P < 0.0001). We provide a new estimate of AAV prevalence in France and show a higher prevalence of MPA in non-European patients.

Massachusetts Prevalence of Opioid Use Disorder Estimation Revisited: Comparing a Bayesian Approach to Standard Capture-Recapture Methods.

The National Survey on Drug Use and Health (NSDUH) estimated the prevalence of opioid use disorder (OUD) among the civilian, noninstitutionalized people aged 12 years or older in Massachusetts as 1.2% between 2015 and 2017. Accurate estimation of the prevalence of OUD is critical to the success of treatment and resource planning. Various indirect estimation approaches have been used but are subject to data availability and infrastructure-related issues. We used 2015 data from the Massachusetts Public Health Data Warehouse (PHD) to compare the results of two approaches to estimating OUD prevalence in the Massachusetts population. First, we used a seven-dataset capture-recapture analysis under log-linear model parameterization, controlling for the source dependence and effects of age, sex, and county through stratification. Second, we applied a benchmark-multiplier method in a Bayesian framework by linking health care claims data to death certificate data assuming an extrapolation of death rates from observed untreated OUD to unobserved OUD. Our estimates for OUD prevalence among Massachusetts residents (aged 18-64 years) were 4.62% (95% CI = 4.59%, 4.64%) in the capture-recapture approach and 4.29% (95% CrI = 3.49%, 5.32%) in the Bayesian model. Both estimates were approximately four times higher than NSDUH estimates. The synthesis of our findings suggests that the disease surveillance system misses a large portion of the population with OUD. Our study also suggests that concurrent use of multiple methods improves the justification and facilitates the triangulation and interpretation of the resulting estimates. ClinicalTrials.gov Identifier: NCT04111939.

Refining Incidence and Characteristics of Inflammatory Myopathies: A Quadruple-Source Capture-Recapture Survey Using the 2017 European League Against Rheumatism/American College of Rheumatology Classification Criteria.

Inflammatory myopathies (IM), characterized by muscle inflammation and weakness, are rare systemic diseases. Our previous study estimated an IM incidence rate of 7.98 cases per million people per year (95% confidence interval 7.38-8.66) and highlighted important variations that were likely because of methodologic issues rather than true epidemiologic differences. In this study, we aimed to refine the incidence of IM, using the 2017 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for IM and a quadruple-source capture-recapture method during a 6-year period in Alsace, France, a region with a population of 2 million having benefits of good access to health care and accredited IM referral centers. Clinical data of potential IM patients were obtained from 4 sources (general practitioners and community specialists, public and private hospital records, public and private laboratories, and archives from the pathology department). Patients residing in Alsace and who fulfilled the 2017 EULAR/ACR criteria for IM between January 1, 2006, and January 1, 2013, were included. We corrected potentially incomplete ascertainment of cases with capture-recapture analyses. We studied both spatial and temporal distributions of incidence of IM. We also assessed systemic manifestations of the disease. Our review of 1,742 potential cases identified 106 patients with IM. No spatial or temporal heterogeneity was observed. Use of log-linear models showed an estimated 14.9 additional missed cases. Thus, the incidence rate of IM was 8.22 new cases per million inhabitants per year (95% confidence interval 6.76-9.69). Extramuscular manifestations other than dermatomyositis rash were frequently recorded. The stringent methodology used in our study provides an accurate estimation of the incidence of IM. This study also demonstrates, in a population-based cohort, the systemic nature of IM.

A multidisciplinary approach to estimating wolf population size for long-term conservation.

The wolf (Canis lupus) is among the most controversial of wildlife species. Abundance estimates are required to inform public debate and policy decisions, but obtaining them at biologically relevant scales is challenging. We developed a system for comprehensive population estimation across the Italian alpine region (100,000km2 ), involving 1513 trained operators representing 160 institutions. This extensive network allowed for coordinated genetic sample collection and landscape-level spatial capture-recapture analyses that transcended administrative boundaries to produce the first estimates of key parameters for wolf population status assessment. Wolf abundance was estimated at 952 individuals (95% credible interval 816-1120) and 135 reproductive units (i.e., packs) (95% credible interval 112-165). We also estimated that mature individuals accounted for 33-45% of the entire population. The monitoring effort was spatially estimated thereby overcoming an important limitation of citizen science data. This is an important approach for promoting wolf-human coexistence based on wolf abundance monitoring and an endorsement of large-scale harmonized conservation practices.

Assessing the impact of free-ranging cats (Felis silvestris catus) and dogs (Canis lupus familiaris) on wildlife in a natural urban reserve in Mexico City

Conservation of natural ecosystems embedded in urban contexts is a big challenge because diverse anthropogenic factors continuously impact native biodiversity and ecological processes. One such factor is the pervasive presence of free-ranging predators, especially cats (Felis silvestris catus) and dogs (Canis lupus familiaris), which may severely affect local wildlife. The “Reserva Ecológica del Pedregal de San Ángel” (REPSA), located within the main campus of the Universidad Nacional Autónoma de México (UNAM), in southern Mexico City, is an important natural area that protects a peculiar volcanic spill ecosystem holding native and endemic biodiversity. In 2012, UNAM launched a control program of cats and dogs in REPSA that is still active. To assess the potential impact of cats and dogs on wildlife species, we used live and camera traps coupled with capture-recapture analyses to evaluate changes in the vertebrate community, particularly in the presence and abundance of two medium-size native mammals (Didelphis virginiana and Bassariscus astutus), before (2008–2009) and during (2017–2019) the control program. Results showed that the abundance of dogs decreased between the two periods, but not so the abundance of cats, whereas the native vertebrate diversity increased from the pre-control stage to the control period. Furthermore, we found a negative, non-significant relationship between the abundance of D. virginiana and that of dogs, and a positive, also non-significant relationship between the presence and abundance of B. astutus with the abundance of dogs. We conclude that the control program of free-ranging predators has been beneficial for the conservation of native vertebrates and recommend its continuation and enhancement.

Estimación de casos de VIH no diagnosticados en la región Cajamarca, Perú: vinculación probabilística entre bases de datos

Undiagnosed HIV cases contribute to the increase in new infections, therefore estimating this figure is important in order to assess strategies in HIV control programs. The objective of this study was to estimate the number of undiagnosed HIV cases in the Cajamarca region in Peru between 2015 and 2021. HIV cases were obtained from three sources of information: The Regional Health Strategy for HIV Prevention and Control (ESPC-HIV); the HIV epidemiological notification application (Noti-HIV), and the laboratory information system (Netlab). The three databases were linked; a capture-recapture analysis using a log-linear model provided estimates of the number of undiagnosed HIV cases, taking into account interactions and the Akaike information criterion. After linkage, 991 registered HIV cases were obtained. An estimated 1388 cases (95%CI: 1265.6-1542.8) of people living with HIV were estimated, of which 393 (28.4%) were not diagnosed. The underreporting of each source was: 51.9% in the ESPC-HIV; 63.6% in Netlab; and 88% in Noti-HIV. The conclusion drawn was that a high number of HIV cases went undiagnosed, and strategies need to be reconsidered to increase the systematic detection of HIV cases.

Effect of kelp gull harassment on southern right whale calf survival: a long-term capture-recapture analysis.

Kelp gulls (Larus dominicanus) commonly feed on the skin and blubber of surfacing southern right whales (SRW, Eubalaena australis) in the near shore waters of Península Valdés (PV), Argentina. Mothers and especially calves respond to gull attacks by changing their swimming speeds, resting postures and overall behaviour. Gull-inflicted wounds per calf have increased markedly since the mid-1990s. Unusually high mortality of young calves occurred locally after 2003, and increasing evidence points to gull harassment as a factor contributing to the excess deaths. After leaving PV, calves undertake a long migration with their mothers to summer feeding areas; their health during this strenuous exertion is likely to affect their probabilities of first-year survival. To explore the effects of gull-inflicted wounds on calf survival, we analysed 44 capture-recapture observations between 1974 and 2017, for 597 whales photo-identified in their years of birth between 1974 and 2011. We found a marked decrease in first-year survival associated with an increase in wound severity over time. Our analysis supports recent studies indicating that gull harassment at PV may impact SRW population dynamics.

Nest Change and Individual Fitness in a Scopoli’s Shearwater Population: A Capture-Recapture Multistate Analysis

Seabirds are compelled to nest on land, away from their feeding areas, which they can only reach by leaving eggs or chicks in the nest, often for long periods of time. For this reason, almost all of them have evolved social monogamy as a reproductive system, cooperation between partners for incubation and chick rearing, and long-lasting pair bonds. Additionally, nesting conditions are essential for successful reproduction, and the nest can be considered a resource if it provides more guarantees in this aspect. As a result, the nest may be a source of contention and intraspecific competition, especially among males. In this work, we analyze long-term data of the Scopoli’s shearwater (Calonectris diomedea) population to address the fitness consequences of nest change regarding survival and reproductive success. We used capture–recapture multistate models and the AICc model selection approach to test three hypotheses: breeding failure triggers nest change; nest change affects breeding success probability; nest change affects survival. Each year, about 5% of the breeders move to a new nest. For males, it was mainly a way to improve their breeding conditions and was observed in their early years as a breeder. Conversely, for females, it was a way to improve their reproductive performance by trying with a new mate after a failure. Males that changed nests improved their breeding success probability. Instead, in females, there was no causal relation between nest change and breeding success, the latter having been more influenced by the intrinsic quality of the female as a breeder. We did not even find a link between nest change and survival. Instead, we demonstrated that reproductive failure could affect the apparent survival of females, probably because it induces breeding dispersal.

The use of camera traps to study the hooded skunk &lt;i&gt;Mephitis macroura&lt;/i&gt; (Carnivora: Mephitidae) abundance

Skunks are important for the ecosystems as consumers of fruits, seeds, and insects. The hooded skunk (Mephitis macroura) is a medium-sized mammal common in North America, but its abundance is poorly known throughout its range. In a semiarid location in southern Mexico, we deployed a camera traps array to study the populations of meso-carnivores in three seasons. With 2520 camera days of sampling effort, we obtained 41 photographs of the hooded skunk, an average of 6.2 photographs per station, meaning a capture rate of 1.63 photographs/camera day per 100. Based on pelage color patterns and specific characteristics, we identified 25 individuals (seven to twelve skunks per season). Single camera-trap stations recorded up to seven different skunk individuals (an average of 3.6 individuals). The maximum number of capture-recaptures was four for three skunk individuals, and the average capture-recapture record was 1.4 per skunk. Although the survey area was appropriate for mesocarnivores, no spatial recaptures were observed for hooded skunks because the distance between cameras was longer. Traditional capture-recapture models estimated hooded skunk abundance at 12.60, 21.10, and 20.20 skunks during the dry, pre-rainy, and rainy seasons, respectively. The capture rate was higher than reported in other camera trapping surveys in Mexico, and estimated abundances were the lowest but, in the range, reported for the species using other techniques. Idiosyncratic characteristics of hooded skunks are useful to the recognition of individuals, but we recommend testing short distances among cameras to achieve spatial recaptures and to apply contemporary spatial capture-recapture analyses.

Cover Image

EcosphereVolume 14, Issue 5 e4123 COVER IMAGEOpen Access Cover Image First published: 07 May 2023 https://doi.org/10.1002/ecs2.4123AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract COVER PHOTO: To understand how environmental variables influence white-tailed deer (Odocoileus virginianus) fawn survival, Engebretsen et al. (“Noninvasive camera data and spatial capture–recapture models reveal strong temporal variation in fawn survival,” Ecosphere, Volume 14, Issue 4, Article e4497; doi: 10.1002/ecs2.4497) deployed 180 cameras throughout the Florida Panther National Wildlife Refuge and the Big Cypress National Preserve. The authors were able to identify 271 fawns, such as the one shown here traveling with its mother through a cypress dome in the Big Cypress National Preserve. They used the camera data to create a dataset for a spatial capture–recapture analysis that revealed differences in survival to 180 days between fawns born in 2015 and those born in 2016. Their data suggest that extreme weather events likely contributed to lower recruitment in south Florida, USA. Photo credit: the authors. Volume14, Issue5May 2023e4123 RelatedInformation

Abundance of Bering-Chukchi-Beaufort bowhead whales (Balaena mysticetus) in 2004 estimated from photo-identification data

Ice-based surveys near Point Barrow, Alaska, have been used to obtain most estimates of abundance for the Bering-Chukchi-Beaufort (B-C-B) stock of bowhead whales, but global warming has raised concerns that ice-based surveys may not be practical in the future. Aerial photographic surveys provide an alternative method for obtaining abundance estimates and may replace ice-based surveys. Aerial photographic surveys were conducted near Point Barrow during the spring migrations of bowhead whales in 2003 and 2004 and, in 2005, in the northern Bering Sea in spring and near Barrow in fall. The 2003 survey was the most complete photographic survey of the population conducted to date. These surveys provided photo-identification data for use in capture-recapture analyses. A screening procedure was used to define which whales captured in 2003, 2004 and/or 2005 were marked and could be reidentified if photographed on another occasion. An estimate of the number of marked whales was obtained using a closed population model for capture-recapture data. Several models were investigated, including models that accounted for heterogeneity in capture probabilities, but a simple model with no covariates produced the most precise estimate. To account for unmarked whales, the estimate of marked whales was divided by an estimate of the proportion of the bowhead population that was marked based on the 1989–2004 spring photographic surveys near Point Barrow. Abundance of the B-C-B bowhead population in 2004 (excluding calves) was estimated to be 12,631 with CV 0.2442, 95% bootstrap percentile confidence interval (7,900; 19,700) and 5% lower limit 8,400. These results were compared with results that used approximate variance expressions for the estimates of the number of marked whales, the proportion of the population that was marked and population abundance instead of using the bootstrap. The estimates of abundance in 2004 computed for comparison included one based on a modified Petersen estimate of the number of marked whales that omitted the 2005 data as well as the estimate of 12,631 described above. The comparison estimates also included estimates of abundance in 1985 computed from 1984–87 photographic survey data using the same methods. All the abundance estimates computed from photographic data were consistent with expectations based on independent abundance and trend estimates from the ice-based surveys conducted from 1978 to 2001.