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The conservation status of the 2 threatened grizzly bear (Ursus arctos) populations in the Cabinet-Yaak Ecosystem (CYE) of northern Montana and Idaho had remained unchanged since designation in 1975; however, the current demographic status of these populations was uncertain. No rigorous data on population density and distribution or analysis of recent population genetic structure were available to measure the effectiveness of conservation efforts. We used genetic detection data from hair corral, bear rub, and opportunistic sampling in traditional and spatial capture—recapture models to generate estimates of abundance and density of grizzly bears in the CYE. We calculated mean bear residency on our sampling grid from telemetry data using Huggins and Pledger models to estimate the average number of bears present and to correct our superpopulation estimates for lack of geographic closure. Estimated grizzly bear abundance (all sex and age classes) in the CYE in 2012 was 48–50 bears, approximately half the population recovery goal. Grizzly bear density in the CYE (4.3–4.5 grizzly bears/1,000 km2) was among the lowest of interior North American populations. The sizes of the Cabinet (n = 22–24) and Yaak (n = 18–22) populations were similar. Spatial models produced similar estimates of abundance and density with comparable precision without requiring radio-telemetry data to address assumptions of geographic closure. The 2 populations in the CYE were demographically and reproductively isolated from each other and the Cabinet population was highly inbred. With parentage analysis, we documented natural migrants to the Cabinet and Yaak populations by bears born to parents in the Selkirk and Northern Continental Divide populations. These events supported data from other sources suggesting that the expansion of neighboring populations may eventually help sustain the CYE populations. However, the small size, isolation, and inbreeding documented by this study demonstrate the need for comprehensive management designed to support CYE population growth and increased connectivity and gene flow with other populations. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Polar bears ( Ursus maritimus ) of the northern Beaufort Sea (NB) population occur on the perimeter of the polar basin adjacent to the northwestern islands of the Canadian Arctic Archipelago. Sea ice converges on the islands through most of the year. We used open-population capture-–recapture models to estimate population size and vital rates of polar bears between 1971 and 2006 to: (1) assess relationships between survival, sex and age, and time period; (2) evaluate the long-term importance of sea ice quality and availability in relation to climate warming; and (3) note future management and conservation concerns. The highest-ranking models suggested that survival of polar bears varied by age class and with changes in the sea ice habitat. Model-averaged estimates of survival (which include harvest mortality) for senescent adults ranged from 0.37 to 0.62, from 0.22 to 0.68 for cubs of the year (COY) and yearlings, and from 0.77 to 0.92 for 2-–4 year-olds and adults. Horvtiz-Thompson (HT) estimates of population size were not significantly different among the decades of our study. The population size estimated for the 2000s was 980 ±± 155 (mean and 95%% CI). These estimates apply primarily to that segment of the NB population residing west and south of Banks Island. The NB polar bear population appears to have been stable or possibly increasing slightly during the period of our study. This suggests that ice conditions have remained suitable and similar for feeding in summer and fall during most years and that the traditional and legal Inuvialuit harvest has not exceeded sustainable levels. However, the amount of ice remaining in the study area at the end of summer, and the proportion that continues to lie over the biologically productive continental shelf (<300 m water depth) has declined over the 35-year period of this study. If the climate continues to warm as predicted, we predict that the polar bear population in the northern Beaufort Sea will eventually decline. Management and conservation practices for polar bears in relation to both aboriginal harvesting and offshore industrial activity will need to adapt.

In recent years, there has been a fast development of models that adjust for imperfect detection. These models have revolutionized the analysis of field data, and their use has repeatedly demonstrated the importance of sampling design and data quality. There are, however, several practical limitations associated with the use of detectability models which restrict their relevance to tropical conservation science. We outline the main advantages of detectability models, before examining their limitations associated with their applicability to the analysis of tropical communities, rare species and large‐scale data sets. Finally, we discuss whether detection probability needs to be controlled before and/or after data collection. Models that adjust for imperfect detection allow ecologists to assess data quality by estimating uncertainty and to obtain adjusted ecological estimates of populations and communities. Importantly, these models have allowed informed decisions to be made about the conservation and management of target species. Data requirements for obtaining unadjusted estimates are substantially lower than for detectability‐adjusted estimates, which require relatively high detection/recapture probabilities and a number of repeated surveys at each location. These requirements can be difficult to meet in large‐scale environmental studies where high levels of spatial replication are needed, or in the tropics where communities are composed of many naturally rare species. However, while imperfect detection can only be adjusted statistically, covariates of detection probability can also be controlled through study design. Using three study cases where we controlled for covariates of detection probability through sampling design, we show that the variation in unadjusted ecological estimates from nearly 100 species was qualitatively the same as that obtained from adjusted estimates. Finally, we discuss that the decision as to whether one should control for covariates of detection probability through study design or statistical analyses should be dependent on study objectives. Synthesis and applications. Models that adjust for imperfect detection are an important part of an ecologist's toolkit, but they should not be uniformly adopted in all studies. Ecologists should never let the constraints of models dictate which questions should be pursued or how the data should be analysed, and detectability models are no exception. We argue for pluralism in scientific methods, particularly where cost‐effective applied ecological science is needed to inform conservation policy at a range of different scales and in many different systems.

Dispersal is a central component of life history evolution. An increasing number of studies suggest that spatiotemporally variable environments may promote the evolution of \"dispersal syndromes,\" consisting of covariation patterns between dispersal and morphological, physiological, behavioral, and life history traits. At the interspecific scale, the \"colonizer syndrome\" appears to be one of the most frequently recorded associations between dispersal and life history traits, linking a high dispersal rate, high fecundity, and a short lifespan as systematically combined adaptations in spatiotemporally varying environments. However, few studies have highlighted the existence of a \"colonizer syndrome\" at the intraspecific scale, and none have investigated how different degrees of habitat stochasticity might shape covariation patterns between dispersal and life history traits. In this study, we examined this issue in freeranging metapopulations of the yellow-bellied toad (Bombina variegata) using capture-recapture data. Combining the results of this study with another recent study, we found that a high dispersal rate, high fecundity, and a short lifespan are associated in metapopulations experiencing unpredictable environments. In contrast, a very low dispersal rate (close to zero), low fecundity and a long lifespan are associated in metapopulations occupying predictable environments. We discuss these results as well as their demographic and evolutionary consequences.

Recovering small populations of threatened species is an important global conservation strategy. Monitoring the anticipated recovery, however, often relies on uncertain abundance indices rather than on rigorous demographic estimates. To counter the severe threat from poaching of wild tigers (Panthera tigris), the Government of Thailand established an intensive patrolling system in 2005 to protect and recover its largest source population in Huai Kha Khaeng Wildlife Sanctuary. Concurrently, we assessed the dynamics of this tiger population over the next 8 years with rigorous photographic capture-recapture methods. From 2006 to 2012, we sampled across 624-1026 km² with 137-200 camera traps. Cameras deployed for 21,359 trap days yielded photographic records of 90 distinct individuals. We used closed model Bayesian spatial capture-recapture methods to estimate tiger abundances annually. Abundance estimates were integrated with likelihood-based open model analyses to estimate rates of annual and overall rates of survival, recruitment, and changes in abundance. Estimates of demographic parameters fluctuated widely: annual density ranged from 1.25 to 2.01 tigers/100 km², abundance from 35 to 58 tigers, survival from 79.6% to 95.5%, and annual recruitment from 0 to 25 tigers. The number of distinct individuals photographed demonstrates the value of photographic capture-recapture methods for assessments of population dynamics in rare and elusive species that are identifiable from natural markings. Possibly because of poaching pressure, overall tiger densities at Huai Kha Khaeng were 82-90% lower than in ecologically comparable sites in India. However, intensified patrolling after 2006 appeared to reduce poaching and was correlated with marginal improvement in tiger survival and recruitment. Our results suggest that population recovery of low-density tiger populations may be slower than anticipated by current global strategies aimed at doubling the number of wild tigers in a decade. Recuperar las poblaciones pequeñas de las especies amenazadas es una importante estrategia global de conservación. Sin embargo, monitorear la recuperación esperada generalmente depende de índices inciertos de abundancia en lugar de estimados demográficos rigurosos. Para contrarrestar la gran amenaza causada por la cacería furtiva de tigres (Panthera tigris), el Gobierno de Tailandia estableció un sistema intensivo de patrullaje en 2005 para proteger y recuperar la población fuente más grande en el Santuario Huai Kha Khaeng. Simultáneamente, evaluamos las dinámicas de esta población de tigres durante los siguientes ocho años con rigurosos métodos fotográficos de captura-recaptura. De 2006 a 2012 muestreamos a lo largo de 624-1026 km² con 137-200 trampas cámara. Las cámaras desplegadas durante 21,359 días de trampa produjeron registros fotográficos de 90 individuos distinguibles. Usamos métodos espaciales de capturarecaptura y modelo bayesiano cerrado para estimar anualmente la abundancia de los tigres. Los estimados de abundancia estuvieron integrados por análisis de modelo abierto basados en la probabilidad para estimar la tasa anual y las tasas generales de supervivencia, reclutamiento y cambios en la abundancia. Los estimados de los parámetros demográficos fluctuaron ampliamente: la densidad anual varió entre 1.25 y 2.01 tigres/100 km², la abundancia entre 35 a 58 tigres, la supervivencia entre 79-6 y 95.5% y el reclutamiento anual de 0 a 25 tigres. El número de individuos distinguibles que fue fotografiado demuestra el valor de los métodos de captura-recaptura para la evaluación de las dinámicas poblacionales de especies raras y elusivas que son identificables gracias a marcas naturales. Posiblemente por causa de la presión ejercida por la caza furtiva, la densidad general de los tigres en Huai Kha Khaeng fue 82-90% más baja que en sitios ecológicamente comparables de India. Sin embargo, el patrullaje intensivo después de 2006 pareció reducir la caza furtiva y estuvo correlacionado con el mejoramiento marginal de la supervivencia y reclutamiento de los tigres. Nuestros resultados sugieren que la recuperación de las poblaciones de tigres con baja densidad puede ser más lenta de lo esperado por las estrategias globales actuales enfocadas en la duplicación del número de tigres en una década.

Because it modulates the fitness returns of possible options of energy expenditure at each ontogenetic stage, environmental stochasticity is usually considered a selective force in driving or constraining possible life histories. Divergent regimes of environmental fluctuation experienced by populations are expected to generate differences in the resource allocation schedule between survival and reproductive effort and outputs. To our knowledge, no study has previously examined how different regimes of stochastic variation in environmental conditions could result in changes in both the temporal variation and mean of demographic parameters, which could then lead to intra-specific variation along the slow-fast continuum of life history tactics. To investigate these issue, we used capture-recapture data collected on five populations of a long-lived amphibian (Bombina variegata) experiencing two distinct levels of stochastic environmental variation: (i) constant availability of breeding sites in space and time ('predictable environment'), and (ii) variable spatio-temporal availability of breeding sites ('unpredictable environment'). We found that female breeding propensity varied more from year to year in unpredictable than in predictable environments. Although females in unpredictable environments produced on average more viable offspring per year, offspring production was more variable between years. Survival at each ontogenetic stage was slightly lower and varied significantly more from year to year in unpredictable environments. Taken together, these results confirm that increased environmental stochasticity can modify the resource allocation schedule between survival and reproductive effort and outputs and may lead to intra-specific variation along the slow-fast continuum of life history tactics.

1. In iteroparous species, intermittent breeding is an important life-history tactic that can greatly affect animal population growth and viability. Despite its importance, few studies have quantified the consequences of breeding pauses on lifetime reproductive output, principally because calculating lifetime reproductive output requires knowledge of each individual's entire reproductive history. This information is extremely difficult to obtain in wild populations. 2. We applied novel statistical approaches that account for uncertainty in state assessment and individual heterogeneity to an 18-year capture-recapture dataset of 6,631 female southern elephant seals from Macquarie Island. We estimated survival and breeding probabilities, and investigated the consequences of intermittent breeding on lifetime reproductive output. 3. We found consistent differences in females' demographic performance between two heterogeneity classes. In particular, breeding imbued a high cost on survival in the females from the heterogeneity class 2, assumed to be females of lower quality. Individual quality also appeared to play a major role in a female's decision to skip reproduction with females of poorer quality more likely to skip breeding events than females of higher quality. 4. Skipping some breeding events allowed females from both heterogeneity classes to increase lifetime reproductive output over females that bred annually. However, females of lower quality produced less offspring over their lifetime. 5. Intermittent breeding seems to be used by female southern elephant seals as a tactic to offset reproductive costs on survival and enhance lifetime reproductive output but remains unavoidable and driven by individual-specific constraints in some other females.

Wildlife conservation and management need accurate methods for population survey and monitoring. Absolute counts of roe deer populations (Capreolus capreolus) are not possible, but the rapid advancement of motion-sensitive camera technologies and new analytical approaches might potentially lead to more precise estimates at lower costs compared to traditional survey methods. We applied spatially explicit photographic capture–recapture models (SCR) in the Lake Geneva basin, Switzerland, from 25 April to 20 September 2018 to estimate roe deer densities in a pilot survey. We investigated the effect of survey duration and camera density on male roe deer density estimates to select the sampling design that produced density estimates with sufficient accuracy and precision at lower costs (i.e., material, fieldwork, data processing, and analyses). Males could be identified based on their antlers, which allowed us to apply SCR to estimate their density. Because females could not be identified individually, we inferred the overall roe deer density (adult and sub-adult roe deer) based on the sex ratio estimated from motion-sensitive camera photos. According to the results of sub-sampling simulations and by taking into account the financial costs associated with fieldwork and analyses, we conclude that 20 motion-sensitive cameras set over 20 nights (i.e., the 20/20 method) is a good compromise to provide reliable estimates of male roe deer density. Furthermore, studies estimating overall roe deer density using SCR and sex ratio estimates should be conducted from mid-August to the end of October just after rutting season and the peak of yearling dispersal, when the movement rates of males and females, and hence their detection probabilities, are similar and when males are still carrying their antlers. This approach was successfully applied in 4 selected study areas with contrasting roe deer management regimes, resulting in overall roe deer density estimates ranging from 3.9 ± 1.3 (SE) deer/km² forest to 22.5 ± 6.1 deer/km² forest. Our study provides a valuable and cost-effective approach using photographic SCR methodology and sex ratio information to calculate roe deer density estimates that can be used in management measures such as defining hunting quotas.

The decline of wildlife populations due to emerging infectious disease often shows a common pattern: the parasite invades a naive host population, producing epidemic disease and a population decline, sometimes with extirpation. Some susceptible host populations can survive the epidemic phase and persist with endemic parasitic infection. Understanding host–parasite dynamics leading to persistence of the system is imperative to adequately inform conservation practice. Here we combine field data, statistical and mathematical modelling to explore the dynamics of the apparently stable Rhinoderma darwinii–Batrachochytrium dendrobatidis (Bd) system. Our results indicate that Bd-induced population extirpation may occur even in the absence of epidemics and where parasite prevalence is relatively low. These empirical findings are consistent with previous theoretical predictions showing that highly pathogenic parasites are able to regulate host populations even at extremely low prevalence, highlighting that disease threats should be investigated as a cause of population declines even in the absence of an overt increase in mortality.

Dead recoveries of marked animals are commonly used to estimate survival probabilities. Band-recovery models can be parameterized either by r (the probability of recovering a band conditional on death of the animal) or by f (the probability that an animal will be killed, retrieved, and have its band reported). The r parametrization can be implemented in a capture-recapture framework with two states (alive and newly dead), mortality being the transition probability between the two states. The authors show here that the f parametrization can also be implemented in a multistate framework by imposing simple constraints on some parameters. They illustrate it using data on the mallard and the snow goose. However, they mention that because it does not entirely separate the individual survival and encounter processes, the f parametrization must be used with care on reduced models, or in the presence of estimates at the boundary of the parameter space. As they show, a multistate framework allows the use of powerful software for model fitting or testing the goodness-of-fit of models; it also affords the implementation of complex models such as those based on mixture of information or uncertain states. /// La récupération au décès d'animaux marqués sert souvent à estimer les probabilités de survie. Les modèles de retour de bagues peuvent être paramétrés soit par r (la probabilité de retour de la bague d'un animal mort), soit par f (la probabilité qu'un animal soit tué, récupéré et que sa bague soit rapportée). La paramétrisation r peut être employée dans des modèles de capture-recapture à deux états (vivant et mort depuis peu), la mortalité étant la probabilité de transition entre les deux états. Les auteurs montrent ici que la paramétrisation f peut aussi être mise en œuvre dans un cadre multi-états en imposant des contraintes simples sur certains paramètres. Ils l'illustrent au moyen de données sur le colvert et l'oie des neiges. Ils notent toutefois que parce qu'elle ne sépare pas entièrement les processus de survie et de rencontre des individus, la paramétrisation f doit être utilisée avec soin dans les modèles réduits ou si les estimations sont à la frontière de l'espace paramétrique. Comme ils le montrent, l'approche multi-états est facilitée par de puissants logiciels servant à ajuster les modèles ou à tester leur adéquation; elle permet aussi l'emploi de modèles complexes, dont ceux basés sur un mélange d'information ou des états incertains.