Vital Rates Research Articles

Cat: Empirical modelling of Felis catus population dynamics in the UK.

Domestic cats are popular companion animals, however not all live in human homes and many cats live within shelters or as free-roaming, unowned- feral or stray cats. Cats can transition between these subpopulations, but the influence of this connectivity on overall population dynamics, and the effectiveness of management interventions, remain poorly understood. We developed a UK-focused multistate Matrix Population Model (MPM), combining multiple life history parameters into an integrated model of cat demography and population dynamics. The model characterises cats according to their age, subpopulation and reproductive status, resulting in a 28-state model. We account for density-dependence, seasonality and uncertainty in our modelled projections. Through simulations, we examine the model by testing the effect of different female owned-cat neutering scenarios over a 10-year projection timespan. We also use the model to identify the vital rates to which total population growth is most sensitive. The current model framework demonstrates that increased prevalence of neutering within the owned cat subpopulation influences the population dynamics of all subpopulations. Further simulations find that neutering owned cats younger is sufficient to reduce overall population growth rate, regardless of the overall neutering prevalence. Population growth rate is most influenced by owned cat survival and fecundity. Owned cats, which made up the majority of our modelled population, have the most influence on overall population dynamics, followed by stray, feral and then shelter cats. Due to the importance of owned-cat parameters within the current model framework, we find cat population dynamics are most sensitive to shifts in owned cat husbandry. Our results provide a first evaluation of the demography of the domestic cat population in the UK and provide the first structured population model of its kind, thus contributing to a wider understanding of the importance of modelling connectivity between subpopulations. Through example scenarios we highlight the importance of studying domestic cat populations in their entirety to better understand factors influencing their dynamics and to guide management planning. The model provides a theoretical framework for further development, tailoring to specific geographies and experimental investigation of management interventions.

Simulated effects of roadkill and harvest on the viability of a recovering bobcat population

AbstractBobcats (Lynx rufus) were extirpated from many midwestern states in the mid‐1800s owing to habitat loss and overharvesting. Recently, bobcats have recolonized Ohio, USA, and neighboring states and given their furbearer status elsewhere, there is interest in opening a harvest season; however, demographic factors and viability of this population are currently unknown. We developed a spatial population simulation model to assess the long‐term viability of the bobcat population in Ohio in the face of 2 human‐induced factors limiting population growth: potential harvest and road mortality. We combined habitat suitability and road mortality risk data with vital rates for bobcats from Ohio and other populations to simulate possible scenarios for Ohio's population. Our baseline scenario simulations showed no risk of extinction for Ohio's bobcat population in the next 40 years, but population trajectories were lower and exhibited greater uncertainty when we modeled the population with a lower maximum density of animals per cell. At low harvest intensity (αh = 0.05), the bobcat population also exhibits low risk of extinction. When harvest intensity increases (αh = 0.1, 0.15) or when adults (≥2 yr) are targeted by harvest, simulations show declining populations, greater uncertainty in projections, and possible risk of extirpation. Our models indicated that if harvest and road mortality are additive, then the bobcat population could withstand marginal increases in road mortality (αr = 0.1) at low harvest intensity (αh = 0.05). Future increases in road mortality with higher harvest intensity (αh = 0.1, 0.15) were unsustainable. Our results can be used by wildlife managers to assist with decisions on population‐level management. This simulation model can easily be adapted for other large mammals and can be modified to assess a variety of ecological and anthropogenic influences to wildlife populations.

Evaluating the importance of individual heterogeneity in reproduction to Weddell seal population dynamics using integral projection models.

Identifying and accounting for unobserved individual heterogeneity in vital rates in demographic models is important for estimating population-level vital rates and identifying diverse life-history strategies, but much less is known about how this individual heterogeneity influences population dynamics. We aimed to understand how the distribution of individual heterogeneity in reproductive and survival rates influenced population dynamics using vital rates from a Weddell seal population by altering the distribution of individual heterogeneity in reproduction, which also altered the distribution of individual survival rates through the incorporation of our estimate of the correlation between the two rates and assessing resulting changes in population growth. We constructed an integral projection model (IPM) structured by age and reproductive state using estimates of vital rates for a long-lived mammal that has recently been shown to exhibit large individual heterogeneity in reproduction. Using output from the IPM, we evaluated how population dynamics changed with different underlying distributions of unobserved individual heterogeneity in reproduction. Results indicate that the changes to the underlying distribution of individual heterogeneity in reproduction cause very small changes in the population growth rate and other population metrics. The largest difference in the estimated population growth rate resulting from changes to the underlying distribution of individual heterogeneity was less than 1%. Our work highlights the differing importance of individual heterogeneity at the population level compared to the individual level. Although individual heterogeneity in reproduction may result in large differences in the lifetime fitness of individuals, changing the proportion of above- or below-average breeders in the population results in much smaller differences in annual population growth rate. For a long-lived mammal with stable and high adult-survival that gives birth to a single offspring, individual heterogeneity in reproduction has a limited effect on population dynamics. We posit that the limited effect of individual heterogeneity on population dynamics may be due to canalization of life-history traits.

Thermal dependence of Daphnia life history reveals asymmetries between key vital rates

Temperature variation affects virtually every aspect of ectotherms' ecological performance, such as their foraging rate, reproduction, and survival. Although these changes influence what happens at higher levels of organizations, such as populations and communities, qualitative changes in dynamics usually require some degree of asymmetry between key vital rates, i.e. that different vital rates, such as growth, development, fecundity and mortality rates, respond differently to temperature. In order to identify possible asymmetries among vital rates and/or life stages, we characterized the thermal response of individuals a clone of Daphnia sinensis, drawn from a high-mountain environment in Taiwan, and examined the temperature dependence of growth, maturation, reproduction, and mortality rates, as well as fitness measures (r and R0) at eight temperatures. Daphnia sinensis was able to maintain reproductive success over a broad range of temperatures, much wider than the one experienced in its environment. However, negative effects of temperature were perceptible at temperatures much lower than the highest one at which they can achieve reproductive success. Adult mortality greatly increased for temperatures above 23 °C, and other vital rates started to decelerate, resulting in a large drop in lifetime reproductive success. This finding implies that D. sinensis may be able to persist over a wide range of temperatures, but also that it may become more sensitive to the detrimental effect of species interactions at increased temperatures. Different vital rates responded relatively similarly at low temperatures, but the degree of asymmetry among these rates was much more pronounced at higher temperatures. In particular, rates associated with adult performance decelerated more strongly than juveniles’ rates. These findings indicate that elevated temperatures affect the balance between juvenile and adult performance, which is known to have a crucial role in Daphnia population dynamics. We discuss the implications of these results for the dynamics of structured populations.

Conservation implications of a mismatch between data availability and demographic impact.

Cost-effective use of limited conservation resources requires understanding which data most contribute to alleviating biodiversity declines. Interventions might reasonably prioritise life-cycle transitions with the greatest influence on population dynamics, yet some contributing vital rates are particularly challenging to document. This risks managers making decisions without sufficient empirical coverage of the spatiotemporal variation experienced by the species. Here, we aimed to explore whether the number of studies contributing estimates for a given life-stage transition aligns with that transition's demographic impact on population growth rate, λ. We parameterised a matrix population model using meta-analysis of vital rates for the common eider (Somateria mollissima), an increasingly threatened yet comparatively data-rich species of seaduck, for which some life stages are particularly problematic to study. Female common eiders exhibit intermittent breeding, with some established breeders skipping one or more years between breeding attempts. Our meta-analysis yielded a breeding propensity of 0.72, which we incorporated into our model with a discrete and reversible 'nonbreeder' stage (to which surviving adults transition with a probability of 0.28). The transitions between breeding and nonbreeding states had twice the influence on λ than fertility (summed matrix-element elasticities of 24% and 11%, respectively), whereas almost 15 times as many studies document components of fertility than breeding propensity (n = 103 and n = 7, respectively). The implications of such mismatches are complex because the motivations for feasible on-the-ground conservation actions may be different from what is needed to reduce uncertainty in population projections. Our workflow could form an early part of the toolkit informing future investment of finite resources, to avoid repeated disconnects between data needs and availability thwarting evidence-led conservation.

Demographic responses of hybridizing cinquefoils to changing climate in the Colorado Rocky Mountains.

Hybridization between taxa generates new pools of genetic variation that can lead to different environmental responses and demographic trajectories over time than seen in parental lineages. The potential for hybrids to have novel environmental tolerances may be increasingly important in mountainous regions, which are rapidly warming and drying due to climate change. Demographic analysis makes it possible to quantify within- and among-species responses to variation in climate and to predict population growth rates as those conditions change. We estimated vital rates and population growth in 13 natural populations of two cinquefoil taxa (Potentilla hippiana and P. pulcherrima) and their hybrid across elevation gradients in the Southern Rockies. Using three consecutive years of environmental and demographic data, we compared the demographic responses of hybrid and parental taxa to environmental variation across space and time. All three taxa had lower predicted population growth rates under warm, dry conditions. However, the magnitude of these responses varied among taxa and populations. Hybrids had consistently lower predicted population growth rates than P. hippiana. In contrast, hybrid performance relative to P. pulcherrima varied with population and climate, with the hybrid maintaining relatively stable growth rates while populations of P. pulcherrima shrank under warm, dry conditions. Our findings demonstrate that hybrids in this system are neither intrinsically unfit nor universally more vigorous than parents, suggesting that the demographic consequences of hybridization are context-dependent. Our results also imply that shifts to warmer and drier conditions could have particularly negative repercussions for P. pulcherrima, which is currently the most abundant taxon in the study area, possibly as a legacy of more favorable historical climates. More broadly, the distributions of these long-lived taxa are lagging behind their demographic trajectories, such that the currently less common P. hippiana could become the most abundant of the Potentilla taxa as this region continues to warm and dry.

What are The Best Outcome Measures for Persons with Hypermobile Ehlers-Danlos Syndrome and HSD: A Pilot Study?

Background: Hypermobile Ehlers-Danlos, (hEDs), and Hypermobile Spectrum Disorder (HSD) are connective tissue diseases that are often clinically indistinguishable. The purpose of this study was to assess 3 outcomes for utility for persons with these diseases in terms of intrarater, interrater reliability and intertrial reliability as well as, the Health Assessment Questionnaire Disability Index (HAQ-DI) an assessment of participants perception of pain and quality of life. To assess change in vital signs and cortisol saliva measures before and after testing. Lastly, compare participants to normal. Methods: Participants attended 3 sessions within 2 weeks. Two trained examiners assessed the reliability of the two-minute walk test, (2MWT), five times sit to stand (5XSTS), grip strength on five participants. There were 10 participants, each completed the self-report, (HAQ-DI). 10 trained assessors evaluated between 1-10 of the participants for the stability of the scores between three trials. Vital signs and rate of perceived exertion (RPE) were assessed pre and post 2MWT; saliva samples were taken. Statistics: For 5 subjects the ICC (2,3) was computed for intra and interrater reliability. For 10 subjects (ICC3,3) intertrial consistency was done. Paired t tests assessed grip strength, change after 2MWT for vital signs, changes in cortisol, and assess the HAQ-DI between administrations. Pearson correlations were completed on HAQ-DI variables, RPE, saliva, and vital signs. Results: All intra and interrater reliability, intertrial agreement was found to be good to excellent. Paired t tests indicated that the HAQ-DI was stable and indicated a moderate perception of pain and reductions in quality of life. These participants showed evidence of impairments relative to normal. There were no differences in saliva cortisol levels. Conclusion: These tests appear to have utility in identification of impairments in bodily systems, activity levels and participation in these participants. Further investigation is necessary in order to establish the optimal management.

The inclusion of immediate and lagged climate responses amplifies the effect of climate autocorrelation on long‐term growth rate of populations

Abstract Climate variability will increase with climate change, and thus it is important for population ecologists to understand its consequences for population dynamics. Four components are known to mediate the consequences of climate variability: the magnitude of climate variability, the effect size of climate on vital rates, covariance between vital rates and autocorrelation in climate. Recent studies have pointed to a potential fifth component: vital rates responding to climate in different timeframes, with some responding more immediately and some having lagged responses. We use simulations to quantify how all five components modify the consequences of climatic variability on long‐term population growth rates across a range of life histories defined by life expectancy and iteroparity. We use an established method to compose Matrix Population Models for 147 life histories. Our simulations show that including different timeframes for vital rates responses to climate can either reduce or amplify the negative influence of climate variability on long‐term population growth rates. The negative effect of different timeframes for vital rates responses on population growth is amplified when climatic autocorrelations are negative, and when species are long‐lived. Synthesis. The existing literature shows that vital rates often respond to climate in different timeframes, and that studies often ignore climate autocorrelation. Our results show that simultaneously including both of these factors can substantially increase or decrease a population's expected growth rate. Moreover, the relative magnitude of this change increases with the generation time of a life history. Our results are relevant to conservation, population forecasts and population modelling in general.

Zoop to poop: assessment of microparticle loads in gray whale zooplankton prey and fecal matter reveal high daily consumption rates

The ocean continues to be a sink for microparticle (MP) pollution, which includes microplastics and other anthropogenic debris. While documentation of MP in marine systems is now common, we lack information on rates of MP ingestion by baleen whales and their prey. We collected and assessed MP loads in zooplankton prey and fecal samples of gray whales (Eschrichtius robustus) feeding in coastal Oregon, USA and produced the first estimates of baleen whale MP consumption rates from empirical data of zooplankton MP loads (i.e., not modeled). All zooplankton species examined were documented gray whale prey items (Atylus tridens, Holmesimysis sculpta, Neomysis rayii) and contained an average of 4 MP per gram of tissue, mostly of the microfiber morphotype. We extrapolated MP loads in zooplankton prey to estimate the daily MP consumption rates of pregnant and lactating gray whales, which ranged between 6.5 and 21 million MP/day. However, these estimates do not account for MP ingested from ambient water or benthic sediments, which may be high for gray whales given their benthic foraging strategy. We also assessed MP loads in fecal samples from gray whales feeding in the same spatio-temporal area and detected MP in all samples examined, which included microfibers and significantly larger morphotypes than in the zooplankton. We theorize that gray whales ingest MP via both indirect trophic transfer from their zooplankton prey and directly through indiscriminate consumption of ambient MPs when foraging benthically where they consume larger MP morphotypes that have sunk and accumulated on the seafloor. Hence, our estimated daily MP consumption rates for gray whales are likely conservative because they are only based on indirect MP ingestion via prey. Our results improve the understanding of MP loads in marine ecosystems and highlight the need to assess the health impacts of MP consumption on zooplankton and baleen whales, particularly due to the predominance of microfibers in samples, which may be more toxic and difficult to excrete than other MP types. Furthermore, the high estimated rates of MP consumption by gray whales highlights the need to assess health consequences to individuals and subsequent scaled-up effects on population vital rates.

RETRACTED: A primer of community ecology using the R language

AbstractCommunity ecology beginners often struggle to understand theories expressed in complex mathematical formulas and to master computer programming. To remedy this situation, this article provides a practical, R‐based introduction to community ecology by illustrating core concepts (vital rates, carrying capacity, and density dependence) and models that can be used to explore the patterns of species abundance and diversity. The structure of this article consists of three modeling exercises, each asking a general question that can be answered by a combination of theory and R programming: (1) what determines the abundance of species, and what makes a population persist and go extinct?; (2) what determines the distribution of species and species diversity?; (3) what determines the relative abundance of species and what allows species to coexist? Through the exercises, I discuss the following five concepts and ideas that provide valuable insights into the questions: (i) the tragedy of the commons, (ii) the theory of island biogeography, (iii) competitive exclusion, (iv) the neutral theory of biodiversity, and (v) frequency dependence. These materials are thus designed to guide the reader in developing an intuition for ecological thinking that will help capture the essence of the global environmental and biodiversity crisis. Although this article does not delineate the scope and depth of the vast field of community ecology, I hope that it will motivate the reader to step up to a more formal introduction to community ecology.

Vital rates of a burgeoning population of Humpback Chub in western Grand Canyon

AbstractObjectiveThe Colorado River ecosystem has experienced habitat alterations and nonnative species invasions; as a result, many of its native species have had extirpations, abundance declines, and range constrictions. Despite these pitfalls, the Humpback Chub Gila cypha has persisted and in the last 10–15 years has expanded its range to become abundant in western Grand Canyon, a river segment in which it had been rare for the prior three decades. The goal of this study was to evaluate the population dynamics (i.e., growth, survival, movement, abundance) for this “new” group of Humpback Chub.MethodsWe analyzed a 6‐year mark–recapture study from a fixed monitoring reach in western Grand Canyon, and we provide the first estimates of survival and growth (vital rates) for these fish. We compared vital rates in western Grand Canyon to those of two life history forms (residents and migrants, representing fast and slow life history trajectories, respectively) from the more established Little Colorado River (LCR) aggregation in eastern Grand Canyon.ResultCompared to LCR migrants and LCR residents, Humpback Chub in western Grand Canyon had intermediate values for apparent survival, growth, and asymptotic length. Relatively high survival of subadults coupled with fast growth allowed for rapid population growth in western Grand Canyon. However, a large cohort in 2017 failed to lead to noticeable increases in adults. Seasonal survival patterns were distinct in all three groups, and apparent survival was lowest in western Grand Canyon during spring months. Adult Humpback Chub in western Grand Canyon were mobile and had a high probability of transience (i.e., just passing through the reach) and temporary emigration, demonstrating the need for future movement studies in western Grand Canyon to better distinguish emigration from survival.ConclusionThere is considerable spatial variability in viral rates for Humpback Chub in Grand Canyon. We discuss how observations are related to disparate temperature regimes experienced by the three groups and whether (how) the relationship between metabolism and temperature influences vital rates within the river network.

A hierarchical modelling framework for estimating individual‐ and population‐level reproductive success from movement data

Abstract Rapidly advancing animal telemetry technologies paired with new statistical models can provide insight into the behaviour of otherwise unobservable free‐living animals. Changes in behaviour apparent from pairing telemetry with statistical models often occur as animals undertake key life‐history activities, such as reproduction. For many species that are secretive or occupy remote areas, these life‐history events are difficult to detect with conventional survey techniques, and consequently, vital rates are difficult to estimate. We present a hierarchical modelling framework, which integrates movement data observed via animal‐borne telemetry and optional, infrequent survey data, to estimate individual‐ and population‐level reproductive success. The approach combines a mechanistic movement model and survival model, and allows for assessing the effects of hypothesized individual and environmental covariates on reproductive success. We first tested our approach with simulated data, and then applied it to movement data from migratory golden eagles (Aquila chrysaetos) breeding in southcentral Alaska across four breeding seasons. We show that results supported our biological hypotheses that changes in movement coincided with the timing of reproductive failures, and that changes in movement could be used to assess breeding success (and failure) at the individual and population levels. The analysis also provided evidence of inter‐annual variation in population‐level nest success and the timing of nesting failures. This new approach is adaptable to many species that care for young and can be tracked with telemetry devices, and can provide not only individual‐level information useful for testing ecological hypotheses, but estimates of demographic parameters that can directly inform conservation and management if tagged animals are representative of the population.

VITAL RATES, THEIR VARIATION AND NATURAL SELECTION: A CASE FOR AN ATLANTIC FOREST MARSUPIAL

Evolutionary theory predicts that viable wild populations confront environmental variation by maintaining the variance of the most important vital rates low, a phenomenon also known as demographic buffering. However, patterns diverging from the demographic buffering hypothesis have also been reported. Here we used Population Matrix Models to test the hypothesis of buffering in the early survival of an Atlantic Forest marsupial. We used sensitivity analyses, which allow quantifying the effects that perturbations in specific vital rates could have on the population’s growth rate. We obtained the sensitivities, elasticities, and second-order derivatives of the discrete population growth rate with respect to different vital rates for a population of the black-eared opossum ( Didelphis aurita , Marsupialia, Didelphidae) in a preserved Atlantic Forest, the state of Rio de Janeiro, Brazil. The second-order derivatives offer an insight into the selection forces occurring during the life cycle, clarifying the processes behind the common pattern of early-survival importance. We found evidence of buffering in early survival, however, in one of the cohorts, early survival displayed evidence of opposed behavior to the expected under demographic buffering, thus revealing that established life-history patterns can be quickly modified by a small change in one vital rate.

Spatiotemporal variation in pup abundance and preweaning survival of harbour seals (Phoca vitulina) in the St. Lawrence Estuary, Canada

Marine mammal populations worldwide greatly benefitted from conservation measures put in place since the 1970s following overexploitation, and many pinniped populations have recovered. However, threats due to bycatch, interspecific interactions or climate change remain, and detailed knowledge on vital rates, population dynamics, and their responses to environmental changes is essential for efficient management and conservation of wild populations. In this study, we quantified pup abundance and survival of individually marked harbour seal ( Phoca vitulina Linnaeus, 1758) pups during the preweaning period at Bic Island and Métis sites in the St. Lawrence Estuary from 1998 to 2019. We used mark-recapture models to evaluate competing hypotheses regarding variation in daily preweaning survival rates and capture probability during the pups’ first 30 days of life. Pup abundance increased from 76 [95% CI: 59, 101] to 323 [95% CI: 233, 338] in the past two decades at Bic Island and from 66 [95% CI: 47, 91] to 285 [95% CI: 204, 318] at Métis. Preweaning survival was generally higher at Bic (0.73 [95% CI: 0.58, 0.82]) than at Métis (0.68 [95% CI: 0.52, 0.79]). We hypothesize that differences between habitats and human disturbance contribute to lower preweaning survival at Métis, but behavioural studies are needed to understand the impacts of disturbance on mother–pup interactions during the nursing period.

A mathematical model of the impacts of climate change on the winter tick epizootic in moose

The winter tick (Dermacentor albipictus) is a cervid-targeting parasite that poses serious conservation concerns for moose (Alces alces) in North America. Described as a greater “enemy” of moose than wolves, bears, and cougars, winter tick parasitism causes moose to excessively groom during nutritionally limited periods, leading to lethal combinations of malnutrition and wound-infections. We construct two mathematical models using ordinary differential equations (ODEs) parameterized by the empirical literature to simulate in silico the seasonal relationships between winter ticks and moose — ultimately producing the first application of mathematical models to this phenomenon. We then use our mathematical models to forecast the stability of this parasitic relationship as season lengths fluctuate due to climate change. Finally, we test the high-risk conservation hypothesis that limited, seasonal harvesting can improve moose population stability in the face of these challenges. Our model identifies the parameters (i.e. select vital rates) that give rise to cyclic and sustained epizootics and suggests that delayed first-frosts due to climate change pose a serious threat to maintaining moose populations, but that moderate winter and/or autumn harvesting strategies can reduce the threat of extirpation and stabilize population trajectories.

The implications of seasonal climatic effects for managing disturbance dependent populations under a changing climate

Abstract The frequency of ecological disturbances, such as fires, is changing due to changing land use and climatic conditions. Disturbance‐adapted species may thus require the manipulation of disturbance regimes to persist. However, the effects of changes in other abiotic factors, such as climatic conditions, are frequently disregarded in studies of such systems. Where climatic effects are included, relatively simple approaches that disregard seasonal variation in the effects are typically used. We compare predictions of population persistence using different fire return intervals (FRIs) under recent and predicted future climatic conditions for the rare fire‐dependent herb Eryngium cuneifolium. We used functional linear models (FLMs) to estimate the cumulative effect of climatic variables across the annual cycle, allowing the strength and direction of the climatic impacts to differ over the year. We then estimated extinction probabilities and minimum population sizes under past and forecasted future climatic conditions and a range of FRIs. Under forecasted climate change, E. cuneifolium is predicted to persist under a much broader range of FRIs, because increasing temperatures are associated with faster individual growth. Climatic impacts on fecundity do not result in a temporal trend in this vital rate due to antagonistic seasonal effects operating through winter and summer temperatures. These antagonistic seasonal climatic effects highlight the importance of capturing the seasonal dependence of climatic effects when forecasting their future fate. Synthesis. Awareness of the potential effects of climate change on disturbance‐adapted species is necessary for developing suitable management strategies for future environmental conditions. However, our results suggest that widely used simple methods for modelling climate impacts, that disregard seasonality in such effects, may produce misleading inferences.

Estimating population viability of the northern Great Plains piping plover population considering updated population structure, climate change, and intensive management

One challenge in wildlife conservation is understanding how various threats and management actions may influence long-term population viability. This is particularly evident when there is considerable uncertainty regarding population structure and vital rates. Reassessment of current knowledge and population trends is necessary for listed species to improve management actions that benefit conservation. We present an updated population viability analysis for northern Great Plains piping plovers (Charadrius melodus circumcinctus) based on the latest scientific data on survival, fecundity, and connectivity. Further, we explore the consequences of potential management actions and the stochastic effects of global climate change on population viability through changes in survival and fecundity. Our results predict elevated risks of extinction after 50 years (0.088 – 0.373) compared to previous predictions (0.033) based on assumed conditions of low connectivity among four major breeding groups structured as a metapopulation. We explored eight scenarios based on empirically-derived, higher connectivity rates and found that the northern Great Plains population never had a mean predicted population growth rate greater than one (0.946 – 0.996). Two scenarios that simulated a reduction in adult survival showed higher extinction probabilities (0.267 – 0.373), whereas two other scenarios that simulated an increase in fecundity exhibited lower extinction probabilities (0.088 – 0.103). These results indicate that viability of the northern Great Plains population of piping plovers could be improved with management actions that increase fecundity as long as adult survival is not simultaneously reduced. Lastly, breeding groups appeared to function less independently when connectivity rates were higher, as the breeding population was divided evenly among breeding groups. This indicates that the presumed metapopulation structure of our study system may need to be re-evaluated, and that empirically-based estimates of connectivity are essential to assessing population viability of mobile species that exhibit a spatially structured distribution.

Modeling the impacts of a changing and disturbed environment on an endangered beluga whale population

Climate change and disturbance from human activities are key threats facing many wildlife populations worldwide. The ability to quantify the effects of such threats on individual health and population dynamics is critical for effective management and conservation. We used Stochastic Dynamic Programming (SDP), a method for implementing state-dependent life history theory, to explore the impacts of changes in prey availability and anthropogenic disturbance on survival and reproductive success of Cook Inlet belugas (Delphinapterus leucas, CIB), an endangered and isolated population in decline. We predicted behavioral decisions (whether to forage, travel to a new location, or rest) of pregnant CIBs within a spatially and seasonally dynamic prey landscape. We used those decisions to explore time-activity budgets and spatial use under a variety of hypothetical environmental scenarios and estimate the resulting impacts on body condition and vital rates. In all scenarios, foraging activity was highest during summer to capitalize on abundant prey, which in the model was assumed to be eulachon (Thaleichthys pacificus) and salmonids (Oncorhynchus spp.). This resulted in large increases in blubber reserves that pregnant CIBs relied on during October to April when prey was assumed to be less abundant. Prey availability outside of summer months was still critical, as it either exacerbated or buffered against reductions in prey availability during summer months. Spatial predictions of habitat use indicated that pregnant CIBs should forage in areas used historically that now appear to be abandoned, suggesting that prey availability alone is unlikely to explain the recent range contraction of CIBs to upper Cook Inlet. Reductions in prey availability from late spring to early fall adversely affected vital rates, but intermittent disturbances that resulted in lost foraging opportunities, such as those caused by anthropogenic activities during the ice-free season, had little impact on body condition or vital rates if prey were abundant during the summer and early fall. Accurate assessment of the effects of anthropogenic disturbance on CIBs requires robust data on both disturbances and year-round prey availability, as intermittent disturbances adversely affected survival and reproductive success when they occurred in environments with reduced prey availability. Our model represents an initial effort to fill a critical information gap for informing CIB management decisions, providing insights into conditions under which reductions in vital rates might be expected and highlighting key data needed to increase the applicability of the model to this endangered population.

A demographic approach for predicting population responses to multifactorial stressors.

Populations face a suite of anthropogenic stressors acting simultaneously, which can combine additively or interact to have complex effects on population persistence. Yet we still know relatively little about the mechanisms underlying population-level responses to multifactorial combinations of stressors because multiple stressor impacts across organisms' life cycles have not been systematically considered in population models. Specifically, different anthropogenic stressors can have variable effects across an organism's life cycle, resulting in non-intuitive results for long-term population persistence. For example, synergistic or antagonistic interactions might exacerbate or alleviate the effects of stressors on population dynamics, and different life-history stages or vital rates might contribute unequally to long-term population growth rates. Demographic modelling provides a framework to incorporate individual vital rate responses to multiple stressors into estimates of population growth, which will allow us to make more informed predictions about population-level responses to novel combinations of anthropogenic change. Without integrating stressors' interactive effects across the entire life cycle on population persistence, we may over- or underestimate threats to biodiversity and risk missing conservation management actions that could reduce species' vulnerability to stress.

Development of clinically relevant vital signs of goat lambs of different breeds between birth and 28th day of life post natum

Included in the study were 46 healthy, vital born lambs from 28 dams of the breeds White German Edel goat (WGE, n=15), Boer goat (n=7); Toggenburg goat (n=6). The three groups of subjects included 26 WGE, 9 Boer goat and 11 Toggenburg goat lambs. From birth, they were under intensive veterinary control. Vital signs respiratory rate, heart rate, and rectal temperature were measured immediately p.n.; 3rd, 12th, 24th h p.n.; 2nd, 3rd, 5th, 7th, 9th, 14th, 21st, and 28th d p.n. Furthermore, crown-rump length (CRL), birth weight, and weight development until 28th d p.n. Statistical analysis of the data was performed using BMDP/Dynamic Release 7.0 and two-factorial analysis of variance. Vital signs showed a typical course in the first 4 weeks p.n. with a significant decrease in values from the 5th d. p.n. Time as well as breed had significant influence on the development of the respective profiles (covariance analysis; p<0.001). There was a linear correlation for SSL and birth weight (y=0.0037 ×28969; r value 0.7805). Daily weight gain was independent of race and diet type. In contrast, there was a significant dependence between birth type (singleton or multiple birth) and weight gain with p<0.01 and between birth weight and sex (p<0.05). The presented typical, breed-dependent postnatal changes of vital parameters in goat lambs in the period 0-28 days p.n. allow a more specific differentiation between clinically healthy and abnormal individuals in herd management using the physiological value tables. The age-correlated weight gain serves as a further evaluation parameter.