Current Population Trends Research Articles

Habitat selection and population trends of the Torngat Mountains caribou herd

ABSTRACTUnderstanding why species at risk select certain habitat and what components of their life history influence changes in numbers can help mitigate population declines. The Torngat Mountains caribou (Rangifer tarandus) herd in northern Quebec‐Labrador, Canada, is declining, and few studies have examined the potential causes of this decline. We fitted 9 Argos and 26 global positioning system (GPS)‐collars on 35 adult caribou (25 female, 10 male) between 2011 and 2016 to assess seasonal habitat selection at 2 spatial scales, current and future population trends, and interactions with the neighboring Rivière‐George migratory caribou herd. The caribou of the Torngat Mountains herd selected areas with abundant food resources in winter and where prevalence of insects was lower in summer. They did not avoid areas where predation risk was high during calving. Spatial overlap with the Rivière‐George herd range decreased from 1990 to 2015 and was correlated with the size of the Rivière‐George population, which declined drastically during this period. The decline of the Torngat Mountains population was principally attributed to the low survival of adult females (0.72 annual survival rate) owing to subsistence harvest (9/24) and predation (7/24). Demographic models revealed that the growth rate of the population (λ) could vary from 0.83 (current) to 0.94 following a decrease in harvest pressure. Using demographic scenarios, we showed that the Torngat Mountains herd could continue to decrease if no management actions were taken to increase adult female survival. © 2018 The Wildlife Society.

Gender differences in patient and system delay for primary percutaneous coronary intervention: current trends in a Swiss ST-segment elevation myocardial infarction population.

Women with ST-segment elevation myocardial infarction (STEMI) experience greater delays for percutaneous coronary intervention-facilitated reperfusion than men. Whether women and men benefit equally from current strategies to reduce ischaemic time and whether there are gender differences in factors determining delays is unclear. Patient delay (symptom onset to first medical contact) and system delay (first medical contact to percutaneous coronary intervention-facilitated reperfusion) were compared between women ( n=967) and men ( n=3393) in a Swiss STEMI treatment network. Trends from 2000 to 2016 were analysed, with additional comparisons between three time periods (2000-2005, 2006-2011 and 2012-2016). Factors predicting delays and hospital mortality were determined by multivariate regression modelling. Female gender was independently associated with greater patient delay ( P=0.02 vs. men), accounting for a 12% greater total ischaemic time among women in 2012-2016 (median 215 vs. 192 minutes, P<0.001 vs. men). From 2000-2005 to 2012-2016, median system delay was reduced by 18 and 25 minutes in women and men, respectively ( P<0.0001 for trend, P=n.s. for gender difference). Total occlusion of the culprit artery, stent thrombosis, a Killip class of 3 or greater, and presentation during off-hours predicted delays in men, but not in women. A Killip class of 3 or greater and age, but not gender or delays, were independently associated with hospital mortality. STEMI-related ischaemic time in women remains greater than in men due to persistently greater patient delays. In contrast to men, clinical signs of ongoing chest discomfort do not predict delays in women, suggesting that female STEMI patients are less likely to attribute symptoms to a condition requiring urgent treatment.

Strategic Responsiveness and the Minority Public Manager

Representation of minority groups has become an increasingly vital feature of the public sector as a result of current population trends. The purpose of this article is to shed new light on the effect of public organizations on minority communities by addressing the following question: are minority public managers strategic in their responses to minority consumers of public services and the multiple dimensions of their organization's performance? Building upon current perspectives on representation and diversity, this article contributes to existing research by introducing a theory of strategic responsiveness. This theory addresses an important deficiency in existing studies by providing an account of how minority managers in local organizations respond to multiple performance disparities when they seek to maximize the performance of their organizations and the quality of service delivery to underrepresented communities. The findings suggest that when faced with multiple performance pressures, minority managers channel their representation through the area of performance that is linked to their organization's most salient performance objective. These findings have implications for our understanding of the relationship between diversity in public management and organizations' responsiveness to minority communities.

Spatial niche partitioning may promote coexistence of Pygoscelis penguins as climate-induced sympatry occurs.

Climate‐induced range overlap can result in novel interactions between similar species and potentially lead to competitive exclusion. The West Antarctic Peninsula (WAP) is one of the most rapidly warming regions on Earth and is experiencing a poleward climate migration from a polar to subpolar environment. This has resulted in a range expansion of the ice‐intolerant gentoo penguins (Pygoscelis papua) and a coincident decrease in ice‐obligate Adélie penguins (P. adeliae) near Palmer Station, Anvers Island, WAP. Ecologically similar species that share a limited prey resource must occupy disparate foraging niches in order to co‐exist. Therefore, we determined the extent of foraging and dietary niche segregation between Adélie and gentoo penguins during the austral breeding season near Palmer Station. This research was conducted across six breeding seasons, from 2009 to 2014, which allowed us to investigate niche overlap in the context of interannual resource variability. Using biotelemetry and diet sampling, we found substantial overlap in the diets of Adélie and gentoo penguins, who primarily consumed Antarctic krill (Euphausia superba); however, our results showed that Adélie and gentoo penguins partitioned this shared prey resource through horizontal segregation of their core foraging areas. We did not find evidence that Antarctic krill were a limiting resource during the breeding season or that climate‐induced sympatry of Adélie and gentoo penguins resulted in competition for prey or caused the subsequent differing population trajectories. This apparent absence of resource competition between Adélie and gentoo penguins throughout this study implies that current population trends in this region are governed by other biological and physical factors. Our results highlight the importance of understanding the mechanistic processes that influence top predator populations in the context of climate‐driven ecosystem shifts.

Seroprevalence and trends of transfusion transmitted infections in blood donors of rural tertiary care hospital blood bank: a 3 year retrospective study in Chamba (HP)

Background: Timely transfusion of blood saves millions of lives, but unsafe transfusion practices puts millions of people at risk of transfusion transmissible infections (TTIs). Blood transfusion carries the risk of transfusion-transmissible infections including human immunodeficiency virus (HIVI&amp;II), hepatitis B virus (HBV), hepatitis C virus (HCV), malaria and syphilis. With every unit of blood there are 1% chances of transfusion associated diseases.Methods: This study was conducted over a period of 3 years (1stJanuary 2015-31st December 2017) at hospital blood bank of Pt. Jawaharlal Nehru Government Medical College, Chamba (H.P). The study was conducted on both voluntary and replacement blood donors who came to our blood bank and voluntary blood donation camps in and around Chamba. Statistical analysis used. Collected data was analyzed using appropriate statistical softwares such as EPI-INFO and MS-Excel.Results: In our study, we observed a total of 2616 donors over a period of 3 years. In the present study, 847 (32.37%) were voluntary donors and 1769 (67.62%) were replacement donors. Out of 2616 blood samples, 8 were HBsAg positive, 1 HCV positive.Conclusions: Our study shows that the number of blood donors is increasing every year. In our study, the seroprevalence of HBsAg was 0.3% and Hep C was 0.03% in total blood donors. The knowledge of current infectious disease pattern and trends in donor population can help in planning of future blood transfusion related health challenges.

Should the Endangered Status of the Giant Panda Really Be Reduced? The Case of Giant Panda Conservation in Sichuan, China.

Simple SummaryThis study evaluates the effect of local, regional, and global factors on the recovery of giant panda populations and their habitat, questioning the recent downgrading in the conservation status of this iconic species. We highlight the actions taken over the last decade, which were primarily local scale changes and efforts for protecting pandas. Broader regional development and global climate change are expected to negatively affect current population trends in the long-term; this phenomenon has been documented in other wildlife populations also showing a recent recovery. Thus, we call for a revision of the assessments stipulated by the International Union for Conservation of Nature to incorporate broader potential impacts in predicting the future survival of threatened populations, thereby, ensuring that appropriate and objective protection measures are implemented well in advance.The International Union for Conservation of Nature (IUCN) reduced the threat status of the giant panda from “endangered” to “vulnerable” in September 2016. In this study, we analyzed current practices for giant panda conservation at regional and local environmental scales, based on recent reports of giant panda protection efforts in Sichuan Province, China, combined with the survey results from 927 households within and adjacent to the giant panda reserves in this area. The results showed that household attitudes were very positive regarding giant panda protection efforts. Over the last 10 years, farmers’ dependence on the natural resources provided by giant panda reserves significantly decreased. However, socio-economic development increased resource consumption, and led to climate change, habitat fragmentation, environmental pollution, and other issues that placed increased pressure on giant panda populations. This difference between local and regional scales must be considered when evaluating the IUCN status of giant pandas. While the status of this species has improved in the short-term due to positive local attitudes, large-scale socio-economic development pressure could have long-term negative impacts. Consequently, the IUCN assessment leading to the classification of giant panda as “vulnerable” instead of “endangered”, should not affect its conservation intensity and effort, as such actions could negatively impact population recovery efforts, leading to the extinction of this charismatic species.

Reconstructed and Projected U.S. Residential Natural Gas Consumption during 1896–2043

AbstractUsing state-level monthly heating degree-day data, reconstructed per capita natural gas (NGr) consumption records for each state of the continental United States were calculated for 1895–2014 using linear regressions. The regressed monthly NGr values estimate the effects of twentieth- and early twenty-first-century climate variation on per capita natural gas usage, assuming a modern (1990–2013) consumption environment. Using these extended consumption records, the hypothetical effects of climate on past, current, and future natural gas (NG) use are estimated. By controlling for nonclimatic consumption effects, these extended reconstructions provide estimates of the sensitivity of NG consumption to historical climate variation, particularly long-term warming trends, occurring before the period of available consumption records. After detrending, the reconstructions are used to form improved estimates of interannual NG variation under current climate conditions. Given estimates of each state’s current consumption climatology and long-term trends in per capita consumption and current population trends, the net effect of warming and increasing population on future consumption is estimated. Significant long-term negative trends in per capita NG consumption are found in western and northeastern states and in Florida, while southeastern consumption effects reflect a multidecadal temperature cycle. Climate-related consumption effects found here are generally consistent with previous studies, with long-term trend effects limited to less than 12% and multidecadal regime effects limited to less than 9%. Given the stronger positive effects of increasing population on total state natural gas consumption, reduced per capita use associated with warming trends has a weak moderating effect on estimates of projected total consumption in 2043.

Occurrence of large carnivores – Lynx lynx, Canis lupus, and Ursus arctos – and of Felis silvestris in the Czech Republic and western Slovakia in 2012–2016 (Carnivora)

Abstract In the last decades, large carnivores – the grey wolf (Canis lupus), Eurasian lynx (Lynx lynx) and brown bear (Ursus arctos), and to a certain extent also the wildcat (Felis silvestris) – have increased their distribution ranges throughout Europe. Monitoring of their current distribution and population trends in the Czech Republic is crucial for the effective conservation and elimination of possible conflicts with humans in the future. In the last years, many projects focused on small-scale monitoring of large carnivores were implemented in the Czech Republic and the neighbouring mountain ranges of Slovakia. Using their results, we compiled the dataset from different regions and analysed the recent distribution of large carnivores and the wildcat. The distribution maps are based on verified data on the presence and reproduction in 2012–2016. This is consistent with the standardized methodology used across Europe. The Eurasian lynx was the most widespread of all large carnivore species in the Czech Republic, with the two trans-boundary populations (Carpathian and Bohemian-Bavarian-Austrian) occupying 94 out of 868 squares (10.8%) of the mapping grid of the Czech Republic. Reproduction was confirmed in 46.8% of the occupied squares. The grey wolf occupied 6.8% of the squares in the Czech Republic and its reproduction was confirmed in 10.2% of the occupied squares. Three reproducing packs belonging to the Central European lowland population were confirmed and the area occupied by the species increased three times within the study period. The brown bear occupied 2.8% of the squares of the Czech Republic – the area is restricted to the Carpathians – with no signs of reproduction; its distribution fluctuated heavily during the study period. The wildcat occupied the smallest range of the Czech Republic among the studied species (1.4% of the squares) but its reproduction was confirmed in a trans-boundary area (White Carpathians) at the Slovakian side of the border. The wildcat also significantly increased its range from one to six squares during the study period.

High annual survival in infected wildlife populations may veil a persistent extinction risk from disease

AbstractHost response to emerging pathogens is variable, causing uncertainty about population‐level impacts and challenging effective disease management. White‐nose syndrome (WNS) has caused catastrophic declines in some bat species, while others appear less impacted. Developing predictive models based on observed survival patterns can generate testable hypotheses about mechanisms driving population dynamics and contribute to the development of targeted approaches to disease management. We conducted a mark–recapture study of federally endangered Indiana bats (Myotis sodalis) during 2011–2016. Annual survival decreased from 0.78 (95% CI: 0.59, 0.89) and 0.79 (95% CI: 0.70, 0.86) for females and males, respectively, in 2011 to 0.74 (95% CI: 0.33, 0.94) and 0.75 (95% CI: 0.53, 0.89) for females and males, respectively, in 2015. We then modeled two explanatory mechanisms potentially driving the observed patterns: (1) phased exposure to disease through the spatial spread of the pathogen within the hibernaculum; and (2) cumulative mortality risk from iterative yearly WNS infection. Under a phased exposure scenario, models suggest that infected individuals have an average survival probability of 0.68, and disease prevalence is predicted to reach 100% within 9 yr of disease emergence. Under the cumulative mortality risk hypothesis, survival probability of individuals decreases with each infection cycle. In either case, infected populations are predicted to stabilize at a negative growth rate. Results suggest that Indiana bats tolerate a pathogen load prior to onset of infection, leading to a less pronounced population decline than for other susceptible species. However, the long‐term risk of WNS to Indiana bats may be more severe than current population trends suggest. To inform current conservation management, we performed a vital rate sensitivity analysis, which suggested that modest increases in survival (4–5%) through targeted intervention may return declining populations to stability (λ = 1.0). Demographic modeling approaches coupled with continued population monitoring can highlight important differences in disease response, and ultimately extinction risk, in host species allowing conservation practitioners to tailor intervention actions so that they will be most effective.

No evidence of critical slowing down in two endangered Hawaiian honeycreepers.

There is debate about the current population trends and predicted short-term fates of the endangered forest birds, Hawai`i Creeper (Loxops mana) and Hawai`i `Ākepa (L. coccineus). Using long-term population size estimates, some studies report forest bird populations as stable or increasing, while other studies report signs of population decline or impending extinction associated with introduced Japanese White-eye (Zosterops japonicus) increase. Reliable predictors of impending population collapse, well before the collapse begins, have been reported in simulations and microcosm experiments. In these studies, statistical indicators of critical slowing down, a phenomenon characterized by longer recovery rates after population size perturbation, are reported to be early warning signals of an impending regime shift observable prior to the tipping point. While the conservation applications of these metrics are commonly discussed, early warning signal detection methods are rarely applied to population size data from natural populations, so their efficacy and utility in species management remain unclear. We evaluated two time series of state-space abundance estimates (1987–2012) from Hakalau Forest National Wildlife Refuge, Hawai`i to test for evidence of early warning signals of impending population collapse for the Hawai`i Creeper and Hawai`i `Ākepa. We looked for signals throughout the time series, and prior to 2000, when white-eye abundance began increasing. We found no evidence for either species of increasing variance, autocorrelation, or skewness, which are commonly reported early warning signals. We calculated linear rather than ordinary skewness because the latter is biased, particularly for small sample sizes. Furthermore, we identified break-points in trends over time for both endangered species, indicating shifts in slopes away from strongly increasing trends, but they were only weakly supported by Bayesian change-point analyses (i.e., no step-wise changes in abundance). The break-point and change-point test results, in addition to the early warning signal analyses, support that the two populations do not appear to show signs of critical slowing down or decline.

Nitrogen enrichment of host plants has mostly beneficial effects on the life-history traits of nettle-feeding butterflies

Butterflies rank among the most threatened animal groups throughout Europe. However, current population trends differ among species. The nettle-feeding butterflies Aglais io and Aglais urticae cope successfully with the anthropogenic land-use change. Both species are assumed to be pre-adapted to higher nitrogen contents in their host plant, stinging nettle (Urtica dioica). However, it is currently unknown, whether this pre-adaptation enables both Aglais species to cope successfully or even to benefit from the excessive nitrogen availabilities in nettles growing in modern farmlands. For this reason, this study focused on the response of both Aglais species to unfertilized nettles compared to nettles receiving 150 or 300 kg N ha−1 yr−1 (i.e., common fertilizer quantities of modern-day agriculture). Fertilized nettles were characterized by higher nitrogen concentrations and lower C:N ratios compared to the control group. In both Aglais species, the individuals feeding on fertilized nettles had higher survival rates, shorter larval periods and heavier pupae and, in A. urticae also longer forewings. All these trait shifts are beneficial for the individuals, lowering their risk to die before reproduction and increasing their reproductive potential. These responses agree with the well-accepted nitrogen-limitation hypothesis predicting a positive relationship between the nitrogen content of the diet and the performance of herbivorous insects. Furthermore, our findings suggest that the increasing abundance of both Aglais species may result not only from the increasing spread of nettles into the farmland but also from changes in their quality due to the eutrophication of the landscape during recent decades.

Artificial wetlands as tools for frog conservation: stability and variability of reproduction characteristics in Sahara frog populations in Tunisian man-made lakes.

Amphibian populations are in decline principally due to climate change, environmental contaminants, and the reduction in wetlands. Even though data concerning current population trends are scarce, artificial wetlands appear to play a vital role in amphibian conservation. This study concerns the reproductive biology of the Sahara frog over a 2-year period in four Tunisian man-made lakes. Each month, gonad state (parameters: K, GSI, LCI), fecundity, and fertility of females (using 1227 clutches) were evaluated in the field under controlled conditions. Clutches were present for 110-130days at two of the sites, but only for 60-80days at the other two. Maximum egg laying occurred in May, corresponding to the highest point in the gonad somatic index. Clutch densities were higher in the smaller lakes. Female fecundity was in relation to body size; mean clutch fecundity attained 1416 eggs, with no differences observed according to site. Egg fertility varied over a 1-year period, with a maximum in May followed by a decrease when water temperature was at its highest. Eggs were smaller at the beginning of spawning; maximum size was in May, which might explain the higher fertility, but no maternal influence was detected. Embryonic development was strictly dependent on temperature. The population at each site appeared as a small patch within a metapopulation in overall good health, as shown by the relative temporal stability in reproduction variables. Constructed wetlands may therefore play an important role in the conservation of amphibians, especially in semi-arid zones.

Current threats faced by Neotropical parrot populations

Psittaciformes (parrots, cockatoos) are among the most endangered birds, with 31% of Neotropical species under threat. The drivers of this situation appear to be manifold and mainly of anthropogenic origin. However, this assessment is based on the last extensive consultation about the conservation situation of parrots carried out in the 1990s. Given the rapid development of anthropogenic threats, updated data are needed to strategize conservation actions. Using a population approach, we addressed this need through a wide-ranging consultation involving biologists, wildlife managers, government agencies and non-governmental conservation organizations. We gathered up-to-date information on threats affecting 192 populations of 96 Neotropical parrot species across 21 countries. Moreover, we investigated associations among current threats and population trends. Many populations were affected by multiple threats. Agriculture, Capture for the Pet Trade, Logging, each of them affected >55% of the populations, suggesting a higher degree of risk than previously thought. In contrast to previous studies at the species level, our study showed that the threat most closely associated with decreasing population trends is now Capture for the local Pet Trade. Other threats associated with decreasing populations include Small-holder Farming, Rural Population Pressure, Nest Destruction by Poachers, Agro-industry Grazing, Small-holder Grazing, and Capture for the international Pet Trade. Conservation actions have been implemented on <20% of populations. Our results highlight the importance of a population-level approach in revealing the extent of threats to wild populations. It is critical to increase the scope of conservation actions to reduce the capture of wild parrots for pets.

Use of U.S. Census Bureau Data to Expose Students to Dynamic Population Growth

Global human population size and understanding how it has changed and will change in the future are important concepts for students. Here I describe exercises that use online databases provided by the U.S. Census Bureau to show students how both population size and the rate of change vary over time. In the first exercise, the U.S. population clock is used to calculate daily birth, death, and migrant and death rates, and how the world population clock is used to calculate the rate of change. These rates can be used to predict what the population size would be if the rates remained unchanged for a predetermined time interval. In the second exercise, historical data are used to determine the years with the most change in U.S. and world population size, then calculate how much larger the current population would be if those historical rates of change remained constant. These exercises have improved quantitative literacy while showing students current and historical trends in human population.

A COMPARISON OF THE PREVALENCE OF DEMENTIA IN THE UNITED STATES IN 2000 AND 2012

Importance The aging of the US population is expected to lead to a large increase in the number of adults with dementia, but some recent studies in the United States and other high-income countries suggest that the age-specific risk of dementia may have declined over the past 25 years. Clarifying current and future population trends in dementia prevalence and risk has important implications for patients, families, and government programs. Objective To compare the prevalence of dementia in the United States in 2000 and 2012. Design, Setting, and Participants We used data from the Health and Retirement Study (HRS), a nationally representative, population-based longitudinal survey of individuals in the United States 65 years or older from the 2000 (n = 10 546) and 2012 (n = 10 511) waves of the HRS. Main Outcomes and Measures Dementia was identified in each year using HRS cognitive measures and validated methods for classifying self-respondents, as well as those represented by a proxy. Logistic regression was used to identify socioeconomic and health variables associated with change in dementia prevalence between 2000 and 2012. Results The study cohorts had an average age of 75.0 years (95% CI, 74.8-75.2 years) in 2000 and 74.8 years (95% CI, 74.5-75.1 years) in 2012 ( P = .24); 58.4% (95% CI, 57.3%-59.4%) of the 2000 cohort was female compared with 56.3% (95% CI, 55.5%-57.0%) of the 2012 cohort ( P P P Conclusions and Relevance The prevalence of dementia in the United States declined significantly between 2000 and 2012. An increase in educational attainment was associated with some of the decline in dementia prevalence, but the full set of social, behavioral, and medical factors contributing to the decline is still uncertain. Continued monitoring of trends in dementia incidence and prevalence will be important for better gauging the full future societal impact of dementia as the number of older adults increases in the decades ahead.

Genetic population structure of black‐browed and Campbell albatrosses, and implications for assigning provenance of birds killed in fisheries

Abstract Previous genetic studies found evidence of at least three distinct groups of black‐browed Thalassarche melanophris and Campbell Thalassarche impavida albatrosses in the Southern Ocean. Almost 350 individuals including samples from additional breeding sites on the Falkland Islands and South Georgia Island were screened using mitochondrial DNA. The new sequence data using lineage specific PCR primers provided further support for the taxonomic split of T. melanophris and T. impavida and separate management of the two distinct T. melanophris groups. In total, 207 black‐browed albatrosses killed in longline fisheries were screened. Approximately 93% of the bycaught birds from the Falkland Islands belonged to the Falkland mtDNA group and the remaining birds had mtDNA from the Widespread T. melanophris group; these proportions were similar to those in the local Falklands breeding population. The South African and South Georgia bycatch samples predominantly comprised the Widespread T. melanophris group, with only one bird from each area containing Falkland mtDNA. Lastly, 81% of the albatrosses bycaught off New Zealand had T. impavida mtDNA and the remaining four birds were Widespread T. melanophris. These differences in bycatch composition matched what is known from tracking and banding data about the at‐sea distribution of black‐browed albatrosses. Based on the mtDNA results and current population trends, consideration should be given to assigning regional IUCN status for the different breeding populations.

Threshold of long-term survival of a coastal delphinid in anthropogenically degraded environment: Indo-Pacific humpback dolphins in Pearl River Delta

Defining demographic and ecological threshold of population persistence can assist in informing conservation management. We undertook such analyses for the Indo-Pacific humpback dolphin (Sousa chinensis) in the Pearl River Delta (PRD) region, southeast China. We use adult survival estimates for assessments of population status and annual rate of change. Our estimates indicate that, given a stationary population structure and minimal risk scenario, ~2000 individuals (minimum viable population in carrying capacity, MVPk) can maintain the population persistence across 40 generations. However, under the current population trend (~2.5% decline/annum), the population is fast approaching its viability threshold and may soon face effects of demographic stochasticity. The population demographic trajectory and the minimum area of critical habitat (MACH) that could prevent stochastic extinction are both highly sensitive to fluctuations in adult survival. For a hypothetical stationary population, MACH should approximate 3000-km2. However, this estimate increases four-fold with a 5% increase of adult mortality and exceeds the size of PRD when calculated for the current population status. On the other hand, cumulatively all current MPAs within PRD fail to secure the minimum habitat requirement to accommodate sufficiently viable population size. Our findings indicate that the PRD population is deemed to become extinct unless effective conservation measures can rapidly reverse the current population trend.

Simulation and "Seduction" at the Policy Interface

Simulation and "Seduction" at the Policy Interface Kevin T. Baker (bio) At a press conference held at the Smithsonian Institution in 1972, an interdisciplinary team of researchers from one of the world's most prestigious scientific institutions predicted the end of industrial civilization. If current trends in population and economic growth continued, they argued, pollution and the depletion of natural resources would cause billions to die of starvation and environmentally induced illnesses by the middle of the 21st century. The MIT team behind this study, led by Donella and Dennis Meadows, reached this conclusion using a new method of computer simulation. Their work was sponsored by the Club of Rome, a predominantly European organization of industrialists, intellectuals, and academics led by Aurelio Peccei, a charismatic, globetrotting automobile executive. The Club of Rome had organized the Smithsonian conference to announce the release of The Limits to Growth, a book based on the MIT team's study. The Limits to Growth went on to sell over 12 million copies worldwide and was translated into nearly 40 languages.1 The book's harrowing predictions about the consequences of economic growth sparked a debate that dominated international politics in the 1970s and remains with us today. Although the book—and the "World 3" simulation model that formed the book's methodological core—carried the prestige of computation and quantification with it, this new kind of simulation lacked the prestige of econometric modeling, a discipline with a long postwar pedigree and a close relationship with policy making. Lay audiences may have been electrified (and terrified) by World 3's gloomy projections, but most policymakers and the people who advised them were decidedly more skeptical. Seeking to address these problems, the researchers in the new field of global modeling developed new ways of presenting their simulations to policymakers, leaning on the new affordances offered by time-sharing and interactive terminals. Beginning in the 1980s, scholars in science and technology studies have investigated how expert communities have incorporated computer simulation in their work and how these computer programs have altered the character of that work. This field has been defined by the work of Sherry Turkle, who, starting with The Second Self, has stressed the seductive, immersive nature of simulations. For Turkle, these technologies enable us to go beyond mere representation; simulation allows users to build, inhabit, and manipulate new worlds. "Simulation," as she puts it, "demands immersion and immersion makes it hard to doubt simulation."2 Yet this was not always the case. Practitioners in the field of global modeling found it all too easy for their audiences to doubt simulation. My dissertation deals with how researchers in the new field of global modeling inspired by the Limits report sought to address and overcome this skepticism. In the world of public policy, the usual way to do this was by offering quantitative evidence. Since the start of the 20th century, experts had relied on quantitative data to establish authority and to inspire confidence in the plausibility and objectivity of their recommendations. As historians of science such as Theodore Porter have shown, researchers began to offer their assessments in a quantified form at a historical moment when the culture's trust in elites was eroding in the face of a democratizing, growing society.3 Partly as the result of this shift, "trust in numbers" had come to stand in for trust in people in public policy debates in the first half of the 20th century. But the global modelers I study faced a situation where trust in numbers was no longer sufficient. These "simulationists" were working within a new, relatively unknown discipline with a methodology illegible to most policymakers and bureaucrats. Faced with these problems, as this discipline matured in the mid-1970s, its practitioners increasingly saw their goal as not only producing truth with their models but also imbuing them with trust. In doing so, designers reimagined policymakers as users and began to focus on creating interactive experiences that could incorporate the experienced judgment of these users. The spread of time-sharing and terminals in the 1970s offered new possibilities, including that of close real-time interactivity. Simulationists seized on this more intimate...

What drives current population trends in forest birds – forest quantity, quality or climate? A large-scale analysis from northern Europe

Changes in forestry practices and on-going climate change may both have large impacts on forest bird populations. However, large-scale analyses of the effects of temporal changes in forest structure on forest bird numbers are largely lacking. We compared temporal trends from two Swedish nationwide long-term monitoring schemes, the Swedish Bird Survey (1998–2015) and the Swedish National Forestry Inventory (1983–2014), giving representative values for both forest and bird changes over an area of 35millionha. Since 1998 the total area of middle-aged and mature forest increased by 6.4%. In parallel, several forest structures potentially beneficial to birds (dead wood, retention trees on clear cuts, multi-layer forests, old forest and broadleaved forest) increased somewhat in abundance, most likely as a result of legislation changes and increasing areas under forest certification schemes. Summer temperatures also increased, with warm summers dominating since 2002. In 1998–2015, the population sizes of 58 forest bird species on average increased, as did the number of species observed per route, with no general difference between forest specialists (16 species) and generalists (42 species). However, from around 2005, the positive trends in bird numbers and many forest structures have levelled out. An analysis of species population trends in relation to a measure of climate sensitivity (Species Temperature Index, STI) suggested that forest birds, just like Swedish birds in general, have indeed been affected by a warming climate. But given their STI, forest birds on average had more positive trends than non-forest birds, suggesting that other factors than climate have affected them positively. Strong candidate factors are the documented changes in forest quality and quantity. Whereas our data and analyses are correlational, and no firm conclusions on causality therefore can be drawn, it is reasonable to assume that the recent increases in forest quantity, forest quality, and summer temperatures, all have contributed to the general increase in forest bird numbers in Sweden. But the relative contribution of these driving forces remains to be determined. When it comes to the potentially positive effects of improving forest quality in terms of increases in old forest, stratification, retention trees and dead wood, it is noteworthy that many of the positive trends in forest structures since the mid-1990s seem to have ceased recently.

A Comparison of the Prevalence of Dementia in the United States in 2000 and 2012

ImportanceThe aging of the US population is expected to lead to a large increase in the number of adults with dementia, but some recent studies in the United States and other high-income countries suggest that the age-specific risk of dementia may have declined over the past 25 years. Clarifying current and future population trends in dementia prevalence and risk has important implications for patients, families, and government programs.ObjectiveTo compare the prevalence of dementia in the United States in 2000 and 2012.Design, Setting, and ParticipantsWe used data from the Health and Retirement Study (HRS), a nationally representative, population-based longitudinal survey of individuals in the United States 65 years or older from the 2000 (n = 10 546) and 2012 (n = 10 511) waves of the HRS.Main Outcomes and MeasuresDementia was identified in each year using HRS cognitive measures and validated methods for classifying self-respondents, as well as those represented by a proxy. Logistic regression was used to identify socioeconomic and health variables associated with change in dementia prevalence between 2000 and 2012.ResultsThe study cohorts had an average age of 75.0 years (95% CI, 74.8-75.2 years) in 2000 and 74.8 years (95% CI, 74.5-75.1 years) in 2012 (P = .24); 58.4% (95% CI, 57.3%-59.4%) of the 2000 cohort was female compared with 56.3% (95% CI, 55.5%-57.0%) of the 2012 cohort (P < .001). Dementia prevalence among those 65 years or older decreased from 11.6% (95% CI, 10.7%-12.7%) in 2000 to 8.8% (95% CI, 8.2%-9.4%) (8.6% with age- and sex-standardization) in 2012 (P < .001). More years of education was associated with a lower risk for dementia, and average years of education increased significantly (from 11.8 years [95% CI, 11.6-11.9 years] to 12.7 years [95% CI, 12.6-12.9 years]; P < .001) between 2000 and 2012. The decline in dementia prevalence occurred even though there was a significant age- and sex-adjusted increase between years in the cardiovascular risk profile (eg, prevalence of hypertension, diabetes, and obesity) among older US adults.Conclusions and RelevanceThe prevalence of dementia in the United States declined significantly between 2000 and 2012. An increase in educational attainment was associated with some of the decline in dementia prevalence, but the full set of social, behavioral, and medical factors contributing to the decline is still uncertain. Continued monitoring of trends in dementia incidence and prevalence will be important for better gauging the full future societal impact of dementia as the number of older adults increases in the decades ahead.