Changes In Demographic Parameters Research Articles

Demographic Transformations in the Historical Process in the Light of Technological Development: Theoretical Approach

The analysis of the demographic component and of the demographic dimension of historical process has unfortunately not been sufficiently studied in the social sciences. The demographic development of humankind is even more rarely studied in its close connection with technological development. However, this is an extremely important aspect that can not only explain essential dimensions of the development, but also provide a basis for explaining current processes and forecasting our futures. Moreover, in many ways, it is an integral aspect of analysis, because it focuses on people, the population, that is the main subject of society and humanity. Accordingly, the changes in demographic parameters (both quantitative and qualitative) have an impact on the entire social system, from technology to ideology as well as on the World System at whole. Population growth is undoubtedly the most important driving force of the development of society. The most important subsystem of society, which constitutes its material basis, combines population and production. The link between demography and production is seemingly obvious, since, on the one hand, production determines population growth opportunities and, on the other hand, population size affects the production and other opportunities of a society. However, this relationship is not so simple and is also non-linear, and in addition, the correlation between the demographic and production components of societies changes significantly over the course of the historical process. It is also not always so easy to explain strong fluctuations and transformations in population dynamics. In the present study, the authors provide an analysis of the demographic development of humankind in its close connection with technological development, including the twenty-first century trends. This work, consisting of two articles, aims to provide a theoretical framework for the correlation between the development of production and technology, on the one hand, and demographic transformations, on the other, during the historical process, and to describe all major demographic transformations during human history. The work describes the historical types of population reproduction (TPR) and the reasons for their change. All this makes it possible to make a forecast about the vectors and main features of the coming demographic transformation in the twenty-first century. This (first) article describes theoretical approaches and models of the connection between production revolutions (Agrarian, Industrial and Cybernetic) and the largest demographic transformations, and also reflects important points influencing on population growth and its limitatio-ns. It is shown that the production revolution and the development of the production principle cycle in general change the type of population reproduction, and together they provide the most powerful impulse for the qualitative reorganization of the entire social structure and social relations and further world-system configurations. The authors conclude that every production revolution is followed by a fundamental change in demography. And vice versa, population growth causes such changes in society and inter-societal relations, communications and diffusion of innovations that it greatly accelerates technological development. However, there are many nuances and external inconsistencies in this correlation that require explanation. The latter are given in the second article, which also makes predictions about future demographic transformations.

On two conjectures about perturbations of the stochastic growth rate

SummaryThe stochastic growth rate describes long‐run growth of a population that lives in a fluctuating environment. Perturbation analysis of the stochastic growth rate provides crucial information for population managers, ecologists and evolutionary biologists. This analysis quantifies the response of the stochastic growth rate to changes in demographic parameters. A form of this analysis deals with changes that only occur in some environmental states. Caswell put forth two conjectures about environment‐specific perturbations of the stochastic growth rate. The conjectures link the stationary distribution of the stochastic environmental process with the magnitude of some environment‐specific perturbations. This note disproves one conjecture and proves the other.

An Assessment of Population Size and Demographic Drivers of the Bearded Vulture Using Integrated Population Models

Conventional approaches for the assessment of population abundance or trends are usually based on a single source of information, such as counts or changes in demographic parameters. However, these approaches usually neglect some of the information needed to properly understand the population as a whole, such as assessments of the non-breeding proportion of the population and the drivers of population change. The Bearded Vulture Gypaetus barbatus is a threatened species and its Pyrenean population (the largest in Europe) inhabits parts of Spain, Andorra, and France. We developed an Integrated Population Model (IPM) using data from a long-term study (1987–2016) in the three countries, including capture–mark–recapture of 150 marked individuals, to assess population size and age structure at the whole population scale, and obtain estimates of survival and breeding parameters of this population. The breeding population experienced a geometric mean population increase of 3.3% annually, falling to 2.3% during the last 10 yr. The adult proportion of the population increased with time, from 61% to 73%. There were 365 (95% Bayesian credible interval [BCI]: 354–373) adult breeding birds in 2016, representing 49% of the adult population and 36% of the total population (estimated at 1,026 individuals, 95% BCI: 937–1,119). The large number of non-breeding adults probably led to higher mean age of first reproduction than previously estimated, and to an estimated 30–35% of territories occupied by polyandrous trios. Population growth rate was positively and strongly correlated with adult survival, which had a much greater effect on population growth than productivity. The effects of subadult and juvenile survival on population growth were weaker. We found strong evidence for a density-dependent decrease in juvenile survival, productivity and adult survival, leading to reduced population growth with increased population size. Our approach allowed us to identify important conservation issues related to the management of supplementary feeding sites and geographic expansion of this population. Our study supports the use of IPMs as a tool to understand long-lived species, allowing simultaneous estimates of the non-breeding size of the population (which is critical for understanding population functioning), better estimates of population parameters, and assessment of demographic drivers.

An assessment of population size and demographic drivers of the Bearded Vulture using integrated population models

AbstractConventional approaches for the assessment of population abundance or trends are usually based on a single source of information, such as counts or changes in demographic parameters. However, these approaches usually neglect some of the information needed to properly understand the population as a whole, such as assessments of the non‐breeding proportion of the population and the drivers of population change. The Bearded Vulture Gypaetus barbatus is a threatened species and its Pyrenean population (the largest in Europe) inhabits parts of Spain, Andorra, and France. We developed an Integrated Population Model (IPM) using data from a long‐term study (1987–2016) in the three countries, including capture–mark–recapture of 150 marked individuals, to assess population size and age structure at the whole population scale, and obtain estimates of survival and breeding parameters of this population. The breeding population experienced a geometric mean population increase of 3.3% annually, falling to 2.3% during the last 10 yr. The adult proportion of the population increased with time, from 61% to 73%. There were 365 (95% Bayesian credible interval [BCI]: 354–373) adult breeding birds in 2016, representing 49% of the adult population and 36% of the total population (estimated at 1,026 individuals, 95% BCI: 937–1,119). The large number of non‐breeding adults probably led to higher mean age of first reproduction than previously estimated, and to an estimated 30–35% of territories occupied by polyandrous trios. Population growth rate was positively and strongly correlated with adult survival, which had a much greater effect on population growth than productivity. The effects of subadult and juvenile survival on population growth were weaker. We found strong evidence for a density‐dependent decrease in juvenile survival, productivity and adult survival, leading to reduced population growth with increased population size. Our approach allowed us to identify important conservation issues related to the management of supplementary feeding sites and geographic expansion of this population. Our study supports the use of IPMs as a tool to understand long‐lived species, allowing simultaneous estimates of the non‐breeding size of the population (which is critical for understanding population functioning), better estimates of population parameters, and assessment of demographic drivers.

Simulated 2017 nationwide sampling at 13,940 major U.S. sewage treatment plants to assess seasonal population bias in wastewater-based epidemiology

Wastewater-based epidemiology (WBE) is an economical technique for monitoring and managing the health and behavior of human populations. Using 2017 nationwide data on geospatial population demographics as a test case, we simulated repeated sampling at all major U.S. wastewater treatment plants (WWTPs; n = 13,940) under constant biomarker loading conditions, to explore the potential sensitivity of WBE for generating skewed data. Simulation of repeated sewage sampling over all four seasons of 2017 yielded a number of expected, inter-dependent phenomena triggered by cooler wintertime temperatures compared to summertime results, including relatively (i) slower in-sewer biomarker decay, (ii) longer distal reach of WBE, (iii) larger effective sewershed monitoring areas, and (iv) an increase in the population represented. Additional important but not necessarily anticipated simulation outcomes included (v) distinct, non-random changes in demographic parameters of monitored subpopulations (e.g., by household income, educational attainment, military service, unemployment, and lack of health insurance), (vi) recurring observation of the latter demographic patterns across various geospatial scales and regions, and (vii) more evenly distributed results in the winter. In contrast, data obtainable by WBE in the summertime were dominated by households residing closest to the WWTP and subpopulations of relatively lesser wealth, educational achievement, healthcare access and employability. The analytical approach presented here should be readily applicable to other regions worldwide and may help to improve the design, robustness and interpretation of future WBE studies.

Population dynamics of three lizard species from the genus Sceloporus: short-term changes in demographic parameters.

Most demographic studies focus on numerical changes that occur within populations across years. However, typically studies at an interannual scale do not provide information on the particular times of the year (particular months or seasons) when rates of survival, recruitment, or migration increase or decrease due to physiological, behavioral or ecological processes. These monthly or seasonal changes in demographic parameters may lead to substantial variations in population abundance. In this study, we collected capture–mark–recapture data on 3 species of lizards of the genus Sceloporus (Sceloporus torquatus, Sceloporus grammicus and Sceloporus megalepidurus) found in ecologically similar habitats to examine potential changes in demographic rates among 3 different climatic seasons: rainy, cold‐dry and warm‐dry seasons. We tested different hypotheses about the effect of these seasons on survival, recruitment of new adults, and temporary emigration. We found that during the season with severe thermal constraints, the cold‐dry season, survival of S. torquatus decreased markedly. We also detected a considerable increase in the recruitment rate of S. grammicus during the rainy season, when these lizards are establishing territories and finding mates. In contrast, we found no evidence of intra‐annual changes in the rate of temporary emigration. In addition, we calculated abundance and population growth rates for each species and for each season. Our study represents a significant contribution to the understanding of intra‐annual demographic variation in lizards.

Comparative Study to Evaluate Efficacy, Safety and Quality of Life of Metoprolol and Telmisartan versus Metoprolol and Ramipril in Patients of Hypertension

Background: Hypertension(HTN) is a major cardiovascular disease and is a major worldwide clinical problem. The prevalence of hypertension increases in urban and rural areas. The treatment of hypertension began in the 1960s with oral diuretics. The other modalities of treatment of hypertension are beta – blockers, calcium-channel blockers, alphareceptors blockers, ACE inhibitors and ARBs. The better compliance occurs with single-pill combination, and may be even double or even triple pill combination therapy should be used. Also quality of life was improved better with Metoprolol and Telmisartan as compared with Metoprolol and Ramipril. Quality of life was assessed by SF -36 Quiestionnare. Objective: To compare the effect of Metoprolol and Telmisartan versus Metoprolol and Ramipril on BP and quality of life in patients of hypertension. Material and Methods: In this prospective, open, randomized, parallel group, comparative study, 80 patients of hypertension attending the Cardiology Outpatient Department, Govt. Medical College & Rajindra Hospital, Patiala were recruited. This randomized comparative study was done on 80 patients for 4 months. Quality of Life: In my project of Quality of life, I had taken total 80 patients and the patients were divided into two groups and 40 patients each of Metoprolol and Ramipril versus Metoprolol and Telmisartan. To assess quality of life questionnaire SF-36 was administered to the patients. Results: There was a marked decrease in SBP and DBP with the use of Metoprolol and Telmisartan than Metoprolol and Ramipril. There was also no change in demographic parameters. There was significant improvement in the quality of life with Metoprolol and Telmisartan. Conclusion: Metoprolol and Telmisartan was a better choice than Metoprolol and Ramipril in treating hypertension as this combination causes more reduction in BP and little effect on HR.

Estimating age-dependent survival from age-aggregated ringing data-extending the use of historical records.

Bird ring‐recovery data have been widely used to estimate demographic parameters such as survival probabilities since the mid‐20th century. However, while the total number of birds ringed each year is usually known, historical information on age at ringing is often not available. A standard ring‐recovery model, for which information on age at ringing is required, cannot be used when historical data are incomplete. We develop a new model to estimate age‐dependent survival probabilities from such historical data when age at ringing is not recorded; we call this the historical data model. This new model provides an extension to the model of Robinson, 2010, Ibis, 152, 651–795 by estimating the proportion of the ringed birds marked as juveniles as an additional parameter. We conduct a simulation study to examine the performance of the historical data model and compare it with other models including the standard and conditional ring‐recovery models. Simulation studies show that the approach of Robinson, 2010, Ibis, 152, 651–795 can cause bias in parameter estimates. In contrast, the historical data model yields similar parameter estimates to the standard model. Parameter redundancy results show that the newly developed historical data model is comparable to the standard ring‐recovery model, in terms of which parameters can be estimated, and has fewer identifiability issues than the conditional model. We illustrate the new proposed model using Blackbird and Sandwich Tern data. The new historical data model allows us to make full use of historical data and estimate the same parameters as the standard model with incomplete data, and in doing so, detect potential changes in demographic parameters further back in time.

Winter and summer weather modulate the demography of wild turkeys at the northern edge of the species distribution

AbstractTemperate species occupying habitats at the northern limit of their geographical distribution are limited by weather and climatic conditions. Such conditions often directly affect population dynamics, and thus, influence shifts in distribution via changes in demographic parameters. We examined this question by following three distinct populations of wild turkeys inhabiting areas exposed to a gradient of meteorological conditions at the northern limit of the species distribution. Four years of radio‐telemetry on 181 birds and monitoring of 95 nests revealed that population demographics of wild turkeys were influenced by snow depth, winter temperature and summer rainfall. During winter, survival of turkeys decreased drastically when snow depth remained >30 cm for >10 days and also decreased as temperatures got colder. In the spring, snow persistence delayed nest initiation, whereas nest survival was negatively affected by rainfall. Our findings show that the effects of critical meteorological factors such as snow and temperature can be compounded when both reach the limit of a species tolerance simultaneously.

Structural uncertainty limits generality of fall harvest strategies for wild turkeys

ABSTRACTWild turkey (Meleagris gallopavo) populations are broadly distributed, occupy a variety of habitats, and have demographic rates that are heterogeneous through space and time. Dynamics of turkey populations are sensitive to the magnitude of fall either‐sex harvest, yet there have been few attempts to study performance of fall harvests systematically across a range of plausible demographic scenarios. Thus robustness of existing recommendations to structural uncertainty in population dynamics is marginally understood. We used a stochastic, sex‐specific theta‐logistic model to simulate performance of fall harvests (0–15%) across scenarios representing uncertainty about current rates of population productivity (3 levels), female losses during spring hunting (2 levels), and spring male harvest (3 levels), with uncertainty in the strength of density dependence as a common attribute. We demonstrated that performance of previously recommended fall harvests was not robust to changes in demographic parameters that occur within and among populations, and thus previous management recommendations may not be appropriate for all regions. Fall harvest rates capable of maintaining large populations with high probability varied from 0–6% with changes to population productivity, when median male and female spring harvests were 30% and 5%, respectively. In general, risks and management tradeoffs accompanying fall harvests were tightly linked to assumed values of population parameters, where changes to productivity and female loss had particularly strong effects on management outcomes. Specifically, reduced productivity or increased female loss decreased the ability to maintain large populations for a given fall harvest rate. Thus, fall harvest recommendations deduced from models that considered only a small portion of the demographic parameter space may not meet modern management objectives over a broader range of conditions. Moreover, our results suggest that future management could be improved by reducing structural uncertainty about turkey demography to allow for region‐specific harvest strategies, or by using decision‐theoretic approaches to identify harvest strategies that are robust to uncertainty about population parameters. © 2017 The Wildlife Society.

Demographic Changes Underpinning the Population Decline of StarlingsSturnus vulgarisin The Netherlands

Declines in farmland bird populations are often linked to changes in agricultural practices, but little is known about the demographic changes underlying these adverse trends. Identifying the demographic drivers of population change is critical for understanding why populations are declining. In this study we assessed the demographic changes in the declining Dutch Starling Sturnus vulgaris population. We estimated productivity per breeding attempt and survival rates over a period of 52 years (1960–2012). The results show that juvenile survival decreased significantly over time. Adult survival fluctuated between years, with (non-significant) lower survival rates between 1990 and 2012. No trend in reproductive output was found over the study period. A population model was built for three different phases of population change within the study period: 1960–1978, 1978–1990 and 1990–2012. The contribution of changes in demographic parameters to population growth rate (lambda) between the different periods was examined by performing a life table response experiment (LTRE). The LTRE analysis showed that changes in juvenile survival explained most of the differences in population growth rate between periods. Our results therefore suggest that a decline in juvenile survival rather than changes in adult survival or reproductive success is the most important cause of the decline of the Starling population in The Netherlands.

Man-induced activities modify demographic parameters in a long-lived species: effects of poisoning and health policies.

Recent changes in sanitary policies within the European Union (EU) concerning disposal of carcasses of domestic animals and the increase of non-natural mortality factors, such as illegal poisoning, are threatening European vultures. However, the effects of anthropogenic activities on demographic parameters are poorly studied. Using a long-term study (1994-2011) of the threatened Pyrenean Bearded Vulture Gypaetus barbatus population, we assess the variation in the proportion of breeding pairs, egg-laying dates, clutch size, breeding success, and survival following a sharp reduction in food availability in 2005 due to the application of restrictive sanitary policies decreasing livestock carcass availability. We found a delay in laying dates and a regressive trend in clutch size, breeding success, and survival following policy change. The maintenance of specific supplementary feeding stations for Bearded Vultures probably reduced the negative effects of illegal poisoning and food shortages, which mainly affected subadult survival. A drop in food availability may have produced changes in demographic parameters and an increase in mortality due to an increased exposure to contaminated food. As a result, supplementary feeding as a precautionary measure can be a useful tool to reduce illegal poisoning and declines in demographic parameters until previous food availability scenarios are achieved. This study shows how anthropogenic activities through human health regulations that affect habitat quality can suddenly modify demographic parameters in long-lived species, including those, such as survival, with high sensitivity to population growth rate.

PIN127 - Assessing the Fiscal Consequences of Immunizing the Female and Male Population Against Human Papillomavirus (HPV) in Germany

net and gross discounted tax revenues for the government. • The gross tax results suggest that the combined vaccination results in higher tax revenue compared to the option of not immunizing the population. • Every €1 spent immunizing the combined male/female cohort resulted in positive societal benefits of €2.10 and in €1.81 fiscal benefits suggesting that the cost of immunization is counterbalanced by the additional gross tax gained as a result of reducing mortality and morbidity. • This prospective single-cohort model does not capture the additional benefits that herd immunity may generate neither potential future changes in demographic parameters, age of retirement or cancers’ incidence. • This analysis may complement existing cost-effectiveness analyses and inform national level decision makers (i.e. treasuries) as it quantifies the fiscal value of HPV immunization and may inform cross-sectorial resource allocation decisions from governments ASSESSING THE FISCAL CONSEQUENCES OF IMMUNIZING THE FEMALE AND MALE POPULATION AGAINST HUMAN PAPILLOMAVIRUS (HPV) IN GERMANY

Increasing trend in the number of Southern Rockhopper Penguins (Eudyptes c. chrysocome) breeding at the Falkland Islands

The Falkland Islands currently supports one of the largest Southern Rockhopper Penguin (Eudyptes c. chrysocome) populations. Archipelago-wide censuses conducted in 2000 and 2005 revealed that the number of breeding pairs had declined by 30 % during this period. To establish whether the breeding population continued to decline, an archipelago-wide census was conducted in 2010. We report a conservative estimate of 319,163 ±SD 24,820 pairs breeding at the Falkland Islands in 2010. This represents a 51 % increase when compared with the number counted in 2005. A simple stochastic population model was developed to investigate the extent to which changes in demographic parameters between 2005 and 2010 could account for the increase in breeding pairs. The population model predicted a 38 % increase in the number of breeding pairs over a 5-year period (289,431 ±SD 24,615). The increase in the number of breeding pairs was therefore probably attributed to improved vital rates in the period between the 2005 and 2010 archipelago-wide censuses in combination with other factors such as a reduction in the proportion of adult birds that abstained from breeding. Based on the 2010 Falkland Islands estimate, the global population of the subspecies E. c. chrysocome is now closer to 870,000 breeding pairs of which the Falkland Islands accounts for approximately 36 %, the second largest proportion after Chile. We conclude that despite fluctuations, the number of Southern Rockhopper Penguins breeding at the Falkland Islands has increased over the last 15 years and suggest that the ‘Vulnerable’ conservation status of the species be re-assessed.

Beyond the Mean: Sensitivities of the Variance of Population Growth.

Populations in variable environments are described by both a mean growth rate and a variance of stochastic population growth. Increasing variance will increase the width of confidence bounds around estimates of population size, growth, probability of and time to quasi-extinction. However, traditional sensitivity analyses of stochastic matrix models only consider the sensitivity of the mean growth rate. We derive an exact method for calculating the sensitivity of the variance in population growth to changes in demographic parameters. Sensitivities of the variance also allow a new sensitivity calculation for the cumulative probability of quasi-extinction. We apply this new analysis tool to an empirical dataset on at-risk polar bears to demonstrate its utility in conservation biology We find that in many cases a change in life history parameters will increase both the mean and variance of population growth of polar bears. This counterintuitive behaviour of the variance complicates predictions about overall population impacts of management interventions. Sensitivity calculations for cumulative extinction risk factor in changes to both mean and variance, providing a highly useful quantitative tool for conservation management. The mean stochastic growth rate and its sensitivities do not fully describe the dynamics of population growth. The use of variance sensitivities gives a more complete understanding of population dynamics and facilitates the calculation of new sensitivities for extinction processes.

Is life‐history buffering or lability adaptive in stochastic environments?

It is commonly thought that temporal fluctuations in demographic parameters should be selected against because of the deleterious impacts variation can have on fitness. A critical underpinning of this prediction is the assumption that changes in environmental conditions map linearly into changes in demographic parameters over time. We detail why this assumption may often break down and why selection should not always favor buffering of demographic parameters against environmental stochasticity. To the contrary, nonlinear relationships between the environment and demographic performance can produce asymmetric temporal variation in demographic parameters that actually enhances fitness. We extend this result to structured populations using simulation and show that ‘demographic lability’ rather than ‘buffering’ may be adaptive, particularly in organisms with low juvenile or adult survival. Finally, we review previous ecological work, and indicate cases where ‘demographic lability’ may be adaptive, then conclude by identifying research that is needed to develop a theory of life‐history evolution that encompasses both demographic buffering and lability.

Unconfounding the effects of climate and density dependence using 60 years of data on spiny dogfish (Squalus acanthias)

The confounded effects of changes in climate and density on a population’s demography are hard to separate for long-lived species because demographic traits are usually the aggregated result of conditions faced over years. Demographic parameters are compared for spiny dogfish ( Squalus acanthias ) in the Northeast Pacific, the longest lived and latest maturing of all sharks, using samples from the 1940s and 2000s. This 60-year interval has seen ocean temperatures rise by almost 1 °C and dogfish harvests peak above 50 000 tonnes (t)·annum–1 and then drop below 50 t·annum–1. Over this period, the age at 50% maturity for dogfish declined from 43 to 32 years, while the estimated average number of embryos per litter for a 100 cm dogfish increased from 5.9 to 6.7. Growth parameters changed significantly, with faster growth to a smaller size. Leslie matrix analysis showed that these changes could lead to an increase in population growth rate of about 1%. Comparison with published demographic parameters from the 1970s and 1980s indicated that the greatest change in demographic parameters occurred between the 1940s and 1970s, prior to the largest changes in ocean temperatures. The implications for fishing on long-lived populations during times of rapid environmental change are explored.

Changes in Demographic Parameters of Macaca fuscata at Takasakiyama in Relation to Decrease of Provisioned Foods

Though researchers have studied population dynamics extensively in many free-ranging primate populations, information on the relationship between food abundance and demographic parameters based on long-term data is sparse. We examined changes in demographic parameters in relation to decreased provisioning of foods based on data gathered for >50 yr in a provisioned, free-ranging Japanese macaque (Macaca fuscata) population at Takasakiyama, Oita Prefecture, in the southern region of Japan. At Takasakiyama, population size increased linearly because of heavy provisioning in the 1950s and 1960s. The provisioning of food to macaques decreased from 1965. We examined changes in the physique index of full adult females, primiparous age, birth percentage, infant mortality rate, population density, and annual population growth rate relative to the decrease of provisioned foods between the 1970s and 1990s. As a result of the drastic decrease in the amount of foods provisioned, the physique index of full adult females decreased, primiparous age increased, birth percentage decreased, and infant mortality rate increased, such that annual population growth rate diminished substantially. Ours is the first study to demonstrate quantitatively the relationship between provisioned food abundance and demographic parameters based on long-term data.

U.S. Family Household Momentum and Dynamics: An Extension and Application of the ProFamy Method

The classic headship-rate method for demographic projections of households is not linked to demographic rates, projects a few household types without size, and does not deal with household members other than heads. By comparison, the ProFamy method uses demographic rates as input and projects more detailed household types, sizes, and living arrangements for all members of the population. Tests of projections from 1990 to 2000 using ProFamy and based on observed U.S. demographic rates before 1991 show that discrepancies between our projections and census observations in 2000 are reasonably small, validating the new method. Using data from national surveys and vital statistics, census microfiles, and the ProFamy method, we prepare projections of U.S. households from 2000 to 2050. Medium projections as well as projections based on smaller and larger family scenarios with corresponding combinations of assumptions of marriage/union formation and dissolution, fertility, mortality, and international migration are performed to analyze future trends of U.S. households and their possible higher and lower bounds, as well as enormous racial differentials. To our knowledge, the household projections reported in this article are the first to have found empirical evidence of family household momentum and to have provided informative low and high bounds of various indices of projected future households and living arrangements distributions based on possible changes in demographic parameters.

Demographic processes in a local population: seasonal dynamics of the Sinai Baton Blue butterfly

Quantifying abundance and determining the factors affecting it are critical to understanding and conserving small animal populations. The seasonal dynamics of a local population of butterflies Pseudophilotes sinaicus (Lycaenidae) occupying a discrete patch of habitat were investigated using data from a capture-recapture study that sampled the local population every day during the adult flight season in 2002 and 2003. Throughout the study (re)capture rates were extremely high, meaning that intra-seasonal changes in demographic parameters could be accurately assessed. ‘Survival’ rates were not related to the age of adult butterflies, but were lower early in the season compared with later on. This is probably due to emigration of butterflies early in the season, rather than within-patch mortality. Lower survival rates in females compared with males were probablybecause females have both higher within-patch mortality and a higher emigration rate. This confirms results from another study (see James 2007d) that suggested migration in the Sinai Baton Blue was linked to the phenology of its hostplant, Thymus decussatus. Daily variation in the sex ratio is a consequence of between-sex differences in daily recruitment and within-patch survival rates. Males were most abundant relative to females early in the season, indicating protandry. Total adult population size was small and showed dramatic variation between the two years, indicating how vulnerable the local population is to demographic extinction.