Population growth trends in India: 1991 census

The decennial census counted the total population of India at 843.931 million as of the sunrise of March 1, 1991. The total is 160.6 million higher than that of a decade earlier in 1981. The actual census count exceeded by 45 million the official projections for 1991 based on the 1971 census. However, the official projections for the same year based on the 1981 census fell short by 7.6 million only. Most of the observed differences are explained by the slower decline in the fertility levels. The population growth ratepeaked during 1971–81, perhaps in 1972–73 (based on the Sample Registration Scheme data). The average annualexponential growth rate declined marginally to 2.11 per cent (4.5%) after having remained at a plateau for the previous two decades of 1961–71 and 1971–81. At this point in time, the fertility and mortality trends indicate that India will reach the replacement level fertility [Net Reproductive Rate of Unity] by the years 2010–2015. It can be said with a greater degree of certainty that the official target of reaching the replacement level fertility by the year 2000a.d. will not be reached. Based on the 1991 census results, it can be said that India will reach the billion mark by the turn of the century. The World Bank projects a population of 1,350 million by the year 2025a.d., and a stationary population of 1,862 million by the year 2150a.d., assuming that the replacement level fertility [Net Reproductive Rate = 1] in India is reached about the year 2015a.d.     

Fertility trends in Australia

Using published data from the Australian vital registration and census systems, several time series are compiled: crude birth rates from the 1860s; fertility rates from the 1880s; age-specific and parity-specific measures from the 191Os; cumulative fertility measures by birth year of parent beginning with the 1890s; and cumulative fertility measures for marriages by year contracted from the 1910s.The decline in fertility to the 1930s, the upswing to 1961, and declines thereafter revealed by annual fertility measures show far more variation than do measures of total generation fertility—2.7 children per woman born in 1893–95, 2.3 1906–10, 2.8 1921–25, and perhaps 3.0 for women born in the 1930s. Both annual and generation measures show a younger age at parenthood, a decrease in childlessness, and progressively fewer large families. In the light of present experience, it seems not unreasonable to project generation fertility of 2.5 children, implying a crude birth rate of about 20 per thousand for the next fifteen years or so.     

Population dynamics ofMalacosoma neustria testacea (Lepidoptera: Lasiocampidae): Stabilizing process in a field population

Summary Stabilizing mechanism in population ofMalacosoma neustria testacea was investigated in a central part of Japan based on eight year survey. Population fluctuation in each developmental stage in the experimental field was rather small, i.e., 5.9 times in egg and 85.0 times in female adult. Pupal weight negatively correlated with the densities of 5th instar larvae and prepupae (cocoons) and correlation coefficient was highly significant in females. Population density was stabilized by density-dependent dispersal of female moths in preovipositional period. Comparison between fecundity of emerged moths and that of actually oviposited ones in the experimental field suggested that density-dependent dispersal took place as the result of density-dependent size variation, i.e., small-sized female months have higher flying ability. This hypothesis was supported by the experiment in which flying ability of newly emerged female moth was measured. Similar stabilizing mechanism is expected to occur in semelparous or pro-ovigenic insects. Contribution Ser. A, No. 64 from Fruit Tree Research Station, Ministry of Agriculture and Forestry, Japan     

Life tables and population parameters of the green leafhopper,Nephotettix cincticeps (Uhler), in the southwestern district of Japan with special reference to the first generation on foxtail grass

Summary The three year (1988–1990) life tables ofNephotettix cincticeps were constructed, and the daily survival rate and longevity of female adults were estimated by Hokyo and Kiritani’s (1967) method for the overwintering and the first-generations on the foxtail grass in Okayama, southwestern Japan. The life tables and the population parameter values estimated were compared with those in the other generations on rice. The FARMCOP suction sampler was employed to survey the population density. The durations of pre-ovarial maturation of female adults of the 1st generation on foxtail grass and rice seedling were similar. Longevity of adults of the overwintering and the first generations which emerged on the wild host was longer than that of the other generations (2nd and 3rd generations) on the rice plants. Fecundity of females decreased successively as the generation proceeded and it became lowest in the final 3rd generation. Only about 3.5 percent of first-instar nymphs of the 1st generation emerged as adults in the fallow field. The survival rate of nymphs on foxtail grass was always lower in comparison with that on rice plants. However, the survival rates of nymphs on foxtail grass and rice seedling were not significantly different from each other under laboratory conditions. In the fields, senescence of foxtail grass occurred in the midst of nymphal period of the 1st generation. The survival rate of nymphs on foxtail grass decreased with the increasing in the nymphal density. Abundance of spiders during the 1st generation was higher than that in the early stage of rice plants.     

Determinants Of Cumulative Fertility In Ghana

The relatively few studies conducted on fertility differentials in Ghana have not controlled for the effect of important demographic variables, such as age at first marriage and current age of respondent. This paper attempts a multivariate analysis of the relationship between cumulative fertility and age at first marriage, level of education, religion, form of marriage and residence of husband. Data drawn from a census sample survey in 1971 include 72,816 currently married females aged 15–49 years. Age at first marriage was inversely related to cumulative fertility. The differentials were more pronounced for older women. Among the older women, the differentials were larger for rural than urban women. There were also significant fertility differentials associated with level of education, religion and form of marriage. Husband’s residence was a poor predictor of cumulative fertility. As a policy measure, it is suggested that priority be given to providing young women with more education or employment opportunities as an alternative to early marriage.     

Population dynamics of a phytophagous lady-beetle,Epilachna vigintioctopunctata (Fabricius), living in spatio-temporally heterogeneous habitats. III. Effects of habitat structure on population dynamics

Temporal changes in the population size of a phytophagous lady-beetle were analyzed to identify mechanisms affecting lady-beetle population dynamics at different spatial scales. The study area (15 ha) included 18 habitat patches. The major host plants were potato for first generation larvae and eggplant for second generation larvae. The habitat patches were classified into three groups according to the major host plants in each patch: P-E patches (both host plants available), P patches (potato only), and E patches (eggplant only). The winter disappearance of adults in the whole study area, and larval mortality in E patches were apparently the most important factors disturbing the overall population density. Density-dependent movement of females appeared to have the greatest stabilizing effect on the yearly fluctuation of population density. Rate of increase of female adults from the first to the second generation,R, was generally higher on eggplants in E patches than in P-E patches because the adult density of the first generation was much higher in P-E patches. The yearly fluctuation of adult density in each generation tended to be less in patches with all habitat components necessary for the full life cycle (P-E patches). However, such patches were not favorable for first generation females, as indicated by the lower rate of increase from the first to the second generation. The density and stability of lady-beetle populations is discussed in relation to habitat structure.     

Assesssing Cohort Birth Expectations Data from the Current Population Survey, 1971–1981

Data from the fertility supplements to the Current Population Survey from 1971 to 1981 indicate that in the aggregate, the lifetime birth expectations of married women 18 to 39 years old in 1971 will closely approximate their completed cohort fertility. During this period, the youngest group of women, 18 to 24 years old, delayed their childbearing; their short-term expectations (1971–76) were not realized, but they made up enough births in the latter half of the decade to enable them to attain their lifetime birth expectations. In retrospect, the “failure” of birth expectations data to predict the “period” fertility downswing in the 1970s resulted not from poor predictions of married women, but rather from unanticipated marital and subsequent childbearing patterns of women who were single at the beginning of the decade. The authors conclude that birth expectations are useful predictors of completed cohort fertility, if adjustments are made to incorporate changes in the proportions married within the birth cohort.     

The fertility transition around the world

In this paper, we study the evolution of the distribution of fertility rates across the world from 1950 to 2005 using parametric mixture models. We demonstrate the existence of twin peaks and the division of the world’s countries in two distinct components: a high-fertility regime and a low-fertility regime. Whereas the significance of twin peaks vanishes over time, the two fertility regimes continue to exists over the whole observation period. In 1950, about two thirds of the world’s countries belonged to the high-fertility regime and the rest constituted the low-fertility regime. By the year 2005, this picture has reversed. Within both the low- and the high-fertility regime, the average fertility rate declined, with a larger absolute decline within the high-fertility regime. Visually, the two peaks moved closer together. For the low-fertility regime, we find both β- and σ -convergence but we cannot establish any convergence pattern for the high-fertility regime. Our results support the idea of conditional convergence where the condition is the successful initiation of the fertility transition. The results are less supportive of the existence of a unique high-fertility equilibrium.     

Fertility of Australian birth cohorts: Components and differentials

The paper examines the change in the level and pattern of fertility that took place in the post-1971 period, and the downward completed fertility of successive generations of Australian women born since 1933–37. The change in cohort fertility is assessed in terms of the cohort parity progression ratios, and the four components of cohort total fertility: the proportion of women who proceeded to have a birth, mean age at first birth, mean age at last birth, and average interbirth interval for women who had at least two births. The other aspects discussed are the cohort fertility differentials and the implications of the current trends for future fertility in Australia.     

Urbanization and the fertility transition in Ghana

This paper examines the way in which migration and urban residence operate to alter fertility outcomes. While urban-rural fertility differentials have long been established for most developing societies, the nature of these differences among migrants and between migrants and those of succeeding generations is not well understood. The evidence presented here suggests that rural-urban migration and urbanization may contribute positively to processes of fertility transition. Using data from the 1998 Kumasi Peri-Urban Survey, which included a 5-year retrospective monthly calendar of childbearing, we suggest that migrants adapt quickly to an urban environment. Our results also reveal generational differences in recent and cumulative fertility. While migrants exhibit higher cumulative fertility than urban residents of the second and third generation, their fertility is significantly lower than rural averages in Ghana. Children of migrants exhibit childbearing patterns quite similar to those in higher-order generations. Most noteworthy is the nature of the disparities in childbearing patterns between migrants and the succeeding generations. Migrant women have higher lifetime fertility than urban natives. Migrant women also exhibit higher fertility over the last 5 years than second generation or high-order urban natives. But these first generation women exhibit lower fertility (vs. urban natives) for the year immediately prior to the survey. These patterns lend support to an interpretation that combines rather than opposes theories of selectivity, disruption, adaptation and socialization. We conclude by discussing mechanisms that might explain these interrelated processes of fertility adjustment and suggest that policies discouraging rural-urban migration need to be revisited.     

Immigrant fertility patterns and differentials in Australia, 1971–1976

In this paper the fertility patterns and differentials among various immigrant groups in Australia are examined. Official vital statistics for the period 1971–76 are used.

Fertility ratios standardized by age and marital status suggest that the overall fertility of foreign-born women was higher in both 1971 and 1976; however, some evidence -of convergence towards an ‘Australian’ norm was found.

Four distinct patterns of fertility were noted. In two of them, Arab and South European, marital fertility was substantially higher but non-marital fertility quite low. The North-West European pattern was closest to that of the native-born; however, in the East European pattern fertility was lowest. Component analysis showed that most of the differences between the total fertility rate of Australians and those of the other groups reflect the significantly higher marital fertility rates and proportions married among the foreign-born groups.     

“The decline of the size of the domestic group in England”

This paper examines the relationship between the number of partnerships ever engaged in and fertility, as measured by the average number of live births. It was found that the larger the number of partnerships in which a woman had been engaged the higher is her fertility. This relationship between partnerships and fertility remains even when such variables as present age, age at first partnership, age at first pregnancy, time lost between unions, time spent in partnerships, time since entry into the first partnership, type of sexual union at first pregnancy, present type of sexual union, and current use or non-use of contraceptives are controlled by cross tabulation. Correlation analysis also bears out the positive relationship between partnerships and fertility. The data for this study came from a sample survey of 4,199 women of lower, and lower middle, socio-economic status who were interviewed in 1971 on the island of Barbados. The authors have confidence in the reliability and validity of their data and hence in their findings and conclusions.

The authors believe that their findings contradict the previously established positive relationship between patterns of stability of sexual unions and fertility in English-speaking Caribbean societies. They conclude that the relationship was either not rigorously examined in the past or else has undergone changes as these societies modernize economically and socially.     

Change of marital fertility in China from 1964 to 1981]

In 1982 the Chinese National Family Planning Commission conducted a nationwide (excepting Taiwan and Tibet) .001 random sampling of the total population to gather data on the fertility and age structures of married women. In comparing general marital fertility and standardized fertility, findings show that from 1964 to 1970 both rates averaged 225.1/1000. When family planning work began on a wide scale in 1971, the rates steadily declined, reaching 116.7/1000 in 1980. However, in 1967-68 the standard fertility rate rose by 21.34% due to the chaos of the Cultural Revolution, and in 1980-81 the rate increased by 13.2%, indicating that problems still remain in family planning. The total marital fertility rate dropped 2.84/1000 from 1964 to 1981. The rate of decline in rural areas was greater than in the cities, but the cities had a larger percentage decline than the countryside. In the 5-year periods of 1965, 1970, 1975, and 1980, marital fertility rates tended to decline in 1970 and 1975 among women aged 30-40 years because during those periods greater control was placed on women having multiple children. For 1980 and 1975, combined total rates for 15-19 year olds dropped 17.1%, but the combined total rates of 30-49 year olds dropped by 61.2%, indicating that in recent years the drop in marital fertility is mostly among those over 30 years of age.     

Period Parity Progression Ratios and Birth Intervals in England and Wales, 1941–1971: A Synthetic Life Table Analysis

A method is presented for analysing maternity history data to provide period estimates of parity progression ratios, birth intervals and related indices. This is applied to a sample of the marriage and maternity histories from the Census of England and Wales of 1971 and shows: (a) a general increase through the 1950s and into the 1960s in period estimates of marriage and parity progression ratios, especially in the progression from first to second birth; (b) a general acceleration of fertility with, again, the second birth interval becoming particularly short and compact; and (c) very steep declines in third and fourth birth progression ratios from the mid-1960s. Birth interval distributions altered during the period examined. Decomposition of a progression-based total fertility index shows change in the ratios for lower birth orders to have dominated the fertility upswing and declines in ratios for higher birth orders to have initiated the subsequent decline.     

Fertility and number of partnerships in Barbados

Abstract This paper examines the relationship between the number of partnerships ever engaged in and fertility, as measured by the average number of live births. It was found that the larger the number of partnerships in which a woman had been engaged the higher is her fertility. This relationship between partnerships and fertility remains even when such variables as present age, age at first partnership, age at first pregnancy, time lost between unions, time spent in partnerships, time since entry into the first partnership, type of sexual union at first pregnancy, present type of sexual union, and current use or non-use of contraceptives are controlled by cross tabulation. Correlation analysis also bears out the positive relationship between partnerships and fertility. The data for this study came from a sample survey of 4,199 women of lower, and lower middle, socio-economic status who were interviewed in 1971 on the island of Barbados. The authors have confidence in the reliability and validity of their data and hence in their findings and conclusions. The authors believe that their findings contradict the previously established positive relationship between patterns of stability of sexual unions and fertility in English-speaking Caribbean societies. They conclude that the relationship was either not rigorously examined in the past or else has undergone changes as these societies modernize economically and socially.     

Spatial variation in female fertility related to interactions with flower consumers and pathogens in a forest metapopulation ofPrimula sieboldii

Antagonistic biological interactions with flower consumers and pathogens may influence reproductive success of flowering plants, affecting population dynamics and natural selection for floral traits. However, ecological and evolutionary consequences of the interactions may depend on both spatial and temporal patterns of the interactions. In a forest metapopulation ofPrimula sieboldii E. Morren, an endangered clonal plant species, we measured between-subpopulation patterns of seed sets and interactions with an influential flower consumer, a rove beetle,Eusphalerum bosatsu Watanabe, and a specific smut fungal pathogen,Urocystis tranzschelina (Lavrov) Zundel (Ustilaginales), for three years. Mean female fertility (seed set per flower) for individual subpopulations fluctuated moderately among years but was highly variable within each year among the five subpopulations studied. In two subpopulations, the impact ofEusphalerum beetle, was sufficiently large to result in almost complete failure in seed production over eight years including the three study and five previous preliminary observation years. In the two other subpopulations, seed set failure was caused by infection by the smut fungus. Infected capsules which constitute 10–30% of the capsules produced in the subpopulations were filled with ustilospores instead of seeds. In the subpopulation that escaped flower damage byEusphalerum beetles and smut fungal infection, seed sets of both pin and thrum flowers were much higher than in the other subpopulations. The spatial restriction of individual antagonistic agents to a part of subpopulations suggest that dispersal of the agents, as well as the mode of spatial subdivision of the plant population would be important for determining the overall effects of antagonistic interactions on plant performances at the metapopulation level.     

The influence of first generation fertility and economic status on second generation fertility

This paper examines the impact of parental economic status and family size on the actual and expected fertility of adult children using longitudinal data from two generations of families participating in the Panel Study of Income Dynamics. There was a modest positive relationship between first generation family size and second generation fertility. More importantly, the ideal family size of the parental family was more closely related to fertility behavior and plans in the second generation than was actual parental family size. In addition, the data revealed the hypothesized negative correlation between parental financial status and second generation fertility behavior and plans. Several mechanisms which could produce the correlation between parental characteristics and the fertility of their children are explored.The analysis reported in this paper was supported by Contract NO1-HD-42856 from the National Institute for Child Health and Human Development, Center for Population Research. Dr. Thornton is affiliated with the Survey Research Center, Institute for Social Research, University of Michigan, Ann Arbor, MI 48106. Requests for reprints should be directed to him.     

Growth of U.S. population, 1940–1971, in the light of an interactive two-sex model

Since it is logically impossible to hold constant both male and female age-specific fertility rates, the intrinsic growth rates or the net reproduction rates for males and females, based on that assumption, are internally inconsistent. The interactive two-sex model presented in this paper holds constant a set of bivariate age-specific fertility rates by age of men and women and allows the male and female age-specific fertility rates to adjust themselves to achieve stability. The model gives the same intrinsic growth rate for both sexes and generates intrinsic age-specific fertility rates and intrinsic net reproduction rates for males and females which are consistent and can operate simultaneously on a population. The model is applied to the U.S. data for 1940–1971, and the results are compared with those obtained from the one-sex models.     

Seasonal host alternation by the andromeda lace bug,Stephanitis takeyai (Heteroptera: Tingidae) between its two main host-plant species

I studied the seasonal occurrence of the andromeda lace bug,Stephanitis takeyai, on its two main host-plant species. In a secondary forest in Kyoto, this bug altered its hosts seasonally, i.e., from an evergreen shrub,Pieris japonica, in winter to a deciduous shrub,Lyonia elliptica, in summer. In contrast, in Nara park where fewL. elliptica were available, the bug exploited onlyP. japonica. Thus, seasonal host alternation by this bug is not obligate. A comparison of adult longevity and fecundity on the two host-plant species demonstrated the higher quality ofL. elliptica as a food resource. Corresponding to this difference in host quality, there was a dramatic difference in the seasonal population growth in the two study sites. In Nara, the population size at the beginning of the 2nd generation was almost the same as in the overwintered generation, whereas in Kyoto the population size in the 2nd generation was approximately one hundred times as large as in the overwintered generation. Thus seasonal host alternation is adaptive for the bug. In a previous study, I reported that overwintering as eggs in living leaves of their hosts is likely to be common among all the related species of this bug. Thus, this trait can be considered to be a phylogenetic constraint to the group. I speculate that host alternation by this bug has been derived because it is more adaptive from autoecy on an evergreen plant, similar to the pattern currently found in Nara, and that this bug can not only exploit deciduous host due to a phylogenetic constraint.