First observation of the courtship behaviour of the giant devil ray Mobula mobular (Myliobatiformes: Mobulidae)

Courtship behaviour of the giant devil ray Mobula mobular is described from northern New Zealand, temperate southwest Pacific Ocean, for the first time. A mating train consisting of a full-term pregnant female and up to four males was observed over a period of 147 minutes. Their behaviour was similar to courtship behaviour observed in other large mobulids. Biting of the female was not observed, possibly due to the female’s use of the surface to prevent males positioning themselves above her. However, the lead male pressed the female’s abdomen and underside each time the female reached or stopped at the surface. The occurrence of pregnant females and mating behaviour off northern North Island confirms breeding occurs in New Zealand waters.     

First intercourse, contraception and first pregnancy in Flanders: changes during the past 30 years

The investigation of women in Flanders born between 1931 and 1962 shows that premarital sexual intercourse has become almost general and that the age at the onset of sexual intercourse is steadily declining. Until the 1970s in spite of the improving contraceptive behavior of youngsters, the number of women experiencing premarital pregnancy increased and 1st conceptions occurred at an increasingly younger age. The 1970s marked a turning point: fewer women became pregnant before marriage or in adolescnece. From that time, the contraceptive revolution kept pace with the sexual revolution.     

Probabilities of marriage in two outer Hebridean islands, 1861-1990.

A study has been made of the probabilities of marriage of females and males aged 15-49 (either as a whole or in 5-year age groups) in two Outer Hebridean islands, Harris and Barra. The results were compared with ages of marriage and with the frequencies of permanent celibacy. The marriages took place between 1861 and 1990. Median ages of marriage rose to maxima in the 1930s and 1940s, then fell steeply, levelling out latterly. Permanent celibacy was consistently high among females, but rose from much lower levels in males to maxima in the 1970s and 1980s. It is concluded that in these populations age at marriage and the extent of permanent celibacy are largely independent of one another. In both islands the overall probabilities of females marrying fell until the 1920s, and then rose. The last decades showed stability (Barra) and a fall (Harris). Males showed only slight falls to about 1910; data were absent for between 1911 and 1960, but subsequently there was little rise in probability. These overall changes seemed to be associated with reciprocal variations in probabilities in the younger and older age groups. Declining overall probabilities were associated with declines in younger and increases in older age-group probabilities, and vice versa. Non-parametric correlations between median ages of marriage and probability of marriage were negative and generally significant for the 15-19 age group. Among the older age groups coefficients were generally positive. There was some evidence of an association between probability of marriage and sex ratio in any group of potential mates. The effect appeared more marked among 15- to 19-year-old females. Local factors which might explain at least part of the decline in nuptiality for the greater part of the period under study include the decline in the fishing industry and the 'land hunger' which existed until the late 1920s. This decline is interpreted as a 'Malthusian' response to economic and social conditions, but it coexisted with a 'neo-Malthusian' strategy, in the shape of declining marital fertility. The 'Malthusian' strategy seems to have been largely abandoned around the 1950s, but it may have reappeared during the 1980s.     

Modelling population persistence on islands: mammal introductions in the New Zealand archipelago

Islands are likely to differ in their susceptibility to colonization or invasion due to variation in factors that affect population persistence, including island area, climatic severity and habitat modification. We tested the importance of these factors in explaining the persistence of 164 introductions of six mammal species to 85 islands in the New Zealand archipelago using survival analysis and model selection techniques. As predicted by the theory of stochastic population growth, extinction risk was the greatest in the period immediately following introduction, declining rapidly to low probability by ca 25 years. This suggests that initially small populations were at greatest risk of extinction and that populations which survived for 25 years were likely to persist subsequently for much longer. Islands in the New Zealand archipelago become colder and windier with increasing latitude, and the probability of mammal populations persisting on islands declined steeply with increasing latitude. Hence, our results suggest that climatic suitability was an important determinant of the outcome of these invasions. The form of the relationship between latitude and persistence probability differed among species, emphasizing that the outcome of colonization attempts is species-environment specific.     

The relationship between legal abortion and marriage.

A study using the abortion-birth ratios for residents of each U.S. state for the second half of 1970 and for all of 1971 was done to determine if legal abortions reduced marriages. Data showed that trends were consistent with the hypothesis that a relationship exists between l egalized abortion-birth ratios and trends in crude marriage rates among states between 1967 and 1971 with reduction in crude marriage rates in the states with the relatively high abortion-birth ratios. Change in po licy on induced abortions may be responsible for the increased trend in the U.S. crude marriage rate from 1959-1970 and for its levelling off in 1971 and 1972. Analysis of data also suggested that there is a relation ship between less restrictive abortion policies and a decline in crude marriage rates. An estimation of the number of marriages postponed for at least one year following legal abortion indicated that about 1 abortion in 10 delays a marriage when all the decline in marriage rates were caused by increased abortions and when no legal abortions were subs titutes for illegal abortions. Results were obtained employing general measures for variables, but stronger relationships might be produced if more refined measures which consider race, age, parity, and marital status were introduced.     

Down syndrome: interaction between culture, demography, and biology in determining the prevalence of a genetic trait

The incidence of Down syndrome (DS) at conception is highly dependent upon the maternal age distribution and age-specific pregnancy rates. Live-birth prevalence of DS reflects these factors and fetal deaths. Since the introduction of prenatal diagnosis in the early 1970s, the role of fetal deaths in the equation has increased. Between 1920 and the early 1980s, DS live-birth prevalence decreased in many populations due to declining fertility rates, particularly among older women. In the late-1970s the trend reversed, as the median age of populations and birth rates among older women steadily increased. This paper illustrates these interactions using data we have analyzed for New York State (NYS) and comparative data obtained from the literature. Between 1983 and 1997 DS live-birth prevalence in NYS remained stable at about 9.9 per 10,000 live births. The number of prenatal tests performed increased by 158%, and the number of DS fetuses detected prenatally more than quadrupled. Fertility rates of women aged 35-49 continued to increase. The proportion of DS cases born to these older mothers increased from 23% in 1985 to 43% in 1997. We estimated that without prenatal diagnosis, DS live-birth prevalence would have been 17.0 per 10,000 live births by 1995. Cultural factors influence demographic trends, birthing technologies, physician practices, and women's decision-making regarding prenatal screening and diagnosis for DS.     

The potential beginning of a postwhaling recovery in New Zealand humpback whales (Megaptera novaeangliae)

Between the 1940s and 1970s Southern Hemisphere populations of humpback whales (including eastern Australia and Oceania populations) were hunted to near extinction by extensive commercial whaling activities in Antarctica, with fewer whales taken in shore whaling operations in New Zealand, Australia (including Norfolk Island) and Tonga. Variable rates of recovery of these populations have been documented, ranging from recovery to prewhaling numbers in eastern Australian humpbacks to very little sign of recovery in many Oceania populations. Here we analyze recent sighting data collected over 12 yr, from annual surveys in Cook Strait, New Zealand. The data show an increase in sightings, at an estimated rate of 13% (95% CI of 4.9% and 21.7%) in 2015, of humpback whales migrating through Cook Strait. The wide confidence intervals preclude substantive conclusions about the rate of increase but suggest humpback whales are returning to this region in increasing numbers, indicating an influx of immigrants from neighboring areas, namely eastern Australia.     

The recent and Paleogene craniid brachiopod,Valdiviathyris quenstedti Helmcke, 1940

Recent and fossil (mid‐Cenozoic) specimens of the brachiopod Valdiviathyris quenstedti Helmcke, 1940 are described from New Zealand. The unusual median processes of this genus are shown to be the attachment sites of the brachial protractor muscles. Valdiviathyris is compared with Ancistrocrania, Neoancistrocrania and Novocrania and is considered to be a valid separate genus in the family Craniidae.     

Stable aggregate fertility in a time of family change: a decomposition of trends in American fertility, 1970-1999

Population-level birth rates in the United States were largely stable between 1970 and 1999. This stability contrasts with rapid change in marriage rates and fertility timing during the same period. In this article, I use decomposition techniques to analyze this seeming paradox. I decompose the general fertility rate into four components: age distribution, marital status, age-specific nonmarital fertility, and age-specific marital fertility. Absent other changes, declining time spent married would have led to substantial decline in fertility. Several factors combined to counterbalance these changes in marital behavior. Among white women in the 1970s and 1980s, marital fertility rates increased at older ages, consistent with a scenario in which women postponed both marriage and childbearing; increased nonmarital birth rates during this period were not a driving factor in overall fertility trends. Increased nonmarital fertility was more important in compensating for declining time spent married among African American women and among white women in the 1990s.     

REBUILDING SEAL STOCKS IN THE KATTEGAT-SKAGERRAK

The harbor seal ( Phoca vitulina ) population in the Kattegat-Skagerrak area has been dwindling for several centuries due to excessive hunting pressure. Corrected hunting statistics during 1890–1976 are used to estimate changes in population size over the past century. After protection was introduced in the 1960s and 1970s the harbor seal population in the area increased at an exponential rate of 0.12 and exceeded 5,000 animals in 1986. The present rate of population growth is used for modelling the influence of fertility and age-specific mortality. It is found that the observed high rate of increase is only realistic if female fertility rate is very high, the range of juvenile mortality rate is 0.33–0.52 and adult mortality is less than 0.15. Commonly cited higher mortality rates are not realistic in the Kattegat-Skagerrak area.     

Responses of kukupa (

The kukupa or New Zealand pigeon (Hemiphaga novaeseelandiae) is gradually declining on the New Zealand mainland, due mostly to predation by introduced pest mammals including ship rats (Rattus rattus) and brushtail possums (Trichosurus vulpecula). We report on a co-operative project between Maori landowners, the Department of Conservation, and Manaaki Whenua–Landcare Research researchers to restore a Northland kukupa population and to examine kukupa nesting success in relation to pest abundance. Ship rats and possums were targeted by trapping and poisoning throughout Motatau Forest (350 ha) from 1997 to 1999; only possums were targeted in 2000. All 13 kukupa nests located before pest control started in late 1997 failed at the egg stage, but all seven nests located in 1998–99 successfully fledged young when trapping and tracking indices of possums and ship rats were less than 4%. After pest control, counts of kukupa and some other bird species increased at Motatau compared with counts in a nearby non-treatment block, suggesting numbers of adult kukupa can be increased in small forest areas by intensive pest control. This increase is due at least partly to increased nest success. Evidence from time-lapse video cameras, sign remaining at nests, and nest success rates under different pest control regimes suggest both ship rats and possums are important predators at kukupa nests.     

A period analysis of parity distribution among white and nonwhite women in the United States, 1940–1974

Abstract

The historical trends of childlessness and of one‐child, two‐child, and three‐or‐more‐child families among white and nonwhite women in the United States are studied in terms of period fertility tables. Given the age and parity of a woman, we can read from the fertility tables how her parity is expected to change at successive ages during the rest of her childbearing period, if she is subjected to the age‐parity‐specific fertility rates for a particular year. The fertility tables for white and nonwhite women are constructed for the years 1940, 19S0, 1960, 1970, and 1974. These tables show that among white women who have completed their childbearing (with period rates), the percentage with more than two children has decreased from 66 in 1960 to 27 in 1974, whereas the corresponding reduction among nonwhite women is from 67 to 48 per cent (Table 1, Case 1).     

藏北牧区地表湿润状况对气候变化的响应

利用1961～2006年藏北牧区6个站月平均最高气温、最低气温、降水量、风速、相对湿度、日照时数资料,应用Penman-Monteith模型计算得出潜在蒸散,分析了地表湿润指数的变化趋势、年代际变化特征及季节差异,并讨论了影响地表湿润指数的气象因子.研究表明:近46a藏北牧区年地表湿润指数呈现增大趋势,增幅0.01～0.05/10a;四季地表湿润指数大部分牧区也呈增大趋势,春、秋季增幅明显.近26a(1981～2006年)、季潜在蒸散表现为明显的减少趋势,降水量显现增多趋势,地表湿润指数增大趋势加大,以夏季最为突出.就年平均而言,藏北牧区20世纪60年代初、中期以高湿低温为其主要气候特征;20世纪60年代后期至80年代中期,表现为冷干型的气候特征;90年代初之后,气温持续升高,地表湿润指数显著增加,呈现以暖湿为主的年代际变化特征.湿润指数对降水量、相对湿度和气温日较差的响应最为敏感,而对日照时数和风速的响应也较为明显.     

Fur seals at Macquarie Island: post-sealing colonisation,trends in abundance and hybridisation of three species

Commercial sealers exterminated the original fur seal population at Macquarie Island in the early 1800s. The first breeding record since the sealing era was not reported until March 1955. Three species of fur seal now occur at Macquarie Island, the Antarctic (Arctocephalus gazella), subantarctic (A. tropicalis) and New Zealand (A. forsteri) fur seal. Census data from 54 breeding seasons in the period 1954–2007 were used to estimate population status and growth for each species. Between the 1950s and 1970s, annual increases in pup production for the species aggregate were low. Between 1986 and 2007, pup production of Antarctic fur seals increased by about 8.8% per year and subantarctic fur seals by 6.8% per year. The New Zealand fur seal, although the most numerous fur seal species on Macquarie Island, has yet to establish a breeding population, due to the absence of reproductively mature females. Hybridisation among species is significant, but appears to be declining. The slow establishment and growth of fur seal populations on Macquarie Island appears to have been affected by its distance from major population centres and hence low immigration rates, asynchronous colonisation times of males and females of each species, and extensive hybridisation.     

Economics of sheep production

The aims of this paper are to give a brief overview of world sheep production at present and to describe in detail sheep production and profitability using New Zealand as a case example. Sheep numbers have been declining throughout the world over the last five years, resulting in decreased sheep meat production and a resultant shortage of supply. There is evidence that demand in the short-term will not be met by the major exporters (New Zealand and Australia). Although sheep numbers have declined in New Zealand, production has increased dramatically, with lambing percentages increasing from 98% in 1987 to 125% in 2008 and carcass weights from 14 to 17 kg, respectively. Despite this production increase, return on capital in the farming business has been around 1% per annum. However, property values have increased by around 10% offsetting the low return on capital from farming sheep. There are a number of challenges facing New Zealand's sheep farmers, namely changing land-use patterns, climate change and greenhouse gas mitigation, all of which will potentially impact on future profitability.     

Mortality from asthma: a new epidemic in New Zealand

Trends in mortality attributed to asthma in the 5-34-year age group were examined in New Zealand, Australia, England and Wales, the United States, Canada, and West Germany for the years 1959-79. An epidemic of deaths from asthma occurred in the mid-1960s in New Zealand, Australia, and England and Wales but not in the other countries. In Australia and England and Wales the death rate quickly returned to pre-epidemic levels, but in New Zealand the decline in mortality was slow, and by 1974 the death rate was still almost double the pre-epidemic level. Of great concern was an abrupt increase in reported deaths from asthma in New Zealand after 1976 with the mortality rate during 1977-9 being greater than during the previous epidemic. In contrast, asthma mortality had remained relatively stable in the other populations.The new epidemic in New Zealand was investigated and appeared to be real. It could not be explained by changes in the classification of deaths from asthma, inaccuracies in death certification, or changes in diagnostic fashions. The most likely explanation appeared to be related to the management of asthma in New Zealand, and this is being investigated.     

Climatic regime shifts and decadal-scale variability in calanoid copepod populations off southern California

Decadal‐scale climatic regimes and the shifts between them have important impacts on marine ecosystems. Climatic regime shifts have been observed or hypothesized in the North Pacific basin in 1976–77 and 1989. This paper examines long‐term (1951–99) trends in calanoid copepod populations off southern California, and the evidence for responses to regime shifts. Most of the species of calanoid copepod that were analysed underwent one or more step changes during the 49 years covered by the study. All but one of these changes occurred in five periods: the late 1950s, late 1960s, mid‐1970s, early 1980s and around 1990. The late 1960s changes are considered to be artifacts of an increase in sampling depth. Strong El Niño conditions affected California waters during the late 1950s and early 1980s. The step changes of the mid‐1970s and late 1980s to early 1990s may have been responses to regime shifts or other climatic events. 28% of the species and subspecies responded to the 1976–77 event, all increasing in abundance. Another 28% of the copepod categories underwent step changes around 1990, most decreasing. Evidence for regime shifts in the hydrographic variables that were examined is mixed. The 10‐m temperature increased in the mid‐1970s. Abrupt changes in variables around 1990 were short‐lived. However, the population responses around 1990 and to the El Niños of the late 1950s and early 1980s indicate that some species of calanoid copepods may respond on longer time scales to environmental conditions that persist only a few years.     

The Effect of Male Incubation Feeding,Food and Temperature on the Incubation Behaviour of New Zealand Robins

Because of finite resources, organisms face conflict between their own self‐care and reproduction. This conflict is especially apparent in avian species with female‐only incubation, where females face a trade‐off between time allocated to their own self‐maintenance and the thermal requirements of developing embryos. We recorded incubation behaviour of the New Zealand robin (Petroica longipes), a species with female‐only incubation, male incubation feeding and high nest predation rates. We examined how male incubation feeding, ambient temperature and food availability (invertebrate biomass) affected the different components of females’ incubation behaviour and whether incubation behaviour explained variation in nest survival. Our results suggest that male incubation feeding rates of 2.8 per hour affect the female’s incubation rhythm by reducing both on‐ and off‐bout duration, resulting in no effect on female nest attentiveness, thus no support for the female‐nutritional hypothesis. The incubation behaviours that we measured did not explain nest survival, despite high nest predation rates. Increased ambient temperature caused an increase in off‐bout duration, whereas increased food availability increased on‐bout duration. While males play a vital role in influencing incubation behaviour, female robins attempt to resolve the trade‐off between their own foraging needs and the thermal requirements of their developing embryos via alternating their incubation rhythm in relation to both food and temperature.     

Trends in the Supply and Distribution of Physicians in Saskatchewan: January 1962 to June 1964

Using all the readily available sources of information, a study was designed to describe the changes in supply and distribution of physicians in Saskatchewan during the inception of the Province''s controversial Medical Care Insurance Act. Baselines were obtained in January 1962, and comparisons made in June 1963 and June 1964. The physician:population ratio was 1:1037 in January 1962 and 1:980 in June 1964. The average yearly physician turnover rate of 10% was exceeded in 1960 and in 1961 and then levelled off. The levelling off continued from January 1962 to June 1963. But between June 1963 and June 1964 the total number of physicians was sufficient both to re-establish the rising trend of the previous decade and to offset some of the losses of 1960-1962.     

Ethnic fertility differences in Canada, 1926-71: an examination of assimilation hypothesis

The changing pattern of fertility differences among ethnic groups in Canada during the period 1926-71 is studied. 2 specific questions are addressed. The 1st is do ethnic groups assimilate the fertility patterns of the general Canadian population over time, e.g. are the fertility differences disappearing? Secondly, is the extent of assimilation in fertility greater in urban than in rural areas? The indirectly standardized general fertility rates, calculated by using the ethnic age distribution data from the censuses of 1931 to 1971, indicate a tendency for the population to become more homogeneous during times of increasing fertility, thus supporting the assimilative possibilities, whereas in times of declining fertility there is a tendency for the population to become more heterogeneous. The data also seem to support weaker assimilatory tendencies in rural areas than in urban areas during only the most recent period, 1966-71, and not in earlier periods.