Demographics of China

The demographics of China demonstrate a large population with a small youth component a result of China's one-child policy. China's population reached 1 billion in 1982; as of November 2019, China's population stands at 1.435 billion, the largest of any country in the world. According to the 2010 census, 91.51% of the population was Han Chinese, 8.49% were minorities. China's population growth rate is only ranking 159th in the world. China conducted its sixth national population census on 1 November 2010. Unless otherwise indicated, the statistics on this page pertain to mainland China only. During 1960–2015, the population grew to nearly 1.4 billion. Under Mao Zedong, China nearly doubled in population from 540 million in 1949 to 969 million in 1979; this growth slowed because of the one-child policy instituted in 1979. The People's Republic of China conducted censuses in 1953, 1964, 1982, 1990, 2000, 2010. In 1987, the government announced that the fourth national census would take place in 1990 and that there would be one every ten years thereafter.

The 1982 census is accepted as more reliable and thorough than the previous two. Various international organizations eagerly assisted the Chinese in conducting the 1982 census, including the United Nations Fund for Population Activities, which donated US$15.6 million for the preparation and execution of the census. China has been the world's most populous nation for many centuries; when China took its first post-1949 census in 1953, the population stood at 583 million. By the sixth census in 2010, the total population had reached to 1,370,536,875, with the mainland having 1,339,724,852, Hong Kong having 7,097,600, Macau having 552,300. In 1982 China conducted its first population census since 1964, it was by far the most thorough and accurate census taken since 1949 and confirmed that China was a nation of more than 1 billion people, or about one-fifth of the world's population. The census provided demographers with a set of data on China's age-sex structure and mortality rates, population density and distribution.

Information was gathered on minority ethnic groups, urban population, marital status. For the first time since the People's Republic of China was founded, demographers had reliable information on the size and composition of the Chinese work force; the nation began preparing for the 1982 census in late 1976. Chinese census workers were sent to the United States and Japan to study modern census-taking techniques and automation. Computers were installed in every provincial-level unit except Tibet and were connected to a central processing system in the Beijing headquarters of the State Statistical Bureau. Pretests and small scale trial runs were conducted and checked for accuracy between 1980 and 1981 in twenty-four provincial-level units. Census stations were opened in urban neighborhoods. Beginning on 1 July 1982, each household sent a representative to a census station to be enumerated; the census required about a month to complete and employed 5 million census takers. The 1982 census collected data in nineteen demographic categories relating to individuals and households.

The thirteen areas concerning individuals were name, relationship to head of household, age, registration status, educational level, occupation, status of nonworking persons, marital status, number of children born and still living, number of births in 1981. The six items pertaining to households were type, serial number, number of persons, number of births in 1981, number of deaths in 1981, number of registered persons absent for more than one year. Information was gathered in a number of important areas for which previous data were either inaccurate or nonexistent, including fertility, marital status, urban population, minority ethnic groups, sex composition, age distribution, employment and unemployment. A fundamental anomaly in the 1982 statistics was noted by some Western analysts, they pointed out that although the birth and death rates recorded by the census and those recorded through the household registration system were different, the two systems arrived at similar population totals.

The discrepancies in the vital rates were the result of the underreporting of both births and deaths to the authorities under the registration system. The 1982 census was a watershed for both Chinese and world demographics. After an eighteen-year gap, population specialists were given a wealth of reliable, up-to-date figures on which to reconstruct past demographic patterns, measure current population conditions, predict future population trends. For example and foreign demographers used the 1982 census age-sex structure as the base population for forecasting and making assumptions about future fertility trends; the data on age-specific fertility and mortality rates provided the necessary base-line information for making population projections. The census data were useful for estimating future manpower potential, consumer needs, utility and health-service requirements; the sudden abundance of demographic data helped population specialists immeasurably in their efforts to estimate world population.

There had been no accurate information on these 21% of the Earth's inhabitants. Demographers, conducting research on global populati


The Diveria is an Alpine river which flows through Switzerland and Italy. It is a tributary of the Toce and therefore, of the Po; the valley crossed by the Diveria, the Val Divedro, is the only one in the Valais to form part of the Po basin rather than that of the Rhône. From its source at an elevation of 2,005 metres in Swiss territory near the Simplon Pass it flows through the hamlet Egga to the village of Simplon. From here it follows a south-easterly course through the Gondo gorge to the hamlet of Gondo in the municipality of Zwischbergen. Turning to the east it enters Italy and passes the villages of Paglino, Iselle di Trasquera and Varzo; this original version of this article included text translated from its counterpart in the Italian Wikipedia, from that in the French Wikipedia

Song sparrow

The song sparrow is a medium-sized American sparrow. Among the native sparrows in North America, it is one of the most abundant and adaptable species. Adult song sparrows have brown upperparts with dark streaks on the back and are white underneath with dark streaking and a dark brown spot in the middle of the breast, they have a long brown rounded tail. Their face is gray with a brown streak through each eye, they are variable in size across numerous subspecies. The body length ranges from 11 to 18 cm and wingspan can range from 18 to 25.4 cm. Body mass ranges from 11.9 to 53 g. The average of all races is 32 g but the widespread nominate subspecies weighs only about 22 g on average; the maximum lifespan in the wild is 11.3 years. The eggs of the Song sparrow are brown with greenish-white spots. Females lay three to five eggs per clutch, with an average incubation time of 13–15 days before hatching. In the field, they are most confused with the Lincoln's sparrow and the Savannah sparrow; the former can be recognized by its shorter, grayer tail and the differently-patterned head, the brown cheeks forming a clear-cut angular patch.

The Savannah sparrow has yellowish flecks on the face when seen up close. Though a habitat generalist, the Song sparrow favors brushland and marshes, including salt marshes across most of Canada and the United States, they thrive in human dominated areas such as in suburbs, agricultural fields, along roadsides. Permanent residents of the southern half of their range, northern populations of the song sparrow migrate to the southern United States or Mexico during winter and intermingle with the native, non-migratory population; the song sparrow is a rare vagrant to western Europe, with a few recorded in Great Britain and Norway. These birds forage on the ground, in shrubs or in shallow water, they eat insects and seeds. Birds in salt marshes may eat small crustaceans, they nest either in trees or shrubs. Song Sparrows with areas of shrub cover in their territory, away from the intertidal coastline, have greater over-winter survival, as well higher reproductive success; the song sparrow has been the subject of several studies detailing the physiological reactions of bird species to conditions such as daylight length and differing climatic conditions.

Most birds gain mass in their reproductive organs in response to some signal, either internal or external as the breeding season approaches. The exact source of this signal varies from species to species - for some, it is an endogenous process separate from environmental cues, while other species require extensive external signals of changing daylight length and temperature before beginning to increase the mass of their reproductive organs. Male specimens of M. melodia gain significant testicular mass in response both to changes in the daily photoperiod and as a result of endogenous chemical signals. Females undergo significant ovarian growth in response to both photo-period and endogenous signals. In this way, M. melodia is amongst only a handful of birds that use both external and engodenous signalling to dictate their breeding season. Hormone levels in both males and females were found fluctuate throughout the breeding season, having high levels in March and late April and declining until May.

These studies suggest that there are multiple factors at work that influence when and how the song sparrow breeds other than just increasing day length. Due to the myriad subspecies of the song sparrow and the varied climate of southern California, where many of these subspecies make their homes, physiological studies were undertaken to determine how climatic conditions and local environment influenced the bill size of M. melodia subspecies. The bill of a bird is important for thermoregulation as the bare surface area makes a perfect place to radiate excess heat or absorb solar energy to maintain homeostasis. Knowing this, comparisons of bill length between individual song sparrows collected in different habitats were made with regard to the primary habitat type or microclimate that they were collected in. Larger beaked subspecies were correlated with hotter microclimates - a correlation that follows from the conditions of Allen's Rule; the sparrow species derives its name from its colorful repertoire of songs.

Enthusiasts report that one of the songs heard in suburban locations resembles the opening four notes of Ludwig van Beethoven's Symphony No. 5. The male uses a complex song to declare ownership of its territory and attract females. Singing itself consists of a combination of repeated notes passing isolated notes, trills; the songs are crisp and precise, making them distinguishable by human ears. A particular song is determined not only by pitch and rhythm but by the timbre of the trills. Although one bird will know many songs—as many as 20 different tunes with as many as 1000 improvised variations on the basic theme,—unlike thrushes, the song sparrow repeats the same song many times before switching to a different song. Song sparrows learn their songs from a handful of other birds that have neighboring territories, they are most to learn songs that are shared between these neighbors. They will choose a territory close to or replacing the birds that they have learned from; this allows. It has been demonstrated that song sparrows are able to distinguish neighbors from strangers on the basis of song, that females are able