How Net Migrants Affect the Sex Ratio in Population Studies?

The third factor affecting the over-all sex ratio of any population is the sex ratio of the net migrants, which is essentially socio-economic in nature.

Migration is ordinarily sex-selective, in the sense that persons of either sex participate in migration rather than persons of both sexes participating equally.

In most countries, the volume of international migrations is not significant enough to have any marked impact on the sex structure of the population. In Argentina and Singapore, however, immigration has influenced the sex structure of the population.

The case of Singapore may be studied in detail. The total population of this country is composed of persons from various ethnic groups Chinese, Indians, Pakistanis, Europeans, Malaysians, Eurasian and others.

The sex ratios of these ethnic groups have undergone considerable changes from 1871 to 1957 because of the sex composition of the various inflows of migrants. In 1871, the sex ratio for the Chinese, Indians-Pakistanis and Europeans was 630.7, 484.4 and 365.6 respectively.

In 1957, however, it was 102.9, 225.7 and 114.0 respectively. The sex ratio for the indigenous Malaysians was 126.8 in 1871, but 110 in 1957.

As a result of these historical facts, the over-all sex ratio of the total population of Singapore decreased from 326.6 in 1871 to 111.7 in 1957, while in 1970 it was only 105 and in 1995 it was 101.

Internal migration is also sex selective but more so in the case of males. When persons of one sex dominate among internal migrants, the sex ratios of the various regions of the country are affected.

For instance, it is known that, in India, among the migrants who go from rural areas to urban areas, the proportion of males is high.

As a result, the sex ratio of the urban population in India has always been higher (111.9 in 1991 and 111.0 in 2001) than that of the rural population (106.6 in 1991 and 105.7 in 2001).

Indian cities have unusually high sex ratios. The sex ratios of some important Indian cities having more than one million population in 1991 are presented.

These figures provide ample proof of the fact that the cityward migration in India is male-dominated. According to the 1971 Census, the Calcutta urban agglomeration has the highest sex ratio (142.6), followed by Greater Bombay (139.6), Kanpur (131.2), Delhi (125.3), and Ahmedabad (120.5).

However, the figures on sex ratio of these 9 cities with population size of more than one million, for 2001 indicate that the value of sex-ratio of each city has gone down considerably compared to 1971. This suggests that over a period of 30 years, the number of females among migrants has increased.

In India, the sex ratio in urban areas is favourable to males. Many European countries, however, as well as United States and Chile present a completely different picture.

In these countries, the sex ratios are lower in urban areas than in rural areas, indicating that women outnumber men in urban areas, while there is preponderance of men in rural areas.

This situation has occurred mainly because of female-dominated internal migration, which is a pattern created by socio-cultural conditions.