Consequences of migration are as diverse as the causes. The consequences are felt in both the regions i.e. the areas of origin of the migrants and the areas of destination. The consequences of migration can be grouped as economic, social and demographic.
Among the economic consequences, the effects on the resource-population ratio is most significant. This ratio undergoes change in both the areas involved. The resource-population ratio may be such in an area which might be called either under populated or over populated or adequately populated or optimum populated.
The condition of under population means a condition of too low a population to allow development and utilization of its resources. On the other hand, over population is a condition, when the pressure of population on resources is very high and generally results in low standards of living.
A country having enough number of people to enable development and utilization of its resources without lowering the quality of life is called adequately populated. If the people are moving from an area of over-population to an area of under population, the result is in the direction of balancing the resource-population ratio.
On the other hand if the migration is from an area of under population to over populated or adequately populated, the consequences may be harmful to both the areas.
Migration affects the occupational structure of the population in both the regions. Generally the proportion of working population in source areas is lowered and the same proportion in the receiving areas is increased. Thus the population of the receiving areas tends to become more productive and in the source areas it results in increasing the dependency ratio by reducing the proportion of the working people in the population.
One of the serious consequences of migration is ‘brain drain’. This refers to the migration of the skilled persons from the poorer countries to the developed countries in search of better economic opportunities. An example can be of the migration of the doctors and engineers from India to the USA, the UK and Canada. This type of migration does not alter the resource-population ratio significantly as the number of people involved in migration is not very large.
However the quality of human resources in the source region suffers a lot. The resource of the source regions, which are generally poorer countries can not be developed fully because of the huge size of the population.
Migration involves interaction of different cultures. The receiving areas might receive through migration people belonging to different cultures and this might lead to cultural enrichment. India is a country which received migrants belonging to different cultural groups and the modern culture of India is a result of this inter-mixing of different cultures. Sometimes people, coming together having different cultures might result in cultural conflicts also.
Many migrants (mainly male member) those who stay alone in the city involve in extramarital and unsafe sexual practice. Some of them start taking drugs through infected syringes. Due to these unsafe practices, many of them got HIV infected. But this does not stop here. When these people go back to their home, they infect their spouses. HIV is also transmitted to their unborn child. Why does this happen?
Due to migrations, the characteristics of the populations in both the regions undergo changes not only the age and sex structure of the population but also the rate of growth of population is altered. Generally the proportion of the old, children and females is increased in the source areas due to migration.
On the other hand the proportion of these persons in the population of the receiving areas is generally lowered. So this is one of the reason for high sex ratio in source areas and low sex ratio in the receiving areas. This happens because it is the youthful male population which is mostly involved in migration.
Thus, not only the number of people but also the structure of population in both regions involved in migration is changed. This results in changes in rates of fertility, mortality and consequently in the growth of population. The source regions are depleted of the youthful population and this results in lowered rates of births and comparatively lower rates of growth. An inverse impact is observed in the case of population structure of the receiving areas.