Population control for animals is a common practice to keep wild and domesticated animals under control. This can be achieved simply by separating male and female animals to keep them from procreating. This is not a likely scenario with animals in the wild though. The animals are therefore, killed off to ease the overpopulation problem.
The next issue may be human population control. China has a law that only allows couples to have one child. That seems fair enough if the population is such that it would create bigger problems for couples to have more children. Problems such as not enough food and water come to mind. Japan has an unintentional way of dealing with overpopulation. This country is dealing in a down economy. Couples voluntarily forgo having children or decide, on their own, to have fewer children. Japan has a record for highly educated people who make wise decisions; therefore, the population explosion has been kept to a minimum.
What are the other options? There are several. Mandatory abortion for people who have more than a certain number of children is one. The Chinese law could also be put into effect in other countries. Another is to take away any type of health insurance for senior citizens, forcing them to forgo medication and succumbing to illness.
There are hundreds of ways that population control could be enforced in countries suffering from overpopulation. Most of these solutions are inhumane. Those that are not inhumane are not likely to be accepted by democratic societies. The best solution to overpopulation is to educate people to make wise decisions where procreation is concerned.
People are inclined to wish to make their own decisions about family matters. A down economy is not likely to be a popular form of birth control, although it can work, as witnessed in Japan. The two most viable circumstances are to educate people on the disadvantages of adding to an already explosive population and make birth control easier to obtain.