Overpopulation or overabundance occurs when a species' population becomes so large that it is deemed exceeding the carrying capacity and must be actively intervened. It can result from an increase in births (fertility rate), a decline in the mortality rate, an increase in immigration, or a depletion of resources.

What causes overpopulation of animals?

Pet “overpopulation” encompasses two primary factors: (1) allowing cats and dogs to reproduce with little chance to find homes for the offspring and (2) pets being relinquished by owners who can no longer keep their animals, or who no longer want them.

What are the main causes of overpopulation?