Rodent infestations arise because the habitat and the environment provide them with the means to survive. The environment will be supplying the food and the water they need, as well as somewhere to live, shelter move around and to breed successfully.
The more the availability of these factors is limited, the lower the carrying capacity of that environment will become and the lower the level of rodent activity that it will support.
One of the objectives of the survey discussed earlier was to identify where the rodents were feeding, drinking and finding shelter, as well as the routes they were taking to exploit the environment.