Sanitation must be used constantly in rodent control to be effective. Yearly clean-up programs are generally ineffective for rodent control. Predators - Many people have relied on cats and dogs to control rats, but in general cats and dogs are not good tools for control. Food put out for pets is excellent rat food. Most people put out more food than the pet can consume in one day.
Rats then clean the bowl overnight.
Because pets are well-fed, they are too lazy to hunt. Studies have shown that although predators can keep an area rat free, they can not remove an existing infestation. Birds of prey, hawks and owls, feed on large numbers of rodents. Barn owls are exceptional rat killers and a pair can be expected to kill several hundred rats over a one year period. Many species of non-poisonous snakes are very beneficial in rodent control.