Controlling Rodent populations: National Park Service Tips
– Make a thorough inspection of the exterior and interior of a building. The main purpose of an inspection is to identify structural defects which allow rodents to enter buildings. Inspections also provide information on the species of rodent’s present, key shelter areas, locations where animals obtain food and water, and identify conditions around buildings favoring infestations. Those findings are used to set priorities for repairs needed to keep animals out of buildings and to recommend changes in conditions supporting rodent populations.
– Effective exclusion. Rodent control in structures is based on one simple rule: rodents must be prevented from entering a building or a room. Excluding rodents by closing all possible holes where they can enter or leave a structure is always the most important measure against infestation.
– Good sanitation practices that eliminate food, water, and shelter for rodents. Good sanitation removes essential resources (water, food and shelter) needed by rodents and limits the numbers of animals that can live in an area. Good sanitation is very important for controlling rodent populations, but even the best of sanitation measures will not prevent infestations where exclusion is not adequate.
– Continually removing 85 to 95 percent of the rodents present capable of reproduction. Rodents mature quickly and produce large numbers of young. The numbers of animals present will not change much or may continually increase unless most of the breeding adults are removed.
– Regularly checking for new rodent activity. Regular documented re-inspection (monitoring) of sites is important to determine if previous control efforts were effective; to find any newly opened holes animals could use; to watch for changes in sanitation and harborage conditions; and to determine if the numbers of animals present are increasing, decreasing, or unchanging. The importance of continual watchfulness is clear when it is known how rapidly rodent populations can increase and how difficult it is to control established infestations.
– Cooperation between people. Rodent management must always be a team effort between building occupants (affected persons), maintenance workers (for repairs), and area managers(decision makers). It is urgent for all involved persons to be totally committed to and have a clear understanding of the program needs
– Assign responsibilities. Assigning responsibilities to the people involved in the rodent management project is essential to success. Responsibilities with completion dates should be determined by the participants and put in writing. This ensures each team member is aware of what is being done and their responsibilities.
None of the above activities are difficult to do but when any of them are overlooked or not sufficiently stressed, rodent control is often unsuccessful.
Common failures in controlling rodent infestations in buildings are usually the result of one or more oversights:
– Under-estimating the severity of a rodent infestation – either in regard to the numbers of animals present
– Failing to find or satisfactorily closing holes used by animals to enter rooms or buildings.
– Using too few traps, trapping stations, or improperly placing traps.
– Failing to have “buy in” or cooperation of site occupants and management. Usually the result of failure to assign responsibilities in writing.
– Failing to remove trapped rodents which become food for surviving animals.
– Failing to secure garbage and other food supplies.
– Placing too much reliance on poison bait as a means of control.
Mice are actually somewhat smaller than they appear and can squeeze their head through a
hole only about 1/4-inch in diameter, about the same size as a wooden pencil. After getting its head through a hole, a mouse has no trouble getting the rest of its body through.