Biology and Habits

Norway rats produce 3-6 litters per year with an average of 7-8 young. Rats reach sexual maturity after 5-6 month and the gestation period lasts for approximately 23 days. The average lifespan of a rat is 6-12 months, but they can live longer in captivity. Rans are most active at night, but can be seen during the day, especially when populations are high.  They are excelent climbers and will travel between 100-150 feet from their nest in search of food and water. They are cautious animals and do not often interact with new objects found in their environment. After establishing territories, rats often follow the same routes from their nests to their food and water source. 

Outdoors, Norway rats typically nest in burrows which consist of a main entrance and one or more concealed escape holes. Indoors, they are often found in lower level rooms and basements, but are capable of nesting on upper floors and attics.  As social animals, their nests may contain multiple individuals. Rats are opportunistic eaters, but prefer meats, fish, and cereals. 

Control

Norway rats are effectively controlled through a variety of methods. With existing indoor infestations, snap traps or bait are effective means of control, however it is important to ensure that bait is placed in tamper proof containers to prevent access by non target organisms, people, and pets. Since rats are cautious, it may be necessary to prebait traps by leaving triggers unset until feeding has occurred at least once.  Exterior control can also be achieved with baits and traps. Burrow baiting can be effective, but it is important to place approved baits deep enough into the burrows to avoid consumption by non target animals. 

Where possible, exclusion is effective in preventing entry into the structure. Sealing up openings with hardware cloth, steel wool, spray foam, or other means will effectively block access. Look for areas where pipes, conduits, or wires enter the home, under siding, around worn out door or window frames, or areas where additions to a home or building meet the original construction. Unfortunately, there are many situations where exclusion is not realistic, either due to cost of repair or location of the opening. For example, many rats gain access to homes from inaccessible entry points located under decks.