The unusual weather conditions during 2009 have me concerned that there well may be an increase in rat activity in the early part of 2010. The Norway rat is also called the brown rat, barn rat, house rat, sewer rat, or gray rat. Like the house mouse the Norway Rat is not native to North America but arrived on ships with early colonists around 1775. Norway rats spread quickly throughout the contiguous 48 states and can now be found wherever humans live.

Since the Norway rat lives in close association with people, they may be in and around houses, barns, warehouses, stores, dog kennels, cellars and basements. They will also burrow under decks, patios and concrete slabs to make their nest. Although they can climb, Norway rats tend to inhabit the lower floors and basement areas of buildings. Just like the house mouse, rats have physical capabilities that enable them to gain entry to structures by gnawing, climbing, jumping and swimming.

Unlike mice, rats are cautious and fear new objects in their environment. Therefore, objects such as traps and bait stations will likely be avoided for several days or more. After a period of avoidance, rats will cautiously investigate them. Norway rats will eat nearly any type of food but when given a choice will select a nutritionally balanced diet. They prefer cereal grains, meats and fish, nuts and fruit. Rats require ½ to 1 ounce of water daily but a can survive on less if feeding on moist foods. Norway rats contaminate more food than they consume and their burrowing can cause structural damage to buildings. They also gnaw on electrical wire and through wood to gain entrance into an area. They often nest between walls and in attics. Rats gnaw not only to gain entrance into an area but to keep their incisors worn down. A rat’s paired incisor teeth grow continuously at a rate of about 5 inches per year. Therefore, nearly constant gnawing is needed to keep the fastgrowing teeth in check.

Effective rat prevention and control include sanitation, rodent proofing and population reduction. Controlling weeds and limiting grass growth, in addition to removing trash and debris from around structures is the first step when battling rats. Storing foodstuffs in rodent-proof containers and reducing sources of food, water and shelter is also helpful in reducing populations. All holes and openings ½ inch and larger around the home, barn and outbuildings should be sealed. There are several effective chemical rat control products available, many being anticoagulants. However, trapping is the preferred method to try first in homes and other structures. Since rats are more cautious than mice, leaving traps unset until bait has been taken off the trap at least once reduces the chance of rats becoming trap-shy. Traps should be placed on natural courses of travel so that the rat will pass directly over the trigger.