Rats are pests that can cause structural damage to buildings that result in significant financial loss. They may also damage furniture, destroy food containers, and contaminate food. Rats are primarily active at night, usually when people are absent from their homes. However, it is not unusual for a hungry rat to eat during the day.
Often Norway rats build their nest in the ground. First they look for food outdoors, and if this is not possible, will enter buildings in search of food, returning outside when they are done. Some rats, however, may spend their entire lives inside, building their nest in an enclosed area where there is no human activity. Rats prefer food rich in fat but they are not picky and will eat whatever is available.
Rats' eyesight is very poor and they are color-blind, only distinguishing different intensities in light. Nevertheless, they have keen sense of smell, touch, taste, and hearing, which compensates for their weak eyesight. Norway Rats are cautious and shy away from newly introduced objects in their territory. This wariness is even more pronounced in the adult rat.
Rats jump, climb, swim, and gnaw. Some can jump one meter (3 ft.) into the air and when in difficulty, won't hesitate to leap into space, even if the drop is quite far proportional to their size. They can easily climb pipes, wires, and rough walls. Rats also have amazing balance: they can run horizontally on a wall or electrical wire, using their tail as a counterbalance. Norway Rats are also very good swimmers. Because they must drink water at least once a day, their dens are often close to a water source.