Norway Rats Norway rats are the most abundant North American rodent species because they adapt to a wide variety of climates.
Generally a burrowing animal, Norway rats build elaborate underground systems. The main entrance, two to three inches in diameter, leads to the central den. Norway rats also incorporate one or more well-hidden "bolt" holes, or emergency escape routes.
Females can bear up to 12 litters annually but usually average five litters each year. Newborn pups are born hairless with their eyes and ears closed. They grow quickly, opening their eyes at two weeks, eating solid food at 2 1/2 to three weeks and are independent at three to four weeks.
Norway rats are sexually mature at three months. Some females breed even earlier if there is abundant food available to support additional animals.
Unlike man, Norway rats have six senses: touch, taste, smell, hearing, sight and kinesthetic (muscle sense).
Norway and roof rats are nocturnal creatures and cannot always rely on sight to orient themselves. Very sensitive whiskers, or vibrissae, on their noses and longer "guard hairs" on their bodies act as tactile sensors, allowing rats to maneuver around objects in total darkness in their environment. Rats also gain a sense of security when their whiskers and guard hairs are in contact with objects in their territory.
Closely related to this sense of touch is kinesthetic sense. Simply stated, it is the rats' ability to memorize their environment by body or muscle movement alone. If danger arises, Norway and roof rats react automatically to escape danger.
Norway and roof rats become so ingrained by body movements that when objects are removed from their territory, rats continue to move around them as if the objects were still there.
Norway rats have a very keen sense of taste and can detect specific food ingredients at levels of 0.5 parts per million. although they eat almost any kind of food, Norway rats usually choose fresh, wholesome items over stale, contaminated foods. Norway rats will eat good-tasting items, even if the smell is offensive.
Both Norway and roof rats eat 10 to 40 percent of their body weight every day or 20 to 40 pounds of food each year. If necessary, they will eat anything to survive except food contaminated with chemicals or pesticides.
Not only do rats use their sensitive sense of smell to locate food sources, but they use smell to locate and recognize rats of the opposite sex.
Extending into the ultrasonic range, their excellent hearing enables Norway rats to detect and escape danger.
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Norway Rats