Left untouched, a rat’s incisor teeth would grow 4 inches in a year. So rats must chew continuously to wear down their incisors. Rats will chew on wood, aluminum siding, wallboard, plaster, paneling, frozen ground, concrete…anything but glass and most metals.
Because they are so adept at hiding and scurrying, rats can exist in large numbers unknown. Unlike the mouse, rats are fearful of anything new. Even so, they quickly adapt to new places to live, new routines, new places to eat, and new kinds of food.
People see rats more often from April through June (spring breeding), and again in October and November as the season changes. But rats are active year-round. Outdoors, rats burrow in earth banks, along walls, under rubbish or concrete slabs, but they always locate close to sources of food and water. Rats follow the same routes as they make their rounds foraging for food each night, so they leave obvious runways in the grass. Rats often travel under objects like bales, planks, granaries and machinery to conceal their movement. A rat will normally travel no more than 150 feet from its nest, but at harvest time rats will travel much further to forage for corn, wheat or beans left in farm fields.
Rats will make holes in walls or floors soon after invasion. Rat holes are circular, average 2-3 inches in diameter, and are usually just inches off the floor. Holes in floors are generally close to walls. Rats leave behind a distinctive musk odor, particularly if they are confined to a small space.
A rat can eat a third of its body weight each day. The rat is a true omnivore. It will eat anything, including soap, leather, furs, candy, milk, meat, vegetables, poultry, eggs, grain, seeds, fruit, nuts, snails and other rodents. Rats will catch fish, and they readily eat carrion. Near homes, rats thrive on pet food, birdseed, grass seed, garbage, dog feces, and the uneaten or spoiled food we discard. While rats will eat nearly anything, they prefer grain, livestock feed, and meat. Unlike the mouse, which nibbles a little at a time, rats will fill up at one sitting, if possible. Rats will hoard and cache food, which can result in insect infestations. Like mice, rats will live in freezers, feeding only on frozen food. Rats eat so much that one rat can leave behind 25,000 droppings per year. The rat’s main constraint is that it cannot go long without water unless its diet supplies enough. Rats need up to one ounce of water every day.
The number and behavior of rats change throughout the year. Many rats die during winter, as outdoor foods become hard to find. Breeding in winter is comparatively low, so rat populations are at their lowest. A mild winter means fewer rats will die of natural causes, so more can be expected in the spring. But if rats are controlled in winter, fewer will be available to resume the breeding cycle in spring. Heavy breeding begins in March when the weather turns. Spring rains spur vegetation which provides cover and additional food. So rats are more abundant in late spring. Young rats have to seek food and new nests. In summer, food and vegetation are abundant, so rats continue breeding. Breeding peaks in early September as temperatures begin to fall. Sources of food and shelter start to diminish in fall, so rats look for shelter inside buildings and homes.