What do you think of when you hear the word rodent? Well, if you guessed mice and rats, you were certainly correct. Those are the mischievous little creatures we try to keep out of our houses, garages, barns and sheds, especially in wintertime. They eat our grain, birdseed, bread and any other food supplies they can get their hands on. And we fear the potential diseases they might introduce into our living space. But mice and rats are only the beginning.

     There are more than 1,500 living species of rodents, or Rodentia, as they are officially known. Some of the members of the family might surprise you. Rodents are the single largest group of mammals, comprising more than 40 percent. The only continent where they are not found is Antarctica.

     So what other creatures belong to this order? You’re probably familiar with squirrels, beavers, muskrats, porcupines, gophers, woodchucks, chipmunks, prairie dogs, marmots, chinchillas, voles, lemmings, hamsters, gerbils and guinea pigs. With the exception of gophers and voles, most do not interfere much with our gardens.

     All rodents have two long incisors, or teeth, in each jaw. These incisors grow continually, but rodents keep them sharp and at a useful length by regular gnawing. The teeth have thick enamel layers on their front portion and softer, exposed dentine on the rear. As a result, the constant gnawing wears the tooth down to a chisel shape. These teeth are used for cutting wood, cracking shells, biting through the skin of fruit and for protection. Behind each incisor is a gap and then a few molars in the rear for chewing food.

     Rodents gnaw with their incisors by pushing their lower jaw forward, and they chew with the molars by pulling the lower jaw back. Of course they need strong jaw muscles to carry out these procedures. Many rodents have cheek pouches for temporarily storing food. In some species, the pouches are inside the mouth, but pocket gophers and pocket mice have fur-lined pouches outside the mouth.

     Most rodents are herbivorous, meaning they eat only plants. However, a few of them eat insects or fish, and some squirrels have been known to eat young birds such as cardinals and blue jays, as well as bird eggs.

     Rodents cause large economic losses to crops every year, and some carry human diseases such as bubonic plague, typhus and Hanta fever. But some also have important economic functions. They serve as food sources in many parts of the world. Many types are pets, and several are used extensively in biomedical research.

     Most rodents are small. For example, the pygmy mouse is just over two inches in length and weighs about a quarter of an ounce. On the other hand, a capybara may grow to be as large as a black bear and weigh up to 100 pounds.

     The most prevalent mice are house mice and deer mice. House mice are light brown to black in color and about two inches in length. They are the most common rodent species. They can bring fleas, mites, ticks and lice into our homes. Deer mice are brown with white feet and underbelly, and they range from five to eight inches in length. They prefer the outdoors and only rarely enter the house. Mice can enter your home through a hole the size of a nickel or smaller.  

     The most common rats are Norway rats and roof rats. The brown, black or gray Norway rats typically have an eight-inch body and a four-inch tail. They are excellent climbers and will often enter the house seeking warmth in the late fall and winter. Roof rats have an eight-inch body and an eight-inch tail. They tend to reside in the upper parts of buildings and cause damage by chewing on materials and eating stored foods. Rats can easily crawl through a hole the size of a quarter.

     Mammals that may resemble rodents but aren’t in the family include bats, shrews, treeshrews, moles, hedgehogs, hares, rabbits, pikas, weasels and mink.

     The next time you see a mouse scurrying across the floor, or a rat sitting on your washing machine, or find your birdseed bag torn apart, remember that you’re harboring only one member of a vast family. Then, after holding that thought for about a millisecond, set your trap or put out the rat bait and get rid of the darned thing.