Rodents: Rodentia

Rodents show a wide range of lifestyles and habits, depending upon the family and species. There are rodents that form burrows (holes or tunnels), such as gophers and moles; those that live in trees, such as the commonly called flying squirrels; rodents that spend most of their time in water, such as the capybara; and those that are specialized to life in the desert, such as kangaroo rats and jerboas.

Many rodents are social animals, living in large groups and interacting with one another frequently. Prairie dogs, naked mole-rats, and ground squirrels all live in these large colonies (groups). Other rodents live in smaller colonies. The beaver lives in a colony made up of the adult male and female, and their offspring. Each colony lives in a specific territory.

The prairie dog, for example, lives in a set area that can contain hundreds of these small animals (they look similar to squirrels, not dogs). These colonies or towns are broken up into certain neighborhoods. The prairie dogs post guards, they babysit and they help build one another's homes. There is a great deal of playing, mutual grooming, and vocal communication among the prairie dogs.

Some rodents are solitary, such as porcupines, pocket gophers, and pocket mice. Many desert species are solitary. Some of these species that burrow, dig, will construct and live in their own burrow system. However, during the mating season there may be more than one individual, or a mother and her offspring may live together.

Most rodents are active throughout the year. Some species, such as ground squirrels, may hibernate for several months. Species communicate with one another using sounds, smells, and sights. For example, squeaks, grunts, and calls can be used as alarm calls in mating and when a parent is searching for its young.

Many rodents have large numbers of offspring, which is one of the primary reasons they make up the largest group of mammals. Rodent reproduction can be divided into two forms. One group of families has a short gestation (pregnancy) period, produces multiple litters per year, and has large numbers of helpless offspring. Gestation periods can range from seventeen to forty-five days and the number of litters can be up to four. Rodents in this group include mice, rats, and pocket gophers. The other group of families has longer gestation periods (60 to 238 days), fewer litters per year (generally one to two), and have a relatively fewer number of offspring.

The mating system of rodents depends upon the species. A few species of rodents are monogamous (muh-NAH-guh-mus), such as the Patagonian mara, which forms male-female pairs that can last for multiple mating seasons. Other species have a harem-based (HARE-um based) mating system, one male with a set group of females for the mating season. Many rodents are promiscuous (prah-MISS-kyoo-us), meaning they mate randomly.