Wild About Illinois Rodents!

Mammals have hair/fur, four limbs (arms/legs) and a large brain. They are warm-blooded, that is, they can keep their body temperature at the same level no matter what the outside temperature is. Females of most mammal species give birth to young that have developed inside a special organ called the uterus. Some mammal species lay eggs instead of having live birth, but none of these species live in Illinois. After birth, mammal young are fed for a time by milk produced in the female’s mammary glands. Rodents are small- to medium-sized mammals. They have incisors that grow continually throughout their life and must be worn down by gnawing on hard materials. Rodents have a large gap between their incisors and the rest of their teeth. This order contains the largest group of mammals in Illinois.​

Kingdom: Animalia - Animals are multicellular organisms that rely on other organisms for nourishment. There cells do not have cell walls. Most animals are capable of movement at least in some portion of their life cycle. Reproduction is generally sexual, but in some animals asexual reproduction may be utilized at certain times.
Phylum: Chordata - The Phylum Chordata contains the vertebrate animals. Mammals, birds, reptiles, amphibians and fishes are included in this phylum. These animals have a notochord at some point in their development. They have a tubular nerve cord along the back. Gill slits and a tail are present at some point in their life cycle. They have an internal skeleton.
Class: Mammalia (Mammals) - Mammals are warm-blooded. Most mammals have young born after developing inside the mother's body in a special organ called a uterus. After birth, the young are fed with milk produced in the female’s mammary glands. A mammal has a large and complex brain.
Order: Rodentia (Rodents) - Rodents are small- to medium-sized mammals. They have incisors that grow continually throughout their life and must be worn down by gnawing on hard materials. Rodents have a large gap between their incisors and the rest of their teeth. This order contains the largest group of mammals in Illinois.
Family Sciuridae: (Squirrels) - Squirrels are medium-sized, mostly diurnal (active in the daytime) mammals. There are four toes on each front foot and five toes on each back foot. The tail is hairy. Some squirrels are arboreal (tree-dwellers), and some live on the ground.
     eastern chipmunk (Tamias striatus)
     woodchuck (Marmota monax)
     thirteen-lined ground squirrel (Spermophilus tridecemlineatus)
     Franklin's ground squirrel (Poliocitellus franklinii) [Illinois threatened]
     eastern gray squirrel (Sciurus carolinensis)
     eastern fox squirrel (Sciurus niger)
     red squirrel (Tamiasciurus hudsonicus)
     southern flying squirrel (Glaucomys volans)

Family Geomyidae: (Pocket Gophers) - The mammals in this family are adapted for living in soil. They do not have a distinct neck but do have short, strong legs. There are five toes on both the front and hind feet, and each of them has a claw. The claws on the front feet are large and use for digging. The eyes, ears and tail are small. The lips can be closed behind the incisors. They have fur-lined cheek pouches that are used for transporting food.
     plains pocket gopher (Geomys bursarius)

Family Castoridae: (Beavers) - The beaver is a large rodent. It is well-adapted for its aquatic lifestyle. The ears and nose have valves that close while under water. The tail is enlarged and flattened. The back feet are webbed. The lips shut behind the incisors. Anal scent glands are used to mark territorial boundaries.
     American beaver (Castor canadensis)

Family Cricetidae: (New World Rats and Mice, Voles, Hamsters and Relatives) - Cricetidae is one of the largest families of mammals, and there is much diversity in its members, so it is difficult to make a general description. Most of them are small with an elongated body. The fur is gray or brown with lighter or white hair on the belly and chin. The tail is long, and the eyes are large. The ears are easily seen. Whiskers are present.
     marsh rice rat (Oryzomys palustris)
     western harvest mouse (Reithrodontomys megalotis)
     deer mouse (Peromyscus maniculatus)
     white-footed mouse (Peromyscus leucopus)
     cotton mouse (Peromyscus gossypinus)
     golden mouse (Ochrotomys nuttalli)
     eastern woodrat (Neotoma floridana)
     meadow vole (Microtus pennsylvanicus)
     prairie vole (Microtus ochrogaster)
     woodland vole (Microtus pinetorum)
     muskrat (Ondatra zibethicus)
     southern bog lemming (Synaptomys cooperi)

Family Muridae: (Old World Mice and Rats, Whistling Rats, Gerbils and Relatives) - Old World rats and mice are small- to medium-sized rodents. Most have four toes on the front feet, and all have five toes on the rear feet. All have 16 teeth, four for gnawing and 12 for grinding.
     brown rat (Rattus norvegicus) [nonnative]
     house mouse (Mus musculus) [nonnative]

Family Dipodidae: Jerboas, Jumping Mice and Birch Mice - This family includes the jerboas, jumping mice and birch mice, of which only one species of jumping mouse is found in Illinois. They are small- to medium-sized rodents that are adapted for jumping. Most are omnivores that eat insects and seeds.
     meadow jumping mouse (Zapus hudsonius)