Squirrels ARE rodents.
More Info: Squirrels occupy the rodent family of mammals and span several different branches within the Rodentia family. While most are diurnal, meaning sleeping almost entirely at night and awake during the day, a few might be considered crepuscular or active during low-light times, such as twilight or dawn. Almost all, however, are members of the Sciuridae branch.
Ground squirrels, tree squirrels, gray squirrels and other squirrels may be colored differently with alternate markings, but most common squirrel species share a bushy tail and small, round ears. All squirrels have elongated, curved teeth, but the length and degree of curvature differ. The average weight of squirrels found within the United States totals less than two pounds, though just before winter hibernation, that weight can extend to 2.5 pounds in larger species.
Differences from Other Rodents
Hares and rabbits are not rodents, but they share incisor shape and back-to-front jaw motions when gnawing on food, so teeth and feeding patterns are not indicative of species or family. Tails, on the other hand, are often longer than the animals’ back feet. Squirrel tails are often bushy while other rodents have tails of other shapes. Adult rats, for example, have thin tails that are at least as long as their bodies but are very thin.
What Determines Squirrels Are Rodents?
According to biologist Paolo Viscardi of the Horniman Museum in London, a squirrel is a rodent because of the single pair of “chisel-like” incisors per upper and lower jaw. Rodents have a space or diastema between the front and back teeth, which squirrels have.
Batcheller, G. and Gawalt, J., “The Squirrel Family”; the New York State of Environmental Conservation; found at http://www.dec.ny.gov/docs/administration_pdf/squirrels.pdf, accessed October 29, 2012.
“Wildlife Directory—Ground Squirrel,” <i>Living with Wildlife in Illinois</i>; found at http://web.extension.illinois.edu/wildlife/directory_show.cfm?species=groundsquirrel, accessed October 29, 2012.
“Rodent definition (Page 1) – Mammals – Ask a Biologist Q&A.” Welcome to Ask a Biologist | Ask A Biologist. N.p., n.d. Web. 1 Nov. 2012. <http://www.askabiologist.org.uk/answers/viewtopic.php?id=5497>.