Date of this Version
The Franklin ground squirrel (Spermophilus franklinii) is a rather drab grayish brown. Black speckling gives a spotted or barred effect. Head and body average 10 inches (25.4 cm) with a 5- to 6-inch (12.7- to 15.2-cm) tail. Adults weigh from 10 to 25 ounces (280 to 700 g).
The Richardson ground squirrel (S. richardson) is smaller and lighter colored than the Franklin. Some are dappled on the back. The squirrel’s body measures about 8 inches (20.3 cm) with a tail of from 2 to 4 inches (5 to 10 cm). Adults weigh from 11 to 18 ounces (308 to 504 g).
The Columbian ground squirrel (S. columbianus) is easily distinguished from others in its range by its distinctive coloration. Reddish brown (rufous) fur is quite evident on the nose, forelegs, and hindquarters. The head and body measure 10 to 12 inches (25.4 to 30.5 cm) in length with a 3- to 5-inch (7.6- to 12.7-cm) tail. An average adult weighs more than 16 ounces (454 g).
The Washington ground squirrel (S. washingtoni) has a small smoky-gray flecked body with dappled whitish spots. The tail is short with a blackish tip. This squirrel is similar to Townsend and Belding squirrels except the latter have no spots. Head and body are about 6 to 7 inches long (15.2 to 18 cm); the tail 1.3 to 2.5 inches long (3.4 to 6.4 cm); and adults weigh 6 to 10 ounces (168 to 280 g).
The Townsend ground squirrel’s (S. townsendi) head and body range in length from 5.5 to 7 inches (14 to 18 cm). It has a short bicolored tail about 1.3 to 2.3 inches (3 to 6 cm) long, and weighs approximately 6 to 9 ounces (168 to 252 g). The body is smoky-gray washed with a pinkish-buff. The belly and flanks are whitish.
Other species not described here because they cause few economic problems are Idaho (S. brunneus), Uinta (S. armatus), Mexican (S. mexicanus), Spotted (S. spilosoma), Mohave (S. mohavensis), and roundtail (S. tereticaudus) ground squirrels.
Ground squirrels are common throughout the western two-thirds of the North American continent. Most are common to areas of open sagebrush and grasslands and are often found in and around dryland grain fields, meadows, hay land, and irrigated pastures.
Exclusion: Limited usefulness.
Cultural Methods: Flood irrigation, forage removal, crop rotation, and summer fallow may reduce populations and limit spread.
Repellents: None are registered.
Toxicants: Zinc phosphide. Chlorophacinone. Diphacinone. Note: Not all toxicants are registered for use in every state. Check registration labels for limitations within each state.
Fumigants: Aluminum phosphide. Gas cartridge.
Trapping: Box traps. Burrow-entrance traps. Leghold traps.
Shooting: Limited usefulness.