GROUND SQUIRRELS (Franklin, Richardson, Columbian, Washington and Townsend Ground Squirrels)

Identification
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.

Range
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. The ranges of some species overlap occasionally.

Food Habits
Ground squirrels eat a wide variety of food. Most prefer succulent green vegetation (grasses, forbs, and even brush) when available, switching to dry foods, such as seeds, later in the year. The relatively high nutrient and oil content of the seeds aids in the deposition of fat necessary for hibernation. Most store large quantities of food in burrow caches. Some species, like the Franklin , eat a greater amount of animal matter, including ground-nesting bird eggs. Insects and other animal tissue may comprise up to one-fourth of their diet.

General Biology, Reproduction, and Behavior
Ground squirrels construct and live in extensive underground burrows, sometimes up to 6 feet (2 m) deep, with many entrances. They also use and improve on the abandoned burrows of other mammals such as prairie dogs and pocket gophers. Most return to their nests of dried vegetation within the burrows at night, during the warmest part of summer days, and when they are threatened by predators, such as snakes, coyotes, foxes, weasels, badgers, and raptors.

The squirrels generally enter their burrows to estivate , escaping the late summer heat. They hibernate during the coldest part of the winter. Males usually become active above ground 1 to 2 weeks before the females in the spring, sometimes as early as late February or early March. A few may be active above ground throughout the year. Breeding takes place immediately after emergence. The young are born after a 4-to 5-week gestation period with 2 to 10 young per litter. Generally only 1 litter is produced each year. Densities of the ground squirrel populations can range from 2 to 20 or more per acre (5 to 50/ha).

Damage and Damage Identification
High populations of ground squirrels may pose a serious pest problem. The squirrels compete with livestock for forage; destroy food crops, golf courses, and lawns; and can be reservoirs for diseases such as plague. Their burrow systems have been known to weaken and collapse ditch banks and canals, undermine foundations, and alter irrigation systems. The mounds of soil excavated from their burrows not only cover and kill vegetation, but damage haying machinery. In addition, some ground squirrels prey on the eggs and young of ground-nesting birds or climb trees in the spring to feed on new shoots and buds in orchards.

Economics of Damage Control
Very little is known about the economic consequences of ground squirrels foraging in agriculture. A single pair and their offspring can remove about 1/4 acre (0.1 ha) of wheat or alfalfa during one season. Water lost from one canal can flood thousands of acres or cause irrigation failures. The crop loss and cost of repair can be very expensive. Prevention, by incorporating a rodent management plan into the total operation of an enterprise, far outweighs the cost of added management practices.

Legal Status
Ground squirrels generally are unprotected. However, species associated with them, such as black-footed ferrets, weasels, wolves, eagles, and other carnivores may be protected. Local laws as well as specific label restrictions should be consulted before initiating lethal control measures.

Damage Prevention and Control Methods

Exclusion
Limited usefulness.

Habitat Modification
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.

ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee).