Spermophilus richardsonii is found in central Alberta and western Montana to western Minnesota.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Northern Great Plains; southern Alberta, southern Saskatchewan, southern Manitoba, Montana, North Dakota, northeastern South Dakota, western Minnesota, and northwestern Iowa (Hoffmann et al., in Wilson and Reeder 1993).

Total body length for Richardson's ground squirrels is from 283 to 337 mm in males and 264 to 318 mm in females. Tail length varies from 65 to 88 mm in males and 55 to 82 mm in females. Pre-hibernation males ranged in weight from 440 to 745 g, and from 290 to 500 grams post-hibernation. Pre-hibernation females ranged from 330 to 590 grams and from 120 to 290 grams post-hibernation . They are dark brown along the top of the body and lighter brown on the sides with a whitish underbelly. The tail is short and covered with fur, but is not bushy.

Average mass: 342.5 g.

Average basal metabolic rate: 0.788 W.

Length: 36 cm

Weight: 469 grams

• Terrestrial

Richardson's ground squirrel lives in areas of open plains with short grasses. The animal also spends large amounts of time in the soils of these areas in burrows. The animal avoids heavily forested areas.

Terrestrial Biomes: savanna or grassland

Comments: Grasslands, rolling hills, fields and croplands. Prefers gravelly or sandy soils for digging burrows. Burrows consist of extensive network of passages and entrances with several chambers. Young are born in underground nests. The nests are spherical and are lined with grasses in which straw or oat hulls may be found (Jones et al. 1983).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

The diet of S. richardsonii consists of seeds, nuts, grains, bulbs, green vegetation, insects and other types of small invertebrates. Food is stored in the burrow, but is eaten only after awakening from hibernation.

Comments: Feeds on a wide variety of herbaceous vegetation in spring and early summer and on seeds and fruits in late summer and fall. Also feeds on insects and carrion, and often damages agricultural crops. Stores seeds in burrows.

Lives in loose colonies. Home range probably is not larger than 100 yds in diameter (Banfield 1974). Densities of 10/acre are considered average but may range higher (Jones et al. 1983). May host fleas that transmit bubonic plague. In Alberta, larvae of the sarcophagid fly Neobellieria citellivora caused lethal cutaneous myiasis, especially in juveniles (Michener, 1993, J. Mamm. 74:148-155).

Comments: Hibernation period varies, but usually enters late August-October; emerges by late March or April. Activity peaks: 2 hours after dawn; 10 am to 2 pm; 4 pm to sunset. Most active during good weather; remains in burrow during extreme heat or rain.

Females are monestrous and have one litter per year. Mating takes place soon after hibernation ends, from late March to early May. Intense male competition for access to females occurs during the mating period. Each females is receptive for only about 3 hours but will mate with several males during that time. As soon as a female is impregnated she becomes aggressive towards males. Females prepare nest chambers where their litter will be born and reared. Gestation lasts for 23-31 days and litters are typically 6 to 8 young. The young are weaned at 4 to 6 weeks of age. The young reach adult size and sexual maturity at about 11 months. Females live for 2 to 4 years, sometimes living as long as 6 years. Male Richardson's ground squirrels rarely live longer than two years as a direct result of energetic expense and mortality associated with male-male competition during mating.

Average birth mass: 6.35 g.

Average gestation period: 24 days.

Average number of offspring: 6.06.

Average age at sexual or reproductive maturity (male)

Sex: male: 335 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 335 days.

Females typically mate 3-5 days after emergence from hibernation, give birth 22-23 days later. Litter size is 3-11, usually 6-8. Young first leave natal burrow at 28-30 days, sexually mature in 1 year (Michener 1985). Females live up to 6 years.

Due to the clearing of forests for farm land, the natural habitat and population size of S. richardsonii has increased dramatically.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Richardson's ground squirrels carry fleas that transmit the bacterial disease bubonic plague. They have also been known to cause the spread of tularemia and Rocky Mountain spotted fever. Richardson's ground squirrels are a major agricultural pest in Canada and the northern United States, they can cause massive crop destruction.

Richardson's ground squirrels are important members of their ecosystems, acting to recycle soil nutrients and providing an important source of prey for many predator species, they are also available as pets.

Comments: Spermophilus elegans formerly was included in this species (Zegers 1984). Several studies have demonstrated the specific distinctness of S. elegans and S. richardsonii (see Hoffmann et al., in Wilson and Reeder 1993).