Spermophilus lateralis

Golden-mantled Ground Squirrels are familiar residents of open woodlands, brushy forest-edge habitats, dry margins of mountain meadows, and rocky slopes. They are quick to invade sunny, disturbed areas where pioneer plants provide good food resources. Because they have a stripe on the flank, they are sometimes mistaken for chipmunks, but the stripe does not continue onto the cheek as it does in Tamias species. Golden-mantled Ground Squirrels are solitary burrow-dwellers. They eat almost anything, including fungi, a variety of plants, fruits, and seeds, insects in all life-cycle stages, nestling birds and eggs, small mammals, and carrion. They hibernate from late summer through early spring, and like other hibernating mammals, put on fat reserves beforehand.

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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: Western North America. Eastern British Columbia and western Alberta south through the western U.S. to California, Arizona, and New Mexico. Elevations of 1220-3965 m (Bartels and Thompson 1993).

This species is found in western North America, from eastern British Columbia and western Alberta, south through the western United States to California, Arizona, and New Mexico, at elevations of 1,220-3,965 m asl (Bartels and Thompson 1993). There are disjunct population segments in the southern portion of the range.

Spermophilus lateralis is found in Canada and the United States. It ranges from southeast British Colombia and southwest Alberta, into the western United States as far east as western Colorado and down to northwestern New Mexico and southern California.

(Bartels and Thompson, 1993; National Wildlife Federation, 2000)

Biogeographic Regions: nearctic (Native )

Spermophilus lateralis is a strikingly colored ground squirrel. This species has a golden-red mantle that extends from the head down over their shoulders. One white stripe, bordered by two black stripes, extends horizontally down the body, similar to chipmunks. Although chipmunks have a white stripe through their eyes, Spermophilus lateralis has a whitish fur eye ring and no facial striping. The back is gray, brownish or buff, and their undersides are whitish or yellowish-gray. The tail is brownish-black above, and reddish brown on the underside. Winter pelage is grayer and the mantle is duller. The species is sexually dimorphic, with males having a brighter red mantle as well as a significantly larger brain size.

These squirrels range in weight from 120 to 394 grams, and in length from 235 to 295 mm.

(Bartels and Thompson, 1993; Iwaniuk, 2001; National Wildlife Federation, year unknown)

Range mass: 120 to 394 g.

Range length: 235 to 295 mm.

Average basal metabolic rate: 0.967 W.

Length: 31 cm

Weight: 276 grams

Length:
Average: 275 mm
Range: 245-295 mm

Weight:
Range: 175-350 g

Comments: Inhabits mountain slopes and foothills, alpine tundra, chaparral, open areas in pine, spruce, and fir forests, rocky outcroppings and slides, margins of mountain meadows, and rocky sagebrush country; campgrounds. Often in areas with abundant stumps, rocks, of fallen logs. When inactive or tending young, occupies burrows under rocks, stumps, logs, trees, bushes, or cabins, in rock crevices, or in banks or along washes.

Habitat and Ecology

Systems

• Terrestrial

Spermophilus lateralis is found from 1,220 m in the northern Sierra Nevada mountains of California, up to 3,965 m at Pike's Peak, Colorado. This species occurs in mixed coniferous forests of the Klamath, Cascade and Sierra Nevada ranges. Golden-mantled ground squirrels are found up to and above the timberline, provided that there is enough cover for them. Forest-edged meadows and rocky slopes can be occupied, as well as chaparral habitat in southern California. Spermophilus lateralis is abundant in campgrounds in where these squirrels enjoy human handouts.

(Bartels and Thompson, 1993)

Range elevation: 1,200 to 3,965 m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: chaparral ; forest ; scrub forest ; mountains

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.

Comments: Omnivorous. Feeds on seeds, fungus, leaves, flowers, fruits and roots. Also feeds on arthropods and meat, including carrion. In one study underground fungus comprised 65% of summer food and 90% of fall food. May store food in burrow in summer.

Spermophilus lateralis is omnivorous. Individuals of this species dig up and consume underground fungi, locating it by smell. The nuts of Pinus are a dietary staple. They also eat other nuts, acorns, seeds, forbs, flowers, bulbs, fruit, shrubs and leafy greens. Animal matter consumed consists of adult and larval insects, birds and eggs, including mountain bluebirds (Sialia currocoides) and Oregon juncos (Junco oreganus), young microtus, voles, entrapped yellow-pine chipmunks (Tamias amoenus), lizards (Sceloporous gracilis), and carrion, including road-killed conspecifics.

(Bartels and Thompson, 1993)

Animal Foods: birds; mammals; reptiles; eggs; carrion ; insects

Plant Foods: leaves; roots and tubers; seeds, grains, and nuts; flowers

Other Foods: fungus

Primary Diet: omnivore

Spermophilus lateralis is a primary consumer, and is therefore responsible for converting plant energy into a form useable by predators in the animal kingdom. There are many different types of predators that prey upon S. lateralis (listed under Predation). Golden-mantled ground squirrels probably affect predator populations and reproduction, depending upon how heavily any predator species relies on S. lateralis as a food source.

Spermophilus lateralis may also regulate populations of birds, lizards, and other small mammals upon which it preys.

Tunneling behavior can aerate the earth.

Competition between S. lateralis and other rodents can occur over food sources, which can therefore cause a negative effect on other rodent populations.

(Bartels and Thompson, 1993)

Ecosystem Impact: disperses seeds; soil aeration

Golden-mantled ground squirrels are primary consumers, and are eaten by many different secondary consumers. Predators include various diurnal and nocturnal raptors, including red-tailed hawks and northern goshawks; mammals like coyotes, bobcats, skunks and various weasles; and snakes.

Predator avoidance behaviors include alarm calls accompanied by tail jerks. Spermophilus lateralis and yellow-bellied marmots respond to each others' alarm calls for predator warnings. Golden-mantled ground squirrels will ascend rocks and logs as lookout stations, occasionally sitting upright for a better view. They will also dive into the nearest cover or hole when a predator is spotted or an alarm call heard. Spermophilus lateralis keeps a series of burrow openings around their feeding areas to escape predation.

(Bartels and Thompson, 1993; Shriner, 1998)

Known Predators:

• red-tailed hawks (Buteo jamaicensis)
• Northern goshawks (Accipiter gentilis)
• coyotes (Canis latrans)
• bobcats (Lynx rufus)
• striped skunks (Mephitis mephitis)
• weasels (Mustela)
• snakes (Serpentes)

Spermophilus lateralis is prey of:
Serpentes
Mustela
Accipiter gentilis
Buteo jamaicensis
Mephitis mephitis
Lynx rufus
Canis latrans

This list may not be complete but is based on published studies.

Spermophilus lateralis preys on:
fungi
Insecta
Reptilia
Aves
Mammalia
Certhia americana

This list may not be complete but is based on published studies.

Populations usually are distributed evenly over good habitat. Predators include snakes, foxes, weasels, and bears. This species may be an intermediate host for the Rocky Mountain spotted fever tick, DERMACENTOR ANDERSONI.

Comments: Active mainly March-November at low elevations; season is shorter in high mountains and in areas with abundant snowfall.

Lifespan has been recorded by Bartles and Thompson (1993) as an average of 7 years in the wild, and 5 years in captivity. This seems odd, as captive animals, not facing dangers of predation and food shortage, typically live longer than their wild counterparts. The difference in wild and captive lifespans reported by Bartles and Thompson may relfect differences in populations of S. lateralis, which vary greatly in habitat, hibernation pattern, and sociality. Also, it seems likely that their reported average for wild gound squirrels does not take into account juvenile mortality, much of which must remain unknown to observers as the young are hidden away in burrows.

Average lifespan
Status: wild: 7 years.

Average lifespan
Status: captivity: 5 years.

Range lifespan
Status: wild: 7 (high) years.

Maximum longevity: 10.4 years (captivity) Observations: In the wild, these animals appear to live up to 7 years (Bartels and Thompson 1993). One captive specimen lived 10.4 years (Richard Weigl 2005).

Breeding occurs in the spring soon after females emerge from hibernation. Females are monoestrous. Gestation lasts 26-33 days. Litter size is 2-8, usually 4-6. Young emerge from burrow typically in July (to early August at highest elevations). Weaning occurs at minimum age of 4 weeks. Males do not take part in family life. A few may live up to 7 years.

As in many ground squirrels, males are polygynous. After emergence from hibernation, they compete with each other to establish territorial boundaries. Male territories encompass the territories of several females. When females emerge from hibernation, they typically mate with the male on whose territory they are found.

Mating System: polygynous

Copulation begins after adults emerge from hibernation, from March to May. Males emerge from hibernation in breeding condition. They compete with one another during this time, establishing territories. Females follow shortly, 2 to 3 weeks after male emergence.

The gestation period is 26 to 33 days, with young being born from May to the beginning of September, depending on altitude. Most litters arrive from May to late June. Females have one to two litters per year. Litter size ranges from two to eight pups, averaging five. Litter size is larger at lower elevations.

Like many rodents, S. lateralis pups are born hairless except for tiny whiskers and hairs on their head. Their toes are fused together and their ears are closed. They are able to squeak and squirm around, but have little control over their body position. After a week, their fur has grown enough that their markings are visible. Vibrissae are also longer by this time, and they are able to right themselves. After two weeks, teeth erupt, ears open, toes separate and they utter their first adult sounds. Between days 20 to 30, upper incisors erupt, eyes open and grooming begins. They begin to eat solid food at around a month old, at which time their growth rate is rapidly accelerated. Pups leave the natal burrow when they are at least 25% of the adult body size, and are weaned sometime after they are at least 29 days old.

(Bartels and Thompson, 1993; Bihr and Smith, 1998; National Wildlife Federation, year unknown)

Breeding season: Breeding time varies with altitude, usually occurring immediately after hibernation.

Range number of offspring: 2 to 8.

Range gestation period: 26 to 33 days.

Range weaning age: 29 (low) days.

Range age at sexual or reproductive maturity (female): 12 (high) months.

Range age at sexual or reproductive maturity (male): 12 (high) months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 6.26 g.

Average number of offspring: 5.12.

The mother cares for the offspring as they grow inside the natal burrow. Young are highly altricial, but develop rapidly. Nests are built of grasses, dried leaves and shredded bark in underground burrows that can extend up to 30m shallowly underground. Studies have shown that S. lateralis prefers to have burrow entrances under significantly larger than average rocks or stumps

Pups are altricial and require extensive maternal care, which declines when they are weaned between 24 to 32 days. Care for the pups is provided by the female only, and that declines 2 to 3 weeks after the pups leave the nest (when at about 25% of adult body size), after which the female becomes antagonistic towards her offspring. Females and males reach sexual maturity within the first year.

(Bartels and Thompson, 1993; Bihr and Smith, 1998; National Wildlife Federation, year unknown)

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 5
Species With Barcodes: 1

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Lower Risk/least concern
  (Baillie and Groombridge 1996)

These squirrels are common in the areas where they occur.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Population

Population Trend

Major Threats

Conservation Actions

Comments: Sciurid mycophagy may play important role in forest ecology (Maser and Maser 1988). Sometimes may inhibit reforestation by eating conifer seeds and seedlings.

Spermophilus lateralis can have a negative impact on the timber industry. In the fall, coniferous seeds make up a large portion of their diet, and S. lateralis can harm reforestation efforts by eating newly sprouted conifer seeds. They have little impact on agriculture because of habitat selection.

Spermophilus lateralis is a vector for zoonotic diseases, and they are the main mammalian reservoir for Colorado tick fever, a non-lethal, tick-born viral disease. They are also vectors for the plague. Although campers enjoy feeding the squirrels, care should be taken not to get bitten or inhale dried fecal matter.

(Bartels and Thompson, 1993; Encyclopedia Britanica, online, 2001)

Negative Impacts: crop pest

Golden-mantled ground squirrels have little positive economic importance to humans. They do however, provide amusement and enjoyment for many campers as they can become quite tame, living at campgrounds and taking food from eager campers hands. (Bartels and Thompson, 1993)