Mammal Species of the World
Spermophilus beecheyi is found throughout most of California, most of Western Oregon and portions of Western Nevada. This species also occurs in portions of southwestern Washington, and Baja California.
Biogeographic Regions: nearctic (Native )
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: South-central Washington south through California and extreme west-central Nevada to Baja California, Mexico.
California ground squirrels have mottled fur, with gray, light and dark brown, and white present in their pelage. They typically have a darker mantle. The shoulders, neck and sides of this species are a lighter gray. The bushy tail is a combination of the colors that appear on the back. The underside is a lighter combination of light brown, gray and white. California ground squirrels have a white ring around each eye.
The body length can range from 330 to 508 mm and tail length from 127-229 mm. These animals range in weight from 280 to 738 g. The ears are > 10 mm and < 25.4 mm. The dental formula is 1/1 : 0/0 : 2/1 : 3/3 = 22.
Range mass: 280 to 738 g.
Range length: 330 to 508 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Length: 50 cm
Weight: 738 grams
Size in North America
Range: 357-500 mm
Range: 250-885 g
Central and Southern Cascades Forests Habitat
The Oregon slender salamander is endemic to the Central and Southern Cascades forests ecoregion. The Central and Southern Cascades forests span several physiographic provinces in Washington and Oregon, including the southern Cascades, the Western Cascades, and the High Cascades, all within the USA. This ecoregion extends from Snoqualmie Pass in Washington to slightly north of the California border. The region is characterized by accordant ridge crests separated by steep, deeply dissected valleys, strongly influenced by historic and recent volcanic events (e.g. Mount Saint Helens).
This ecoregion contains one of the highest levels of endemic amphibians (five of eleven ecoregion endemics are amphibians) of any ecoregion within its major habitat type. The threatened Northern spotted owl has been used as an indicator species in environmental impact assessments, since its range overlaps with 39 listed or proposed species (ten of which are late-seral associates) and 1116 total species associated with late-seral forests. Late-seral forests in general are of national and global importance because they provide some of the last refugia for dependent species, and perform vital ecological services, including sequestration of carbon, cleansing of atmospheric pollutants, and maintenance of hydrological regimes.
There are a number ofl amphibian taxa present in the Central and Southern Cascades ecoregion; the totality of these amphibian taxa are: the Rough-skinned newt (Taricha granulosa); the endemic and Vulnerable Shasta salamander (Hydromantes shastae); the endemic and Vulnerable Oregon slender salamander (Batrachoseps wrighti); the Endangered Dunn's salamander (Bolitoglossa dunni); the Northwestern salamander (Ambystoma gracile); the Near Threatened western toad (Anaxyrus boreas); the Vulnerable Oregon spotted frog (Rana pretiosa); the Near Threatened Cascades frog (Rana cascadae); Coastal tailed frog (Ascaphus truei); Near Threatened Larch Mountain salamander (Plethodon larselli); California newt (Taricha torosa); Pacific giant salamander (Dicamptodon ensatus); Cope's giant salamander (Dicamptodon copei); Monterey ensatina (Ensatina eschscholtzii); the Near Threatened Foothill yellow-legged frog (Rana boylii); Northern Red-legged frog (Rana aurora); Pacific chorus frog (Pseudacris regilla); Van Dyke's salamander (Plethodon vandykei), an endemic of the State of Washington, USA; Long-toed salamander (Ambystoma macrodactylum); and the Olympic torrent salamander (Rhyacotriton olympicus).
There are a moderate number of reptilian species present in the ecoregion, namely in total they are: Western pond turtle (Emys marmorata); Western fence lizard (Sceloporus occidentalis); Sharp-tailed snake (Contia tenuis); Ringed-neck snake (Diadophis punctatus); Rubber boa (Charina bottae); California mountain kingsnake (Lampropeltis zonata); Yellow-bellied racer (Coluber constrictor); Western rattlesnake (Crotalus viridis); Western gopher snake (Pituophis catenifer); Common garter snake (Thanophis sirtalis); Northwestern garter snake (Thamnophis ordinoides); Western skink (Megascops kennicottii); Southern alligator lizard (Elgaria multicarinata); and the Northern alligator lizard (Elgaria coerulea).
There is a considerable number of avifauna within the Central and Southern Cascades ecoregion; representative species being: Flammulated owl (Otus flammeolus); Western screech owl (Megascops kennicottii); White-tailed ptarmigan (Picoides albolarvatus); and White-headed woodpecker (Picoides albolarvatus).
There are a large number of mammalian taxa in the ecoregion, including: Bobcat (Lynx rufus); Wolverine (Gulo gulo); California ground squirrel (Spermophilus beecheyi); Yellow-bellied marmot (Marmota flaviventris); Ermine (Mustela erminea); Fog shrew (Sorex sonomae), an endemic mammal to the far western USA; Hoary marmot (Marmota caligata); Mountain beaver (Aplodontia rufa); and the Near Threatened red tree vole (Arborimus longicaudus); Yellow pine chipmunk (Tamias amoenus); and the American water shrew (Sorex palustris).
Spermophilus beecheyi has successfully exploited many habitat types. California ground squirrels are terrestrial, and semifossorial, requiring habitats with some loose soil where they can excavate an appropriate burrow.
You may find them colonizing fields, pastures, grasslands and in open areas such as oak woodlands. The only habitat they do not use is deserts. You may find them down in valleys and up on rocky outcrops in the mountains, to an elevation of 2,200 m. They can be found in urban, suburban and agricultural areas. By and large this species is widely distributed within its range.
Range elevation: 0 to 2200 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: chaparral ; mountains
Other Habitat Features: urban ; suburban ; agricultural
Habitat and Ecology
Comments: Found in a wide variety of habitats. Usually in open areas in many plant communities in all life zones up to the Hudsonian. Sleeps and rears young in underground burrow. Digs deep burrow usually under protective object (log, rock, building, bush) if available, or in open.
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.
California ground squirrels use cheek pouches while they are foraging to collect more food than would otherwise be possible in one sitting. They are also known to cache or store food. They exploit a variety of food sources, which probably contributes to their success as a species.
The diet of these animals, as their genus name would suggest, is primarily seed-based. California ground squirrels consume seeds, barley, oats, and acorns (Quercus): valley oak, blue oak, coast oak). They also eat fruits, like gooseberries and pears, and quail (Callipepla) eggs. They include insects in their diets when they are available, and have been known to eat grasshoppers, crickets, beetles and caterpillars. They also eat roots, bulbs, and fungi, such as mushrooms.
Animal Foods: eggs; insects
Plant Foods: roots and tubers; seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore ); omnivore
Comments: Omnivorous. During spring and summer, feeds primarily on green vegetation: leaves, flowers, bulbs, roots, etc. In late summer and fall, may eat more seeds, berries, and nuts. Also eats insects and occasional small vertebrates, including young conspecifics (done mainly by breeding adult females).
Due to their diet, California ground squirrels could play a role in regulating some insect populations. They may aid in seed dispersal when a cache is forgotten. they help to aerate the soil through their excavation of burrows, and create habitat for many other animals, such as other rodents and snakes, which occupy empty burrows.
Ecosystem Impact: disperses seeds; creates habitat; soil aeration
These ground squirrels are highly vulnerable to predation due to their diurnal habits, open habitat, and the concentrations of conspecifics found in any particular colony. They are known to be preyed upon by red-tailed hawks, golden eagles, coyotes, foxes, badgers, weasels, house cats, dogs, and wild cats such as bobcats and pumas. In addition, large snakes may prey upon them.
Spermophilus beecheyi individuals probably avoid predation mainly through the use of burrow systems and vigilance. They are also cryptically colored. Also, they have skin glands on their back, just posterior to the shoulders, which secrete an odorous oil which could deter predators.
- American badgers (Taxidea taxus)
- weasels (Mustela)
- rattlesnakes (Crotalus)
- red-tailed hawks (Buteo jamaicensis)
- golden eagles (Aquila chrysaetos)
- coyotes (Canis latrans)
- domestic dogs (Canis lupus familiaris)
- domestic cats (Felis silvestris)
- bobcats (Lynx rufus)
- mountain lions (Puma concolor)
- rattlesnakes (Crotalus)
Anti-predator Adaptations: cryptic
Canis lupus familiaris
This list may not be complete but is based on published studies.
Known prey organisms
This list may not be complete but is based on published studies.
Usually in loose colonies. About 1/3 to 3/4 of a population consists of yearlings (see Boellstorff and Owings 1995). May carry fleas that transmit sylvatic plague. Predators include dogs, coyotes, and large hawks. Home range usually is less than 50 m across (Burt and Grossenheider 1964). In west-central California, mean home range size was 300-400 sq m in males, 600-900 sq m in females; home ranges overlapped (Boellstorff and Owings 1995).
Life History and Behavior
California ground squirrels use a variety of sounds, tail signals and scent production as means of communication. For example, glandular folds anterior to the tail region are used for individual identification. When finding a mate or mates, females may approach or males may approach, but scent cues are important in identifying reproductive condition.
Communication Channels: visual ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
Comments: May hibernate in some areas; winter inactivity is more pronounced at higher latitudes and elevations (Dobson and Davis 1986). Active throughout the day during warmer months and in good weather.
The lifespan of a California ground squirrel can be up to 6 years in the wild. They have lived as long as 10 years in captivity.
Status: wild: 6 (high) years.
Status: captivity: 10 (high) years.
Females of this species are considered promiscuous. They will often mate with more than one male, either through force or selectivity, and therefore the offspring of a single litter may have multiple paternity. Males may also mate with several females.
Mating System: polygynandrous (promiscuous)
The mating season of S. beecheyi occurs in early spring, typically for a few weeks only. As with most ground-dwelling squirrels, breeding occurs just after the animals emerge from their winter burrows. This is highly dependent on the area and climate the squirrel inhabits, since the timing of hibernation varies geographically, with elevation, and with other ecological factors.
Males possess abdominal testes which drop into a temporary scrotum during the breeding season only.
Females produce one litter per year after of a gestation period of roughly one month. Litters range in size from five to eleven young. The sex ratio of young are about 1:1.
Young S. beecheyi may open their eyes at around 5 weeks of age. They first leave burrows at 5 to 8 weeks of age, and are wenaed between 6 and 8 weeks. The coloring of the young is somewhat lighter than that of adults. Molting for young begins a few weeks after they emerge from their burrows. Young may begin to burrow at 8 weeks of age. They reach sexual maturity no sooner than 1 year old. In the first year of life, some ground squirrels remain above ground and do not hibernate.
Breeding season: Breeding begins shortly after emergence from hibernation. Timing of the breeding seasons varies, depending upon when the animals end their hibernation.
Range number of offspring: 5 to 11.
Average gestation period: 1 months.
Range weaning age: 6 to 8 weeks.
Range age at sexual or reproductive maturity (female): 1 (low) years.
Range age at sexual or reproductive maturity (male): 1 (low) years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
The only active parenting is provided by the mother. Females give birth to their pups in a burrow, and will move young into new burrows frequently to avoid predation. Young are helpless at birth, and their eyes do not open until they are about 5 weeks old. Shortly after their eyes open, the young pups leave the burrow and begin to explore their surroundings.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Breeding occurs soon after hibernation. Gestation lasts 25-30 days. Litter size averages about 6-7. In the lowlands, females usually produce one litter per year. The young are born hairless and their eyes are closed; they remain underground for about 8 weeks. In central Calfornia, young began to emerge from burrows in late April or early May (Boellstorff and Owings 1995).
Molecular Biology and Genetics
Statistics of barcoding coverage: Spermophilus beecheyi
Public Records: 0
Specimens with Barcodes: 6
Species With Barcodes: 1
There are no special conservation practices currently for S. beecheyi. Some control of their numbers has been attempted, costing several hundred thousand dollars. These are generally targeted responses to crop damage or disease outbreaks.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Management Requirements: Control measures may be short-lived; recolonizes former colonies rapidly (within a few months) if adjacent colony is present.
Relevance to Humans and Ecosystems
This species may threaten agricultural crops, such as grain fields and orchards, through their foraging activities. They are potential carriers of diseases, such as tularemia, bubonic plague, and sylvatic plague. The two latter diseases are from fleas the squirrels carry.
Negative Impacts: injures humans (carries human disease); crop pest; causes or carries domestic animal disease
Comments: May be locally destructive to nut, fruit, and cereal crops.
California ground squirrel
The California ground squirrel (Otospermophilus beecheyi), is a common and easily observed ground squirrel of the western United States and the Baja California peninsula; it is common in Oregon and California and its range has relatively recently extended into Washington and northwestern Nevada. Formerly placed in Spermophilus, as Spermophilus beecheyi, it was reclassified in Otospermophilus in 2009 as it became clear that Spermophilus as previously defined was not a natural (monophyletic) group.
The squirrel's upper parts are mottled, the fur containing a mixture of gray, light brown and dusky hairs; the underside is lighter, buff or grayish yellow. The fur around the eyes is whitish, while that around the ears is black. Head and body are about 30 cm (12 in) long and the tail an additional 15 cm (5.9 in). The tail is relatively bushy for a ground squirrel, and at a quick glance the squirrel might be mistaken for a fox squirrel.
As is typical for ground squirrels, California ground squirrels live in burrows which they excavate themselves. Some burrows are occupied communally but each individual squirrel has its own entrance. Although they readily become tame in areas used by humans, and quickly learn to take food left or offered by picnickers, they spend most of their time within 25 m (82 ft) of their burrow, and rarely go further than 50 m (160 ft) from it.
In the colder parts of their range, California ground squirrels hibernate for several months, but in areas where winters have no snow, most squirrels are active year round. In those parts where the summers are hot they may also estivate for periods of a few days.
California ground squirrels are often regarded as a pest in gardens and parks, since they will feed off ornamental plants and trees. They commonly feed on seeds, such as oats, but also eat insects such as crickets and grasshoppers as well as various fruits.
California ground squirrels are frequently preyed on by rattlesnakes. They are also preyed on by eagles, raccoons, foxes, badgers, and weasels. Interdisciplinary research at the University of California, Davis, since the 1970s has shown that the squirrels use a variety of techniques to reduce rattlesnake predation. Some populations of California ground squirrels have varying levels of immunity to rattlesnake venom as adults. Female squirrels with pups also chew on the skins shed by rattlesnakes and then lick themselves and their pups (who are never immune to venom before one month of age) to disguise their scent. Sand-kicking and other forms of harassment provoke the snake to rattle its tail, which allows a squirrel to assess the size and activity level (dependent on blood temperature) of the snake.
Another strategy is for a squirrel to super-heat and swish around its tail. When hunting, rattlesnakes primarily rely on their pit organ, which detects infra-red radiation. The hot-tail-swishing appears to convey the message "I am not a threat, but I am too big and swift-moving for it to be worth trying to hunt me." These two confrontational techniques also distract the snake from any nearby squirrel burrows containing pups.
The swishing of the tail from side to side is called tail-waving. This tail-waving helps the squirrel to deter a snake attack. It was shown that the snakes attacked the squirrels that exhibited the tail-waving at a shorter distance than those that did not and majority of those tail-waving squirrels successfully dodged these attacks. This successful dodging, along with the fact that the adult squirrels are larger than the young ones, helps to deter the predators, as studies have found that the rattlesnakes are 1.6 times more likely to be deterred from attacking an area after an encounter with an adult squirrel. In 30 out of 45 interactions with snakes, the tail-waving behavior of the squirrels stopped the snake in its tracks and the snake attempted to wait for the squirrel to leave before it would consider attacking again, showing that the behavior does deter predatory attacks by the rattlesnakes. This is due to the adult squirrels being vigilant and looking more threatening and also that they are able to more successfully dodge attacks. They also can use their tail-waving to signal to other ground squirrels in the area that a rattlesnake or other predator has recently been spotted. Though the ground squirrels have been found to also exhibit this tail-waving behavior when there is no predator present, they wave their tail faster and for a longer amount of time when they spot a predator or in an area where a predator has recently been spotted.
Vigilant behavior in squirrels is also a defense mechanism to avoid predation. In addition to the tail-waving, the squirrels have been found to be more vigilant and on alert if there had recently been a predator in the area than they were if there had been no predator detected. If the ground squirrels are aware that they are in an area where the rattlesnakes have recently been, the ground squirrels devote more time to being alert and searching for the predators than to hunting and foraging than in an environment where they do not believe there are predators. These vigilant squirrels were found to have a faster reaction time to a stimuli from a predator and jump higher and further away than a squirrel who was not as vigilant. In a simulated environment study, 60% of squirrels that were in an environment with a recent snake encounter exhibited an evasive leap behavior, which propels them father away from their attackers. 20% of squirrels exhibited this behavior in a primary encounter with a snake and roughly 5% of squirrels exhibited this behavior when there was no snake present and no threat detected. This shows that the squirrels are more alert, vigilant, and ready for an attacker after one has been recently seen.
- Linzey, A. V., Timm, R., Álvarez-Castañeda, S. T., Castro-Arellano, I. & Lacher, T. (2008). Spermophilus beecheyi. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 2009-01-08.
- Helgen, Kristofer M.; Cole, F. Russel; Helgen, Lauren E.; and Wilson, Don E (2009). "Generic revision in the Holarctic ground squirrel genus Spermophilus". Journal of Mammalogy 90 (2): 270–305. doi:10.1644/07-MAMM-A-309.1. Archived from the original on 2011-10-22.
- Animal Diversity Web
- Linsdale, J. (1946). The California ground squirrel. Berkeley and Los Angeles: University of California press.
- "California Ground Squirrel". www.naturemappingfoundation.org. NatureMapping. Retrieved 2014-11-03.
- Squirrels Use Old Snake Skins To Mask Their Scent From Predators
- California squirrels yank rattlesnakes' tails
- "Squirrel Has Hot Tail to Tell Snakes". Scientific American. Retrieved 2007-09-29.
- Barbour, M; Clark, R. "Ground squirrel tail-flag displays alter both predatory strike and ambush site selection behaviours of rattlesnakes". Proceedings of the Royal Society B: Biological Sciences. Retrieved 2014-11-03.
- Clark, R; Putman, B. "The fear of unseen predators: ground squirrel tail-flagging in the absence of snakes signals vigilance". Oxford Journals: Behavioral Ecology. Retrieved 2014-11-03.
- Fauna Boreali-Americana or the Zoology or the Northern Parts of British American, page 170. Retrieved 2009-01-11.
|Wikimedia Commons has media related to California ground squirrel.|
|Wikispecies has information related to: California ground squirrel|
- Measures for controlling California ground squirrels
- Squirrels disguise their scent by chewing on rattlesnake skin
- The Best of Enemies (Rattlesnakes and California ground squirrels)
- Prof. Donald Owings photographs of California ground squirrels under study at UC Davis
- Smithsonian article on California ground squirrel
- Original Description of the Species
Names and Taxonomy
Comments: Recent molecular phylogenetic studies suggest that the traditionally recognized genera Marmota (marmots), Cynomys (prairie dogs), and Ammospermophilus (antelope ground squirrels) render Spermophilus paraphyletic, potentially suggesting that multiple generic-level lineages should be credited within Spermophilus (Helgen et al. 2009). As a result, ground squirrels formerly allocated to the genus Spermophilus (sensu Thorington and Hoffman, in Wilson and Reeder 2005) are now classified in 8 genera (Notocitellus, Otospermophilus, Callospermophilus, Ictidomys, Poliocitellus, Xerospermophilus, and Urocitellus). Spermophilus sensu stricto is restricted to Eurasia.