Cape ground squirrels communicate with one another vocally. Alarm calls are used to warn each other of a threat. When the threat is extreme, squirrels let out a high pitched shrill. If the threat is less intense, a medium pitch is used. Young squirrels use chirping calls during play. Young squirrels also use squeaks to advertise their disapproval when their mother handles them. During daily interactions, ground squirrels use growls to communicate. Like most other mammals, it is likely that they use olfaction extensively in communication as well.
Communication Channels: acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
According to the IUCN Red List, this species has maintained a steady population trend with no specific threats.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Cape ground squirrels carry rabies and occasionally damage crops.
Negative Impacts: injures humans (carries human disease); crop pest; causes or carries domestic animal disease
Cape ground squirrels are interesting and important members of native ecosystems.
Cape ground squirrels benefit their environment when they create burrows because meerkats (Suricata suricatta) and yellow mongooses (Cynictis penicillata) use them as protection from predation and to regulate body temperature. Cape ground squirrels also increase visibility when they remove plants from the surface while they eat. Cape ground squirrels have a mutualistic relationship with meerkats. Meerkat alarm calls warn squirrels of potential danger from predators. In turn, Cape ground squirrels provide burrows. A wide variety of parasites are known from Cape ground squirrels.
Ecosystem Impact: creates habitat
Mutualist Species:
Commensal/Parasitic Species:
Cape ground squirrels eat bulbs, grasses, herbs, insects, seeds, and shrubs.
Animal Foods: insects
Plant Foods: leaves; seeds, grains, and nuts
Primary Diet: omnivore
Cape ground squirrels are found in regions ranging from southern Africa in Namibia and Botwsana to South Africa.
Biogeographic Regions: ethiopian (Native )
Cape ground squirrels live in tropical regions. They prefer dry environments, such as savannas and grasslands. They are also found in the Kalahari Desert, which has an elevation of 600 to 1200 m. Cape ground squirrels live in burrows, which protect them from extreme weather conditions as well as from predation. They do not hibernate.
Range elevation: 600 to 1200 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland
Little is known about the lifespan of this species in the wild. However, the longest lifespan found in captivity is 11.5 years.
Range lifespan
Status: captivity: 11.5 (high) years.
Cape ground squirrels have coarse, short hair. The color of the skin is black. On the back of the body, individuals vary between dark and light shades of a reddish brown. The underbody, limbs, neck, and face are white. They have small ears. A defining characteristic is the extended white tail that is almost as large as the body. Females and males are dimorphic, differing in length and mass. Adult males average 452 to 476 mm, while females are around 435 to 446 mm in length. The mass of males is 423 to 649 g and females are 444 to 600 g. Average mass is 528.5 g. Basal metabolic rate has been calculated at 1.7750 W.
Range mass: 423 to 649 g.
Average mass: 528.5 g.
Range length: 435 to 476 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Known predators of Xerus inauris are black-backed jackals (Canis mesomelas). Belton et. al (2007) found that Cape ground squirrels took longer to come out of their burrow when black-backed jackals feces was present. Once out of the burrow, squirrels investigated the feces and searched the area for the predator with extreme caution. This confirms that Cape ground squirrels use olfactory cues to detect predators. Puff adders (Bitis arietans) and monitor lizards (Varanus exanthematicus) are also known predators of Cape ground squirrels. Their social living, cryptical coloration, and vigilance help to protect them from predation.
When a predator approaches, a male and female squirrel will “mob” attack the predator. This “mobbing” involves putting their tails between their own bodies and the predator’s body. This is only a defense, because if the predator attacks, Cape ground squirrels will flee.
Known Predators:
Anti-predator Adaptations: cryptic
Cape ground squirrels mate throughout the year and are promiscuous. Both males and females mate with multiple partners. When females become receptive, interactions with males occur immediately after leaving the burrow in the morning. Females are in estrous multiple times a year. Estrous does not occur at regular intervals, instead, spontaneous ovulation is thought to occur. Males search for females in estrous and copulate right away or chase females into burrows and mate there. Researchers found that mating took place both above and below ground. Waterman (1998) also found that the minimum time needed to ejaculate was 25 seconds. Dominant males have more mates and gain priority access in mating order. Male to male competition occurs, yet no injuries have been reported. Researchers concluded that aggressive fighting is too costly because a male would be unable to mate if injured. Instead, males approach each other side to side and use a non-aggressive leaping display in which the backs are arched and heads are facing each other. Males must use competitive searching to find females in estrous. Since dominant males have more experience, they find females first. Males also constantly disrupt mating in order to mate with the particular female that they have not mated with yet. When this happens, the disrupted male returns later to finish mating with the same female. Even though mating disruptions happen frequently, males rarely guard their mate.
Mating System: polygynandrous (promiscuous)
Breeding takes place all year long with a peak in the winter. Cape ground squirrels live in social groups with around 3 or 4 females. However, only one female is in estrous at a time. Once a female mates with a male, there is an average of a 48 day gestation period that ranges from 42 to 49 days. Females have a litter of 1 to 3 pups that are altricial; they are blind and naked when they are born. Pups come out of the burrow at the age of 45 days. Females nurse the young for an average of 52 days, so the pups eat solid food approximately 7 days after leaving the burrow. At the age of 153 days, the pups have reached adult size of 570 g. Pups do not reach sexual maturity until 8 months for males and 10 months for females. Once males reach sexual maturity, they disperse from the burrow, while females remain in the social group.
Breeding interval: Cape ground squirrels breed year around, with a peak in the winter.
Breeding season: Breeding occurs throughou the year. Only one female is in estrous at a time in a social group.
Range number of offspring: 1 to 3.
Range gestation period: 42 to 49 days.
Average gestation period: 48 days.
Average weaning age: 52 days.
Average time to independence: 153 days.
Average age at sexual or reproductive maturity (female): 10 months.
Average age at sexual or reproductive maturity (male): 8 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Cape ground squirrels offspring are atricial at birth and need parental care until they are independent. Females protect their offspring in the burrows. Once pups are 45 days of age, they can leave the burrows. Females provide food for their young through nursing until pups are 52 days old. After 52 days, pups leave the burrow to forage on their own. Pups reach full adult size at 153 days. Once males reach sexual maturity at 10 months, they no longer associate with the social group. Once females reach sexual maturity at 8 months, they stay with the social group and continue to associate with the mother. Males are found to have no involvement in parental care.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); post-independence association with parents
The Cape ground squirrel or South African ground squirrel[1][2] (Geosciurus inauris)[3] is found in most of the drier parts of southern Africa from South Africa, through to Botswana, and into Namibia, including Etosha National Park.
The name Cape ground squirrel is somewhat misleading as it actually has a much wider area of habitation. This common name may have been arrived at to distinguish it from a tree squirrel (the eastern grey squirrel) found around Cape Town, which was imported from Europe by Cecil John Rhodes.
The species has also been known as the fan-tailed squirrel.
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The Cape ground squirrel has black skin with a coat made of short stiff hairs without underfur. The fur is cinnamon on the back while the face, underbelly, sides of neck and ventral sides of limbs are white.[5] The sides of its body each have a white stripe that stretches from the shoulders to the thighs. The eyes are fairly large and have white lines around them. The pinnae are small. The tail is flattened on the back and underside and is covered with white hair and two black bands at the base.[6] The Cape ground's sexual dimorphism is subtle. Males usually weigh 423–649 grams (0.933–1.431 lb), 8 to 12 percent more than females at 444–600 grams (0.979–1.323 lb).[7] Male Cape ground squirrels have a total length of 424–476 millimetres (16.7–18.7 in), while females are 435–446 millimetres (17.1–17.6 in) long.[5] The dental formula of the ground squirrel is 1.1.0.01.1.3.3.[8] The belly and groin area of the females each have two pairs of mammary glands. The glans penis of the males are large with a prominent baculum.[5] This species is notable for its impressively large testicles, which are roughly golf ball size, around 20% of the length of the head and body.[8] Moulting occurs between August and September and between March and April, once per year.[9]
The Cape ground squirrel is widespread in southern Africa; through Botswana, South Africa, Lesotho, and Namibia.[1][10] Its range covers most of Namibia but is absent from coastal regions and the northwest.[6] Ground squirrels inhabit central and southwestern Kalahari in Botswana.[11] In South Africa, it can be found in central and north-central areas.[6]
Cape ground squirrels live mainly in arid or semiarid areas.[9] They prefer to live in veld and grasslands with hard ground. They can also be found in scrub along pans, on floodplains and in agricultural areas.[11] Ground squirrel are generally active during the day and do not hibernate. They are burrowing animals that dig and live in clusters of burrows averaging around 700 square metres (7,500 sq ft)[12] with 2-100 entrances.[9] Burrows serve to protect the squirrel from extreme temperatures at the surface as well as predators. Nevertheless, most of the day is spent feeding at the surface.[10] Squirrels shade their head and back with their bushy tails, which was originally thought to be important for thermoregulation. However, research has revealed that tail raising does not actually decrease core body temperature and seems to mostly serve as a way for squirrels to cool the skin and increase their thermal comfort as they forage in the hot sun in between visits to their burrows.[13] Burrowing has been shown to reduce the squirrel's core body temperature by a few degrees Celsius.[13] Squirrels tend to leave the burrows earlier in the morning in the summer months to avoid the heat, and in the winter months their core body temperature increases rapidly upon exiting their burrows.[14] Dust bathing is also done.
Ground squirrels eat bulbs, fruits, grasses, herbs, insects and shrubs.[5] They forage daily and do not hoard food,.[9] The Cape ground squirrel usually does not need to drink as it gets sufficient moisture from its food.[5] A ground squirrel's daily activities are made of around 70% feeding, 15-20% being vigilant and around 10% socializing.[9][12] The squirrels use the position of the sun as an orientation marker to hide and recover their food.[15]
The burrows of Cape ground squirrels are also used by meerkats and yellow mongooses.[16] While Cape ground squirrels and meerkats appear to have a mutual relationship, mongoose and squirrel relations appear to be more commensal.[16] Predators of ground squirrels include jackals, snakes and monitor lizards. Ground squirrels may be able to scent the differences in the dropping of predators and non-predators.[17] When threatened by predators ground squirrels engage in mobbing behaviour:[16][18] several squirrels rush at the predator while using their bushy tails to block it. When the predator strikes back, all the squirrels back off. However, multiple mobbings are usually successful in driving away predators.[18]
Cape ground squirrels live in groups of two to three adult females and a maximum of nine sub-adults of either sex[12] as well as the females' dependent offspring.[9] Groups that have more than three females split into smaller groups.[19] Adult males live separately from females and only join when the females are in estrus.[12] Male groups number up to 19 unrelated individuals, which are not agonistic. Within a male group, four to five males may form temporary subgroups that change size and members each day.[5] Female groups live in separate burrow clusters. A female group's home range is c. 4 hectares (9.9 acres) with core areas of around 0.25 hectares (0.62 acres).[12] Home ranges can overlap. Core areas are defended by agonistic behaviour.[10][12] Male groups live in home ranges envelop those of several female groups and average 12.1 hectares (30 acres).[12] Within a female group there is no dominance hierarchy, and members use the same feeding and sleeping ranges. Male groups, by contrast, live in ages-based linear hierarchies. Competition between males usually takes the form of leaping displays that cause no injuries.[20] Unlike female groups, male groups are not territorial, and membership is very open.[5] During oestrus, a female will be approached, solicited and chased by males trying to mate with her. The most dominant males get the first matings.[20] A female will mate with the same male several times. If a male has not yet mated with a female, he will disrupt the copulations she has with other males.[20] However, mate guarding is rare.
When perceiving something as a threat, ground squirrels will emit a whistle-like call as an alarm call.[8][10] The alarm call comes in two forms; the short and shrill "bi-jo" which signals serious danger, and a medium-pitched "bi-joo" sound which is used for lesser dangers.[8] During antagonistic encounters, squirrels emit deep growls as signs of aggression.[10] Juvenile squirrels make play calls, nest-chirpings, and protest squeaks.[5]
Cape ground squirrel mate and reproduce year-round[9][11][21] but mating occurs mostly in dry winter months.[5] Since females copulate with multiple males, the males' large testes are useful for sperm competition. After copulation, males will masturbate, which could serve to keep the genitals clean and reduce the risk of sexually transmitted infections.[22] In groups, only one female at a time enters oestrus which lasts around three hours. Gestation lasts around 48 days[21] or 42–49 days.[8] Lactation begins not long before the pups are born. A lactating female isolates herself in a separate burrow to care for their young but she returns to her group after weaning or if her litter is lost for some reason.[5] There are 1-3 pups in a litter.[9][21] They are born altricial, hairless and blind.[9] The pups stay in the burrows for their first 45 days. By 35 days, the eyes are open.[9] Seven days after emerging from the burrows, the pups can eat solid food. Lactation ends at around 52 days.[21] Males reach sexual maturity at eight months while female mature at 10 months. The former leave their natal groups while the latter remain.[12]
The Cape ground squirrels populations does not seem to be threatened overall. In some areas, it is persecuted as an agricultural pest.[1] In addition, humans have used poisonous grass to control ground squirrel due to crop damage and rabies.[8] It inhabits protected areas, such as Kgalagadi Transfrontier Park in Botswana and South Africa and Etosha National Park in Namibia.[1]
Young Cape ground squirrels
Ground squirrel at burrow entrance
Cape ground squirrels
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Male eating, Tswalu Kalahari Reserve, South Africa
The Cape ground squirrel or South African ground squirrel (Geosciurus inauris) is found in most of the drier parts of southern Africa from South Africa, through to Botswana, and into Namibia, including Etosha National Park.
The name Cape ground squirrel is somewhat misleading as it actually has a much wider area of habitation. This common name may have been arrived at to distinguish it from a tree squirrel (the eastern grey squirrel) found around Cape Town, which was imported from Europe by Cecil John Rhodes.
The species has also been known as the fan-tailed squirrel.
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