Unstriped ground squirrels belong to the Xerini tribe of ground squirrels characteristic of the arid country of northeastern Africa. They are endemic to East Africa and have been recorded in the region encompassed by Sudan, Tanzania and Somalia. They are native to Djibouti, Eritrea, Ethiopia, Kenya, Somalia, Sudan, Tanzania, and Uganda. Considered the most common ground squirrel of eastern Ethiopia, their geographic range in Kenya appears to be contracting in some areas, possibly as a result of displacement by the larger, more aggressive striped ground squirrels (Xerus erythropus). Striped ground squirrels are the only African ground squirrels that occur sympatrically with unstriped ground squirrels. (Coe, 1972; Delany, 1975; Dorst and Dandelot, 1970; Hubert, 1978; Ingersol, 1968; Key, 1990; Kingdon, 1974; Martin, 1986; O'Shea, 1976; O'Shea, 1991; Swynnerton and Hayman, 1951; Toschi, 1945; Yalden, et al., 1976)
Unstriped ground squirrels are fossorial and associated with arid, open shrub and bush savannah, as well as riverine areas where the soil is soft for burrowing. They live in burrows at the stem bases of Salvadora thickets, low-lying stunted acacias or in long-standing zarebas. In Harar Province, Ethiopia, they are also recorded around stands of prickly pear cactus. Unstriped ground squirrels also occupy termite mounds or burrows excavated by other species. The are also found in small gullies associated with lava gravel flats and have been recorded at elevations ranging from sea level to approximately 2000 meters. (Coe, 1972; De Winton, 1898; Delany, 1975; Drake-Brockman, 1910; Hubert, 1978; Ingersol, 1968; O'Shea, 1976; Yalden, et al., 1976)
Unstriped ground squirrels are the smallest ground squirrels in the genus Xerus, weighing between 260 and 420 g, and measuring 200 to 255 mm in head and body length with a 120 to 225 mm long tail. They lack the longitudinal stripes characteristic of other Xerus species. Color varies somewhat according to region, but these squirrels are generally described as tawny to reddish-brown with a darker dorsum. There is considerable variation in the extent of red on the crown and also in the amount of black on the head and nape; specimens from more northern localities are paler. According to Kingdon (1974) the upper parts are heavily ticked with white, but Toschi (1945), Hollister (1919), and Dollman (1911) indicate that they may be speckled black along the back. The large eyes are ringed white and there is a white patch in front of the small, slit-like ears. The tail, colored rufous above and whitish below, is flat in appearance with long hairs projecting from each side. Dorst and Dandelot (1970) indicate that the tail is mixed with black and white. Unstriped ground squirrels have sparsely furred undersides and are described as “harsh-furred” squirrels due to the coarse, bristly texture of the pelage. They appear to molt at all times of the year. The dental formula is 1/1, 0/0, 1/1, 3/3, for a total of 20 teeth. The skull is characterized by an elongated rostrum and a small infraorbital canal. Males have a well-developed 6 mm long baculum. The chromosome number is 2n = 38. (Coe, 1972; Delany, 1975; Dollman, 1911; Dorst and Dandelot, 1970; Drake-Brockman, 1910; Hollister, 1919; Ingersol, 1968; Kingdon, 1974; Mace, et al., 1981; Nadler and Hoffmann, 1974; O'Shea, 1991; Pocock, 1923; Roth and Thorington Jr, 1982; Toschi, 1945; Yalden, et al., 1976)
The mating system of this species is not known. However, there have been observations of mating. In this species, males exert dominance over females. A male will approach a female with a characteristic tail display which involves piloerection of the tail while it is arched over the back. Holding the tail in this position, the male rapidly approaches the female. A receptive female will respond to the male’s tail display by retreating and flicking her tail with rapid up-down movements. The female will stop occasionally to scent-mark the ground by dragging her perineal region along it. The female may also vocalize as she moves away from the male, uttering a soft chirring sound. The male follows the retreating female with the tail extended dorsally, stopping to sniff the female’s scent markings. The male then chases the female, and approaches her posterior region. The female responds by taking a submissive posture and rolling onto her side, allowing the male to approach and investigate. The male approaches and begins sniffing the female, who responds by assuming a prostrate position. The male then mounts the female by grasping behind the shoulders with both forepaws. (Drake-Brockman, 1910; Hollister, 1919; Hubert, 1978; Ingersol, 1968; Kingdon, 1974; O'Shea, 1976; O'Shea, 1991)
Drake-Brockman (1910) indicated that breeding occurs during March and April, which coincides generally with Hubert’s (1978) observation that reproduction in (Drake-Brockman, 1910; Hollister, 1919; Hubert, 1978; Ingersol, 1968; Kingdon, 1974; O'Shea, 1976; O'Shea, 1991)is initiated following the onset of the rainy season. However, Kingdon (1974) collected small juvenile throughout most months of the year and so concluded that breeding occurred throughout the annual cycle. Additionally, O’Shea (1976) indicated that males are in breeding condition throughout the year, as confirmed by testes condition and sexual behavior. It is possible that breeding season varies geographically or with climate conditions. Females likely produce two young per litter. Pregnant females containing two embryos have been collected in both Kenya and Ethiopia and one or two juveniles per female have been reported for a population near Kibwezi in south-central Kenya.
Prior to parturition, pregnant females establish maternity burrows at the peripheries of their home range. Former burrow systems are temporarily abandoned and old, unoccupied burrows are re-excavated for the purposes of rearing young. After 3 to 4 weeks following the emergence and weaning of young, the female abandons the maternity burrow and returns to her original burrow. (O'Shea, 1976; O'Shea, 1991)
Unstriped ground squirrels are diurnal and mainly solitary. They live in isolated burrow systems, which they may occupy alone or with one other adult of either sex. They are not classified as territorial as they allow non-resident squirrels to enter their burrows, even squirrels belonging to striped ground squirrels (X. erythropus). There is a dominance hierarchy, with males dominant over females and juveniles. Burrows are not the centers of diurnal activity for adults. Except for periods immediately following emergence and prior to retreat, unstriped ground squirrels are not usually near the burrows. Upon emergence, they engage in sunbathing for periods up to 30 minutes. They then forage in open areas, retreating to the shade provided by bushes such as Salvadora during the heat of the day, where they continue to forage on fruit and seeds. Unstriped ground squirrels retreat to their burrows in the late afternoon. Unstriped ground squirrels also retreat to burrows during periods of extreme heat or heavy rainfall or when seeking safety. When startled, they seek the nearest cover, traveling fast with their tails down and extended. As soon as they stop, these squirrels raise the tail over their back and sits up on their haunches to confirm the danger before disappearing into the burrow. Piloerection of the tail is also observed as a general alarm reaction. Agonistic behavior in ranges from threat to combat. Threat by a dominant squirrel is conveyed with rough scolding chatter; subordinate ground squirrels respond with a low, gentle chirring sound. Threat may escalate to short lunges. These lunges are initiated from a variety of postures, but most frequently from a quadrupedal stance with the hind feet flat beneath the body, the back slightly arched, and one forepaw lifted off the ground. Chasing normally occurs after the chattering vocalization, but rather than ending in combat, chases tend to end abruptly when the more aggressive individual simply stops running. Actual combat is very rare in . The tail display that is used in mating has only been observed in adult males, but are also exhibited when adult males encounter juveniles of either sex. Juveniles respond to tail displays of adult males with the retreat-submission behaviours described for adult females. Adult males may also visually signal their sexual identity using an upright alert posture which exposes their large, conspicuous scrota. Unstriped ground squirrels exhibit behavioral thermoregulation. After foraging in hot open areas, they return to the shade and press their undersides against the ground to unload excess body heat. (Coe, 1972; Drake-Brockman, 1910; Hubert, 1978; Martin, 1986; O'Shea, 1976)
Unstriped ground squirrels inhabit broadly overlapping home ranges, with each home range encompassing several burrow sites. Home ranges identified during the period December to April were found to be considerably larger for males than females, ranging on average from 7.01 to 1.37 hectares, respectively. Range areas reported for the species are likely underestimated as ranges may expand during other months when food may be scarce. (O'Shea, 1976; O'Shea, 1991)
Communication in unstriped ground squirrels is achieved primarily by posturing, tail positioning, and tail movement. Chirring, chattering and other vocalizations are associated with sexual encounters, threats, and submission. It is possible that chemical cues, such as pheromones, are also used in communication. (O'Shea, 1976)
Unstriped ground squirrels are diurnal foragers. They were originally thought to consume a diet limited to roots, rice, and "jowari" (a variety of cultivated Sorghum), but Kingdon (1974) describes a more generalist diet which includes wild roots, pods, seeds, fruit, stems, and leaves, as well as some insects. Coe (1972) indicates that more than 50 percent of their diet is dry seeds and leaves. Fruits are also consumed, including the fruits of Adansonia, Acacia, and Commiphora. De Winton (1898) identified a preference for aloe seeds. Fanson, et al. (2010) found that they appear unaffected by tannins and forage to some extent on oxalic containing foods. Unstriped ground squirrels adjust their foraging behavior relative to perceived predation risk and store food via scatter hoarding. (Coe, 1972; De Winton, 1898; Drake-Brockman, 1910; Fanson, et al., 2010; Kingdon, 1974; O'Shea, 1976)
The main predators of unstriped ground squirrels have been described for the Ngulia Rhino Sanctuary, Tsavo West National Park, Kenya. They include avian raptors, including tawny eagles (Aquila rapax), bateleurs (Terathopius ecaudatus), martial eagles (Polemaetus bellicosus), as well as mammalian predators including leopards (Panthera pardus) and black-backed jackals (Canis mesomelas). Although snakes were not detected in the study, these and other reptiles also likely prey on them. Unstriped ground squirrels assume an alert posture (rearing up on hind legs) when alarmed, presumably to increase their range of visual field. Anti-predator responses differ according to habitat type, but generally involve escaping to cover habitats such as bushland, using unpredictable dashing movements. Burrow systems are the major refuges used by unstriped ground squirrels when fleeing from danger. (Fanson, et al., 2010; O'Shea, 1976)
Unstriped ground squirrels are potential prey for the rich array of avian, reptilian, and mammalian predators found in East African arid regions. Additionally, they are a host species to several types of parasite. Ectoparasites include fleas (Synosternus somalicus) and ticks (Haemaphysalis calcarata), which appears to be found only on . Known internal parasites include cestodes (Catenotaenia geosciuri) and trypanosomes (Leishmania aethiopica). (Abebe, et al., 1990; Beaucournu, et al., 1972; Fanson, et al., 2010; Hoogstraal, 1955; Joyeux and Baer, 1945; Theiler, 1964)
There are no documented positive effects ofon humans.
Unstriped ground squirrels may serve as a natural reservoir of disease causing organisms and/or their vectors. Leishmania aethiopica, which causes both simple cutaneous and diffuse cutaneous leishmaniasis in humans, has been isolated from . Additionally, the International Union for Conservation of Nature (IUCN) indicates that is a significant agricultural pest species in arid parts of Kenya, with density estimates in Turkana, Kenya, reaching 848 individuals per square kilometer. Ground squirrels belonging to the genus Xerus, including , may cause considerable damage to crops, especially maize, ground nuts, yam, and cassava. (Abebe, et al., 1990; Coe, 1972; Dorst and Dandelot, 1970; Grubb and Oguge, 2008; Hoogstraal, 1955)
There appear to be no major threats to this species as a whole. The IUCN Red List classifies (Grubb and Oguge, 2008)as a species of Least Concern in view of its wide distribution, presumed large population, and its tolerance for some degree of habitat modification. The species occurs in a number of protected areas (such as Samburu National Reserve, Kenya), and is unlikely to be declining fast enough to qualify for listing in a more threatened category.
The name Xerus is derived from the Greek xeros, meaning “dry”, either in reference to the aridity of the species’ habitat or to the bristly texture of its pelage. The epithet rutilus is Latin, and refers to a “red or golden-red” coloration. In the Somali language unstriped ground squirrels are called “dabagalleh”, which means “the possessor of a tail like a sheath or scabbard”. Kingdon (1974) identified the following local names: kindi, kidiri (Swahili), ekunyuk, ngikunyuko (Karamojong), eetata (Kiliangulu). (Drake-Brockman, 1910; Kingdon, 1974; O'Shea, 1991)
Fossilized remains of a terrestrial squirrel belonging to the genus Xerus was unearthed at the Pliocene site of Kossom Bougoudi in Chad. Close phylogenetic affinities of the fossil, Xerus daamsi sp. nov. and extant were determined using cladistic analysis of craniodental characters. (Denys, et al., 2003)
Isabel Martinez-Welgan (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
living in landscapes dominated by human agriculture.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
an animal that mainly eats fruit
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
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