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Xerus erythropusstriped ground squirrel

By Kimberlee Carter

Geographic Range

Xerus erythropus prefer habitats that are fairly dry. Savanas of eastern Sudan and southwestern Kenya, southwestern Morocco, southern Mauritania and Senegal are the native homes of Geoffrey's ground squirrels. (Ellerman, 1940; Hanney, 1975; Happold, 1987; Nowak, 2004)

Habitat

Geoffrey’s ground squirrels prefer open “savanna like” habitats. The climate in which they are found is dry. Africa’s open woodlands, grasslands, and rocky country are home to the majority of this species. (Ellerman, 1940; Hanney, 1975; Happold, 1987; Key, 1990)

  • Range elevation
    1000 to 5000 m
    3280.84 to 16404.20 ft
  • Average elevation
    3500 m
    11482.94 ft

Physical Description

The coarse fur covering its body identifies this species. The fur is frequently tinted the color of the soil in which the animal is found, creating an array of color from brownish to reddish grey to yellowish grey. The pads of the feet lack fur. A few sparse white hairs may occupy the area surrounding the foot. A white, or buff, stripe appears on both sides of the body running from the shoulders to the hind quarters. The total length of the body is between 203 to 463 mm with a tail length of 180 to 274 mm. The tail is somewhat flattened and usually a shade darker than the rest of the body. The ears are small. Claws are present, long and slightly curved, but climbing trees is nearly impossible for Xerus erythropus. (Ellerman, 1940; Hanney, 1975; Nowak, 2004)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    300 to 945 g
    10.57 to 33.30 oz
  • Range length
    203 to 463 mm
    7.99 to 18.23 in

Reproduction

Xerus erythropus live in social colonies. Within these colonies there are several females; males travel between colonies. Chirping and chattering vocalizatins are used by males to attract a mate. Defending mates is unknown in this species; most likely there is no defense of mates due to the fact that males never stay in one social colony for an extended period of time. (Ellerman, 1940; Hanney, 1975; Nowak, 2004)

Breeding occurs year round, but is synchronized among the females of one particular social group. Gestation of Xerus erythropus is 64 to 78 days. The average litter number is about three young. Geoffroy’s ground squirrels have a high rate of litter loss with some 70% of all pregnancies failing to produce a litter. It is unknown when weaning occurs, but sexual maturity is attained at about one year. (Ellerman, 1940; Happold, 1987; Nowak, 2004)

  • Breeding interval
    Female Xerus erthyropus breed once yearly.
  • Breeding season
    Mating occurs throughout the year, but is often coordinated within social groups.
  • Range number of offspring
    2 to 6
  • Average number of offspring
    3
  • Average number of offspring
    3.5
    AnAge
  • Range gestation period
    64 to 78 days
  • Average time to independence
    1 years
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    365 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    1 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    365 days
    AnAge

Young are cared for by the female. Males do not invest time in parental care because it is uncertain which young are genetically related to them. The females in social groups dig elaborate burrows for raising young. A burrow for young consists of a nesting area with soft, dried grasses and several emergency exits. These burrows are usually deeper than standard burrows. Females protect their burrows aggressively. They provide food for their young and often instruct the young in collecting food and avoiding predators. Time to weaning is unknown, but at about 1 year both male and female young become independent and sexually mature. (Ellerman, 1940; Hanney, 1975; Happold, 1987; Nowak, 2004; Rosevear, 1969; )

  • Parental Investment
  • precocial
  • female parental care
  • pre-hatching/birth
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents
  • inherits maternal/paternal territory

Lifespan/Longevity

Longevity of Xerus erythropus is limited by predation. Human disruption of habitats may also limit the lifespan, which averages 2 years in the wild. (Nowak, 2004)

Behavior

Xerus erythropus are very social. No known socail hierarchy exists in this species. The social groups usually consist of groups of 6 to 10 individuals, with a maximum of 30 individuals. The majority of the groups are made up of females. Males only enter social groups when the females are in estrus. When mating is not occurring, males roam from social group to social group.

A typical day in the life of Xerus erythropus consists of making various vocal sounds to communicate and socialize with their neighbors, sunning themselves, and collecting and storing food. Geoffrey’s ground squirrels often sit erect when eating. This allows them to have a greater view of their environment. By sitting erect, the animal is also able to be more alert to sounds that may indicate an approaching predator. The tail of Geoffrey’s ground squirrels is an excellent indicator of their mood. When a squirrel is alert, the tail is held over the back and flicked back and forth with the hairs erect. A frightened squirrel will run with its tail parallel to its body. A state of relaxation is identified by a tail that is so relaxed it is almost dragged along the ground. Xerus erythropus are active during the day. On extremely hot days, this species is active at dawn and dusk to avoid excessive heat during midday. (Ellerman, 1940; Hanney, 1975; Happold, 1987; Nowak, 2004)

  • Range territory size
    750 to 5000 m^2

Home Range

Xerus erythropus establish colonies that are usually occupied by females. A female’s home range is much smaller than a male's at about 1.37 ha. A male’s home range is more extensive with a measurement of 7.01 ha. Geoffrey’s ground squirrels are territorial, but share their burrows with several other burrowing species. (Dobigny, et al., 2000; Ellerman, 1940; Hanney, 1975; Happold, 1987; Nowak, 2004)

Communication and Perception

Vocalizations are an important form of communication. Squeaking and chirping indicate pleasure, protest and distress. A higher pitched chirping or chattering may suggest threats of higher alarm. Mating males and females communicate with one another through olfaction/phermones as well as vocalizations. Geoffrey’s ground squirrels have facial scent glands with which they mark their territory and their food. (Dobigny, et al., 2000; Happold, 1987; Nowak, 2004)

Food Habits

Xerus erythropus are omnivorous. The diet consists of palm nuts, banana, pawpaw, seeds, pods, grains, yams and other roots, insects, small vertebrates, and bird’s eggs. Foods such as nuts and seeds are often stored around the burrows. (Ellerman, 1940; Hanney, 1975; Happold, 1987; Nowak, 2004; Rosevear, 1969)

  • Animal Foods
  • mammals
  • amphibians
  • reptiles
  • eggs
  • insects
  • Plant Foods
  • roots and tubers
  • seeds, grains, and nuts
  • fruit

Predation

The defense system of Xerus erythropus lies in their burrow structures. The burrows provide protection from predators when the alarm call has been heard. Geoffrey’s ground squirrels will often cautiously peep out of their burrows to search for the cause behind the alarm call. The main predators of Xerus erythropus are various carnivores such as raptorial birds and mongooses. (Dobigny, et al., 2002; Hanney, 1975; Happold, 1987; Nowak, 2004)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Several predators of Xerus erythropus also share burrows with this species. Several mongoose species benefit from the burrows that have already been made by Geoffrey’s ground squirrels. In return, the mongooses offer protection from bird of prey and snakes that threaten the colony.

Xerus erythropus disperse seeds by caching their food. Stores are often forgotten and the seeds germinate.

Geoffrey’s ground squirrels serve as a host to ticks. It has also been discovered that Xerus erythropus are susceptible to trypanosomes in the blood and can carry rabies. (Dobigny, et al., 2000; Hanney, 1975; Happold, 1987; Key, 1990; Nowak, 2004)

  • Ecosystem Impact
  • disperses seeds
  • creates habitat
Mutualist Species

Economic Importance for Humans: Positive

Geoffrey’s ground squirrels make good pets. They tame readily and are often kept in houses, analogous to house cats in South Africa. In some parts of Africa Xerus erythropus are hunted for their meat. (Ellerman, 1940; Hanney, 1975; Happold, 1987; Nowak, 2004)

Economic Importance for Humans: Negative

Farmers often try to protect their crops, such as yams, from Xerus erythropus. Open agricultural fields of roots and tubers are an extensive feeding ground for Geoffrey’s ground squirrels causing them to be classified as pests by farmers. As previously mentioned, Geoffrey's ground squirrels can be infected with trypanosomes and rabies. (Dobigny, et al., 2000; Ellerman, 1940; Hanney, 1975; Key, 1990; Logan, et al., 1993; Nowak, 2004; Rosevear, 1969)

Conservation Status

No special status was found for Xerus erythropus.

Other Comments

Interest in the coexistence of Xerus erythropus with several mongoose species has lead to numerous studeis. The pairing is unique since the mongoose is also a predator of Geoffrey’s ground squirrels. This coexistence proves that protective habitats are more important than obtaining food. This may be attributed to the fact that mongooses have many sources of food that are abundant enough that they do not need to rely on Xerus erythropus for nourishment. Several studies have been conducted on this bizarre relationship, and many more are in progress. (Dobigny, et al., 2000; Dobigny, et al., 2002; Logan, et al., 1993; ; )

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Kimberlee Carter (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

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.

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

crepuscular

active at dawn and dusk

cryptic

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.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

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.

female parental care

parental care is carried out by females

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

iteroparous

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).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynous

having more than one female as a mate at one time

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

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.

savanna

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.

temperate grassland

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.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

young precocial

young are relatively well-developed when born

References

Dobigny, G., J. Gautun, A. Nomao. 2002. A cytotaxonomic survey of rodents from Niger: implications for systematics, biodiversity and biogeography. Mammalia, 66/4: 495-523.

Dobigny, G., J. Gautun, A. Nomao. 2000. "Retour" (On-line). An example of expression of the animal biodiversity in the Sahel: the settlement of Rodents of Niger. Accessed April 27, 2004 at http://translate.google.com/translate?hl=en&sl=fr&u=http://www.virtualcentre.org/fr/res/int/atelier_niamey/atelier_niamey02.htm&prev=/search%3Fq%3DXerus%2Berythropus%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26sa%3DG.

Ellerman, J. 1940. The Families and Genera of Living Rodents. London: Jarrold & Sons LTD.

Hanney, P. 1975. Rodents: Their Lives and Habits. New York: Taplinger Publishing Company.

Happold, D. 1987. Mammals of Nigeria. Oxford: Clarendon Press.

Key, G. 1990. Preharvest crop losses to the African striped ground squirrel, Xerus erythropus, in Kenya. Tropical Pest Management, 36/3: 223-229.

Logan, T., J. Cornet, M. Wilson. 1993. Association of ticks (Acari, Ixodoidea) with rodent burrows in northern Senegal. Journal of Medical Entomology, 30/4: 799-801.

Nowak, R. 2004. "Walker's Mammals of the World" (On-line). African Ground Squirrels. Accessed April 27, 2004 at http://www.press.jhu.edu/books/walkers_mammals_of_the_world/rodentia/rodentia.sciuridae.xerus.html.

Rosevear, D. 1969. The Rodents of West Africa. London: Trustees of the British Museum (Natural History).

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