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Galago zanzibaricusZanzibar bushbaby(Also: Zanzibar galago)

By Ryan Satovsky

Geographic Range

Galago zanzibaricus, commonly known as Zanzibar bushbabies, can be found in the East African coastal forests from southern Somalia to Mozambique. As the name suggests, they are also native to the island of Zanzibar. However, this species cannot be found on Pemba and Mafia, two nearby islands. Some researchers maintain that the north boundary of this species is the Tana River in Kenya. They are also found up to a few hundred kilometers inland in the Udzungwa Mountains. (Butynski, 2004)

Habitat

Galago zanzibaricus lives in tropical, lowland coastal forests. They are also found at higher elevations further inland. They have been found at elevations greater than 1,000 m in the montane forests of Tanzania and Malawi. Population densities are highest near rivers. There is little inter-group exchange among G. zanzibaricus as populations are extremely fragmented. ("Ngaramia Riverine Forest Conservation Project", 2003; Butynski, 2004)

  • Range elevation
    0 to above 1,000 m
    0.00 to ft

Physical Description

Zanzibar bushbabies are generally brown in color. The underside is a lighter shade of brown. The fur is heavy and soft. They have stunningly large red eyes which help them to see at night. The ears are extremely large and the hind limbs are strong and significantly longer than the fore limbs. There is little dimorphism between males and females. The average weight of an adult is 146.8 g. The average weight of an infant at birth is 14.1 g. The body length from head to tail ranges from 14 to 15 cm and the tail length varies from 12 to 15 cm. ("An Age entry for Galagoides zanzibaricus", 2005; Butynski, 2004)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    146.8 g
    5.17 oz
  • Range length
    140 to 150 mm
    5.51 to 5.91 in

Reproduction

This species is polygynous. Females form small, territorial groups. Upon entrance into such a group, a male usually mates with all members (usually 1-3 females). The females provide the vast majority of parental care. Young females stay within their natal groups and young males disperse. Details of their social behavior are not know because of their elusive behavior. (Butynski, 2004; Nash, 1983; Nunn, 1999)

Reproduction is seasonal, and Zanzibar bushbabies give birth twice a year. Births occur in August to October and February to March. The average gestation period is 120 days. Females usually give birth to one offspring, although in captivity on a few occasions twins have been born. The average number of offspring in captivity is 1.3 but is probably much closer to 1.0 in the wild. Weaning of infants takes place at around four weeks of age. Weaning is done just before the food supply is the lowest (December to January) and directly after food sources are most abundant (May to June). Female G. zanzibaricus mature sexually at around 265 days of age. Males take about 100 days longer to mature (approx. 1 year). The vagina is sealed at all times except during estrus and birth. ("An Age entry for Galagoides zanzibaricus", 2005; Nash, 1983; Schulke, 2002)

  • Breeding interval
    Zanzibar bushbabies breed twice a year depending on seasonal conditions.
  • Breeding season
    Breeding generally occurs between July and March.
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1.3
  • Average gestation period
    120 days
  • Average weaning age
    4 weeks
  • Average age at sexual or reproductive maturity (female)
    265 days
  • Average age at sexual or reproductive maturity (male)
    365 days

Little is know about parental investment in Zanzibar bushbabies. Females primarily care for the young. Occasionally, male bushbabies will sleep with a female and what is thought to be their offspring. Female young remain in their natal group. (Nash, 1983)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents

Lifespan/Longevity

Some reports estimate maximum longevity in the wild is 16.5 years. The longest lifespan of a captive G. zanzibaricus is 12.2 years. ("An Age entry for Galagoides zanzibaricus", 2005)

  • Range lifespan
    Status: captivity
    12.2 (high) years
  • Typical lifespan
    Status: wild
    16.5 (high) years

Behavior

Zanzibar bushbabies are nocturnal, resting during the day and foraging at night. They are arboreal and spectacular climbers. These animals are agile and use their tail for balance. They have the ability to safely run and leap from limb to limb. Both males and females are territorial and maintain non-overlapping territories (occasionally minor overlapping is seen). Male G. zanzibaricus are rarely found in the same territory other males. Occasionally, however, two females occupy the same territory. They usually sleep together but go their different ways during active periods. Galago zanzibaricus typically travel between 1,500 and 2,000 meters per night. Young females remain in their natal ranges after males disperse. Male dispersal prevents incest from occuring. (Butynski, 2004; Harcourt and Nash, 1986; Nunn, 1999)

  • Average territory size
    22000 m^2

Home Range

In one study, the average home range size was found to be about 2.2 ha. Range size varies from 1.6 to 2.8 ha. (Harcourt and Nash, 1986; Nunn and Barton, 1999)

Communication and Perception

The large eyes of Zanzibar bushbabies provide excellent vision at night and the large ears provide an acute sense of hearing. Both attributes are important for navigation in the dark. These animals have loud, distinctive calls about which little is known. They may be a sort of "advertising" call, but they also seem to be used as a warning to others when potential predators are nearby. Like most mammals, chemical cues are probably also important in communication. (Butynski, 2004; Nash, 1983)

Food Habits

The diet of Galago zanzibaricus is mostly composed of fruits, insects, and tree gums. Seasonal variation in resource availability plays an important roll in determining what the animals eat. For example, when it rains a lot there may be an abundance of insects, but when no rain falls Zanzibar bushbabies must look to other resources. Occasionally a Zanzibar Bushbaby will prey on other small animals. (Butynski, 2004; Nash, 1983)

  • Animal Foods
  • mammals
  • insects
  • Plant Foods
  • leaves
  • fruit
  • nectar
  • sap or other plant fluids

Predation

Their arboreal lifestyle protects Zanzibar bushbabies from many potential predators. They produce warning calls in the presence of genets and puff adders, suggesting that they may be predators of G. zanzibaricus. (Butynski, 2004; Nash, 1983)

Ecosystem Roles

Zanzibar bushbabies may disperse the seeds of the fruits they consume.

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Zanzibar bushbabies are important members of the ecosystems in which they live, they are also a potential draw for ecotourism efforts.

Economic Importance for Humans: Negative

There are no negative impacts of Galago zanzibaricus on humans.

Conservation Status

Galago zanzibaricus is classified as vulnerable on the IUCN Red List. Although the species as a whole is widespread and fairly common, its fragmented range results in potential extinction of individual populations. The main threat to this creature is habitat loss due to urbanization and deforestization. Also, the indigenous forests used by G. zanzibaricus are being replaced with exotic conifers, which do not provide appropriate habitat for this species. Zanzibar bushbabies are protected by law in Kenya as well as in certain conservatories such as the Tanzania Forest Conservation Group. Despite these efforts, only about 12% of their total range is protected. ("Ngaramia Riverine Forest Conservation Project", 2003; Butynski, 2004)

Other Comments

The phylogenetics of G. zanzibaricus has a complicated history. In recent years this creature's place within primate phylogeny has been anything but stable. Three major techniques have been utilized: morphological analyses, molecular analyses, and analysis of vocalization data. Analyses based on these data support different hypotheses of relationship and outgroup rooting seems to be a problem. This species was previously known as Galago zanzibaricus, it was then placed in the genus Galagoides as Galagoides zanzibaricus, and was recently returned to the genus Galago. (Butynski, 2004; Masters and Brothers, 2002)

Galago zanzibaricus has been divided into two subspecies Galago zanzibaricus zanzibaricus and Galago zanzibaricus cocos. There are few morphological differences between the two, and experts cannot tell them apart visually. However, they have highly distinctive vocalizations and Galagoides zanzibaricus cocos was recently elevated to species status, Galagoides cocos. (Butynski, 2004; Masters and Brothers, 2002)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Ryan Satovsky (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

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

chemical

uses smells or other chemicals to communicate

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

fertilization

union of egg and spermatozoan

forest

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

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.

nocturnal

active during the night

omnivore

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

polygynous

having more than one female as a mate at one time

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

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.

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.

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.

References

2005. "An Age entry for Galagoides zanzibaricus" (On-line). Accessed March 20, 2006 at http://genomics.senescence.info/species/entry.php?species=Galagoides_zanzibaricus.

2003. "Ngaramia Riverine Forest Conservation Project" (On-line). Accessed March 19, 2006 at http://www.tfcg.org/docs/project_ngaramia.htm.

Butynski, T. 2004. "Primates on Mt. Kasigau, Kaya Rabai and along the Tana River, Kenya: Preparing for Red List Assesments and Conservation Action" (On-line pdf). Accessed March 20, 2006 at http://www.cepf.net/ImageCache/cepf/content/pdfs/final_2eci_2eprimateskasigau_2epdf/v1/final.ci.primateskasigau.pdf.

Harcourt, C., L. Nash. 1986. Social Organization of Galagos in Kenyan Coastal Forests: I. Galago zanzibaricus. American Journal of Primatology, 10/4: 339-355.

Masters, J., D. Brothers. 2002. Lack of Congruence Between Morphological and Molecular Data in Reconstructing the Phylogeny of the Galagonidae. American Journal of Physical Anthropology, 117/1: 79-93.

Nash, L. 1983. Reproductive Patterns in Galagos (Galago zanzibaricus and Galago garnettii) in Relation to Climatic Variability. American Journal of Primatology, 5/3: 181-196.

Nunn, C. 1999. "Collective action, free-riders, and male extragroup conflict" (On-line). Accessed March 19, 2006 at http://www.eva.mpg.de/primat/staff/charles_nunn/Nunn2000-loudcalls.htm.

Nunn, C., R. Barton. 1999. "Allometric slopes and independent contrasts: a comparative test of Kleiber’s law in primate ranging patterns" (On-line). Accessed March 19, 2006 at http://www.eva.mpg.de/primat/staff/charles_nunn/Nunn_Barton.htm.

Primate Specialist Group, 2004. "IUCN Red List of Threatened Species" (On-line). Accessed March 20, 2006 at http://www.redlist.org/search/details.php?species=8790.

Schulke, O. 2002. "Living apart together- Patterns, ecological basis, and reproductiv consequences of life in dispersed pairs of fork-marked lemurs" (On-line pdf). Accessed March 20, 2006 at http://opus.bibliothek.uni-wuerzburg.de/opus/volltexte/2003/502/pdf/Schuelke.pdf#search='galago%20zanzibaricus%20harcourt'.

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