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Otolemur garnettiismall-eared galago

By Randa Tao

Geographic Range

Otolemur garnettii is also known as the small-eared galago or Garnett’s greater galago. This species is found in East Africa, ranging from the southern half of Somalia to Tanzania (Bearder et al., 2003) and on the island of Zanzibar (Groves, 2001). (Bearder, et al., 2003; Groves, 2001)

Habitat

Middle to high canopies in coastal, riverine, and highland forests form the natural habitat for small-eared galagos. They are also found in farmland plantations. (Bearder, et al., 2003)

  • Average elevation
    5 m
    16.40 ft

Physical Description

Otolemur garnettii are relatively small members of the genus Otolemur, with short ears. They were once considered subspecies of Otolemur crassicaudatus. Average ear length is 45 mm compared to the larger ear length of 62 mm in O. crassicaudatus (Rowe, 1996). (Rowe, 1996)

Small-eared galago males are only slightly larger than females. Adult males weigh an average of 794 grams, females weigh 734 grams (Fleagle, 1999). Otolemur garnettii has a thick and bushy tail that is longer than its entire body. Total body length averages 266 mm and tail length averages 364 mm (Rowe, 1996). (Fleagle, 1999; Rowe, 1996)

Small-eared galagos can be recognized by the red to gray-brown color of their pelage and by the presence of a brown, white, or black tip on their tail (Rowe, 1996). Their faces are uniformly colored (Groves, 2001). There are four subspecies of small-eared galagos that can be distinguished by the coloration of their fur (Groves, 2001). Otolemur garnettii garnettii has slightly greenish tones in its red-brown fur, the yellow color of its underside, and the presence of black tip on the last half of its tail. Otolemur garnettii panganiensis lacks green tones in its pelage and only possesses a black tip on the last quarter of its tail. Otolemur garnettii lasiotis is more gray than O. g. garnettii and tends to have a white-tipped tail. Otolemur garnettii kikuyuensis is characterized by its yellow-white underside, an iron gray pelage, and a black tip on the last quarter of its tail (Groves, 2001). (Groves, 2001; Rowe, 1996)

  • Sexual Dimorphism
  • male larger
  • Range mass
    721 to 822 g
    25.41 to 28.97 oz
  • Range length
    230 to 338 mm
    9.06 to 13.31 in
  • Average length
    266 mm
    10.47 in
  • Average basal metabolic rate
    3.927 W
    AnAge

Reproduction

The O. garnettii mating system is usually described as promiscuous, as both males and females have multiple mates. The act of mating in this species can take up to 120 minutes. It has been suggested that the extremely long duration of mating in this species is one way that males guard females from other males (Rowe, 1996). (Rowe, 1996)

In the wild, O. garnettii has been observed breeding seasonally once each year between August and October (Nash and Harcourt, 1986). Captive populations can give birth throughout the year, which indicates that females have a continuous estrus cycle (Masters et al., 1988). Females usually give birth to one infant and members of both sexes reach sexual maturity when they are about 20 months old (Nash and Harcourt, 1986). Weaning occurs after approximately 140 days (Rowe, 1996). (Nash and Harcourt, 1986; Rowe, 1996; Masters, et al., 1988; Nash and Harcourt, 1986; Price, et al., 1999; Rowe, 1996)

  • Breeding interval
    In the wild, breeding occurs once every year, usually between August and October.
  • Breeding season
    Mating can occur throughout the year.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    130 to 135 days
  • Average gestation period
    130 days
  • Average weaning age
    140 days
  • Average time to independence
    4-5 weeks
  • Range age at sexual or reproductive maturity (female)
    12 (low) months
  • Average age at sexual or reproductive maturity (female)
    20 months
  • Range age at sexual or reproductive maturity (male)
    12 (low) months
  • Average age at sexual or reproductive maturity (male)
    20 months

Parental investment seems to be provided only by mothers. They carry infants in their mouths but leave them while foraging (Rowe, 1996). Before weaning, mothers provide offspring with high-energy milk and protect them from predators and other dangers. (Rowe, 1996)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female

Lifespan/Longevity

Small-eared galagos can live for up to 15 years (Bearder, 1987). (Bearder, 1987)

Behavior

Small-eared galagos are nocturnal and arboreal. It is uncommon to observe small-eared galagos on the ground. Both males and females have home ranges that do not overlap with individuals of the same sex or age (Nash and Harcourt, 1986). Compared to females, males disperse further from the area in which they were born and do so at an earlier age. Males are transient members of groups and usually remain solitary forgers (Rowe, 1996). Females mature and remain in their natal areas, but same-aged females do not share overlapping ranges. Related females are usually the only individuals that share a common home range. This may be explained by the fact that O. garnettii rely on fruit as a significant part of their diet. During different times of the year, the abundance and quality of fruit can vary considerably between forest patches. Thus, O. garnettii may be under pressure to exclude unrelated individuals from important areas of forest that contain variable and limited food resources. (Nash and Harcourt, 1986; Nash and Harcourt, 1986; Rowe, 1996)

Grooming and play occurs in O. garnettii between individuals of both sexes. Small-eared galagos run and climb on four feet, but also engage in bipedal hopping by jumping and landing on the hind limbs first (Nash and Harcourt, 1986). They usually sleep in vine tangles. Males sleep alone while females sleep with offspring (Rowe, 1996). (Nash and Harcourt, 1986; Rowe, 1996)

Home Range

Female home ranges are approximately 11.6 ha, male home ranges are approximately 17.9 ha. (Rowe, 1996)

Communication and Perception

Members of both sexes frequently use vocal communication. Vocalizations can even be used to distinguish between the individuals of this species. Their most notable call may be heard from 400 feet away and lasts for 4 to 5 seconds, longer than the calls of O. crassicaudatus (Rowe, 1996). Researchers have been able to group different calls based on their function and have observed alarm calls, sex calls, distress calls in response to fear, and infant click calls that elicit contact from the mother. Foot-rubbing may even be used for communication. Individuals rub their feet against another material and vary the intensity of the sound they produce. This behavior produces a sound that is not different from background noise, so foot-rubbing may allow small-eared galagos to communicate with conspecifics without alerting predators (Hagar, 2001). Small-eared galago males have been observed using foot-rubbing during aggressive encounters with other males. (Hager, 2001; Rowe, 1996)

Other forms of communication include the use olfactory signals. Otolemur garnettii has been observed to engage in urine washing, which it accomplishes by urinating on its hands and then rubbing the urine on the bottom of its feet. This behavior allows galagos to leave their scent on everything they touch. Males seem to engage in urine washing more often than females (Tandy, 1976). In addition to marking their scent on objects, individuals can communicate by sniffing one another. (Tandy, 1976)

Food Habits

Small-eared galagos primarily feed on fruit and insects. About half of their diet is composed of fruit and half is composed of insects (Nash and Harcourt, 1986). (Nash and Harcourt, 1986)

  • Animal Foods
  • insects
  • Plant Foods
  • fruit

Predation

The most likely predators of small-eared galagos are genets (Genetta tigrina) and puff adders (Vipera berus) (Nash, 1983). (Nash, 1983)

Ecosystem Roles

Small-eared galagos may have an important ecological role in the forests of East Africa because they eat fruit and insects. They may serve as seed dispersers for a variety of plant species, thus influencing the plant composition of the ecosystem.

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Otolemur garnettii individuals are important members of the ecosystems in which they live and they may help in ecotourism ventures.

Economic Importance for Humans: Negative

Small-eared galagos have no negative economic impact on humans.

Conservation Status

Small-eared galagos are labeled as “lower risk” on the IUCN redlist and on Appendix II of CITES to limit international trade of this species.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Randa Tao (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.

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.

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

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

scent marks

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

scrub forest

scrub forests develop in areas that experience dry seasons.

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

solitary

lives alone

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

Bearder, S. 1987. Lorises, Bushbabies, and Tarsiers: Diverse Societies in Solitary Foragers. Pp. 11-24 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: University of Chicago Press.

Bearder, S., L. Ambrose, C. Harcourt, P. Honess, A. Perkin, E. Pimley, S. Pullen, N. Svoboda. 2003. Species-Typical Patterns of Infant Contact, Sleeping Site Use and Social Cohesion among Nocturnal Primates. Folia Primatologica, 74: 337-354.

Fleagle, J. 1999. Primate Adaptation and Evolution. San Diego: Academic Press.

Groves, C. 2001. Primate Taxonomy. Washington, D.C.: Smithsonian Institution.

Hager, R. 2001. Foot-rubbing as a multifunctional form of intraspecific communication in Garnett's greater bushbabies (Otolemur garnettii). Folia Primatologica, 72: 104-107.

Masters, J., W. Lumsden, D. Young. 1988. Reproductive and dietary parameters in wild greater galago populations. International Journal of Primatology, 9: 573-592.

Nash, L. 1983. Reproductive patterns in galagos (Galago zanzibaricus and Galago garnettii) in relation to climatic variability. American Journal of Primatology, 5: 181-196.

Nash, L., C. Harcourt. 1986. Social Organization of Galagos in Kenyan Coastal Forests:II. Galago garnettii. American Journal of Primatology, 10: 357-369.

Price, M., M. Becker, J. Ward. 1999. Play behavior in infant small-eared bushbabies (Otolemur garnettii). (Abstract). American Journal of Primatology, 49: 88-89.

Rowe, N. 1996. The Pictorial Guide to the Living Primates. New York: Pogonias Press.

Tandy, J. 1976. Communication in Galago crassicaudatus. Primates, 17: 513-526.

Whitehead, P., W. Saaco, S. Hochgraf. 2005. A Photographic Atlas for Physical Anthropology. Englewood, Colorado: Morton Publishing Company.

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