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Galago alleniAllen's squirrel galago

By Anna Dengel

Geographic Range

Galago alleni lives in the rainforest of west-central Africa. It has been found nearly as far north as southern Nigeria, west to the delta of the Niger river, as far east as the southwestern corner of the Central African Republic, and south to southern Congo. (Flannery, 2001; Nowak, 1991; Wolfheim, 1983)

Habitat

Galago alleni is most frequently found in the understory of mature primary wet forests. This species is rarely present in secondary growth forests. (Muller and Grzimek, 1990; Wolfheim, 1983)

Physical Description

Galago alleni has thick fur that can range from grey to brown in color with a rust tint on the limbs. The ventral fur tends to be lighter ranging from grey to a yellowed white. This species has distinct dark patches of fur around its eyes. The tail is long and bushy. Head and body length ranges from 155 to 240 mm and mass from 200 to 445 grams.

Like other members of the genus, G. alleni has unusually large eyes, which help to adapt this species to a nocturnal life style. These large eyes have a reflective retina, the tapetum, which facilitates light detection. Interestingly, these animals are color-blind, with only rods in the retina and no true macula.

Like many of their relatives, Allen's bush babies have flexible, naked ears that can moved backward, and be bent down to the base. The nose has a specialized leather-like covering with slits. Galago alleni has the characteristic toothcomb common in galagos, made up of the four incisors and two canines. They are known for their strong hindlimbs and leaping ability. (Muller and Grzimek, 1990; Napier, 1967; Nowak, 1991)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    200 to 445 g
    7.05 to 15.68 oz
  • Range length
    155 to 240 mm
    6.10 to 9.45 in

Reproduction

Males seek to control home ranges that overlap those of several females. Intense competition between males for access to female home ranges is observed. Male dominance seems to be correlated with body mass, with larger males being the most dominant. (Muller and Grzimek, 1990; Nowak, 1991)

Females have one baby at a time. Births occur year round in some parts of the range and in seasonal peaks in other parts of the range. In Gabon, where births occur year-round, there is an increase of births from January to April. Peaks in births occur during times of the year when fruits and insects are most abundant. Gestation is unusually long (around 133 days). Birth weights are low (5 to 10 grams) when compared to other animals of the same size. The female separates herself from the group for two weeks when giving birth. Weaning occurs at about 6 weeks of age. Young Allen's bush babies become sexually mature at around 8 to 10 months of age. (Muller and Grzimek, 1990; Nowak, 1991; Rowe, 1996)

  • Breeding interval
    Females typically have one pregnancy per year.
  • Breeding season
    Breeding occurs seasonally and year-round in different parts of the range.
  • Average number of offspring
    1
  • Average number of offspring
    1.3
    AnAge
  • Average gestation period
    133 days
  • Average gestation period
    133 days
    AnAge
  • Average weaning age
    6 weeks
  • Range age at sexual or reproductive maturity (female)
    8 to 10 months
  • Range age at sexual or reproductive maturity (male)
    8 to 10 months

Galago alleni build nests for their young and sometimes share the care of young with other females with infants. Females carry their young in their mouths. When they leave the nest to forage at night, they carry their dependent offspring to a hiding place. The female leaves her young in hiding while she searches for food. Females nurse their young for about six weeks.

The role of males in parental care appears to be indirect. Because males aggressively maintain their ranges, which overlap those of several females, it can be argued that they help to defend the young from invading males. (Nowak, 1991; Rowe, 1996)

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

Lifespan/Longevity

In captivity G. alleni has been found to live about 12 years. This species has been known to live 8 years in the wild. (Nowak, 1991; Rowe, 1996)

Behavior

Galago alleni is nocturnal. Males are primarily solitary and are aggressive towards other males. Females often stay in small groups with infants. Males and females may share nest sites during the day. Individuals sleep in nests built in tree hollows in groups of about 1 to 4. The males live alone or in small groups of 2 or 3 until the opportunity to be a dominant male arises. Dominant males cover a large territory. They tend to be quite territorial, and there is intense competition for proximity to female home ranges. These more dominant males may go between many female groups. Male aggression is signaled by an upright, bipedal posture, an open mouth, and a hissing vocalization.

Allen's bush babies mark their territory by "urine wiping." They urinate on the soles of their feet and then march around their territory until the scent is well entrenched. This urine marking behavior is common in most galagos. On average there are 15 G. alleni per square mile.

Galago alleni participates in social grooming, using the toothcomb and specialized grooming second toe. Grooming is also a courtship behavior. The toothcomb cleans soiled areas of the fur and a second tongue in the mouth of the bush baby cleans the toothcomb. This is a behavior that is common in galagos. (Bearder, et al., 1986; Flannery, 2001; Muller and Grzimek, 1990; Napier, 1967; Nowak, 1991; Rowe, 1996)

Home Range

Females have a home range of 8 to 16 ha, while males have a larger range of 30 to 50 ha. (Muller and Grzimek, 1990; Napier, 1967; Nowak, 1991)

Communication and Perception

Allen's bush babies communicate through 3 categories of sound--social, aggression, and defense. Social communication tends to be in the form of clicking noises from young to mother, sounding something like "tsic." A maternal call to the group sounds something like a soft croak. More powerful noises are for large groups to assemble. If an alarm call is heard, it can cause G. alleni to gather and mob a predator such as a cat. The aggressive call sounds like "quee, quee, quee."

There is also olfactory communication through urine which marks the territory of G. alleni. This urine territory marking was found to increase by about four times when the territory overlapped with another galago. Galago alleni is very territorial and aggression is frequently seen between males. The aggressive behavior is communicated through an upright posture, on the hind legs, and a vocal hissing sound. Courtship is communicated by mutual grooming and chasing.

Galago alleni has the ability to make many facial expressions, which can communicate a great deal. Facial expressions can be defensive, threatening, or protective, and are also associated with maternal clicks.

Galagos use tactile communication. Upon first encounter with a conspecific, they may sniff each other nose to nose. Then they will touch nose to face. Social grooming is their most important form of touch, and this helps them bond with one another. (Flannery, 2001; Napier, 1967; Nowak, 1991; Rowe, 1996)

Galago alleni has an exceptionally well-developed sense of vision (though lacking color vision) at night. They also have acute hearing, sense of smell, and use tactile cues to sense their environment. (Napier, 1967; Nowak, 1991)

Food Habits

Allen's bush babies are primarily frugivores, especially eating fallen fruit. Fruit makes up an estimated three quarters (75%) of their diet. They also eat insects and occasionally small mammals, which may function as protein supplements. (Muller and Grzimek, 1990; Nowak, 1991; Rowe, 1996)

  • Animal Foods
  • mammals
  • amphibians
  • eggs
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • fruit

Predation

When feeling threatened, G. alleni has the ability to move more quickly by running on its hind legs. When it spots a predator it quickly jumps great distances from branch to branch. Galago alleni uses alarm calls to alert conspecifics of the danger.

Little is known about their predators, although arboreal and volant predators, such as cats and owls, are likely to be their main threats. Humans pose the greatest known threat through habitat destruction. (Muller and Grzimek, 1990; Napier, 1967; Nowak, 1991; Wolfheim, 1983)

Ecosystem Roles

G. alleni is an important predator of insects and possibly disperses the seeds of the fruits that they eat.

Economic Importance for Humans: Positive

There is no significant demand for G. alleni, and it is not routinely hunted or captured. It is also rare that Allen's bush babies are exported for the pet trade or research. (Napier, 1967)

Economic Importance for Humans: Negative

There do not seem to be any negative impacts of G. alleni on humans.

Conservation Status

Galago alleni is on the IUCN Red List as a lower risk threatened species, and is on the CITES Appendix II list. The greatest threat to Allen's bush babies is human impact on their habitat. Expanding human populations, and a civil war in Nigeria, have drastically decreased the extent of available habitat. Because G. alleni so strongly prefers primary forests to secondary forests this destruction of their habitat is a major concern for this species.

Even though human hunting does not appear to be a significant problem for the species, laws protect G. alleni from being hunted or captured without authorization. A reserve also exists in Cameroon where G. alleni has been reported, but many more reserves are needed. (Nowak, 1991; Rowe, 1996; Wolfheim, 1983)

Other Comments

Bush babies get their common name from their alarm call, which sounds like a baby lost in the bushes. (Napier, 1967)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Anna Dengel (author), Andrews University, Tom Goodwin (editor), Andrews University.

Glossary

Ethiopian

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

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

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.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

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

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

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

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.

year-round breeding

breeding takes place throughout the year

References

International Union for Conservation of Nature and Natural Resources. "Galago alleni" (On-line ). IUCN Red List of Threatend Species. Accessed 1/27/03 at http://www.redlist.org/search/details.php?species=8785.

Bearder, S. K., B. Smuts, D. Cheney, R. M. Seyfarth, R. W. Wrangham, T. T. Struhsaker. 1986. Lorises, Bushbabies, and Tarsiers: Diverse Societies in Solitary Foragers. Pp. 11-24 in Primate Societies. Chicago: The Univeristy of Chicago Press.

Flannery, S. 2001. "Galago alleni" (On-line ). Primate Info Net. Accessed 10/15/02 at http://www. primate.wisc.edu/pin/factsheets/galago_alleni.html.

Muller, E., B. Grzimek. 1990. Lorises and Galagos. Pp. 77-95 in Encyclopedia of Mammals, Vol. 2. New York: McGraw Publishing Co..

Napier, J. 1967. A Handbook of Living Primates. London: Academic Press Inc..

Nowak, R. 1991. Galagos, or Bush Babies. Pp. 408-409 in Walker's Mammals of the World, Vol. 1, 5th Edition. Baltimore: Johns Hopkins University Press.

Rowe, N. 1996. The Pictorial Guide to Living Primates. East Hampton: Pogonias Press.

Wolfheim, J. H. 1983. Primates of the World. Seattle: University of Washington Press.

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