SOCIAL ORGANIZATION AND BEHAVIOR
The social fabric of the lives of bushbabies is as varied as their habitats
and for many species, incompletely known. However, the social systems of the
bushbabies are best described as non-gregarious (Pullen et al. 2000). For
example, G. moholi spends 70% of its activity period solitary (Bearder
& Doyle 1974b; Doyle & Bearder 1977). This is not a rule however, with
some populations of G. alleni being found about half of the time in association
with one or several conspecifics while other populations of the same species do
not show this pattern (Ambrose 2003).
Photo: Gerald Doyle
The lives of bushbabies are typified by a dichotomy of daily activity;
divided between solitary evening and nighttime activities alternating with
morning and daytime social aggregation, especially at the sleeping site
(Charles-Dominique 1972; Bearder & Martin 1980; Harcourt & Nash 1986).
Individuals are not often seen together at night (Harcourt & Nash 1986).
Because some of the activity period is spent solitary, social groupings are
perhaps best quantified through sleeping group size, which can vary between
solitary sleeping up to ten individuals per sleeping site (data compiled from
the literature by Bearder 1987 & Bearder et al. 2003). Only G. demidoff
does not sometimes sleep alone and has a minimum sleeping group size of two
individuals (Bearder et al. 2003). Home ranges in G. zanzibaricus males show
only slight overlap, as is mostly the case in females of comparable age; however
females sometimes share ranges with other females who are likely kin (Nash 1984; Harcourt &
Nash 1986). Males will sleep with each individual
whose range overlaps his, mostly one or several adult females and immatures per
night (Harcourt & Nash 1986). Adult male G. moholi never sleep
together (Bearder & Martin 1980). The overlap in male ranges might be
explained by low sample size, tolerance of smaller emigrating males, or the
process of replacement of a resident male. Adults of G. zanzibaricus likely
defend their ranges (Harcourt & Nash 1986). G. moholi females range
structure is related to their age, with like-aged females showing little range
overlap while those with somewhat larger age differences may overlap extensively
(Bearder & Martin 1980). In both G. alleni and G. demidovii, female ranges
vary in their overlap with one another and the ranges of males usually overlap
at least one female range. G. alleni male home ranges are vast and may overlap
the home ranges of more than 8 different females. Male ranges either do not
overlap or overlap to an insignificant degree. Small areas of male overlap are
sometimes deemed common areas, and may be shared by several males in G.
demidovii and G. alleni (Charles-Dominique 1977a).
In G. moholi, males exhibit a linear, age-based dominance hierarchy,
with only the highest ranking males defending their territories. Such
individuals are usually some of the largest present in a given area and initiate
agonistic contact, often resulting in the displacement of subordinate males.
Regardless of rank, adult males are not tolerant of one another (Bearder &
Martin 1980). There are two classes of mature G. moholi males, dominant
heavier males who interact with females more often and submissive,
nonterritorial adult males who weigh less and interact with females less
(Bearder 1987). It is suggested that there are four classes of adult male in G.
demidovii, each with particularities of home range extent and overlap relating
to contacts with both female home ranges as well as with other adult males
(Charles-Dominique 1977a). To show submission, individuals descend to
ground-level (Bearder & Doyle 1974b; Bearder & Martin 1980). Adult male
G. alleni are extremely intolerant of one another and are in pronounced
competition with other males (Charles-Dominique 1977).
Female G. moholi exhibit more ambiguous social relationships, although
agonistic territorial behavior is sometimes seen at the borders of home ranges
(Bearder & Martin 1980). Affiliative interactions in G. senegalensis
consist of urine-washing, grappling, chasing, play and grooming (Bearder &
Females in G. zanzibaricus tend not to emigrate from their natal range while
males do, usually at puberty (Nash 1984; Harcourt & Nash 1986). In some
species, young pubescent males may spend time in a so-called
"vagabond" phase of life, in which they are nomadic and do not spend
much time in a given area (Charles-Dominique 1977a). Emigration in G.
moholi is rigidly defined, with the pre-reproductive pubescent male
traveling either unidirectionally either east or west over several nights,
ending up several kilometers from the natal range (Bearder 1987).
In captivity, aggression is most common between members of the same sex while
affinitive behaviors are mostly seen between the sexes in G. senegalensis (Nash
& Flinn 1978). In the wild, confrontations are usually avoided, but rare
violence can result in serious injury and/or the displacement of a formerly
dominant male by a vagabond male (Charles-Dominique 1977a).
When G. moholi encounters a conspecific they will greet each other with
nose-to-nose contact and smelling, which may be followed by grooming or
agonistic behavior, especially when the individuals are unfamiliar with one
another (Doyle 1974).
The mating system of bushbabies (G. moholi) is best described as dispersed
and not strictly polygynous. Certain males have a better chance of mating
success than others but females may still mate with more than one male (Pullen
et al. 2000). Female bushbabies exhibit estrus swelling of the sex skin and the
vagina is closed at all other times other than estrus (Nash 1983; Zimmermann
1989; Lipschitz et al. 2001). Estrus and the mating period lasts 1-3 days with
some evidence from the wild suggesting that females do not all come into estrus
at the same time (Gucwinska & Gucwinski 1968; Doyle et al. 1971; Pullen et
al. 2000). G. moholi copulations in the wild last, on average, 9 minutes, but
can range from 2 to 53 minutes. Copulation is often serial, with 2-5 prolonged
mounts punctuated with rest and grooming (Pullen et al. 2000). Copulations between
captive G. senegalensis are similarly prolonged (LT Nash, per. comm.).
Photo: Gerald Doyle
In both the wild and captivity, females may mate with more than one male
during a single estrus (Gucwinska & Gucwinski 1968; Pullen et al. 2000). In
G. moholi, larger males have better mating success (Pullen et al. 2000). The
copulation posture of bushbabies is dorso-ventral, with the male grasping the
heels of the female from behind (Charles-Dominique 1977a; Lipschitz 1996b). G.
demidovii copulates while suspended from a branch, while other species do not
practice suspensory copulation (Charles-Dominique 1977a). The typical mating
sequence in captivity of G. moholi consists of the male approaching the female,
chasing her, grabbing her and mounting (Lipschitz 1996a). Nose-to-nose touching
and genital sniffing may also precede copulation (Lipschitz 1996b). In the
wild, all matings in this species are initiated by very persistent males and
females are generally averse to their mating attempts (Pullen et al. 2000). In
captivity however, females sometimes approach present her hindquarters to a male
during behavioral estrus (Lipschitz 1996b).
Several species of bushbaby have two mating and birth seasons per year in the
wild, including G. senegalensis, G. zanzibaricus and G. moholi, while other
bushbabies of comparable size (G. gallarum) likely follow this pattern as well
(Haddow & Ellice 1964; Butler 1967; Harcourt 1986a; Pullen et al. 2000;
Butynski & de Jong 2004). Individual females in some species are capable of
breeding twice in the same year (Harcourt 1986a; Bearder et al. 2003). Just
prior to and during mating seasons, the weight of males and the volume of their
testes increases (Pullen et al. 2000).
Among the bushbabies, gestation lengths can range from around 111 days to
around 142 with smaller species generally having shorter gestation lengths
(Gucwinska & Gucwinski 1968; Doyle et al. 1971; Bearder & Doyle 1974a;
Charles-Dominique 1977a; Izard & Simons 1986; Lipschitz 1996a; Izard &
Nash 1988; Nash et al. 1989; Zimmermann 1989; Nekaris & Bearder 2007). The
average ovarian cycle in captive G. moholi is 38.5 days (Lipschitz 1996b).
Sexual maturity is reached across bushbaby species with available data between 8
and 18 months of age (Charles-Dominique 1977a; Izard & Nash 1988; Nash 1993;
data compiled by Nekaris & Bearder 2007).
Per pregnancy in most bushbaby species, usually one infant is born, with the
possibility of twins and extremely rarely, triplets (Butler 1967; Doyle et al.
1971; Riordan 1971; Nash 1983; Harcourt 1986a; Izard & Simons 1986; Nash et
al. 1989; Zimmermann 1989; Bearder et al. 2003). There are several species that
are exceptions however. One is G. moholi, which has higher rates of twinning
than most other bushbabies (Izard & Simons 1986; Izard & Nash 1988; Nash
et al. 1989; Bearder et al. 2003). Bushbaby mothers can give birth to up to 4
infants per year (G. moholi) (Bearder et al. 2003). Estrus is sometimes seen
for several days directly following birth and conceptions are possible during
this postpartum estrus (Doyle et al. 1969; Zimmermann 1989; Nash 2003).
As the birth of the infant nears, G. zanzibaricus females start sleeping on
their own and isolate themselves whereas before they sleep with conspecifics
(Charles-Dominique 1977a; Harcourt 1986a). Births occur in nests or the hollows
of trees (Bearder 1987). Pooled, multi-species data give the birth weight at
about 5 to 24 g (0.2 to 0.8 oz) (Gucwinska & Gucwinski 1968; Doyle et al.
1971; Izard & Nash 1988; data compiled by Nekaris & Bearder 2007 and
Zimmermann 1989 for older data). The eyes are open at birth and the pelage is
ubiquitously grey and meager (Gucwinska & Gucwinski 1968; Charles-Dominique
1977a; Doyle 1979; Zimmermann 1989). Thick fur comes in between two and three
weeks old (Charles-Dominique 1977a).
Photo: Gerald Doyle
In captivity (G. moholi), at one day old, infants are capable of
clinging to a branch and within the first several days of life, can walk
quadrupedally. By two weeks of age, infants can quadrupedally run (Doyle 1979).
Infants start following their mothers about between 4 and 6 weeks old (Doyle
& Bearder 1977). Play begins very early, within the first week of age
(Doyle 1979). Among juvenile G. senegalensis, young males play more often than
females (Nash 1993).
While the mothers are engaging in other activities, such as foraging nearby,
juveniles are parked, usually in tree forks or tangles, motionlessly hiding from
potential threats (Doyle 1974; Charles-Dominique 1977a; Harcourt 1986a; Bearder
1987; Ambrose 2003). They sometimes remain parked for prolonged periods of
time, up to three hours, but if the parking is prolonged, the mother will
occasionally visit (Doyle 1974; Doyle & Bearder 1977). If directly
disturbed or seemingly forgotten, the infant may emit a distress call and the
mother comes running (Doyle et al. 1969; Charles-Dominique 1977a).
In G. senegalensis, up until 12 weeks of age in captivity, adult-type vocalizations are not
heard, with infants instead producing characteristic "zek" calls (Zimmermann
1989). G. moholi infants utter three distinct types of distress vocalization
which are given in increasing situations of distress to which the mother
responds by coming to the infants and grooming them (Mascagni & Doyle 1993).
In situations of danger, the mother will carry the infant away in her mouth
(Charles-Dominique 1977a). In captivity, infants first emerge from their nest
box at ten to 14 days of age, and in the wild starting between 3 and 7 days of
age, the mother carries the infant out of the nest with her and starts parking
it (Gucwinska & Gucwinski 1968; Doyle et al. 1969; Charles-Dominique 1977a).
In the wild, independent movement and exploration begins about 2-3 weeks old
(Charles-Dominique 1977a). Consumption of solid foods commences at one month of
age, when infants start stealing food from the mouths of their mothers
(Charles-Dominique 1977a). In the wild, juveniles usually forage alone (Bearder
The typical maternal infant carrying posture is in the mouth, often by the
nape (Gucwinska & Gucwinski 1968; Doyle et al. 1969; Ward & Scott 1970;
Doyle & Bearder 1977; Doyle 1979; Harcourt 1986a; Ambrose 2003; Bearder
2003; Nash 2003). Carrying with the infant clinging to the fur of the mother is
rare, but has been observed in G. gallarum (Butynski & de Jong 2004). In
captivity, all sexes and ages are patient with juveniles, and sometimes play,
groom, and show interest towards them (Bearder & Doyle 1972). In
semi-natural captive conditions, grooming frequencies between mother and
offspring do not change as the infant ages, persisting until full adult
separation from the mother (Doyle et al. 1969).
In captivity, both G. moholi and G. senegalensis females lactate for an average of around 100
days after the birth of their infant with weaning at 10-14 weeks of age (Doyle
1979; Izard 1987; Zimmermann 1989). However, wild G. demidoff weans its young
earlier, at around 45 days old (Charles-Dominique 1977a). Females sometimes
nurse infants not belonging to them and there are not profound differences in
contact and nursing between sexes of infants (Nash 2003). By ten months of age,
males have reached puberty and emigrate and also around this time, courting of
females starts (Charles-Dominique 1977a; Bearder 1987). Females in G.
moholi start showing territorial behaviors around 200 days old (Bearder
The vocalizations of bushbabies have been roughly divided into discrete types
by function. These include social cohesion and spacing calls (social contact
calls), agonistic calls (threat and distress calls), and attention and alarm
calls (Charles-Dominique 1977a; Zimmermann et al. 1988). Among G. moholi and G.
senegalensis, there appear to be 14 types of call in common between the two
species (Zimmermann et al. 1988). However, different species vary in the total
numbers of vocalizations they produce. Bushbaby vocalizations are extremely
variable, often grading into one another and are produced both during inhalation
as well as during exhalation (Bearder et al. 1995).
Because morphological differences are not always useful for differentiation,
vocalizations are considered a good way to tell bushbaby species from one another
(Ambrose 2003). This is particularly true of advertising calls, which are often
unique to species in primates and in bushbabies these types of calls are the
most diagnostic (Zimmermann et al. 1988; Zimmermann 1990; 1995). Loud
advertisement calls are often profoundly different than those of other
bushbabies and are used to tell different species apart (for example Harcourt
& Bearder 1989; Butynski et al. 1998; Wickings et al. 1998; Anderson et al.
2000; Perkin et al. 2002; Butynski & de Jong 2004; Ambrose 2006; Butynski et
al. 2006). Vocalizations and olfactory marking are likely the best signals
functioning in intra-species individual recognition by bushbabies (Ambrose 2003).
Vocalizations can be so unique that bushbabies which are not distinguishable
otherwise have been suggested as potential subspecies or even full species based
mainly on differences in vocal structure (Perkin et al. 2002; Ambrose 2003). It
is less likely that species of bushbaby can be be differentiated based on
agonistic, attention, and alarm calls (Zimmermann 1990). Advertisement calls
are usually heard upon emergence from the sleeping site, reconvening before
sleep at the end of the activity period, and for maintaining contact during the
night (Bearder et al. 1995). Further, advertisement calls might also be given
in calling bouts between members of the same sex (Bearder et al. 1995).
While usually considered non-gregarious, G. moholi emits alarm calls when
predators are encountered and the alarm calling is contagious, with other
bushbabies joining in and coming together, mobbing and calling for up to 30
minutes around the threat (Bearder et al. 2002).
Call frequency is affected by population density, with some species calling
more over the course of the nightly activity period if more conspecifics are
nearby (Courtenay & Bearder 1989).
In the wild, urine-washing is a means by which G. alleni may disperse
olfactory clues throughout its home range. In this species, the soles of the
feet are washed with urine, which is subsequently dispersed, especially in areas
of overlap with the home ranges of conspecifics (Charles-Dominique 1977b).
Urine-washing may also communicate social clues to other bushbabies (Nash 1993).
There are several types of scent-marking observed in captive G. demidoff.
These include urine-washing, hand-rubbing, genital-planting,
cheek-/chin-rubbing, chest-rubbing, anogenital-rubbing, and substrate-biting
combined with flehmen (Pitts 1988). However, urine washing may also enhance
grip in some species, e.g. G. moholi (Harcourt 1981).
Displays seen in G. demidoff include defensive displays seen in both sexes,
defensive anti-intruder/anti-predator displays, male-male rank demonstration
displays, and dominant-female self-advertising displays. Further, it is
suggested that the displays given by dominant-males in offensive situations may
be species specific and are a useful tool in differentiating species of bushbaby
(Pitts 1988). In the wild, aggressive postures consist of the bushbaby
extending its body and tail, spreading the ears and opening the mouth
Content last modified: December 8, 2008
Written by Kurt Gron. Reviewed by Leanne Nash.
Cite this page as:
Gron KJ. 2008 December 8. Primate Factsheets: Lesser bushbaby (Galago) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/lesser_bushbaby/behav>. Accessed 2014 September 2.