SOCIAL ORGANIZATION AND BEHAVIOR
Ruffed lemur social organization is marked by significant variation in both
group organization as well as group composition. This has been suggested to be
the result of the social system being adaptable to allow for an inability of the
species to change its feeding ecology (Vasey 2003). Some of the variation in
past studies of ruffed lemur social organization might be attributed to the
short-term or seasonal nature of field studies not adequately covering yearlong
patterns of social behavior (Vasey 2003). Ruffed lemurs are organized into
dispersed social networks which include core groups organized within a core
community. Even though the core community lives within a discrete community
home range, the entire community is never seen together in the same location at
the same time (Morland 1991a; Rigamonti 1993; Vasey 1997a; 2006). The structure
of the core group is variable but often consists of two reproductive females in
addition to males and subadults, and can range from a pair of individuals up to
9 (Vasey 1997a). Rare interactions between group males are typically agonistic
Photo: Pavel Vlcek
Perhaps the ruffed lemur social structure is best described as
multi-male/multi-female fission-fusion social organization (Vasey 1997a; 2006).
Such communities are dispersed core social groups that interact with other core
groups in the community, however interaction between different core social
groups is curtailed during the cold rainy season, the period of gestation and
mating (Rigamonti 1993; Vasey 1997a; 2006). During this period of the year,
small subgroups are formed and range over small areas within the communal home
range (Morland 1991b). Often, these subgroups consist of a male, female, and
their offspring or even just an adult male and adult female and might be
misconstrued as monogamous (Morland 1991b; White 1989). In captivity, the
relationships between mothers and their adult female offspring are not stable
throughout the year, with affiliative behavior seen between the two during the
birth season but not the mating season (White et al. 1992). The fission-fusion
nature of the social organization is manifested on two levels, the yearlong
daily changes in subgroups and the seasonal dispersal of core groups into core
areas (Vasey 2006).
Even though ruffed lemur communities are not cohesive units, the home range is
communally defended. In addition, there is some evidence that only females
participate in communal home range defense against females from other groups,
which includes agonistic behaviors including chasing, scent-marking, calling,
and sometimes physical contact with members of neighboring communities (Morland
1991a; 1991b; Vasey 1997a; 2006). Territorial disputes occur most often during
the hot months when resources are more readily available and happen at the
boundaries between communal home ranges (Morland 1991b; Vasey 2006). During
such disputes, males will scent-mark but will not chase, remain uninvolved and
are relatively silent (Morland 1991b; Vasey 2006). Group size is very variable,
with cohesive groups ranging from a pair to 31 individuals (White 1991; Morland
1991a; Rigamonti 1993; Vasey 1997a; 2003; 2006).
In captive and free-ranging ruffed lemurs, females are almost always dominant to
males, winning almost all agonistic encounters with them and rarely showing
submissive behavior towards a male (Kaufman 1991; Raps & White 1995; Meyer et
al. 1999). In the wild, the nature of female group dominance is more ambiguous.
While it is possible for females to be dominant, wild groups cannot be
described definitively so, as there is some inter-group variation in dominance
patterns (Overdorff et al. 2005).
In the wild, common aggressive behaviors include attacks, cuffs, grapples, and
chases while in captivity the aggressive repertoire includes the stare, charge,
chase, lunge, cuff, feint-to-cuff, bipedal hop, pounce on, push down, and bite
(Pereira et al. 1988; Overdorff et al. 2005). In the wild, chatter
vocalizations are used to signal submission (Overdorff et al. 2005). Captive
animals also chatter to show submission in addition to displacement, head
turning/eye aversion, cowering/flinching, grimacing, backing away, fleeing, and
jumping away (Pereira et al. 1988). In the wild, affiliative behaviors include
the greeting behavior performed by females in which their bodies are
intertwined. In addition, other wild affiliative behaviors include playing and
social grooming. Often, affiliative behaviors are highly seasonal and some are
only performed by one sex, such as the male behaviors of the squeal approach and
anogenital inspections, which only occur during the mating season (Morland
1991a). In captivity, affinitive social behaviors include group movement,
huddling together with bodily contact, greeting by sniffing and social grooming,
an activity performed by all group lemurs over 5 months of age (Pereira et al.
1988). In captivity, all group members will play, but subadults participate
more often than adults. Play can include wrestling, grappling, chasing,
fleeing and solitary play (Pereira et al. 1988).
Photo: Pavel Vlcek
Wild ruffed lemurs exhibit a seasonal polygamous mating system contrary to
initial reports of monogamy in the species (Vasey 2007). In the wild, mating
occurs with community members as well as with members from other communities.
In addition, a single male or female will often mate with more than one partner
in a single mating season and within a community, multiple males and females
actively mate (Morland 1993b; Vasey 2007). Near the northern limit of the
ruffed lemur range, mating occurs in the cold rainy season, between May and July
(Morland 1993b; Vasey 2007). As expected in a species with a specific mating
season, births are also seasonal. In the wild on the Masoala peninsula, births
occur during the hot dry season during November and are highly synchronized
(Vasey 1997a). In captivity, discrete mating and birth seasons are also
observed (Brockman et al. 1987).
Just prior to and during estrus, both wild and captive females exhibit swelling
of the sex skin, peaking around the middle of estrus (Bogart et al. 1977;
Brockman et al. 1987; Vasey 2007). Estrous cycles average 14.8 days in
captivity (Brockman et al. 1987). Male testicular volume also increases as the
mating season nears, peaking prior to or at the time of breeding (Bogart et al.
1977; Foerg 1982; Brockman et al. 1987). Aggression among ruffed lemurs of the
same sex increases as well during the mating season (Morland 1993b).
Before copulation, the male will perform a display which includes moving toward
the female while lowering his head and squealing, roar-shrieking with the
female, licking or sniffing the female's genitals, submissively chattering,
mounting and scent-marking. Females also perform displays that include
roar-shrieking with the male, hitting, biting, and posturing of her body for
mounting (Vasey 2007). The male mounts the female by grasping her hind limbs or
a branch with his hind limbs and grasping her torso and thrusting. Aggressive
behavior by the female is often directed towards the male who is attempting to
mate with her and a mating pair will often copulate a number of times in a bout
of mating (Foerg 1982; Morland 1993b).
In captivity, gestation averages around 102 days and in the wild, is slightly
longer, at 106 days with an inter-birth interval of one year (Bogart et al.
1977; Foerg 1982; Rasmussen 1985; Brockman et al. 1987; Vasey 2007).
Reproductive maturity in captivity is reached in both sexes around 18-20 months
of age, during the second post-natal breeding season (Foerg 1982; Porton 1989).
In the wild, reproductive maturity is reached later, with females only coming
into estrus at 3 years old and males showing no signs of reproductive maturity
until at least 5 years old (Morland 1991a). Reproductive activity in captivity
for females can last into the 23rd year of life (Weigler et al. 1994).
In both the wild and captivity, ruffed lemur births are usually multiple,
averaging around two infants per birth in captivity (Boskoff 1977; Morland 1990;
Weigler et al. 1994; Vasey 2007). However, numbers of infants can range from
one per birth up to five (Weigler et al. 1994; Greeley 1982; Pollock 1986).
Birth weight in captivity ranges from 70 to 140 g (.15 to .31 lb), averaging between
83.0 to 101.7g (.18 to .22 lb) (Boskoff 1977; Brockman et al. 1987). At birth,
newborns are covered with fur and their eyes are open (Foerg 1982). Before
giving birth, a ruffed lemur mother will construct an arboreal nest within her
core area, normally between 10 to 25m (32.8 to 82.0 ft) above the ground, out of
branches, leaves and other foliage (Morland 1990; Vasey 1997a; 2007). Such
nests are shallow and dish-shaped with only one apparent entry point (Vasey
2007). In captivity, for the first two weeks of life, mothers spend between 70%
and 90% of their time in their nests with the newborns (Pereira et al. 1987).
Photo: T. Keith-Lucas
In the wild, the infant remains in the nest until about one to three weeks of
life, at which point the mother moves them out for the first time and "stashes"
them while she performs other activities (Pereira et al. 1987; Morland 1990;
Vasey 2007). Infant "stashing" involves placing the infant or infants in
concealing foliage in the canopy and leaving them there for up to several hours
at a time while she forages elsewhere, sometimes out of earshot (Morland 1990;
Vasey 2007; see Vasey 1997a:42-3 for discussion of the term "stashing").
Transport of infants by the mother occurs singly, with the mother grasping the
infant's belly crosswise in her mouth and continues until they are too big to
carry, at around 2.5 months old (Morland 1990; Downman 1993; Vasey 2007). While
"stashed," infants will rest, sit still, and not vocalize (Pereira et al. 1987;
Often, while the mother is away from her offspring, other group members will
guard them in addition to emitting alarm calls when sensing danger, responding
to the alarm calls of others and providing care for the infants. Males provide
a lot of infant care as well; guarding, huddling, grooming and playing with the
offspring of up to several different mothers (Vasey 2007). In captivity,
females related to a mother have been observed nursing her offspring and close
kin have served as foster parents for infants rejected by their mother (Pereira
et al. 1987; Kerridge 1999). Indeed, alloparenting is widespread in wild ruffed
lemur populations, with all members of the community participating in the
raising of offspring (Vasey 2007). In the wild and in captivity, community
members take part in "coordinated vigilance displays" in which a community
member guarding or near to an infant will alarm call if leaving the infant alone
or encountering a predator. Upon hearing the alarm call, other community
members will alarm call as well, resulting in the communal transmission of the
alarm call throughout the forest and potentially summoning the mother back to
her "stashed" offspring (Pereira et al. 1987; Vasey 2007).
At one month of age, wild infants will begin climbing and clinging. By two to
three months old, the infants will start following their mother and group
members for up to 50 to 100m (164.0 to 328.1 ft) and adult mobility and behavior
including traveling full-time with adults is attained at 3-4 months old (Morland
1990; Vasey 2007). In captivity, 75-80% of play in the first three months of
life is with the mother (Downman 1993). By 10 weeks old, infants begin
participating in greeting displays and calling begins at about 16 weeks old
(Vasey 2007). Scent marking commences at six months old (Vasey 2007). Also, at
around 4 months old in captivity, the infant weighs about 70% of the weight of
the adults (Pereira et al. 1987). The wild infant will first sample, but not
necessarily ingest, solid foods at around two months old. Wild weaning is
estimated to occur at around 4 months of age but some individuals have nursed as
late as 7-8 months old (Morland 1990; Vasey 2007).
Infant mortality in the wild shows great variance, and can range from a quite
high 64%, possibly due to falls from arboreal nests, to zero mortality over a
birth season (Morland 1990; Vasey 2007).
Wild ruffed lemurs are extremely noisy and can be heard from about a kilometer
away (Morland 1991a). Captive ruffed lemurs have three rough classes of
vocalizations, high-, medium- and low-amplitude calls. High-amplitude calls
include the contagious "roar/shriek chorus" which probably functions in
inter-group spacing and communication as well as social functions and is
communally participated in by all wild group members including 3-4 month old
infants (Pereira et al. 1988; Morland 1991a; Geissmann & Mutschler 2006).
"Roar/shriek choruses" can occur throughout the day but are concentrated during
periods of high activity (Morland 1991a; Geissmann & Mutschler 2006). Other
calls of this time are "abrupt roars" which might function to alert group
members to avian predators, to communicate between group members out of visual
contact and also probably to communicate a more general aggressive/defensive
response to a disturbance, and "pulsed squawks" which primarily alerts group
members to mammalian predators, shows high arousal and is a signal for the group
to quickly aggregate (Pereira et al. 1988; Macedonia 1990; Morland 1991a). In
the wild, "roar/shriek choruses" and "abrupt roars" are emitted more often
during the hot seasons than during the rest of the year (Morland 1991a). Other
high-amplitude calls are the "wail," which functions to bring the group back
together or signal all-clear, and the "bray" and "quack," which serve possible
mating functions as a male display (Pereira et al. 1988; Morland 1991a). Loud
calls are delivered with the lemur's body in a "taut" posture (Vasey 2003).
Photo: T. Keith-Lucas
Moderate-amplitude calls are the "growl" which alerts the group to a mild
disturbance or to the approach of an individual, the "growl-snort" which alerts
the group, "chatter" which signals subordinate status, and the "whine" which
signals appeasement by males in the mating season or submission (Pereira et al.
1988; Morland 1991a). Low-amplitude calls are the "grunt," signaling mild
annoyance, the "huff," signaling intense aggravation, especially when avian
predators are present, and the "mew," often exchanged between mother and
offspring when separated or during adults during travel (Pereira et al. 1988;
Morland 1991a). Other wild vocalizations are the "cough," which signals
aggression between a female and a male during mating and birth seasons, the
"grumble" which advertises the presence of a male to another, the "squeak" which
infants use to signal distress, and the "squeal" of affiliation between females
In the wild and in captivity, scent-marking is also an important means of
communication to the ruffed lemur and likely communicates information about sex,
location and identity (Morland 1991a). Female ruffed lemurs predominantly use
their ano-genital scent glands to mark while males use chest, neck, and mandible
glands (Pereira et al. 1988; Vasey 2003). Females mark by squatting and rubbing
their ano-genital region over a horizontal surface excepting the ground. Males
mark by rubbing their chest, chin, and neck on a horizontal or vertical surface
including the ground. Both sexes occasionally mark in the characteristic
fashion of the opposite sex (Pereira et al. 1988; Morland 1991a). Scent-marking
also plays a role in greeting displays, in which individuals "leapfrog" over one
another and scent-mark the back of the other individual (Vasey 2007).
Content last modified: August 17, 2007
Written by Kurt Gron.
Cite this page as:
Gron KJ. 2007 August 17. Primate Factsheets: Ruffed lemur (Varecia) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/ruffed_lemur/behav>. Accessed 2014 October 2.