SOCIAL ORGANIZATION AND BEHAVIOR
The social organization of black spider monkeys is closely related to their
ecological niche as large-bodied frugivores.
In addition to ranging over large areas to find the amount of fruit necessary
to meet their feeding requirements, black spider monkeys exhibit another
behavior that helps them cope with seasonally restricted fruit. Like
chimpanzees (Pan troglodytes), spider monkeys exhibit a
fission-fusion social system;
there is a large community of individuals that regularly associate with one
another but individuals within the larger community spend much of their time
traveling in smaller, temporary sub-groups led by dominant adult females
(Mittermeier & van Roosmalen 1981; van Roosmalen 1985). Spider monkeys
break up into small foraging
groups that travel together and feed throughout
the day within a core area of the larger group's home range (Simmen &
Sabatier 1996). The subgroups or parties that are formed by individuals within
the troop are temporary and can change in composition frequently throughout the
day, but average three individuals, most commonly an adult male, and adult
female, and her dependent offspring (van Roosmalen 1985; Norconk & Kinzey 1994).
The composition of the subgroup can remain stable for up to a few weeks and then
changes as group members shift to other subgroups or out of the larger social group
(van Roosmalen 1985). The larger social group is usually between 15 and 20
animals and is defined as a group of animals that interact peacefully or
amicably (van Roosmalen 1985). When two different troops of spider monkeys come
together, the males in each troop display
agonistic
and territorial behavior such as calling and barking. These interactions happen
with much distance between the two groups and do not involve physical contact,
indicating that groups respect distinct territory boundaries (van Roosmalen
1985). Members of a community might not ever be observed together at the same
place, but their mutual tolerance of each other when they come into contact
indicates they are part of the larger troop (van Roosmalen 1985).
One of the reasons this fission-fusion social system evolved could be as a
coping mechanism for seasonal shortages in fruit availability and as a response
to competition between group members (Norconk & Kinzey 1994). When a large
group feeds in a fruit tree, there is likely to be less food per group member
than if a small group feeds in a tree. During the months when food scarcity is
at its peak, average subgroup size is the smallest and during months of highest
fruit availability, subgroup size is the largest, indicating that competition
for scarce resources necessitates breaking into smaller feeding groups (van
Roosmalen 1985; van Roosmalen & Klein 1988). One reason spider monkeys break
into smaller feeding groups but still remain part of a larger social unit is
the advantage to individual group members in terms of increased mating
opportunities and protection from predators.
Dominance relationships between black spider monkeys have not been intensely
studied and there are few published reports of these interactions. In one
study, males and females have separate
linear dominance hierarchies,
but some females are dominant and act as leaders within their subgroups.
These dominant females are followed by members of their foraging party
throughout the day and can displace other spider monkeys, both male and female,
from feeding sites (van Roosmalen 1985). Relationships between adult black
spider monkeys are friendly, with few instances of aggression. Most aggressive
interactions revolve around access to limited resources and are brief, not
resulting in serious injury (van Roosmalen & Klein 1988).
While little data are available on dispersal patterns of young black spider
monkeys, research on other members of the genus Ateles reveals that males remain in their
natal groups
while females transfer between groups in search of mating opportunities
(A. chamek: McFarland Symington 1987; 1988; A. belzebuth: Nunes & Chapman
1997). In Suriname, van Roosmalen (1985) observed A. paniscus females breaking
away from their subgroups and joining neighboring troops for time periods ranging
from several hours to overnight, but did not conclude if these ventures led to
female transfer.
REPRODUCTION
The ovarian cycle
in wild black spider monkeys lasts between 26 and 27 days, with the period of
sexual receptivity lasting for eight to 10 days and the period between peaks of
sexual receptivity lasting 15 to 17 days (van Roosmalen 1985). There is a peak
period of births during the short wet season, from November to February,
indicating that the estrus
cycles of females within a group occur at the same time (van Roosmalen 1985).
This pattern is also seen among captive A. geoffroyi
(Hernández-López et al. 1998). Copulatory
behavior among black spider monkeys first involves the female approaching a
potential male and presenting her genitals. If he shows interest, the mating
pair separate themselves from the group either briefly or up to several days
(van Roosmalen 1985). If a female is ranging in a subgroup without males,
she will react to the calls of males from neighboring groups by leading her
group in the direction of the calls and will either choose to mate with one
of the males of this new subgroup or will continue on, looking for other
potential mates (van Roosmalen 1985).
Gestation
lasts approximately 226 to 232 days (7.5 months) in captive black
spider monkeys. After giving birth, female black spider monkeys experience
lactational amenorrhea
for about three years. They will begin to cycle again after the infant is
weaned (van Roosmalen 1985). If a female successfully raises and weans an
infant, there will be a four year gap between births. This
interbirth interval
is dependant on the infant's survival; if a female loses an infant, she resumes
cycling and will reproduce sooner than if she successfully raised the infant
(van Roosmalen 1985). Among other species of spider monkeys (A. chamek),
there is evidence that maternal rank affects the length of interbirth interval,
with low-ranking females experiencing longer gaps between infants compared to
high-ranking females. This pattern has not been reported in black spider
monkeys (McFarland Symington 1987).
PARENTAL CARE
Spider monkey mothers are the primary caregivers for infants and in the wild,
a young spider monkey will remain close to its mother until about four years of
age (van Roosmalen & Klein 1988). For the first six months, an infant will
cling to the ventrum
of the mother, nursing frequently and depending on her entirely for nourishment.
The infant will begin to ride dorsally
at about six months of age and will continue to do so until it reaches one year,
or longer (van Roosmalen & Klein 1988). During this time, the infant gradually
becomes more independent, taking short jaunts away from its mother to locomote
or play with other young spider monkeys in the group. It is during this time
that an infant will also start eating solid foods, but still relies heavily on
nursing (van Roosmalen & Klein 1988). As they continue to grow, the
independence in travel increases and juvenile spider monkeys, those older than
15 months, will depend on their mothers for transport only when fatigued or
when crossing large gaps between trees. Spider monkey mothers exhibit a
behavior called 'bridge-gapping' in which they form a bridge with their bodies
between two trees and allow their juvenile offspring to climb across them
between trees. The females use their prehensile tails,
adept grasping feet, and hands to form a stable bridge for the young spider
monkeys to cross and aid them in crossing distances that are too large for
the young animals to navigate on their own (van Roosmalen 1985). As they
grow, juvenile spider monkeys depend less on their mothers for food and are
weaned around three years. The young animals will remain with their mothers
until they are between four and five years old, even if their mother has
given birth to a new infant (van Roosmalen & Klein 1988; Milton 1993).
COMMUNICATION
The majority of published information about spider monkey communication is
based on captive research on A. fusciceps while wild studies have
focused on the communication of A. geoffroyi. Most of the research on
A. paniscus communication comes from van Roosmalen's (1985) work in
Surinam. One of the most common black spider monkey calls is given by adult
males and serves as the main communication between neighboring subgroups and
larger social groups. These long-calls or 'whoops' can be heard at distances
of 800 to 1000 m (.497 to .621 mi) on the forest floor, but when given above
the canopy, the sound can travel distances up to 2000 m (1.24 mi) (van
Roosmalen & Klein 1988). Other common vocalizations heard include
'whinnies,' 'sobs,' and 'tee-tee' vocalizations during friendly interactions
and while feeding. During times of social discomfort, 'trills,' 'twitters,'
and 'squeaks' are heard and escalate into screams as a spider monkey becomes
frightened or highly anxious (van Roosmalen & Klein 1988). Another
communicative gesture seen in black spider monkeys is a greeting ritual between
members of the same social group. After a period of separation in different
foraging subgroups, male and female black spider monkeys greet each other.
The subordinate animal approaches the dominant monkey and embraces him or her
and then they each take turns sniffing the chest and genital areas of the other
(van Roosmalen & Klein 1988). During contact with unfamiliar animals or at
the boundaries of the territory, males may exhibit agonistic displays that
include head shaking, arm and chest scratching,
piloerection,
and branch shaking, all accompanied by defecation (van Roosmalen 1985).
Content last modified: April 10, 2007
Written by Kristina Cawthon Lang. Reviewed by Dionisios Youlatos.
Cite this page as:
Cawthon Lang KA. 2007 April 10. Primate Factsheets: Black spider monkey (Ateles paniscus) Behavior. <http://pin.primate.wisc.edu/factsheets/entry/black_spider_monkey/behav>. Accessed 2008 July 4.
