Uakari

SOCIAL ORGANIZATION AND BEHAVIOR

Uakari group size is extremely variable, from as small as a pair to a hundred individuals and perhaps as many as 200 individuals with many observations intermediate between the largest and smallest estimates and observations. Most groups appear to be < 70 individuals and significantly smaller groups are likely subdivisions of larger ones (Mittermeier & Coimbra-Filho 1977; Ayres & Johns 1987; Bartecki & Heyman 1987; Aquino 1988; Ayres 1990; Defler 1991; Heymann 1992; Boubli 1994; Barnett & Brandon-Jones 1997; Boubli 1997a; Aquino 1998; Defler 1999; Bennett et al. 2001; Bowler 2002; Ward & Chism 2003; Barnett et al. 2005a). Groups numbering over 100 individuals are the largest groups of any New World primate (Boubli 1994). Numbers are variable between populations as well, with some authors placing the maximum group size far lower, around 30 individuals (Barnett et al. 2000). This large variation in observed group size might be indicative of a fission-fusion type of social organization (Defler 1999). However, some long-term observations did not observe fluctuating group size or fission-fusion, while others recorded a seasonal dispersal of the larger groups into mating pairs and bachelor groups (Ayres 1990; Boubli 1997a; 1997b).

Larger groups aggregate particularly at times of more abundant food but also potentially the result of other factors (Defler 1999; Aquino 1998). Some researchers have observed large groups breaking into smaller subunits during travel and during foraging, subunits that sometimes last for several days and some researchers postulate that perhaps there could be several levels of social organization within uakari groups (Ayres & Johns 1987; Bartecki & Heyman 1987; Ayres 1989; Heymann 1992; see also Grüter & Zinner 2004 for speculation). Groups are multi-male/multi-female and are usually composed of multiple adult males and females, subadults (including juveniles and infants) and group membership is roughly evenly divided between the sexes (Ayres 1989; Boubli 1997a; 1997b; Aquino 1998). However, bachelor male groups of up to 8 males have been seen in certain times of the year (Ayres 1990).

The group is dispersed as it travels, and comes together at large food patches and during rest periods and members of subgroups can be spread as far as 1-2 km (0.6-1.2 mi) from one another (Ayres 1989; 1990; Boubli 1999). Contact within the group is maintained through calling (Boubli 1997b; 1999).

In general, very little is known about the social structure of wild uakari troops. In the wild, if the group is disturbed one male has been seen to remain behind and vocalize in the direction of the intruder although what this means about the social structure of the troop remains to be clarified (Barnett et al. 2005a). It is suggested that wild uakari social organization is non-hierarchical (Barnett & Brandon-Jones 1997). However, a dominance hierarchy is seen in captive uakaris, maintained predominantly through fighting (Fontaine & DuMond 1977; Fontaine 1981). Further, in the wild, males have been seen aggressively interacting although again, the meaning of these interactions is ambiguous, and aggression appears to be very rare (Barnett et al. 2005a; Barnett 2008). During rest, grooming sometimes occurs and is initiated by female uakaris (Aquino 1998). In captivity, grooming is frequent and helps maintain friendly social relationships. However, most of the time individual uakaris are usually at least several meters from the nearest conspecific (Fontaine & DuMond 1977). Grooming is rarely seen in the wild, at least for C. m. ouakary (Barnett 2008).

Aggression in captivity is signaled by branch shaking, rocking, breaking, carrying and dropping. It is also signaled by hind leg extension and rubbing, the bouncing of the hindquarters, strutting, and the urine-washing of the chest (Fontaine & DuMond 1977). Further, dominant individuals in captivity intervene in disputes between other group members (Fontaine & DuMond 1977).

Tail-wagging is almost constant in uakaris (Boubli 1997a). Though Fernandes (1993) considers this to be a sign of alarm, Defler (2004) considers it a sign of contentment in C. m. ouakary, noting that an alarmed or fearful animal will curl its tail under its body, like a submissive dog.

In captivity, play is seen not only involving sub-adults, but also between adult individuals (Fontaine 1981). Play is extensive in young wild C. m. ouakary (Barnett 2008).

REPRODUCTION

Both species of uakaris appear to have birth seasons or peaks. C. calvus sees a peak in births during the dry season, between October and November while C. melanocephalus has a birth season between March and April (Ayres 1986 cited in Norconk 2007; Ayres 1990; Boubli 1997a; Defler 2004; Barnett 2005). However, births can occur outside of the birth season and new evidence that C. m. ouakary might have two annual breeding peaks (Defler 2004; Barnett 2008). Wild births are single and in the wild and in captivity, the interbirth interval is estimated roughly at two years (Fontaine & DuMond 1977; Defler 2004; Barnett 2005).

In captivity, females show their receptivity by directing their hindquarters at a male and raising their tail (Fontaine & DuMond 1977). Females are receptive only about 3 or 4 days per ovarian cycle (Fontaine & DuMond 1977). In captive individuals, copulation is usually dorso-ventral with the male behind the female although in at least one wild observation, face-to-face copulation was seen (Fontaine & DuMond 1977; Boubli 1997a). In the wild, copulation generally lasts less than two minutes (Ayres 1990). In captivity, post-copulation, genital sniffing and grooming follows (Fontaine & DuMond 1977). Gestation is approximately six months (Ayres 1990). Data about the age of reproductive maturity in uakaris is extremely limited but based on exceedingly small samples, males in captivity are reproductively successful at 6 years old while a single female was reproductively mature at 3 years old (Fontaine & DuMond 1977).

PARENTAL CARE

Almost all of the available information on parental care and infant development comes from a single semi-natural captive population of C. calvus in Florida observed over twenty years ago (see Fontaine & DuMond 1977; Fontaine 1981). Neither C. melanocephalus sub-species has ever been bred in captivity (Barnett 2005). Size at birth is at best 10% of that of the mother and the face and head are grayish and have hair (Fontaine 1981; Ayres 1990). All births occurred at night in an outdoor captive enclosure and for the first three months of life, the mother will reduce her interactions with the rest of the group (Fontaine & DuMond 1977; Fontaine 1981). The infant is not very active during its first month (Fontaine & DuMond 1977). Solid foods are first consumed around three months old. From birth until the third or fourth month, the infant is carried ventrally and to the side. After this age the infant rides on the mother’s back (Fontaine 1981). From three months old to one year old the face will start to transition from grey to pink, however at this time the head has thick hair, in contrast to the adults, a condition which persists through the second year of life. The baldness characteristic of C. calvus species develops in the third year (Fontaine & DuMond 1977; Fontaine 1981). In the sixth and seventh months of life, play starts with other infants. In the wild, while playing, juveniles vocalize a characteristic “hissing” sound (Boubli 1997a). Towards the end of the first year in captivity, the infant starts moving around independently (Fontaine 1981). Full weaning occurs in the 2nd year of life, is complete by two years old, and involves little weaning conflict (Fontaine 1981).

In the wild, C. calvus infants nurse for 3-5 months, and start eating solid foods between 4 and 6 months of age. By one year old, the diet approximates the foods eaten by adult uakaris (Ayres 1990). Further, in C. melanocephalus, adult males are patient and tolerant of juveniles in the wild (Boubli 1997a).

COMMUNICATION

The wild contact calls of uakaris consist of “keeks,” “hics” and “chics” which are described as sounding roughly bird-like and are heard virtually non-stop (Boubli 1997a; 1997b; Ward & Chism 2003; Barnett 2005). Uakari vocalizations are best studied in captivity in C. calvus, and can be roughly separated into two categories, high- (“hic,” “chyook,” “chick,” “wee-ook,” “rhork,” “kreek,” “wa,” “kik” and “rhä”) and low-amplitude vocalizations (“purr,” “hiss,” and “keh”) (Fontaine 1981). In captivity, males use visual signals more than vocalizations, while females and immature individuals use vocalizations more than visual signals. Vocalizations are often contagious between individuals and are sometimes combined into sequences. “Hic,” “chyook,” and “chick” respectively are uttered in situations of increasing stimulus (Fontaine 1981). “Wa” vocalizations are loud and usually emitted during inter-individual fights and convey intense fear (Fontaine 1981; Ward & Chism 2003). “Kreek” and “rhork” convey less intense fear. “Purr,” “hiss” and “keh” vocalizations are uttered in friendly contexts. “Rhä” is heard during aggression and “kik” is motivated by fear during play (Fontaine 1981). Calls heard in the wild include the “purr” which is heard in affectionate situations, “ki-ki-kis” and “harsh screams” which are contact calls, “wai-wah-wah,” which is uttered during arousal, “chee-chee” which is a danger call, “screams” which are given by animals which are being punished, and the “harsh ehh” which is a play vocalization (Defler 2003 cited in Defler 2004).

In the wild, tail-wagging commonly occurs at the same time as vocalization (Walker & Ayres 1996). A wagging tail likely communicates the well-being of the animal while a lowered tail communicates a tense situation to other uakaris (Defler 2004). In captivity, tail-wagging is seen in situations of general arousal (Fontaine 1981).

In captivity, aggressive adult male visual signals include the single leg jerk, hindquarters bounce, branch slapping and arm raising, quadrupedal stand and stare, strut, branch rocking, and urine washing. Other agonistic visual signals include leg extension, arched back, piloerection, branch shaking, breaking, and dropping (Fontaine 1981). Further, the uakari draws on a canon of facial expressions which communicate a spectrum of meanings from agonism to affiliation to appeasement to fear as well as other meanings (see Fontaine 1981 for full description of facial expressions). Tactile patterns which the uakari uses to communicate through touch include allogrooming, body contact, contact aggression, and dorsal mounting, embracing, and sidling (Fontaine 1981).

In the wild, visual signals include penile displays, piloerection, tail wag in upright position, tail-down, posterior display, and urine washing (Defler 2003 cited in Defler 2004).

Olfactory communication in captivity consists of genital sniffing and licking, anal rubbing, rubbing substances in the fur, and urine washing (Fontaine 1981). The sternal glands present in both sexes might be involved in olfactory communication (Fontaine & DuMond 1977).

Content last modified: July 21, 2008

Written by Kurt Gron. Reviewed by Adrian Barnett.

Cite this page as:
Gron KJ. 2008 July 21. Primate Factsheets: Uakari (Cacajao) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/uakari/behav>. Accessed 2020 July 7.

INTERNATIONAL STATUS

For individual primate species conservation status, please search the IUCN Red List.
Also search the current scientific literature for primate conservation status (overall as well as for individual species), and visit CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora).

Conservation information last updated in 2008 follows, for comparison:

C. melanocephalus and its subspecies are listed as Least Concern; however, this may be in error and the result of observations of seasonal aggregations of animals feeding in flooded forests. The status of C. melanocephalus (and C. m. ouakary) should be reviewed (Adrian Barnett pers. comm.).

CONSERVATION THREATS & POTENTIAL SOLUTIONS

Threat: Human-Induced Habitat Loss and Degradation

Logging has detrimental effects on uakaris and their habitat, even if the desired tree is not favored by uakaris. This is due to collateral felling of uakari food trees to help float commercial logs to points of sale, a reduction in selectivity of loggers resulting in food species being felled, and the alteration of the ecology of plant life in habitats precipitated by dams created by logged trees (Ayres 1986; 1990). Logging is in fact helped by the seasonal inundation of some uakari habitats as the water provides an easy way to extract logs by floating (Ayres 1990). Habitat degradation for agriculture also threatens uakari habitat as does the clearing of forests for pastureland (Heymann 1990). Further, the clearing of land for the establishment of ranches also has the potential to deplete uakari habitat (Barnett & da Cunha 1991). Illegal gold mining has also caused disturbances in uakari habitat, even in protected areas (da Cunha & Barnett 1989; Boubli 1994). One of the ways it does so is by damaging small watercourses by washing topsoil into them as well as by clearing of vegetation by burning it (Boubli 1997b). Several species of tree in the diet of the golden-backed uakari (C. m. ouakary) are also exploited commercially for timber (Barnett 2008).

Threat: Harvesting (hunting/gathering)

Across the genus Cacajao, the degrees of and the purposes for hunting uakaris are variable. For example, in Brazil, white uakaris (C. c. calvus) are not typically hunted for food, partially due to their anthropomorphic, or human-like, appearance. However in Peru, C. calvus is hunted intensively, for food as well as for skulls for the tourist souvenir trade (Mittermeier & Coimbra-Filho 1977; Ayres 1986; Bartecki & Heyman 1987; Aquino 1988). In Venezuela, hunting pressure is likely the most profound threat to C. melanocephalus, especially by illegal gold miners for which bushmeat is an important food source (Barnett & da Cunha 1991; Lehman & Robertson 1994). In addition, miners sometimes hire indigenous hunters to procure bushmeat (Boubli 1997b). Sometimes, the large numbers of uakari individuals occurring in one place make them easy to hunt from a canoe (Defler 2001). Commercial hunting also threatens uakaris and occurs for the procurement of animal protein in the diets of some communities (Heymann 1990; Barnett & da Cunha 1991). Uakaris are also hunted for use as bait, particularly for fish, turtle, or cats, and even in areas where they are not hunted for food (Mittermeier & Coimbra-Filho 1977; Barnett & da Cunha 1991). While in some areas, hunting has formerly focused on the largest primates for food, depletion of those populations can cause an increase in hunting of somewhat smaller primates including uakaris who had been previously unaffected (Ward & Chism 2003).

Uakaris are also collected as pets, often as infants when their mothers are killed and sometimes specifically for this purpose (Aquino 1988; Ward & Chism 2003).

Threat: Pollution

Mercury, a byproduct of illegal mining sometimes makes its way into watercourses within uakari habitats and has the potential to adversely affect the health of the species (Lehman & Robertson 1994).

Threat: Intrinsic Factors

Bald uakaris have one of the highest rates of malarial infection in Amazonian primates. This infection rate might be attributable to their large group size and has the potential to have detrimental effects on their health (Davies et al. 1991).

Threat: Harvesting (hunting/gathering)

Across the genus Cacajao, the degrees of and the purposes for hunting uakaris are variable. For example, in Brazil, white uakaris (C. c. calvus) are not typically hunted for food, partially due to their anthropomorphic, or human-like, appearance. However in Peru, C. calvus is hunted intensively, for food as well as for skulls for the tourist souvenir trade (Mittermeier & Coimbra-Filho 1977; Ayres 1986; Bartecki & Heyman 1987; Aquino 1988). In Venezuela, hunting pressure is likely the most profound threat to C. melanocephalus, especially by illegal gold miners for which bushmeat is an important food source (Barnett & da Cunha 1991; Lehman & Robertson 1994). In addition, miners sometimes hire indigenous hunters to procure bushmeat (Boubli 1997b). Sometimes, the large numbers of uakari individuals occurring in one place make them easy to hunt from a canoe (Defler 2001). Commercial hunting also threatens uakaris and occurs for the procurement of animal protein in the diets of some communities (Heymann 1990; Barnett & da Cunha 1991). Uakaris are also hunted for use as bait, particularly for fish, turtle, or cats, and even in areas where they are not hunted for food (Mittermeier & Coimbra-Filho 1977; Barnett & da Cunha 1991). While in some areas, hunting has formerly focused on the largest primates for food, depletion of those populations can cause an increase in hunting of somewhat smaller primates including uakaris who had been previously unaffected (Ward & Chism 2003).

Uakaris are also collected as pets, often as infants when their mothers are killed and sometimes specifically for this purpose (Aquino 1988; Ward & Chism 2003).

Threat: Pollution

Mercury, a byproduct of illegal mining sometimes makes its way into watercourses within uakari habitats and has the potential to adversely affect the health of the species (Lehman & Robertson 1994).

Threat: Intrinsic Factors

Bald uakaris have one of the highest rates of malarial infection in Amazonian primates. This infection rate might be attributable to their large group size and has the potential to have detrimental effects on their health (Davies et al. 1991).

LINKS TO MORE ABOUT CONSERVATION

CONSERVATION INFORMATION

• No current links for Cacajao
• Links for all species

CONSERVATION NEWS

• New monkey species is already endangered  (New Scientist; January 19, 2008)
• Links for all species

ORGANIZATIONS INVOLVED IN Cacajao CONSERVATION

• Estacion Biologica Caparu

Content last modified: July 21, 2008

Written by Kurt Gron. Reviewed by Adrian Barnett.

Cite this page as:
Gron KJ. 2008 July 21. Primate Factsheets: Uakari (Cacajao) Conservation . <http://pin.primate.wisc.edu/factsheets/entry/uakari/cons>. Accessed 2020 July 7.

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Content last modified: July 21, 2008

IMAGES

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	Cacajao calvus Photo: Primates in Art & Illustration
	Cacajao calvus calvus Photo: Luiz Claudio Marigo
	Cacajao calvus calvus Photo: Luiz Claudio Marigo
	Cacajao calvus calvus Photo: Luiz Claudio Marigo
	Cacajao calvus rubicundus Photo: Roy Fontaine
	Cacajao calvus rubicundus Photo: Roy Fontaine
	Cacajao calvus rubicundus Photo: Roy Fontaine
	Cacajao calvus rubicundus Photo: Roy Fontaine
	Cacajao calvus rubicundus Photo: Roy Fontaine
	Cacajao calvus rubicundus Photo: Roy Fontaine
	Cacajao melanocephalus Photo: Luiz Claudio Marigo
	Cacajao melanocephalus Photo: Luiz Claudio Marigo
	Cacajao melanocephalus Photo: Luiz Claudio Marigo