Humboldt's Woolly Monkey (Lagothrix lagotricha)


MORPHOLOGY:
The Humboldt's woolly monkey has a prehensile tail, which is lacking hair on the ventral side. This species has relatively enlarged lower incisors (Eaglen, 1984; cited in Peres, 1994) and bunodont molar crowns (Rosenberger and Strier, 1989; cited in Peres, 1994). The forms of sexual dimorphism for this species are the canines of the males being longer than that of the females, the body and head length of the male is longer than that of the female, and the mid-ventral fringe is longer, thicker, and darker in males as compared to females (Ramirez, 1988). The tail of the female, however, is usually longer than the tail of the male (Ramirez, 1988). Adult males also have well-developed bumps on both sides of the head (Nishimura, 1994). The females' clitoris is as long or longer than the males' penis, which makes identification in the wild difficult. The average body mass for this species is 7.5 kilograms (Peres, 1990). Humboldt's woolly monkey has a pelage color that can be dark brown, pale smoky brown, dark smoky gray, pale gray, red-brown, or olivaceous on the dorsal side and dark on the ventral side (Emmons, 1997). The limbs, tail, and/or head is usually darker than the back (Emmons, 1997). The face of this species is black (Emmons, 1997). The infant pelage color is paler than that of the adult's and the palms of the hands and feet are a deep pink color (Ramirez, 1988).
Humboldt's Woolly Monkey


RANGE:
The Humboldt's woolly monkey is found in the countries of Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela. In the Amazon basin of western Brazil, eastern Peru, and eastern Ecuador, this species is found west of the Rios Negro and Tapajos (Ramirez, 1988). In eastern Colombia and western Venezuela this species is found near the Andean headwaters of the Orinoco south of the Rio Sarara (Ramirez, 1988). In central Colombia this species is found in the basin of the upper Rio Magdalena, and there are isolated populations in Colombia found in the Department of Cordoba and in south-western Bolivar (Ramirez, 1988). This species lives in mature, continuous, undisturbed humid forests (Mittermeier et al., 1977; Ramirez, 1988). In the eastern plains of Colombia, this species was found to live in gallery and palm forests (Ramirez, 1988). Humboldt's woolly monkey has also been found to live in seasonally flooded or high terrain rainforests and cloud forests (Ramirez, 1988). This species spends most of its time in the canopy of the forest (Ramirez, 1988). In the Pacaya-Samiria National Reserve, Peru, this species was found to live in tall, mature old-levee forest from July to February, and from March to June live the low ground forest where most of the time was spent in the middle to upper levels of the canopy and occasionally going up into the emergent trees (Soini, 1986). In the Colombian Amazon this species was found to prefer to live in hilly forests and igapo forests (Defler, 1996).

ECOLOGY:
The Humboldt's woolly monkey is primarily frugivorous but leaves, seeds, flowers, and invertebrates also constitute an important part of the diet (Peres, 1994; Rameriz, 1988). At Tinigua National Park, Colombia the most important fruit species consumed was found to be Spondias venulosa followed by Henriettella sylvestris (Nishimura, 1997). This was also found to consume Chrysophyllum colombianum, which they threw accurately at researchers when disturbed (Toyne, 1998). Fruit consumed tends to be ones with soft-skin and a thin pericarp (Peres, 1994; Defler and Defler, 1996). Seeds are also an important part of the diet during the early rainy season when there is a lack of ripe fruits (Soini, 1986). Seeds consumed tend to be dispersed 1.5 kilometers from the crown of the parent tree; this species disperses a large quantity of seeds and may be considered important seed dispersers in the forest (Stevenson, 2000). In captivity this species was found to prey upon birds that would fly into their cage (Stearns et al., 1988). The only bird species to be prey upon was the house sparrow, Passer domesticus (Stearns et al., 1988). In Colombia, this species spent 14.1% of feeding time on insects, especially ants of the genera Crematogaster and Eciton (Yumoto et al., 1999). In Tinigua National Park, feeding aggregate size for this species was found to average 4.2 individuals (Nishimura, 1997). Adult males rarely feed in trees with other adult males, but will be found in the same tree with adult females (Nishimura, 1997). Adult females will feed together in the same tree at high rates, suggesting a highly gregarious nature of adult females (Nishimura, 1997; Nishimura, 1994). During the dry season when fruits become more scarce, this species will rely more heavily on young leaves, young seeds, flowers, and exudates of seed pods (Peres, 1994). Foraging tends to in the middle to upper levels of the canopy of the forest (Ramirez, 1988). Foraging occurred mostly in the morning and the afternoon (Stevenson et al., 1994). This species may forage in several groups together, as an individual group, or split up into subgroups (Ramirez, 1988).

The vegetative diet for the subspecies Lagothrix lagotricha cana in the central Amazonia was made up of fruit (80.7%), young leaves (14.4%), flowers (3.1%), and mature leaves (0.1%) (Peres, 1994). Amongst fruit eaten by Lagothrix lagotricha cana, whole ripe fruits and fruit parts account for 82.5% of the diet, 9.8% for unripe fruits, and 7.7% for exudates of the mature seed pods of Parkia sp. (Peres, 1994). Some of the important subspecies of plants consumed came from the genera Chrysophyllum, Pouteria, and Ficus (Peres, 1994). This subspecies was found to increase greatly the consumption of exudates from the seed pods of Parkia nitida during the earl dry season, where these exudates could make up as much as 39% of the diet (Peres, 1994). During the middry season, young leaves will account for up to <47% of the diet (Peres, 1994). This subspecies does not consume much animal matter, arthropods were only found to make up 0.1% of the overall diet (Peres, 1994). It has been suggested that the lack of animal matter in the diet of this subspecies is due to its poor foraging ability, prohibitively large body size, and the lack of a true opposable thumb (Peres, 1994). Humboldt's woolly monkey may incorporate more non-fruit vegetative matter in the diet when a frugivorous competitor is sympatric, such as spider monkeys, Ateles (Defler, 1996).

For the subspecies Lagothrix lagotricha lagotricha in southeastern Colombia the diet is made up of: 78.9% fleshy fruits, 11.4% leaves, 4.3% seeds, 4.9% invertebrate animals, 0.3% bark, 0.1% flowers, and 0.1% tendrils (Defler and Defler, 1996). The color of the fruit consumed for this subspecies is mostly yellow to orange (43.4%), but brown (16.9%), green (16.9%), red (15.3%), and purple (7.4%) colored fruits are also consumed (Defler and Defler, 1996). The most important fruit species genera eaten by this subspecies include: Inga, Chrysophyllum, Pouteria, Pourouma, and Manilkara (Defler and Defler, 1996). Leaves consumed by this subspecies tended to be new growth leaves (Defler and Defler, 1996). The most frequently consumed invertebrates by this subspecies were termites (Isoptera) and katydids (Orthoptera) (Defler and Defler, 1996). Spiders and hymenopteran eggs and larvae were also eaten by this subspecies (Defler and Defler, 1996). The diet of Lagothrix lagotricha lagotricha varies throughout the year with the most species rich diet occurring in March and the least occurring in the months of August, November, and December (Defler and Defler, 1996). During the dry season fruits of Iriartea ventricosa and immature seeds of Micrandra spruceane become important food sources when other food sources become scarce (Defler and Defler, 1996).

In Tinigua National Park, Colombia the diet of the woolly monkey is as follows: fruits 60%, arthropods, 23%, leaves, stems, roots, and flowers 17%, and other items (soil from termitaria nest, fungi, a frog) 1% (Stevenson et al., 1994). Most arthropods consumed came from Coleoptera and Lepidoptera larvae, adult Orthoptera, Diptera, and Arachnidae (Stevenson et al., 1994). Woolly monkeys here would also consume ants (Hymenoptera) and mantids (Stevenson et al., 1994). This species would mostly forage for arthropods in green leaves (52%) with dry leaves (25%) being the second most important place (Stevenson et al., 1994). Mostly juveniles and non-lactating females would consume on arthropods as compared to adult males and lactating females (Stevenson et al., 1994). When fruit is scarce, vegetative parts and flowers are consumed at a higher frequency, with young tree leaves being the most important vegetative part of the plat consumed (Stevenson et al., 1994). This species will mostly consume vines leaves during October and tree leaves during November (Stevenson et al., 1994). Young leaves were consumed more than mature ones with young leaves from Brosimum alicastrum being consumed the most (23%) (Stevenson et al., 1994). Ripe fruits are consumed more than unripe fruits (Stevenson et al., 1994).

In Pacaya-Samiria National Reserve, Peru the diet of Humboldt's woolly monkey is as follows: fruits 74%, seeds 17%, leaves and shoots 6%, and flowers 3% (Soini, 1986). There was also a small amount of invertebrates present in the diet (Soini, 1986). Ripe and unripe fruits were both consumed with the unripe fruits of Coussapoa and Inga aff. punctata being important (Soini, 1986). The most important fruit source is from the genus Ficus (Soini, 1986). Seeds are a more important part of the diet from October thru January with seeds from Echweilera being the most important (Soini, 1986). When ripe fruits are scarce in the forest, seeds, leaves, shoots, and flowers become more important (Soini, 1986).

This species is arboreal and diurnal. The group sizes range from 10-45 individuals (Ramirez, 1988). Adult males tend to show a preference for spending time within the group near adult females with infants, and adult females tend to spend most of their time near juveniles of both sexes (Stevenson, 1998). Related individuals also spend more time closer to each than non-related individuals (Stevenson, 1998). Spacing patterns for this species are determined by: age/sex class, individual differences, activity, development, and reproductive status of females (Stevenson, 1998). This species may divide into smaller subgroups of 2 to 6 individuals when foraging (Ramirez, 1988). Feeding subgroup size tends to be determined by intragroup competition for fruits (Stevenson et al., 1998). Feeding subgroups will feed in trees separately, with one groups waiting in a neighboring tree for the other subgroup to vacate the feeding tree (Peres, 1996). During the first hours of the morning will spend the time foraging and traveling, then around midday they will rest for on average two and a half hours, then for the last hours of the afternoon resume traveling and foraging (Ramirez, 1988). Females will usually follow one or two males when moving (Nishimura, 1994). Different groups will travel together through the forest (Nishimura, 1990b). This species will spend most of its time in the core area of the home range rather than on the periphery (Defler, 1996). From May to July this species will spend more time in igapo forests, which corresponds to the period of highest fruiting in these forests (Defler, 1996). The sleeping posture for this species is that it lies horizontally with the limbs flexed, and the tail wrapped around the body (Ramirez, 1988). Groups tend to sleep in the upper canopy of the forest (Soini, 1986). Sleeping sites tend to be on the middle to distal parts of a stout branch (Soini, 1986).

LOCOMOTION:
The Humboldt's woolly monkey travels through the forest quadrupedally and uses its tail as a fifth arm (Fleagle, 1988). This species also moves by suspensory postures, using any combination of all four limbs and the tail (Ramirez, 1988). The tail of this species is always anchored to something, and this species will occasionally rest by hanging just from the tail (Ramirez, 1988; Turnquist et al., 1999). When semi-brachiating, or suspensory, this species always uses a tail grasp with every hand grasp, which differs from spider monkeys, Ateles who uses a tail grasp with every other hand grasp (Turnquist et al., 1999). Also when semi-brachiating, Humboldt's woolly monkeys will take shorter and more frequent strides as opposed to spider monkeys (Turnquist et al., 1999). When semi-brachiating this species will show a free-flight phase where no appendages are touching a substrate (Turnquist et al., 1999). The tail may also be used for picking up objects (Ramirez, 1988). Humboldt's woolly monkey will cross gaps in the forest by dropping vertically (Ramirez, 1988). This species also uses its tail to position itself when it feeds (Fleagle, 1988).

SOCIAL BEHAVIOR:
The Humboldt's woolly monkey has a multi-male group social system. This species has a polygamous mating system (Kinzey, 1997). A receptive female will copulate with every adult male in the group, with the most dominant male receiving the most copulations (Stevenson, 1997; Nishimura, 1990a; Nishimura, 1994). During the breeding season every male will copulate with every female, but only one female is copulated with at any given time (Stevenson, 1997; Nishimura, 1990a; Nishimura, 1994). Thus in the short term this species could be said to have a polyandrous mating system, but in the long term it has a promiscuous mating system. However in groups with smaller numbers of females, the dominant male may be able to monopolize all of the copulations and not allow any to the lower ranking males (Strier, 2000). Thus hierarchy exists amongst the males in the group (Kinzey, 1997; Stevenson, 1997). The most dominant males in the group receive the most social grooming (Kavanagh and Dresdale, 1975). Adult and subadult males are dominant over all other members of the group (Ramirez, 1988). The dominance hierarchy is determined by play-fighting episodes that test the strength of the hierarchy (Ramirez, 1988). Juvenile and subadult males will harass adult females until they submit to them (Ramirez, 1988). Either unrelated or related females will join up to fight against lower ranking males (Ramirez, 1988). In this species there is male philopatry (the males stay in the group they were born in) and female dispersion (females leave the group they were born in) (Nishimura, 1990; Nishimura, 1994; Nishimura et al., 1995; Nishimura, 1999). Females will leave their natal group when are between 5.5 and 6 years of age (Nishimura et al., 1992; Nishimura, 1999). Although females will begin to mate between 5.5 and 6 years of age, they remain sterile and do not conceive until 1.5 to 3 years after the leave their natal group (Nishimura et al., 1992). Passive food sharing has been shown to occur amongst group members, except adult males, and involves leafy materials (Ramirez, 1988). The most dominant males are protective of mothers with their infants, chasing away other members of the group (Ramirez, 1988). Passive food sharing and stealing occurs between group members (Stearns et al., 1988). Groups do not defend all of their home range rather they temporarily defend some of the areas, with the adult males more active than adult females in agonistic encounters (Stevenson et al., 1994). A group's home range can be overlapped by other groups' ranges (Defler, 1996). Lactating females will suckle non-infants, usually males over the age of 3.5 years and sometimes other adult females (Nishimura, 1994). This species was found to form associations with monk sakis, Pithecia monachus (Rowe, 1996).

Play is seen in this species by all age and sex classes (Ramirez, 1988). Juveniles of both sexes play more than any other group and young infants tend to play with adult males (Ramirez, 1988). Play groups usually do not include young infants and adult males and number from 2 to 4 individuals (Ramirez, 1988). Play can include wrestling, chasing, jumping on one another, and swatting at leaves with the hands (Ramirez, 1988). Adult males will engage in a play-fight that could morph into a more aggressive encounter that ends with one participant running away screaming (Ramirez, 1988). Play may also occur between individuals as they hang by their tails from tree branches (Nishimura, 1990b). The vocalization huh-huh and hughh-hughh usually will occur with social play (Nishimura, 1990b).

Humans, Homo sapiens, are the main predator of Humboldt's woolly monkeys (Ramirez, 1988). Humans hunt this species for meat and for pets (Rowe, 1996). Avian predators of this species include Harpia harpyja, Morphnus guianensis, and Oroates isidori (Ramirez, 1988). The jaguar, Panthera onca, may also be a potential predator based on experiments done in captivity (Ramirez, 1988). The site of a margay, Felis wiedi, or an ocelot, Felis pardalis, will elicit "guardian behavior" in this species (Ramirez, 1988).

VOCAL COMMUNICATION:
eeolk: This is a sharp, high pitched call that is performed by all members of the group, more frequently by adult females (Ramirez, 1988). This common vocalization is uttered towards conspecifics, other group members, and prior to feeding (Ramirez, 1988). This call serves to communicate well being and may be responded to by a chorus of eeolks (Ramirez, 1988).

eeeooolk: This is a high intensity eeolk (Ramirez, 1988). This common vocalization is emitted by all members of the group and is heard in the same situations as eeolk, but when the callers are separated by greater distances (Ramirez, 1988). This call serves to communicate well being and may be responded to with a chorus of eeolks (Ramirez, 1988).

huh-huh: This is a strongly expelled chuckle or laugh accompanied by head shaking (Ramirez, 1988). This common vocalization is emitted by young monkeys and is heard in situations of rough-tumble play (Ramirez, 1988). This call serves to communicate invitation to play and this may be responded to with play (Ramirez, 1988).

hughh-hughh: This is an intense form of huh-huh (Ramirez, 1988). This common call is emitted by adults of both sexes and is seen during play-fights (Ramirez, 1988). Aggression is the motivation of this call (Ramirez, 1988).

scream: This call is a piercing sound that is emitted by all members of the group (Ramirez, 1988). This common call is heard during play-fights towards conspecifics or during agonistic encounters (Ramirez, 1988). This call serves to communicate submission or defeat and may be responded to with ending of play or fight (Ramirez, 1988).

argck-argck: This call is continuous and intermittent, short, and sharp with the mouth open and the teeth exposed (Ramirez, 1988). This call is emitted by all members of the group and is heard in situations of play-fight and during disturbances (Ramirez, 1988). This call serves to communicate readiness to fight and may be responded to with fighting, running, or sobbing (Ramirez, 1988).

offwharff: This is an explosive, short, and strong cough bark (Ramirez, 1988). This call is rare and is emitted by the dominant male only (Ramirez, 1988). This call is uttered towards intruders and serves to communicate a warning (Ramirez, 1988).

nyonk, nyonk: This is a continuous call that is emitted by all members of the group (Ramirez, 1988). This call is heard in situations by individual observing another monkey assisting one during play-fight (Ramirez, 1988). This call serves to encourage an ongoing situation (Ramirez, 1988).

yoohk-yoohk: This is a continuous call that is emitted by all members of the group (Ramirez, 1988). This is a rare call that is heard in situations of outside disturbance or danger (Ramirez, 1988). The call serves to alert the rest of the group and may be responded with chorusing (Ramirez, 1988).

tuff-tuff: This is a continuous and intermittent call emitted by infants and juveniles of both sexes (Ramirez, 1988). At the age of 18 months, this call changes to oohh, oohh (Ramirez, 1988). This call is given to adults and serves to communicate appeasement and to solicit attention and may be responded to with playing or snuffling (Ramirez, 1988).

ogh-ogh: This call is continuous and intermittent and uttered by the adult male (Ramirez, 1988). This call is emitted towards infants and serves to communicate accessibility and may be responded to with the infant approaching (Ramirez, 1988).

long call session: This is a high intensity call where the lower canines are exposed and there is excessive salivation (Ramirez, 1988). This call is uttered by adult males and is heard in situations of outside disturbances (Ramirez, 1988). This call serves to communicate threat (Ramirez, 1988).

long call bouts: This is a high intensity call emitted in the early morning and evening hours (Ramirez, 1988). This call is uttered by adults of both sexes with the male call being louder (Ramirez, 1988).

OLFACTORY COMMUNICATION:
chest-rubbing: This is where an individual will wet a surface with saliva, then rub the chest with strong upward pushes (Ramirez, 1988). This common behavior is performed by adults and juveniles of both sexes, but mainly by males and is seen with various aspects of behavior (Ramirez, 1988). This behavior serves to scent mark (Ramirez, 1988).

defecate: This is where an individual will release feces and is performed by adults and juveniles of both sexes, but mainly by males (Ramirez, 1988). This behavior is seen in situations of strong excitement and disturbance (Ramirez, 1988).

urine tasting: This is when an individual will smell and taste urine with the tip of the tongue (Ramirez, 1988). This behavior is performed by adult females and is done towards the urine of other adult females (Ramirez, 1988).

anogenital rubbing:This is when an individual will rub the anus against a surface in a circular motion (Ramirez, 1988). This behavior is performed by adult males and females and serves to function as a marking behavior (Ramirez, 1988). This behavior may be responded to by other conspecifics sniffing the area (Ramirez, 1988).

anal drag: This is when an individual will drag the anus against a flat surface by pulling itself forward with the arms while sitting in an erect position (Ramirez, 1988). This behavior serves to function as a marking behavior (Ramirez, 1988).

VISUAL COMMUNICATION:
head shake: This is where an individual will look at their partner, move the head from side-to-side rapidly, and sometimes grapple with the partner (Ramirez, 1988). This behavior is performed by infants of both sexes and is seen in situations of vigorous playing and in agonistic encounters (Ramirez, 1988).

cut-off: This is when an individual will turn the head sideways quickly, while sometimes lifting the chin and turning the back (Ramirez, 1988). This common behavior is performed by all members of the group and occurs towards conspecifics and humans (Ramirez, 1988). This is a submissive signal that functions in non-provocation (Ramirez, 1988).

head-roll: This is when an adult male will move his head rapidly in a counterclockwise circle (Ramirez, 1988). This display is seen in situations of food begging and agonistic encounters (Ramirez, 1988).

sobbing: This is a chest display where an individual lifts the forearm while the hand shields the eyes and occurs with the ogh-ogh vocalization (Ramirez, 1988). This common behavior is performed by adult males and females and is seen in situations of greeting (Ramirez, 1988). This friendship display functions to indicate submission and may be responded to with embracing and snuffling (Ramirez, 1988).

high-intensity sobbing: this display starts with sobbing then the head and chest go to the ground with the rump raised and the tail curled up (Ramirez, 1988). This behavior is performed by adult males towards other adult males and is seen in high intensity encounters (Ramirez, 1988). This friendship display is responded to with embracing and snuffling (Ramirez, 1988).

sexual overture: This is when an estrus female will stare at a male with the shoulders hunched up and round, elbows out, teeth-chattering, and lip-smacking (Ramirez, 1988). This behavior is common during the time of estrus and this is seen in situations of when an estrus female is near a male (Ramirez, 1988). This display functions to solicit mounting from the male and may be responded to by mounting by the male (Ramirez, 1988).

penile erection: This is when juvenile and adult males will have the penis erect (Ramirez, 1988). This display is seen in situations of males greeting infants and during play mounting (Ramirez, 1988). This is described as a high intensity arousal behavior (Ramirez, 1988).

groom solicitation: This is when an individual will present the pectoral area with having one or both hands extended to touch the groomer (Ramirez, 1988). This behavior is performed by all members of the group and is seen in situations of grooming sessions (Ramirez, 1988). This display functions to solicit grooming and may be responded to with grooming (Ramirez, 1988).

leaping: This is when a male performs a series of springing movements starting from a bipedal or quadrupedal posture (Ramirez, 1988). This common display is seen prior to feeding and has a sexual arousal motivation (Ramirez, 1988).

chase: This is when an individual will follow another conspecific (Ramirez, 1988).This common behavior is performed by all members of the group and is seen in situations of conspecific aggression or play (Ramirez, 1988). This display functions to communicate an attack or to make a friendly contact (Ramirez, 1988). This may be responded to by the receiver running off or may turn to make contact (Ramirez, 1988).

branch shake: This when an individual will shake a tree branch (Ramirez, 1988).This common behavior is mostly performed by adult males and is seen in situations of the presence of an outside disturbance and during mating (Ramirez, 1988). This display functions to communicate a high threat by the sender and may be responded to by the rest of the group becoming alerted (Ramirez, 1988).

threat display: This is when an adult males will hang by the tail, have the arms outstretched, and emitting the yoohk vocalization (Ramirez, 1988). This common behavior is seen during situations of interspecific aggression (Ramirez, 1988). The display functions to communicate threat on the part of the sender (Ramirez, 1988).

guardian behavior: This is when an individual will be on the look-out from a high position in a tree (Ramirez, 1988). This common behavior is performed by adult males and females and is seen in situations when there is a mild disturbance from within or from outside the group (Ramirez, 1988). This display serves to communicate a mild threat on the part of the sender and may be responded to with contact avoidance (Ramirez, 1988).

anogenital rubbing:This is when an individual will rub the anus against a surface in a circular motion (Ramirez, 1988). This behavior is performed by adult males and females and serves to function as a marking behavior (Ramirez, 1988). This behavior may be responded to by other conspecifics sniffing the area (Ramirez, 1988).

anal drag: This is when an individual will drag the anus against a flat surface by pulling itself forward with the arms while sitting in an erect position (Ramirez, 1988). This behavior serves to function as a marking behavior (Ramirez, 1988).

snuffling: This is when an individual will have the mouth covered with the hand, teeth chattering, and cheek-puffing, and this usually ends with embracing and huddling (Ramirez, 1988). This common behavior is performed by all members of the group and this is done to conspecifics (Ramirez, 1988). This behavior serves to communicate a greeting or friendship and may be responded to with huddling and sobbing and infants respond with tuff-tuff vocalization and head shake (Ramirez, 1988).

teeth-chattering: This is when an individual will look at the receiver having the teeth exposed and chattered and females combine this with lip-smacking (Ramirez, 1988). This common behavior is performed by all members of the group and occurs with sobbing, snuffling, and sexual overtures (Ramirez, 1988). This behavior serves to promote contact and to communicate appeasement (Ramirez, 1988).

lip-smack: This is when an estrus female will open and close the lips very rapidly (Ramirez, 1988). This common behavior is seen during estrus and serves to communicate sexual state (Ramirez, 1988). This display is responded to with mounting (Ramirez, 1988).

grimace: this is when an individual will have the lips partially opened and the lower teeth and canines exposed (Ramirez, 1988). This common behavior is mostly performed by adult males and is seen in situations of long calls, vigilant behavior, and defecation (Ramirez, 1988).

play face: This is where an individual has the mouth open with the lower teeth bare (Ramirez, 1988). This common behavior is performed by all members of the group and is seen in situations of play (Ramirez, 1988). This display serves to communicate an intention to play (Ramirez, 1988).

TACTILE COMMUNICATION:
mouth-to-mouth contact: For the Humboldt's woolly monkey this serves as a greeting behavior (Nishimura, 1990a). This occurs between adults and between adult females and infants (Ramirez, 1988).

social grooming: This behavior occurs most frequently at the midday rest period (Ramirez, 1988). Mothers perform this behavior on their infants, and adults, subadults, and juveniles will perform this behavior on members of their own and other age-sex classes (Ramirez, 1988). An individual will use fingers and teeth or tongue to remove particles from fur (Ramirez, 1988). This behavior can be simultaneously reciprocal (Kavanagh and Dresdale, 1975).

anogenital investigation: This is where one individual will bring the nose or mouth to the anogenital region to another (Ramirez, 1988). This is done between adult males and females, and this serves to communicate sexual status (Ramirez, 1988).

penile lick: This is when an adult male will lick the penis of an infant (Ramirez, 1988). This common behavior occurs during greeting and serves to establish contact (Ramirez, 1988).

embrace: This is when one individual will put the arms and/or tail around another or itself (Ramirez, 1988). This common behavior is performed by all members of the group and occurs during friendly situations (Ramirez, 1988). This behavior serves to communicate reassurance and may be responded to with embrace (Ramirez, 1988).

grappling: This usually occurs with wrestling, pushing, mock biting, slapping, and chasing (Ramirez, 1988). This common behavior is performed by all members of the group and is common between adult males and infants (Ramirez, 1988). This behavior occurs in situations preceding an agonistic encounter or play and serves to establish dominance (Ramirez, 1988). This may be responded with play agonistic actions (Ramirez, 1988).

bouncing: This is when an individual will place arms on another's shoulders and leap up and down two or three times (Ramirez, 1988). This common behavior is done by adult males and females (Ramirez, 1988).

boxing: This is when an individual will direct a series of light blows to the head of another (Ramirez, 1988). This behavior occurs in situations of food stealing (Ramirez, 1988).

extend, touch: This is when an individual will extend an arm or leg towards any part of another's body then touch that particular part (Ramirez, 1988). This behavior is motivated by both friendly and aggressive intentions (Ramirez, 1988).

REPRODUCTION:
The Humboldt's woolly monkey gives birth to a single offspring. The birth season for this species occurs between August and December (Nishimura et al., 1992). Even though there was found to be a birth season, matings will occur at any time during the year (Nishimura et al., 1992). The gestation length for this species was found to be between 7 and 7.5 months (Nishimura et al., 1992). The interbirth interval is 3 years for the Humboldt's woolly monkey (Nishimura et al., 1992). Infants are born head first and is able to immediately cling to the fur of the mother (Ramirez, 1988). During the first two weeks the infant will cling to the ventral surface of the mother, then after that move to riding on her back or clinging to her side (Ramirez, 1988). By six months the infant travels independently for most of the time (Ramirez, 1988). Infants will nurse from 16 to 20 months (Ramirez, 1988).

Before copulations would begin, females will show sexual displays: jumping up and down on all fours or shaking tree branches; after this the female will turn the head and look straight at the male while raising the tail, then repeat the displays (Ramirez, 1988). During estrus, males will sniff the anogenital region and lick the clitoris (Ramirez, 1988). Copulations were also found to be preceded by the female presenting her genitals and teeth-chattering and by embracing and huddling by the pair (Ramirez, 1988). During copulation the male will mount the female from behind, dorso-ventral, lock the legs over her thighs, wrap the arms around her abdomen, then make thrusts with the pelvis (Ramirez, 1988). During mounting both the males and females will perform teeth chattering (Nishimura, 1988; cited in Nishimura, 1990). Females may also mount the males during sexual encounters (Ramirez, 1988).

REFERENCES:
Burton, F. 1995. The Multimedia Guide to the Non-human Primates. Prentice-Hall Canada Inc.

Defler, T.R. 1996. Aspects of the ranging pattern in a group of woolly monkeys (Lagothrix lagotricha). American Journal of Primatology. Vol. 38, 289-302.

Defler, T.R. and Defler, S.B. 1996. Diet of a group of Lagothrix lagotricha lagotricha in southeastern Colombia. International Journal of Primatology. Vol. 17(2), 161-190.

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Last Updated: May 13, 2007.
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