Sakis, titis, and uakaris

(Pitheciidae)

Class Mammalia

Order Primates

Family Pitheciidae

Thumbnail description
Diverse family of small- to medium-sized monkeys with long, thickly haired tails (except Cacajao) and long, coarse or dense hair (except Chiropotes), which range in color from white, buffy, yellow, and orange to brown, black, gray, and agouti

Size
Length: 9.1–21.7 in (232–550 mm); weight: 1.5–7.6 lb (700–3,450 g)

Number of genera, species
4 genera; 28 species

Habitat
Highland and lowland rainforest, tropical dry forest, liana forest, savanna forest, mountain savanna forest, secondary forest, igapó, várzea, swamp, gallery forest, and disturbed habitat

Conservation status
Critically Endangered: 2 species; Endangered: 1 species; Vulnerable: 9 species; Data Deficient: 2 species

Distribution
Found in South America in the Amazon and Orinoco basins, Atlantic coastal forest of Brazil, parana forests of Bolivia and Paraguay

Evolution and systematics

The platyrrhine family Pitheciidae includes four genera in two subfamilies. The subfamily Pitheciinae includes sakis (Pithecia, 5 species, 5 subspecies), bearded sakis (Chiropotes, 2 species, 3 subspecies), and uakaris (Cacajao, 2 species, 5 subspecies). The subfamily Callicebinae includes only titi monkeys (Callicebus, 19 species, 5 subspecies). The genus Pithecia is further subdivided into two groups: the Pithecia pithecia group containing two subspecies of Pithecia pithecia, and the P. monachus group (P. monachus, 2 subspecies; P. irrorata, 2 subspecies; P. albicans, and P. aequatorialis). Callicebus is also further subdivided. Prior to Hershkovitz's revision of the genus in 1990, only three species were recognized. Taxonomies published in 2000 and 2001 modify his revision, listing 19 species in four species groups: the Callicebus modestus group (1 species), the C. donacophilus group (4 species), the C. moloch group (12 species), and the C. torquatus group (2 species, 5 subspecies). Callicebus taxonomy is in a state of flux.

The saki-uakari group has long been considered a distinctive adaptive radiation and titi monkeys have usually been considered a sister group to it based on both morphological and genetic evidence. Previous classifications have also considered night monkeys (genus Aotus) a sister group to the pitheciins, but as of 2001, this genus has been place in its own monogeneric family.

Several fossil primates from early Miocene localities in Argentina (Soriacebus, Proteropithecia, Homunculus, Carlocebus), Middle Miocene localities in Colombia (Cebupithecia, Nuciruptor), and Quarternary localities in the Caribbean (Xenothrix, Antillothrix, Paralouatta) have been aligned with both the Pitheciinae and the Callicebinae. Earlier forms are more primitive and not readily aligned with any extant taxa, but it is possible to identify lineages leading to extant pitheciins in later forms.

Physical characteristics

Pitheciids are small- to medium-sized monkeys. Callicebus is the smallest, followed by Pithecia, Chiropotes, and Cacajao. Both Chiropotes and Cacajao are sexually dimorphic in size, with males 20–23% larger than females. Sexual dichromatism is uncommon, but is found in Pithecia pithecia and P. aequatorialis.

It is most pronounced in Pithecia pithecia: males are solid black with a white face and black nose, while females are blackish-agouti with white stripes from under each eye to the corners of the mouth.

Other pitheciids range in color from dark agouti with paler hands and feet and sex-specific patterns of facial hair (Pithecia species), black with light to dark brown back and shoulders (Chiropotes satanas), silky black with a white nose (C. albinasus), reddish orange to orange, or white (Cacajao calvus), or black with a reddish brown to orange back, belly, and thighs (Cacajao melanocephalus). Callicebus is a very diverse genus in terms of coloration. The pelage ranges from black hands (Callicebus personatus), or black all over with yellow hands (Callicebus torquatus), while other species vary from agouti to roufous to grayish with various facial markings.

The four genera are quite distinct in appearance. Pithecia and Cacajao have long, coarse, fluffy hair, Callicebus has long, dense, fluffy hair, while Chiropotes is distinctive in having short body hair. Pithecia and Chiropotes have long, bushy, nonprehensile tails, Callicebus has a long, thickly haired tail, and Cacajao is unique in having a short, bushy haired tail that measures only one-third the length of its body. Distinctive beards, bulbous temporal swellings, and distinctive pink scrotums in males and pink vaginal lips in females characterize bearded sakis (Chiropotes). The bald uakari (Cacajao calvus) is unique in having a bright red, naked face and a bald head

The major defining feature of pitheciids is a shared dental complex. Enormous laterally splayed canines that are functionally separated from the incisors by a diastema are used to open fruits protected by hard, thick husks. The incisors are inclined anteriorly for cropping fruit, and the lower ones are styliform. The molars have low occlusal relief and crenulations. Pitheciids have been characterized as "sclerocarpic foragers" because of their specialization for exploiting heavily protected fruit, such as species of the Brazil nut family (Lecythidaceae).

Distribution

All four pitheciid genera are only found in South America. Callicebus has the largest distribution, inhabiting tropical forests in the Amazon and Orinoco basins (C. moloch and C. torquatus groups), the Atlantic coastal forest in Brazil (C. personatus), and the parana forests of Bolivia and Paraguay (C. donacophilus). The two Pithecia species groups are separated by the Amazon River, with the Pithecia pithecia group found in the Guiana Shield north of the Amazon River and east of the Rios Negro and Orinoco, and the P. monachus group found

south of the Amazon and west to the Andean foothills. Chiropotes is found north of the Amazon in the Guiana Shield and between Rios Xingu and Garupi south of Amazon (C. satanas), while C. albinasus is found south of the Amazon in Brazil west of the Rio Xingu. The two species are not sympatric. The genus Cacajao is restricted to western Amazon flooded forests, with Cacajao calvus inhabiting inundated forests south of the Amazon on whitewater rivers (várzea) in Brazil and Peru, while C. melanocephalus is only found in inundated forests on black-water rivers (igapó) north of the Amazon in Brazil and Venezuela.

Habitat

All pitheciid species are predominately or exclusively arboreal, but habitat use by the four genera is variable. Both Pithecia and Callicebus are found in a wide variety of habitats. Pithecia species are found in highland and lowland forests, tropical dry forest, igapó, high várzea, secondary forests, disturbed habitats, liana forest, savanna forest, and mountain savanna forests. Callicebus species are found in inundated forests, swamps, and river and lake edges (C. moloch), open canopy in mixed, gallery, evergreen, and tall forests near streams (C. torquatus), and secondary but not primary forest with low canopy, thickets, and vine tangles in the Atlantic Coastal rainforest (C. personatus).

Both Chiropotes and Cacajao are found in fewer habitat types. Chiropotes species are restricted to terra firme, high rainforest, high mountain savanna forest, savanna forest, and high moist forest. They have not been observed in lowland, disturbed, secondary, flooded, or gallery forests. Cacajao species are found almost exclusively in igapó and várzea, but have been observed to seasonally migrate to terra firme forest.

Behavior

Pitheciid social organization is quite variable. Callicebus is unique among pitheciids in exhibiting a pair-bonded, monogamous social structure, living in groups of 2–6 individuals (adult couple and offspring). Pithecia species live in small multimale/multifemale groups. Chiropotes lives in

multimale/multifemale groups of 10–30 individuals with a roughly equal sex ratio, while Cacajao lives in large multimale/multifemale groups of up to 100 individuals.

Grooming behavior is important in reinforcing social bonds in Callicebus and may account for 10% of a day's activity. Group members also twine their tails when sitting together. When aggravated, Pithecia exhibits an aggressive display of piloerection, body shaking, an arched posture, and a growling vocalization. Chiropotes has a distinctive tail wagging behavior that denotes excitement, and a characteristic high-pitched whistling vocalization. Cacajao also exhibits tail wagging and piloerection, and the naked-faced Cacajao calvus has the largest repertoire of facial expressions of any platyrrhine.

Callicebus lives in small, well-defined territories that in most species are defended using loud vocalizations (solo male calls and male-female duets). In other species there is overlap of home ranges, and calls are used to define territories without boundary defense. They rarely associate with other primate species, but have been observed occasionally with tamarins (genus Saguinus) and marmosets (genus Callithix). Pithecia generally occupies small home ranges, but some species may have large ones. The home ranges of some species may overlap, while others may have relatively exclusive areas with defined boundaries and little overlap. They have not been observed to form polyspecific associations with other primates. Both Chiropotes and Cacajao have large home ranges that are not defended. Chiropotes has been observed in polyspecific groups with squirrel monkeys (genus Saimiri), capuchin monkeys (genus Cebus), and Cacajao; and Cacajao has been observed to associate with squirrel monkeys (genus Saimiri), capuchin monkeys (genus Cebus), woolly monkeys (genera Lagothrix, Pithecia, and Chiropotes).

Both Pithecia and Chiropotes have relatively shorter day ranges than do the other two pitheciid species. Pithecia has short day ranges, usually less than 0.6 mi (1.0 km). Most Pithecia species locomote by vertical clinging and leaping and tend to prefer the lower and middle strata of the forest canopy, although Pithecia albicans uses the middle and upper canopy and does little vertical clinging. Some species will forage occasionally on the ground. Day ranges are much longer in Chiropotes (0.6–2.8 mi [1.0–4.5 km]), and increase during periods of food scarcity. Groups may fission for feeding. Travel is cohesive but they may also travel in subgroups. Chiropotes is an arboreal quadruped that prefers the upper canopy, traveling rapidly between feeding trees and then engaging in intense feeding bouts. Cacajao also has very long day ranges (greater than 3 mi [5 km]), and prefers the middle and upper canopy, but will forage on the ground during the dry season due to the paucity of terrestrial mammals in flooded forests. They are arboreal quadrupeds, but employ more leaping and bipedal suspension postures than other pitheciids. All Callicebus species are primarily arboreal quadrupeds and rarely forage on the ground. Some species use the lower canopy, some the middle canopy, and some others the upper canopy.

Feeding ecology and diet

The three pitheciin genera, and to a lesser extent Callicebus, are specialized seed predators. Pithecia, Chiropotes, and Cacajao all include a large percentage of fruit in their diets, and the majority of these fruit are exploited for the seeds they contain. Most species prefer young seeds from unripe fruit. The

fruits these primates include in their diets are primarily large, hard, indehiscent fruits with one or a few large seeds, such as the Brazil nut family (Lecythidaceae). Pithecia supplements its diet with leaves, flowers, and invertebates, as does Cacajao. Chiropotes eats fewer leaves, but will eat some invertebrates. Callicebus species eat more fruit pulp and fewer seeds than other pitheciids. Some species supplement their diet with insects while others eat leaves.

Reproductive biology

Saki (Pithecia) reproductive biology is variable. All species give birth to single offspring. Some species (P. pithecia and P. monachus) reproduce seasonally, while others (P. albicans) do not. Groups may have a single reproductive female (P. monachus) or more than one (P. pithecia). Adult coloration may develop in weeks (P. albicans), months (P. pithecia), or years (P. monachus). There is typically no paternal care, although fathers may groom infants. In some species, subadult and adult daughters may help. Offspring are independent at 6–7 months and are weaned at one year of age.

Chiropotes satanas gives birth in the dry season in Suriname and Venezuela. There are occasional copulations year-round with a peak from July to September, and gestation is 4.5–5.5 months. By two months, infants are carried ventrally, but begin a shift to dorsal carrying. Other group members groom infants. At three months, infants are always carried dorsally, and they exhibit some self-locomotion at rest. At six months, infants locomote independently for short distances, but are still carried dorsally for long trips. Infants are fully independent at 10–13 months. Chiropotes albinasus does not breed seasonally, but may give birth in February-March or August-September. Adult females exhibit bright red labia during estrus.

In captivity, Cacajao mates promiscuously and has seasonal births of single offspring. Females show no external sign of estrus, and gestation length is unknown. Only mothers carry offspring, and infants are carried ventrally for three months, and then are carried dorsally. At 12 months, infants independently locomote but may still sleep with the mother. Suckling and sleeping on proximity to the mother may last two years. The birth season for wild Cacajao in Peru is December to March.

Callicebus also breeds seasonally and gives birth to a single offspring. These monkeys are unique among pitheciids in that males provide nearly all of the infant care. Male titis begin carrying infants within 48 hours of birth, and infants return to the mother only to nurse. Infants are carried until 4–6 months of age, and weaning occurs at this time. Offspring reach maturity at 3–4 years, at which time they abruptly leave the natal group. No aggression accompanies the departure.

Conservation status

The IUCN lists Miller's monk saki (Pithecia monachus milleri) as Vulnerable due to habitat loss, fragmented populations, and declining numbers of adults. The Napo monk saki (P. monachus napiensis) is listed as Data Deficient.

The IUCN lists Uta Hick's bearded saki (Chiropotes satanas utahicki) as Vulnerable due to habitat loss and the southern bearded saki (C. satanas satanas) as Endangered due to habitat loss and the fragmenting and decline of population sizes. The white-nosed bearded saki (Chiropotes albinasus) is listed as CITES Appendix I.

Bald uakaris (Cacajao calvus) are generally listed as Vulnerable due to severe hunting in many parts of Peru and Brazil. The IUCN also lists the Ucayali bald uakari (Cacajao calvus ucayalii) as Vulnerable due to a loss of habitat, and lists three other subspecies, the white bald uakari (C. calvus calvus), Novae's bald uakari (C. calvus novaesi), and the red bald uakari (C. calvus rubicundus) as Endangered due to habitat fragmentation and population decline. All Cacajao species are CITES Appendix I.

A number of Callicebus species are also listed by the IUCN. Two species, the northern Bahian blond titi (Callicebus barbarabrownae) and Coimbra's titi (C. coimbrai), are Critically Endangered. Six additional species, Medem's collared titi (C. medemi), the southern Bahian masked titi (C. melanochir), the black fronted titi (C. nigrifrons), the Andean titi (C. oenathe), the ornate titi (C. ornatus), and the masked titi (C. personatus), are considered Vulnerable. One species, the Beni titi (C. olallae), is listed as Data Deficient.

Significance to humans

All pitheciid genera are either hunted for food or captured to be sold locally or exported as pets. Pithecia and Chiropotes are often hunted solely for their long, bushy tails, which are used as dusters.

Species accounts

List of Species

White-faced saki

Pithecia pithecia

subfamily

Pitheciinae

taxonomy

Pithecia pithecia Linnaeus, 1766, French Guiana.

other common names

English: Flying jack, Guianan saki; Spanish: Parauacu.

physical characteristics

Head and body length is 13.2–13.8 in (335–350 mm); tail length is 13.5–17.5 in (342–445 mm); and weight is 27.5–88.2 oz (779–2,500 g). They possess long, coarse, fluffy hair and long, thickly haired, non-prehensile tail. Males are colored black with a white face and black nose. Females possess agouti with white stripes along the sides of the nose.

distribution

Guiana Shield forests north of the Amazon River and east of the Rios Negro and Orinoco.

habitat

Primary and secondary forests, tropical dry forests, gallery forests, savanna forests, palm swamps.

behavior

Diurnal and predominately arboreal. They live in small multi-male/multi-female groups, and forage in the lower to middle canopy and occasionally on the ground.

feeding ecology and diet

Seed predators. Fruit, seeds, flowers, leaves, and invertebrates.

reproductive biology

Variable mating system. Females give birth to a single offspring from December to April. There is no paternal care. Infants are weaned at four months, and are sexually mature at 24–36 months.

conservation status

CITES Appendix II. Relatively rare but not threatened.

significance to humans

None known.

Bearded saki

Chiropotes satanas

subfamily

Pitheciinae

taxonomy

Chiropotes satanas Hoffmannsegg, 1807, Brazil.

other common names

English: Black bearded saki; French: Saki noire; Spanish: Capuchino del Orinoco, mono capuchino.

physical characteristics

Male head and body length is 15.7–18.9 in (400–480 mm); tail length is 15.6–16.1 in (395–410 mm); and weight is 4.8–8.8 lb (2.2–4.0 kg). Female head and body length is 15.0–16.1 in (380–410 mm); tail length is 14.6–16.5 in (370–420 mm); and weight is 4.2–7.3 lb (1.9–3.3 kg). They possess a prominent black beard, temporal swellings, and long, bushy, non-prehensile tail. The coat is black with a brownish red back.

distribution

Guiana Shield forests north of the Amazon River and east of the Rios Negro and Orinoco and south of the Amazon east of the Rio Xingu.

habitat

Terra firme forest, igapó, high rainforest, and mountain savanna forest.

behavior

Diurnal and arboreal. They live in multimale/multifemale groups of 10–30 individuals, and forages in the middle and upper canopy. The tail is wagged when excited, and they use distinctive, high-pitched whistling vocalization.

feeding ecology and diet

Seed predators specializing in large, heavily protected fruit; they also eat fruit pulp and some insects.

reproductive biology

Variable mating system. Females exhibit bright red labia during estrus, and give birth to a single offspring from December to April.

conservation status

The IUCN lists the Uta Hick's bearded saki (Chiropotes satanas utahicki) as Vulnerable due to habitat loss and the southern bearded saki (C. satanas satanas) as Endangered due to habitat loss and the fragmenting and decline of population sizes.

significance to humans

None known.

Bald uakari

Cacajao calvus

subfamily

Pitheciinae

taxonomy

Cacajao calvus I. Geoffroy, 1847, Brazil.

other common names

English: Bald-headed uakari, red-and-white uakari; Spanish: Huapo colorado, mono ingles.

physical characteristics

Male head and body length is 21.3–22.1 in (540–560 mm); tail length is 5.9–6.3 in (150–160 mm); and weight is about 7.6 lb (3.5 kg). Female head and body length is 21.3–22.4 in (540–570 mm); tail length is the same as males; and weight is about 6.3 lb (2.9 kg). They have long, coarse, fluffy hair, white in Cacajao calvus calvus to orange-red in C. c. rubicundus. The tail is one-third the length of the body. The face and head is bald and pink to scarlet in color.

distribution

Flooded white water (várzea) forests north of the Amazon in Venezuela, Brazil.

habitat

Found primarily in flooded white water (várzea) forests north of the Amazon.

behavior

Diurnal and arboreal. They forage on the ground during the dry season. The tail is wagged when excited. They have a large repertoire of facial expressions.

feeding ecology and diet

Seed predators specializing in large, hard-husked fruits. They also eat fruit pulp, flowers, and insects.

reproductive biology

Variable mating system. They live in large multimale/multife-male groups in the wild. Promiscuous mating and seasonal births of single offspring is observed in captivity. Infants are weaned at 15–21 months. Females sexually mature at 43 months, males at 66 months.

conservation status

IUCN lists the bald uakari (Cacajao calvus) as Vulnerable due to over-hunting. The IUCN also lists the Ucayali bald uakari (Cacajao calvus ucayalii) as Vulnerable due to a loss of habitat, and lists three other subspecies, the white bald uakari (C. calvus calvus), Novae's bald uakari (C. calvus novaesi), and the red bald uakari (C. calvus rubicundus) as Endangered due to habitat fragmentation and population decline. All Cacajao species are CITES Appendix I.

significance to humans

Uakaris are hunted for food and kept as pets.

Dusky titi monkey

Callicebus moloch

subfamily

Callicebinae

taxonomy

Callicebus moloch Hoffmannsegg, 1807, Brazil.

other common names

Spanish: Mono tití, tocón.

physical characteristics

Head and body length is 13.6–13.7 in (345–348 mm); tail length is 17.0–17.7 in (432–449 mm); and weight is 24.7–42.3 oz (700–1,200 g). Their coat is buffy or grayish agouti with contrasting reddish brown or orange sideburns and underparts. They possess a long, thickly haired, non-prehensile tail.

distribution

Amazon basin south of the Amazon River in Brazil.

habitat

Gallery, swamp, and flooded forests. Lower canopy levels.

behavior

Diurnal and arboreal. Small territories are defended by vocal duets of mated pair at daybreak. They forage in dense tangles of vegetation in the lower levels of the canopy, but will forage

higher occasionally. Group members will twine tails together when sleeping, grooming, and dueting.

feeding ecology and diet

Fruit, leaves, and insects. They are the only largely folivorous small monkey.

reproductive biology

Monogamous. Females gives birth to a single offspring during November–March. Males carry infants the majority of the time, beginning at birth. Infants are weaned at eight months, sexually mature at 30 months, and both sexes leave the group at three years of age.

conservation status

CITES Appendix II. Common, widespread distribution; not threatened.

significance to humans

None known.

Collared titi

Callicebus torquatus

subfamily

Callicebinae

taxonomy

Callicebus torquatus Hoffmannsegg, 1807, Brazil.

other common names

English: Widow monkey, yellow-handed titi; Spanish: Cotoncillo, mono viudo, tocón, viduita.

physical characteristics

Head and body length is 9.1–14.2 in (232–260 mm); tail length is 16.7–19.3 in (425–493 mm); and weight is 38.8–52.9 oz (1,100–1,500 g). They have a dark brown body, black tail, yellow hands, and a white collar around the neck. The tail is long, thickly haired, and non-prehensile.

distribution

Western Amazon Basin lowlands of Colombia, Venezuela, Peru, and Brazil.

habitat

Primary and secondary terre firme forests, forests on white sands and black-water streams.

behavior

Diurnal and arboreal; very active. Small territories are defended by vocal duets of mated pair at daybreak. Group members twine tails together when sleeping, grooming, and dueting. They forage in the middle and upper canopy and rest in the lower canopy.

feeding ecology and diet

Fruit and seeds, leaves, and insects.

reproductive biology

Monogamous. Females give birth to a single offspring at the beginning of the rainy season. Males carry infants the majority of the time, beginning at birth. Infants are weaned at 4–5 months. Females become sexually mature at 24–36 months, males at 24–42 months. Both sexes leave the group at three years of age.

conservation status

CITES Appendix II. Patchily distributed, locally common; not threatened

significance to humans

None known.

Masked titi

Callicebus personatus

subfamily

Callicebinae

taxonomy

Callicebus personatus E. Geoffroy, 1812.

other common names

Spanish: Guigoacute.

physical characteristics

Head and body length is 12.2–16.5 in (310–420 mm); tail length is 16.5–21.7 in (418–550 mm); and weight is 34.2–58.2 oz (970–1,650 g). They have a black face, hands, and feet. The body is grayish to yellowish or orange, with a long, thickly haired, non-prehensile tail.

distribution

Atlantic coastal forest of Brazil.

habitat

Primary and secondary forest.

behavior

Diurnal and arboreal. Small territories are defended by vocal duets of mated pair at daybreak. Group members twine tails together when sleeping, grooming, and dueting. They feed mainly in small-crowned trees, and spend the majority of the day resting.

feeding ecology and diet

Fruit, leaves, and flowers. May eat very small amount of insects.

reproductive biology

Monogamous. Females give birth to single offspring during August–October. Males carry infants the majority of the time, beginning at birth.

conservation status

IUCN Red List lists them as Vulnerable due to habitat loss. Also listed on CITES Appendix II.

significance to humans

None known.

Resources

Books

Clutton-Brock, T. H., ed. Primate Ecology: Studies of Feeding and Ranging Behavior in Lemurs, Monkeys, and Apes. New York: Academic Press, 1977.

Eisenberg, John F., ed. Mammals of the Neotropics, Volume 1: The Northern Neotropics: Panama, Colombia, Venezuela, Guyana, Suriname, French Guiana. Chicago, IL: University of Chicago Press, 1989.

——, ed. Mammals of the Neotropics, Volume 3: The Central Neotropics: Ecuador, Peru, Bolivia, Brazil. Chicago, IL: University of Chicago Press, 1997.

Emmons, Louise H., and Francois Feer. Neotropical Rainforest Mammals: A Field Guide, 2nd ed. Chicago, IL: University of Chicago Press, 1997.

Fleagle, John G. Primate Adaptation and Evolution, 2nd ed. San Diego, CA: Academic Press, 1999.

Groves, Colin P. Primate Taxonomy. Washington, D.C.: Smithsonian Institution Press, 2001.

Hartwig, Walter Carl, ed. The Primate Fossil Record. New York: Cambridge University Press, 2002.

Kinzey, Warren G., ed. New World Primates: Ecology, Evolution, and Behavior. New York: Aldine de Gruyter, 1997.

Norconk, Marilyn A., Alfred L. Rosenberger, and Paul A. Garber, eds. Adaptive Radiations of Neotropical Primates. New York: Plenum Press, 1996.

Peetz, Angela Ecology and Social Organization of the Bearded Saki Chiropotes Satanas Chiropotes (Primates: Pitheciinae) in Venezuela. Bonn, Germany: Society of Tropical Ecology, 2001.

Rowe, Noel. The Pictorial Guide to the Living Primates. East Hampton, NY: Pogonias Press, 1996.

Sussman, Robert W. Primate Ecology and Social Structure, Volume 2: New World Monkeys Needham Heights, MA: Pearson Custom Pub., 1999.

Periodicals

Ayres, J. M. "Comparative Feeding Ecology of the Uakari and Bearded Saki, Cacajao and Chiropotes." Journal of Human Evolution 18 (1989): 697-716.

Barnett, A. A., and D. Brandon-Jones. "The Ecology, Biogeography, and Conservation of the Uakaris, Cacajao (Pitheciinae)." Folia Primatologica 68 (1997): 223-235.

Boubli, J. P. "Feeding Ecology of Black-Headed Uakaris (Cacajao melanocephalus melanocephalus) in Pico Da Neblina National Park, Brazil." International Journal of Primatology 20 (1999): 719-749.

Brush, J. A., and M. A. Norconk. "Early Behavioral Development in a Wild White-Faced Saki Monkey (Pithecia pithecia)." American Journal of Physical Anthropology Suppl. 28 (1999): 99.

Easley, S. P., and W. G. Kinzey. "Territorial Shift in the Yellow-Handed Titi Monkey (Callicebus torquatus)." American Journal of Primatology 11(1986): 307-318.

Ferrari, S. F. "Observations on Chiropotes albinasus from the Rio Dos Marmelos, Amazonas, Brazil." Primates 36 (1995): 289-293.

Happel, R. E. "Ecology of Pithecia hirsuta in Peru." Journal of Human Evolution 11 (1982): 581-590.

Hershkovitz, P. "A Preliminary Taxonomic Review of the South American Bearded Saki Monkeys Genus Chiropotes (Cebidae, Platyrrhini), with the Description of a New Subspecies." Fieldiana Zoology 27 (1985): 1-46.

——. "Uacaries, New World Monkeys of the Genus Cacajao (Cebidae, Platyrrhini): A Preliminary Taxonomic Review with the Description of a New Subspecies." American Journal of Primatology 12 (1987): 1-53.

——. "The Taxonomy of South American Sakis, Genus Pithecia (Cebidae, Platyrrhini): A Preliminary Report and Critical Review with the Description of a New Species and a New Subspecies." American Journal of Primatology 12 (1987): 387-468.

Kinzey, W. "Dietary and Dental Adaptations in the Pitheciinae." American Journal of Physical Anthropology 88 (1992): 499-514.

Kinzey, W. G., and M. Becker. "Activity Pattern of the Masked Titi Monkey, Callicebus personatus." Primates 24 (1983): 337-343.

Kinzey, W. G., and M. A. Norconk. "Hardness as a Basis of Fruit Choice in Two Sympatric Primates." American Journal of Physical Anthropology 81(1990): 5-15.

——. "Physical and Chemical Properties of Fruit and Seeds Eaten by Pithecia and Chiropotes in Surinam and Venezuela." International Journal of Primatology 14 (1993): 207-227.

Kinzey, W. G., and J. G. Robinson. "Intergroup Loud Calls, Range Size, and Spacing in Callicebus torquatus." American Journal of Physical Anthropology 60(1983): 539-544.

Kinzey, W. G., A. L. Rosenberger, P. S. Heisler, D. L. Prowse, and J. S. Trilling. "A Preliminary Field Investigation of the Yellow Handed Titi Monkey, Callicebus torquatus torquatus, in Northern Peru." Primates 18 (1977): 159-181.

Kinzey, W. G., and P. C. Wright. "Grooming Behavior in the Titi Monkey (Callicebus torquatus)." American Journal of Primatology 3 (1982): 267-275.

Lehman, S., W. Prince, and M. Mayor. "Variations in Group Size in White-Faced Sakis (Pithecia pithecia): Evidence for Monogamy or Seasonal Congregations." Neotropical Primates 9 (2001): 96-101.

Mittermeier, R. A., and M. G. M. van Roosmalen. "Preliminary Observations on Habitat Utilization and Diet in Eight Surinam Monkeys." Folia Primatologica 36 (1981): 1-39.

Mittermeier, R. A., W. R. Konstant, H. Ginsberg, M. G. M. van Roosmalen, and E. Cordeiro da Silva Jr. "Further Evidence of Insect Consumption in the Bearded Saki Monkey, Chiropotes satanas chiropotes." Primates 24 (1983): 602-605.

Norconk, M. A., C. Wertis, and W. G. Kinzey. "Seed Predation by Monkeys and Macaws in Eastern Venezuela: Preliminary Findings." Primates 38 (1997): 177-184.

Rylands, A. B., H. Schneider, A. Langguth, R. A. Mittermeier, C. P. Groves, and E. Rodriguez-Luna. "An Assessment of the Diversity of New World Primates." Neotropical Primates 8 (2000): 61-93.

Setz, E. Z. F., and D. D. Gaspar. "Scent-Marking Behaviour in Free-Ranging Golden-Faced Saki Monkeys, Pithecia pithecia chrysocephala: Sex Differences and Context." Journal of Zoology 241 (1997): 603-611.

van Roosmalen, M. G. M., R. A. Mittermeier, and J. G. Fleagle. "Diet of the Northern Bearded Saki (Chiropotes satanas chiropotes): A Neotropical Seed Predator." American Journal of Primatology 14 (1988): 11-35.

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Organizations

Conservation International. 1919 M Street, NW, Suite 600, Washington, DC 20036 United States. Phone: (202) 912-1000; 1 (800) 406-2306. Web site: <http://www.conservation.org>

Primate Center Library, Wisconsin Primate Research Center. 1200 Capitol Court, Madison, WI 53715-1299 United States. Phone: (608) 263-3512. Fax: (608) 263-4031. E-mail: [email protected] Web site: <http://www.primate.wisc.edu/pin/>

World Wildlife Federation (WWF)—The Conservation Organization. 1250 24th Street NW, Washington, DC 20037-1193 United States. Phone: (202) 293-4800. Fax: (202) 293-9211. Web site: <http://www.panda.org>

Brian W. Grafton, PhD