Animal Diversity Web

Ge­o­graphic Range

Chi­ropotes sa­tanas (brown-bearded saki) is found through­out much of north­ern Ama­zo­nia and the Guianas. There are two rec­og­nized sub­species: C. s. sa­tanas is en­demic to Brazil oc­cu­py­ing a small area around the To­can­tin river near the mouth of the Ama­zon, C. s. chi­ropotes oc­curs more widely north of the Ama­zon river and east of the Negro and Orinoco rivers. The total ge­o­graphic range of C. sa­tanas has been es­ti­mated at 62,911 square kilo­me­ters. (Flan­nery, 2007; Flea­gle, 1999; Lehman, 2004; van Roos­malen, et al., 1981; Veiga and Fer­rari, 2006)

• Biogeographic Regions
• neotropical
  • native

Habi­tat

Chi­ropotes sa­tanas is typ­i­cally found in pri­mary trop­i­cal rain­forests. In Brazil, mem­bers of this species are found in terra firma forests and oc­ca­sion­ally in re­gen­er­at­ing forests. In Suri­name, C. sa­tanas has been seen in rain forests, moun­tain sa­van­nah forests and oc­ca­sion­ally in gallery forests. They rarely de­scend to lower canopy lev­els and the for­est floor. Chi­ropotes sa­tanas in­di­vid­u­als spend 60% of their time in the mid­dle and upper lev­els of the for­est canopy. (Flan­nery, 2007; Lehman, 2004; van Roos­malen, et al., 1981; Veiga and Fer­rari, 2006)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• rainforest

• Other Habitat Features
• riparian

Phys­i­cal De­scrip­tion

Brown-bearded sakis are marked by bul­bous tem­po­ral swellings, long bushy tails, and short body hair un­like the long, shaggy hair of their rel­a­tives in the gen­era Ca­ca­jao and Pithe­cia. Brown-bearded sakis are dis­tin­guished from the closely re­lated Chi­ropotes al­bi­na­sus by their larger black beards and their black noses. The two iden­ti­fied sub­species are pri­mar­ily black ex­cept for the light yel­low­ish-brown to ochra­ceous col­or­ing on the back of C. s. chi­ropotes and the dark brown to black back and shoul­ders of C. s. sa­tanas. In both sub­species, as well as in C. al­bi­na­sus, males have dis­tinc­tive, pink scrota and fe­males have pink vagi­nal lips. Black-bearded sakis are slightly sex­u­ally di­mor­phic with an av­er­age weight of 3 kg in males and 2.6 kg in fe­males. Head and body length ranges from 327 to 480 mm and tail length from 370 to 463 mm. Their hindlimbs are slightly longer than their fore­limbs, re­sult­ing in an in­ter­mem­bral index of 83. They have a small thumb lack­ing true op­pos­abil­ity. The foot tends to de­vi­ate lat­er­ally and the tarsal bones have in­creased mo­bil­ity, a trait as­so­ci­ated with their habit of hindlimb sus­pen­sion while feed­ing. (Flan­nery, 2007; Flea­gle and Mel­drum, 1988; Flea­gle, 1999; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981; Walker, 2005)

The jaws of brown-bearded sakis have spe­cial­ized an­te­rior den­ti­tion for open­ing thick, woody, husked fruits. Adapted for pow­er­ful crush­ing, they have strong jaw mus­cles, low, flat molar teeth, broad ca­nines, a deep ro­bust mandible, and a dense max­illa with­out a max­il­lary sinus. (Flan­nery, 2007; Flea­gle and Mel­drum, 1988; Flea­gle, 1999; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981; Walker, 2005)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  2.6 to 3.2 kg

  5.73 to 7.05 lb

• Range length

  327 to 480 mm

  12.87 to 18.90 in

Re­pro­duc­tion

Lit­tle is cur­rently known about the mat­ing sys­tem of Chi­ropotes sa­tanas in the wild. They live and in­ter­act mainly in multi-male multi-fe­male so­cial groups, monog­a­mous groups have been ob­served rarely. (Flea­gle, 1999; Kay, et al., 1988; Peetz, 2000; van Roos­malen, et al., 1981)

Mat­ing has been ob­served in cap­tiv­ity al­though it was be­tween a fe­male Chi­ropotes al­bi­na­sus and a male Chi­ropotes sa­tanas, pro­duc­ing a hy­brid off­spring. Here it was ob­served that the fe­male’s anogen­i­tal re­gion be­came bright red to in­di­cate sex­ual re­cep­tiv­ity and that she made this vis­i­ble to the male by lying in front of him and lift­ing her to ex­pos­ing the red color. She also made a purring vo­cal­iza­tion sim­i­lar to one made by the male dur­ing mat­ing. (Flea­gle, 1999; Kay, et al., 1988; Peetz, 2000; van Roos­malen, et al., 1981)

• Mating System
• monogamous
• polygynandrous (promiscuous)

There is lit­tle in­for­ma­tion avail­able on the re­pro­duc­tive cy­cles of Chi­ropotes sa­tanas in the wild. Birth seem to occur at the be­gin­ning of the rainy sea­son, in De­cem­ber or Jan­u­ary. This co­in­cides with the be­gin­ning of the fruit­ing sea­son of sev­eral im­por­tant species of Es­chweil­era trees that brown-bearded sakis ex­ploit for food. (Flan­nery, 2007; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981)

All other re­pro­duc­tion in­for­ma­tion for C. sa­tanus is based on ob­ser­va­tions of a hy­brid born to a fe­male Chi­ropotes al­bi­na­sus and a male C. sa­tanas in cap­tiv­ity. These ob­ser­va­tions es­ti­mate a ges­ta­tion pe­riod of four to five months. The hy­brid off­spring was weaned and ca­pa­ble of in­de­pen­dent lo­co­mo­tion by the age of three months. (Flan­nery, 2007; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981)

An in­ter­est­ing trait of C. sa­tanas in­fants is their pre­hen­sile tail. Ob­served in the wild as well as with the cap­tive hy­brid, the tail is pre­hen­sile for about the first two months of life. It is used to cling to the mother. The tail ceases being pre­hen­sile at about 2 months old. (Flan­nery, 2007; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• viviparous

• Breeding interval

  Chiropotes satanas seems to give birth once a year.

• Breeding season

  In Surinam young were born at the beginning of the rainy season. This suggests breeding occurs from July to September.

• Range number of offspring

  1 to 1

• Range gestation period

  4 to 5 months

• Range weaning age

  2 to 3 months

Most of the parental care comes from the mother. The re­ac­tion of a male Chi­ropotes sa­tanas to the cries of his hy­brid in­fant in cap­tiv­ity show a level of con­cern that could trans­late in the wild to pre-wean­ing pro­tec­tion. This can­not be truly known given that the off­spring is a hy­brid and in cap­tiv­ity forced to be in close con­tact. The mother nurses the in­fant and car­ries the in­fant on her until the young are weaned. In­fants show some as­so­ci­a­tion with the mother after wean­ing, at 2 to 3 months of age, often re­treat­ing to her for pro­tec­tion when star­tled. (Flea­gle, 1999; van Roos­malen, et al., 1981)

• Parental Investment
• altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifes­pan/Longevity

There have been lim­ited long term stud­ies on Chi­ropotes sa­tanas, so no avail­able in­for­ma­tion on lifes­pan in this species. Re­lated species have been recorded liv­ing up to 20 years.

Be­hav­ior

Chi­ropotes sa­tanas live in rel­a­tively large multi-male multi-fe­male groups of about 8 to 40 in­di­vid­u­als. Larger groups split into smaller troops of about nine while for­ag­ing. While for­ag­ing the troop moves fast, stop­ping briefly for in­tense feed­ing pe­ri­ods. Troops move so rapidly from one clus­ter of feed­ing trees to the next that oc­ca­sion­ally, sin­gle in­di­vid­u­als get lost from their group for days or weeks. In these cases the lost mon­key often tem­porar­ily joins groups of Ate­les or mixed groups of Cebus apella and Saimiri sci­ureus. Brown-bearded sakis use a va­ri­ety of sleep­ing trees and do not re­turn to the same sleep­ing site each night. Lo­co­mo­tion in C. sa­tanas is char­ac­ter­ized as ar­bo­real quadrupedal­ism with some leap­ing and climb­ing. Climb­ing only ac­counts for 2% of lo­co­mo­tion, leap­ing ac­counts for 18%, and quadrupedal branch walk­ing and run­ning ac­count for the vast ma­jor­ity of lo­co­mo­tion at 80%. Brown-bearded sakis typ­i­cally feed in a prono­grade, quadrupedal po­si­tion but also com­monly use hindlimb sus­pen­sion pos­tures to ex­tend their reach to oth­er­wise in­ac­ces­si­ble fruits. In hindlimb sus­pen­sion brown-bearded sakis typ­i­cally drape their long, non-pre­hen­sile tails over a branch for added sup­port. While rest­ing on hor­i­zon­tal boughs or thick branches adults wave their tails to give sig­nals. When on smaller branches, tail waiv­ing is used for bal­ance. The tail of C. sa­tanas is in­ter­est­ing in that it is pre­hen­sile until about two months of age and then be­comes non-pre­hen­sile. (Flan­nery, 2007; Flea­gle and Mel­drum, 1988; Flea­gle, 1999; Nor­conk, 1994; Peetz, 2000; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981; Veiga and Fer­rari, 2006; Walker, 2005)

An in­ter­est­ing be­hav­ior ob­served in C. sa­tanas is hud­dling. Char­ac­ter­ized by two or more in­di­vid­u­als crowd­ing close to­gether or em­brac­ing on hor­i­zon­tal sup­ports, hud­dling be­hav­ior is a re­sponse to threat­en­ing sit­u­a­tions like pre­da­tion avoid­ance, re­source de­fense, and mate de­fense. Ac­com­pa­nied by alarm, chirp­ing sounds, and tail wag­ging, these hud­dling bouts last an av­er­age of 23 sec­onds. In­ter­est­ingly, the ma­jor­ity of hud­dling is done be­tween two males (62%), while none has been ob­served be­tween two fe­males. Males and fe­males have been ob­served hud­dling to­gether in 38% of ob­ser­va­tions and ju­ve­niles have been in­volved in 16%, usu­ally be­cause of an as­so­ci­a­tion with a fe­male. Adult to adult as well as adult to ju­ve­nile groom­ing has been ob­served in Chi­ropotes sa­tanas. (Flan­nery, 2007; Flea­gle and Mel­drum, 1988; Flea­gle, 1999; Nor­conk, 1994; Peetz, 2000; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981; Veiga and Fer­rari, 2006; Walker, 2005)

• Key Behaviors
• arboreal
• scansorial
• diurnal
• motile
• nomadic
• social

Home Range

Day ranges of Chi­ropotes sa­tanas have been recorded av­er­ag­ing 2500 to 3500 m. Home range has never ac­cu­rately been recorded but es­ti­mates range from 75 to 250 ha. (Flan­nery, 2007; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981)

Com­mu­ni­ca­tion and Per­cep­tion

Black-bearded sakis use vo­cal­iza­tions and body lan­guage to com­mu­ni­cate. As is the case with many ar­bo­real pri­mates, vo­cal­iz­ing is an im­por­tant way to keep track of con­specifics in an en­vi­ron­ment with often lim­ited vi­sion. There have been no ex­ten­sive stud­ies on vo­cal­iza­tions of Chi­ropotes sa­tanas, but some re­peat­edly ob­served vo­cal­iza­tions have been recorded. Weak chirps are as­so­ci­ated with eat­ing and sat­is­fac­tion, and a shrill vo­cal­iza­tion was recorded when a group was eat­ing sea­son­ally abun­dant cater­pil­lars in east­ern Brazil­ian Ama­zo­nia. A high pitch whis­tle, de­scribed as start­ing off as a sharp pen­e­trat­ing whis­tle, last­ing for about a sec­ond and then cut­ting off, serves as a con­tact sig­nal while a more in­tense ver­sion serves as an alarm call. A shrill bird like cry is also made when dis­turbed. Purring vo­cal­iza­tions are emit­ted by the fe­male prior to mat­ing and by the male while mat­ing. The hy­brid off­spring in­fant de­scribed above made sim­i­lar sounds when it wanted to nurse prompt­ing the mother's help in find­ing the nip­ple. The in­fant's vo­cal­iza­tion also pro­voked a sim­i­lar vo­cal­iza­tion from the mother which ap­par­ently ex­cited the male. Loud cries by the in­fant dis­turbed the mother and fa­ther prompt­ing close ex­am­i­na­tion by both par­ents.

Tail wag­ging has been ob­served in a num­ber of con­texts. Con­sid­ered a sign of ex­cite­ment, it may also serve as a dis­place­ment ac­tiv­ity and as a silent con­tact sig­nal. (Flan­nery, 2007; van Roos­malen, et al., 1981; Veiga and Fer­rari, 2006)

• Communication Channels
• visual
• tactile
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Pri­mar­ily a scle­ro­carp fru­gi­vore, Chi­ropotes sa­tanas feeds pri­mar­ily on im­ma­ture seeds par­tic­u­larly cov­ered in hard peri­carp. They have been recorded to eat at least 53 dif­fer­ent species of seeds and are es­pe­cially fond of the Brazil nut fam­ily (Lecythi­daceae). Their spe­cial­ized an­te­rior den­ti­tion al­lows them to open very hard fruit for the young, rel­a­tively soft seeds. By eat­ing young im­ma­ture seeds C. sa­tanas not only gets at a re­source un­avail­able to many other pri­mates, but also may avoid tox­ins that only occur in more ma­ture seeds. The abil­ity to break open hard shells of im­ma­ture seeds and fruit also gives C. sa­tanas an ad­van­tage by al­low­ing them first pick of fruit­ing trees often not leav­ing many to ripen to stages that other species can eat. The open­ing of hard fruits and shells by C. sa­tanas is ac­com­plished by first bit­ing a hole into the fruit at the edge of the op­er­cu­lum, then using it’s procum­bent in­cisors to pop off the op­er­cu­lum to get to the seeds in­side. The pow­er­ful wedge-shaped ca­nines of C. sa­tanas, rather than the in­cisors, are used when open­ing very tough foods with thick, hard seed pods.

The most ef­fi­cient seed preda­tor of any mon­key species, C. sa­tanas> in­di­vid­u­als have been ob­served con­sum­ing 66% of their diet in seeds. They com­pli­ment this diet with ripe fruit, flow­ers, leaf stalks, and arthro­pods. Stud­ies in Brazil, Suri­nam, and Venezuela showed 10 tax­o­nomic or­ders of arthro­pods and 85 dif­fer­ent plant species being ex­ploited. The most com­mon arthro­pods eaten are cater­pil­lars, ter­mites and gall wasps. Arthro­pod con­sump­tion in C. sa­tanas is usu­ally fairly low through­out the year peak­ing one to three times a year dur­ing tem­po­rary spikes in prey avail­abil­ity. When cap­tur­ing prey, C. sa­tanas often ex­hibit dex­ter­ity and agility. For ex­am­ple, in­di­vid­u­als can re­move gall wasp lar­vae from galls 4 mm in di­am­e­ter, and oth­ers rest their arms, allow ants to climb onto them, and then eat the ants off their hair.

Cap­tive in­di­vid­u­als often drink by cup­ping their hands to pick up water then suck the fluid from their hands. Al­though not re­cently recorded in the wild, it can prob­a­bly be as­sumed that this is char­ac­ter­is­tic of the species since the sci­en­tific name Chi­ropotes, coined by Hum­boldt, means “hand-drinker.”

In­ter­est­ingly, geophagy (the in­ges­tion of earth, soil or clay) has been ob­served on two oc­ca­sions by C. sa­tanas. In both in­stances in­di­vid­u­als were seen eat­ing a few hand­fuls of ter­mi­taria with­out any in­spec­tion (as they would do when hunt­ing in­sects) in­di­cat­ing that the in­ges­tion of the ter­mi­taria was the pur­pose. This is thought to be an adap­tive be­hav­ior for a num­ber of rea­sons: min­eral sup­ple­men­ta­tion, ab­sorp­tion of harm­ful tox­ins, and for eas­ing gas­troin­testi­nal dis­or­ders such as di­ar­rhea and ex­cess stom­ach acid­ity.

Brown-bearded sakis spend 130 to 200 min­utes a day feed­ing, not in­clud­ing travel time be­tween food re­sources. While for­ag­ing they split up into smaller feed­ing units of around nine in­di­vid­u­als and move rapidly in a co­he­sive man­ner be­tween groups of feed­ing trees. Once the troop has ar­rived at a new feed­ing area they then split up, stay­ing within a ra­dius of 50 to 75 m, well within range of each oth­ers vo­cal­iza­tions which they keep up con­stantly. The pat­tern of rapidly mov­ing be­tween food trees with pe­ri­ods of rel­a­tively short but in­tense feed­ing bouts ob­served in brown-bearded sakis is to be ex­pected of a spe­cial­ized species con­cen­trat­ing on widely dis­persed, sea­sonal, high pro­tein food sources. (Flan­nery, 2007; Flea­gle and Mel­drum, 1988; Flea­gle, 1999; Nor­conk, 1994; Van Roos­malen, et al., 1988; van Roos­malen, et al., 1981; Veiga and Fer­rari, 2006; Veiga and Fer­rari, 2007)

• Primary Diet
• herbivore
  • granivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

• Plant Foods
• seeds, grains, and nuts
• fruit
• flowers

Pre­da­tion

Brown-bearded sakis avoid pre­da­tion largely through oc­cu­py­ing the high­est lev­els of the for­est canopy and through their large body size. Quadrupedal leap­ing is also a help­ful preda­tor avoid­ance mech­a­nism al­low­ing a speedy and dif­fi­cult to fol­low get­away. Harpy ea­gles, jaguars, and hu­mans are the pri­mary preda­tors of Chi­ropotes sa­tanas. (Flea­gle, 1999; van Roos­malen, et al., 1981; Walker, 2005)

• Known Predators

  • harpy eagles (Harpia harpyja)
  • jaguars (Panthera onca)
  • humans (Homo sapiens)

Ecosys­tem Roles

As fru­gi­vores, brown-bearded sakis play a role in dis­trib­ut­ing seeds of fruit­ing trees. Their role as seed dis­persers, how­ever, is de­creased by the fact that they eat im­ma­ture seeds of un­ripe fruits. Their abil­ity to get at im­ma­ture seeds in un­ripe fruits also ef­fects sym­patric fru­giv­o­rous species like Ate­les panis­cus and Cebus apella who eat some of the same fruits, but only when ripe. Brown-bearded sakis often live sym­patri­cally with sev­eral other Platyrrhini species such as Alouatta senicu­lus, Saimiri sci­ureus, Sagui­nus midas, and Pithe­cia pithe­cia. (Flea­gle and Mel­drum, 1988; Flea­gle, 1999; Van Roos­malen, et al., 1988)

• Ecosystem Impact
• disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Some groups of hu­mans ben­e­fit from Chi­ropotes sa­tanas by hunt­ing them for meat and body parts. Hu­mans also may ben­e­fit eco­nom­i­cally from keep­ing some black-bearded sakis in zoos. (van Roos­malen, et al., 1981)

• Positive Impacts
• food
• body parts are source of valuable material
• ecotourism

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of Chi­ropotes sa­tanas on hu­mans.

Con­ser­va­tion Sta­tus

Chi­ropotes sa­tanas is con­sid­ered en­dan­gered be­cause of human in­duced habit degra­da­tion and hunt­ing. The United States En­dan­gered Species Act list lists C. sa­tanas as en­dan­gered. The CITES ap­pen­dices has both sub­species under Ap­pen­dix II since 1977. The for­ma­tion of pro­tected areas may be im­prov­ing the prospects for pop­u­la­tions of Chi­ropotes sa­tanas chi­ropotes.

• IUCN Red List

  Critically Endangered
  More information

• IUCN Red List

  Critically Endangered
  More information

• US Federal List

  Endangered

• CITES

  Appendix II

• State of Michigan List

  No special status

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Adam Berne (au­thor), Uni­ver­sity of Ore­gon, Stephen Frost (ed­i­tor, in­struc­tor), Uni­ver­sity of Ore­gon.

Ref­er­ences

Flan­nery, S. 2007. "Black-bearded Saki (Chi­ropotes sa­tanas)" (On-line). The Pri­mata. Ac­cessed No­vem­ber 05, 2007 at http://​www.​theprimata.​com/​chiropotes_​satanas.​html.

Flea­gle, J. 1999. Pri­mate Adap­ta­tion and Evo­lu­tion. San Diego, Cal­i­for­nia: Aca­d­e­mic Press.

Flea­gle, J., D. Mel­drum. 1988. Lo­co­mo­tor be­hav­ior and skele­tal mor­phol­ogy of two sym­patric pitheci­ine mon­keys, Pithe­cia pithe­cia and Chi­ropotes sa­tanas. Amer­i­can Jour­nal of Pri­ma­tol­ogy, Vol­ume 16/Issue 3: 227-249.

Kay, R., J. Plav­can, K. Glan­der, P. Wright. 1988. Sex­ual Se­lec­tion and Ca­nine Di­mor­phism in New World Mon­keys. Amer­i­can Jour­nal of Phys­i­cal An­thro­pol­ogy, Vol­ume 77/Issue 3: 385-397.

Lehman, S. 2004. Bio­geog­ra­phy of the Pri­mates of Guyana: Ef­fects of Habi­tat Use and Diet on Ge­o­graphic Dis­tri­b­u­tion. In­ter­na­tional Jour­nal of Pri­ma­tol­ogy, Vol­ume 25/Num­ber 6: 1225-1242. Ac­cessed No­vem­ber 20, 2007 at http://​0-www.​metapress.​com.​janus.​uoregon.​edu/​content/​r2913wp6t5113741/?​p=6341f5c3a98646db9a3126660c6f0752&​pi=2.

Nor­conk, M. 1994. Chal­lenge of Neotrop­i­cal Fru­givory: Travel Pat­terns of Spi­der Mon­keys and Bearded Sakis. Amer­i­can Jour­nal of Pri­ma­tol­ogy, Vol­ume 34/Issue 2: 171-183.

Peetz, A. 2000. Hud­dling Be­hav­ior in bearded saki mon­keys (Chi­ropotes sa­tanas chi­ropotes) of Bo­li­vare State, Venezuala. Amer­i­can Jour­nal of Phys­i­cal An­thro­pol­ogy, Sup­ple­ment 30 to the An­nual Meet­ing Issue: 98.

Van Roos­malen, M., R. Mit­ter­meier, J. Flea­gle. 1988. Diet of the north­ern bearded saki (Chi­ropotes sa­tanas chi­ropotes): A neotrop­i­cal seed preda­tor. Amer­i­can Jour­nal of Pri­ma­tol­ogy, Vol. 14/Issue 1: 11-35.

Veiga, L., S. Fer­rari. 2007. Geophagy at ter­mi­taria by bearded sakis (Chi­ropotes sa­tanas) in South­east­ern Brazil­ian Ama­zo­nia. Amer­i­can Jour­nal of Pri­ma­tol­ogy, Vol­ume 69, Issue 7: 816-820. Ac­cessed Oc­to­ber 11, 2007 at http://​www3.​interscience.​wiley.​com/​cgi-bin/​abstract/​114096078/​ABSTRACT.

Veiga, L., S. Fer­rari. 2006. Pre­da­tion of arthro­pods by south­ern bearded sakis (Chi­ropotes sa­tanas) in East­ern Brazil­ian Ama­zo­nia.. Amer­i­can Jour­nal of Pri­ma­tol­ogy, Vol. 68/Issue 2: 346-351. Ac­cessed Oc­to­ber 14, 2007 at http://​www3.​interscience.​wiley.​com/​cgi-bin/​fulltext/​112279241/​PDFSTART.

Walker, S. 2005. Leap­ing be­hav­ior of Pithe­cia pithe­cia and Chi­ropotes sa­tanas in east­ern Venezuela. Amer­i­can Jour­nal of Pri­ma­tol­ogy, Vol. 66/Issue 4: 369-387. Ac­cessed Oc­to­ber 12, 2007 at http://​www3.​interscience.​wiley.​com/​cgi-bin/​fulltext/​111079865/​PDFSTART.

van Roos­malen, M., R. Mit­ter­meier, K. Mil­ton. 1981. Ecol­ogy and Be­hav­ior of Neotrop­i­cal Pri­mates Vol. 1. Rio de Janeiro: Acad­e­mia Brasileira de Cien­cias.