Saguinus graellsi, commonly known as Graell’s tamarin, is native to the upper half of the Amazon between the Napo River and the Pastaza River. It is found in Colombia, Ecuador, and Peru. (de la Torre, et al., 2008; de la Torre, et al., 2008; Macdonald, 1984)
The habitat of S. graellsi includes tropical rain forest, secondary forests that have regrown following a natural disturbance to the rain forest, forest patches within savanna, and along river-edge forests around Amazonian tributaries. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984)
Graell’s tamarins have fine silky pelage and, unlike many other tamarins, are uniformly colored. The head, neck, mantle, and forelimbs are black to blackish brown. The crown is pale brown and the tail is black except for a brownish basal portion. The area surrounding the mouth has short white hairs. Infants are born with very short pelage. Adults weigh 225 to 900 g, and the length of their head and body is 175 to 310 mm. Tail length is 250 to 440 mm. Their prehensile tails are always longer than the combined length of their head and body, and their legs are longer than their arms. Graell’s tamarins have claw-like nails on all digits with the exception of the hallux, which has a flat nail. The hallux is opposable, but the pollex is not. On each side of the upper and lower jaws there are two incisors, one canine, three premolars, and two molars, which gives them a total of 32 teeth. Saguinus graellsi is considered a long-tusked callitrichid because the canines are longer than the incisors. Moderate sexual dimorphism exists within this species, with females larger than males. (Macdonald, 1984; Nowak, 1999)
Saguinus graellsi has a monogamous mating system and only the dominant female and dominant male mate. Fertile ovarian cycles are stifled in the rest of the social group’s females by a combination of the dominant female’s behavioral domination as well as the effects of pheromones exuded by her scent glands. It is also suggested that subordinate females have an active part in determining whether or not they will breed. If a subordinate female does give birth, the dominant female may practice infanticide. Subordinate females may gain breeding experience during this time. Eventually subordinate females form their own groups or join a new social group, then becoming a dominant female and breed. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984; "New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984)
Females do not exhibit external signs of estrus. Males are reported to associate with females more closely during the receptive period of the estrus cycle. Graell’s tamarins are able to give birth twice a year. In one study of Graell's tamarins (De La Torre et al., 2005) 40% of females they observed experienced a second birthing peak. Gestation lasts 130 to 170 days. Peak birthing season occurs in January, and the second peak birthing season is in June. Births occur at night. All Graell’s tamarins have dizygotic twins, which weigh 25 to 50 g at birth – up to 20% of the mother’s weight. With the exception of tarsiers, they are proportionally the heaviest infants among primates. Young begin to explore around 21 days of age, but still ride on their parents’ backs until they are six or seven weeks old. At four weeks infants begin to eat soft, solid foods. At 10 weeks, the young are independent. They reach puberty between 12 and 18 months. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; De La Torre, et al., 2005; Macdonald, 1984)
Fathers assist in birth, receiving and cleaning the newborn. Other adult group members may also help. Born helpless, infants hang on to their mother or father with their hands and feet. Fathers hold the young except during feeding. He gives the infant to the mother every two to three hours and feeding lasts about half an hour. The young feed exclusively on milk for four weeks, then soft foods are introduced and weaning is complete by ten weeks. Help from the male parent is considered a key adaptation in the high reproductive rate of tamarins. Once females become established as the dominant breeding female they have the highest reproductive rate of any other primate. Both parents and all members of the social group help carry infants and give bits of food to young, as well as providing protection and education. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Nowak, 1999)
Graell’s tamarins live in groups of five to ten individuals. Sometimes two or three social groups join together to form large group of ten to twenty, usually staying together for less than a day. They are diurnal, generally leaving their sleeping areas at dawn. Social behavior among the group includes grooming during times of rest. The majority of the time social grooming focuses on the breeding female and does not include the young, who play together during this time by chasing, wrestling, and playful biting. Grooming is initiated when one individual lies down in front of another tamarin with a specific body posture. Mass huddling during resting periods is also common. Aggression between group members is rare. When an aggressive interaction does occur, it is usually in response to limited food resources and consists only of threats and displacements - fighting is extremely rare in the wild. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984; Nowak, 1999)
Groups move between 1,000 and 2,000 m per day. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003)
Graell’s tamarins make a long call audible to humans that travels 150 to 200 m, made up of 2 to 30 notes. The call is different between species, populations, and individuals. Within a group, the construction of the long call may reflect social status. Calls function to keep the social group together and to regulate space between neighboring groups. Graell’s tamarins also have many other calls, including alarm calls when a group member sees a raptorial bird, squawking calls amongst young when seeking food from group members, and harsh atonal calls to communicate aggression. Infants chatter and use calls incorrectly, seeming to learn from group members as they age. Olfaction is another important component of communication. Scent glands are found around the genitals (anogenital or circumgenital glands), lower abdomen (suprapubic glands), and sternum (sternal gland). The glandular secretions, a mixture of fatty acids, esters, proteins, and other organic compounds, communicates information about species, sex, reproductive state, and individual identity. The secretion may be mixed with urine and applied to aspects of the environment (branches, trunks, and lianas) with habitual rubbing motions. Depending on the secretion, it is called anogenital, suprapubic, or sternal scent marking. Adult females scent mark more than adult males. Graell’s tamarins also use physical signals of communication. Arousal is signified by raised hair on the head, ears, shoulders, or whole body. Facial expressions denoting aggression include frowning, opening of the mouth, and shaking of the head. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Nowak, 1999)
All males and one-third of females have dichromatic vision; remaining females have trichromatic vision. While the gene for short wavelength vision is not sex-linked, the genes for medium and long wavelength vision are recessive and located on the X chromosome. It is believed that dichromatic vision enables better detection of camouflaged prey and predators, while trichromatic vision enables better detection of ripe, colorful fruits. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984; Nowak, 1999)
Graell’s tamarins spend 25% to 30% of their active time searching for food. Primarily frugivores, they feed on fruits, flowers, nectar, plant exudates, insects, and small vertebrates. When available, small sweet fruits make up the majority of their diet, especially those from the genera Pourouma, Ficus, Cecropia, Inga, and Miconia. Plant exudates like sap, gums, and resin are also eaten, though unlike short-tusked callitrichids, the long-tusked S. graellsi is unable to gouge trees to stimulate the flow of exudate. They consume exudates available through holes bored by insects or from wind damage. During seasonal fruit shortages, Graell’s tamarins increase their intake of nectar and gum to compensate. Animal prey includes frogs, snails, lizards, and insects - particularly grasshoppers, beetles, and stick insects. They also eat baby birds and probably eggs. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984; Nowak, 1999)
Predators include raptorial birds such as Guianan crested eagles, ornate hawk eagles, and bicolored hawks, snakes such as anacondas, rainbow boas, and jararacas, and tayras. Ocelots may also be predators of tamarins – tamarin hairs have been found in their feces. The response of Saguinus graellsi to predators includes alarm calling, escaping, and hiding. If caught in a tree without anywhere to hide, Graell’s tamarins may drop suddenly to the ground. Once a predator is detected, group members often surround and harass it while emitting specific vocalizations. At least one group member is constantly on guard to prevent surprise attacks by predators and they sleep surrounded by thick foliage to camouflage themselves. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984)
Graell's tamarins play an important role in seed dispersal. They swallow seeds up to 1.5 cm long and pass them through their digestive tract in 1 to 3 hours, depositing them away from parent plant. Their digestive processes don’t harm the seeds. Though they appear to swallow the seeds because it is difficult to separate the fruit pulp from them, it has been suggested that swallowing such large seeds helps dislodge intestinal parasites. (Garber and Kitron, 1997; Macdonald, 1984)
In 2008, the IUCN Red List considered S. graellsi near threatened, stating that the species almost qualifies as threatened and its population is continuing to decline. The severe deforestation of its western Amazon home is considered the cause of this diminishing population. The IUCN estimates that over the next three generations, approximately 18 years, population size will decrease 20% to 25%. Graell’s tamarins were previously considered a subspecies of black-mantled tamarins (Saguinus nigricollis). In 2003, Graell’s black-mantle tamarins (Saguinus nigricollis graellsi) were rated “least concern” on the list. CITES does not list Saguinus graellsi in its appendices (as a separate species or as a subspecies of Saguinus nigricollis) as a trade-restricted species. ("Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)", 2008; "New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003)
Saguinus graellsi was previously recognized as a subspecies of Saguinus nigricollis, S. n. graellsi. ("New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae)", 2003; Macdonald, 1984; Nowak, 1999)
Laura Jadwin (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
helpers provide assistance in raising young that are not their own
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
An animal that eats mainly plants or parts of plants.
(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
chemicals released into air or water that are detected by and responded to by other animals of the same species
"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
2008. "Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)" (On-line). Appendices I, II and III. Accessed April 09, 2009 at http://www.cites.org/eng/app/appendices.shtml.
2003. New World monkeys II: Marmosets, tamarins and Goeldi's monkey (Callitrichidae). Pp. 115-124 in B Grzimek, ed. Grizmek's Animal Life Encyclopedia, Vol. 14, 2nd Edition. New York: Van Nostrand Reinhold Co..
De La Torre, S., F. Campos, T. De Vries. 2005. Home range and birth seasonality of Saguinus nigricollis graellse in Ecuadorian Amazonia. American Journal of Primatology, 37/1: 39-56.
Digby, L., S. Ferrari, W. Salzman. 2007. Callitrichines: the role of competition in cooperatively breeding species. Pp. 85-106 in Primates in Perspective. Oxford: Oxford University Press. Accessed April 20, 2009 at http://www.biology.ucr.edu/people/faculty/Saltzmanpubs/Digby_etal_2006_PIP.pdf.
Garber, P., U. Kitron. 1997. Seed Swallowing in Tamarins: Evidence of a Curative Function or Enhanced Foraging Efficiency?. International Journal of Primatology, 18/4: 523-538.
Macdonald, D. 1984. The Encyclopedia of Mammals. New York, NY: Facts on File.
Nowak, R. 1999. Long-tusked Tamarins. Pp. 120-123 in Walker's Primates of the World. Baltimore, Maryland: The Johns Hopkins University Press.
de la Torre, S., A. Di Fiore, P. Stevenson. 2008. "Saguinus nigricollis ssp. graellsi" (On-line). 2008 IUCN Red List of Threatened Species. Accessed April 09, 2009 at http://www.iucnredlist.org/details/43947.