Tamarins are among the smallest of the primates. Head body length of this species is 6 in.; Tail length is 10 in. Weight is 1 pound. The cotton-top is strikingly marked with the long back fur dark brown, the fur on the underside pure white and the face black with a collar of rufous fur. The common name comes from the white crest which runs laterally across the head from ear to ear. Forelimbs are shorter than the hind limbs. The thumb is not opposable and the tail is not prehensile. All the digits bear pointed, sickle-shaped nails except for the great toe which has a flat nail. Saguinus are considered long-tusked tamarins since the lower canines are longer than the incisors. Voice has a variety of high-pitched trilling and staccato calls. They have loud territorial songs as well as songs when they are excited. A "threat face" consists of lowering the forehead until it forms a bulge which almost covers the eyes; the lips are pushed forward and the head and neck crests are erected. This apparently is sufficient since no other body language is used.
GEOGRAPHICAL RANGE AND HABITAT:
Tropical forests, open woodlands, and secondary growth of northwestern Colombia.
Omnivorous. Primary components are insects, fruits, plant exudates (such as sap and gums) and nectar. Other foods include some tender vegetation, spiders, small vertebrates, and birds' eggs. Mice, frogs, birds and such are skillfully killed by a quick head bite, a learned behavior.
LIFE CYCLE/SOCIAL STRUCTURE:
Tamarins are diurnal and arboreal, sheltering at night in tree cavities or forks. They live in small groups the average 3-9 individuals in a defended territory. A group may consist of a dominant mated pair and their young of both sexes. These subordinates sometimes form small groups of their own within the home range of the main groups. They enter and leave the main groups and possibly sometimes remain and rise to breeding position. Females give birth to two babies, rarely three. Gestation is 140 days and birth takes place between January and June. The father and sometimes other adults assist in birth and carry the offspring, transferring it back to the mother at feeding time. The mother needs help, since this small animal gives birth to twins weighing about 25% of her body weight. At 4 weeks the young will accept soft food in addition to milk. Sexual maturity is attained at 18 months. Life span in captivity has been as high as 25 years.
Claw-like nails help them grip branches better, since their small size and non-opposable fingers make encircling difficult. Long limbs and the extremely long tail make them excellent jumpers. They move from tree to tree by running quadrupedally along horizontal branches and leaping as much as three meters to a branch in an adjacent tree.
Researchers say their repertory of 38 distinct sounds is unusually sophisticated, conforming to grammatical rules and able to express curiosity, fear, dismay, playfulness, warnings, joy and calls to young. Research also shows cotton-tops to be cooperative and pacifist to a surprising degree. Adults share food with the young in their group, even those that are not related to them. They carry each other's children around and protect them from danger. Adults forgo their own fertility for long stretches of time while they practice being good parents by rearing offspring of other monkeys. The breeding female does not keep other females docile through intimidation and constant stress, but instead the helping females are unstressed and seem to be choosing not to ovulate until their turn comes. Cotton-top tamarins are territorial, though males and females react to intruders differently. Males are more tolerant of female intruders and are more aggressive toward male intruders, while females are somewhat intolerant of intruders of both sexes and display threateningly. When neighboring groups of cotton-top tamarins encounter each other, there is not usually physical contact between members of the different groups though there may be threat displays.
The Cotton-top Tamarins can be found in the Tropical Rainforest.
STATUS IN WILD:
The USDI lists S. oedipus as endangered and they are also on appendix 1 of CITES. The IUCN lists them as Critically Endangered and notes that the population is less than 2500 individuals and is continuing to decline. Clearing of forest habitat by people is the main problem and populations also were depleted by taking them for the pet trade and for scientific research. The cotton-top is the only species, apart from humans, that spontaneously develops colon cancer. As a result, research laboratories in the U.S. imported thousands in the past (20, 000 to 30,000 in the 1960's and 1970's). Sources other than the IUCN say there are less than 2000 in the wild, 1150 remaining in medical laboratories and 700 in zoos or private institutions.