Marmosets and Tamarins

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Marmosets and Tamarins

Marmosets and tamarins are South and Central American primates of the Amazon Basin. Their family, Callitrichidae, includes about 40 species that have been described as “near”-monkeys. About 25% are

considered endangered or threatened by the IUCN and other conservation organizations. This plight is mostly caused by deforestation to develop new agricultural land, as well as by disturbance of their forest habitat due to logging, road construction, hunting, and other human activities.

The two groups of small, furry near-monkeys are extremely similar, but the marmosets (mostly in the genus Callithrix ) and the tamarins (genus Saguinus ) are located in different regions, overlapping in only one area near the mouth of the Amazon River.

The lower jaw of marmosets is V-shaped, making their face pointed, while that of tamarins is rounded into a U-shape. Marmosets have elongated lower incisor teeth, which are about the same length as their incisors; for this reason they are sometimes called short-tusked marmosets. The tamarins have canine teeth longer than the incisors, and are called long-tusked marmosets.

Marmosets and tamarins feed on the gum and sap of trees, which they obtain by scraping the bark with their teeth. All other primates that eat gum or sap use holes dug by insects. Marmosets and tamarins also eat fruit, flowers, and insects.

Most marmosets and tamarins have a head-and-body length of 7-12 in (17-30 cm), plus a tail about 3 in (7.5 cm) longer than that. The tail is not prehensile, or capable of grasping. Unlike many other monkeys, marmosets and tamarins do not have an opposable thumb. Their sharp, curved claws allow these lightweight monkeys to hold onto tree branches. Only the great toe bears a nail instead of a claw.

Their face has little or no fur, but there can be large tufts of dense hair coming from the forehead. Most also have tufts of long hair around or from the ears, although the silvery marmoset (Callithrix argentata ) has bare ears.

These small primates are active in the daytime. They sleep in tree holes or tangles of vines during the night. Tamarins and marmosets live in groups of up to 40 individuals, though 12-15 is more usual. They spend a great deal of time grooming each other. Their social groups can create a great amount of noise and commotion.

After a 140-145 day gestation period, a female (usually only one in a group at a time) produces two young (or sometimes one or three). The newborn babies are relatively large in comparison to those of other monkeys, although they are helpless. They ride on the back of a parent (usually the father) until they are about 7 weeks old. They become sexually mature at 12-18 months. The young are allowed to stay around the family even after they have reached sexual maturity, and after a new family is born to the parents. However, they do not produce their own offspring until after they leave the family unit. The young animals help their parents, often relieving the male in carrying his newer offspring. Otherwise, the male turns the young over to the female for short feeding periods every few hours.

Marmosets

There are at least three species of true marmosets in the genus Callithrix. However, some biologists regard several of the subspecies as separate species. The marmoset species do not share habitat with each other. Marmosets have light-colored, almost white genitals, which the males may flash when another enters his territory.

The black-tailed or silvery marmoset (C. argentata ) has naked pink ears, and its face is also hairless.

It is found in two widely separate areas of the Amazon Basin. One is east toward the Atlantic Ocean, and the other is located toward the west, near the foothills of the Andes Mountains.

The common, or white-headed marmoset (C. jacchus ) has a white face and ear tufts that are lighter than its primary coloring of a splotchy gray-and-brown. Its tail has rings. It lives in scattered populations across the eastern bulge of South America. The subspecies differ in the color of their ear tufts.

The tassel-eared marmoset (C. humeralifer ) lives in central Brazil. Its ear tufts are long enough to be called tassels. The western subspecies is mostly whitish, while the eastern is darker, with silvery ear tassels.

Tamarins

Tamarins are found north of the marmosets, thus north of the Amazon River, and primarily west of the Madeira River. They are a little larger than marmosets, averaging about 9 in (23 cm) with a 14 in (36 cm) tail. They exhibit a greater variety of color than the marmosets, occurring in black, brown, and red, and often with a dramatic white crest or moustache. They communicate with high-pitched sounds referred to as “trilling.” Tamarins live primarily on fruit but also eat insects. They are especially fond of grasshoppers, which they obtain by hunting on the forest floor.

The face of some tamarins is naked and in others it is hairy. The facial hair is distinctive of the species. The emperor tamarin (S. imperator ), for example, has a black head with flowing white moustache that apparently reminded someone of the nineteenth century Emperor Franz Joseph of Austria. It lives in parts of Peru, Bolivia, and western Brazil. Unlike most members of this family, the emperor tamarin will share part of its territory with a relative, the saddleback tamarin (S. fuscicollis ). In their shared territory in Peru, the two species apparently gain some reciprocal benefit from their association, probably though communication about food supply. The saddleback tamarin of Colombia has a speckled back, contrasting with its reddish underparts and rump. It has white eyebrows.

The naked-faced tamarins are not truly naked-faced, except for the pied, or bare-faced tamarin (S. bicolor ) of northern Brazil, which has a bare, black face that contrasts dramatically with the white upper half of its body. The lower half is rust-red. This species is critically endangered. Other bare-faced tamarins, such as the cotton-top (S. oedipus ) of Colombia, have fine hair covering the face. It has a startling, long white crown on its black head and a white chest and arms. Cotton-top tamarins live in smaller groups than other tamarins.

The odd ones

In addition to the true tamarins (Saguinus ) and the true marmosets (Callithrix ), four other genera of related animals are classified in the family Callitrichidae. They are the lion tamarins (Leontopithecus ), Goeldi’s monkey (Callimico ), Amazonian marmosets (Mico ), and the pygmy marmoset (Cebuella ). Several of these species are described in more detail below.

The golden lion tamarin (Leontopithecus rosalia ) has long, dark, golden-orange hair. Because the hair on its head appears to be cleanly combed back, this tamarin has also been called the Liszt monkey, after the composer Franz Liszt who wore his thick hair swept back. The golden lion tamarin has considerably longer arms and a shorter gestation period than other tamarins. It has a head-and-body length of about 11 in (27.5 cm) long, plus a tail of 12-15 in (30.5-38 cm).

The golden lion tamarin neared extinction as its low-altitude rainforest in Brazil along the Atlantic Ocean was cut down. Also, it was popular as a pet for many decades. In 1980, the wild population was estimated at fewer than 100 animals. However, the species has been bred in captivity and is being returned to the wild in Poço d’Anta Biological Reserve, which was established to protect this rare species, and in a new protected area, the Uniaão Biological Reserve. The population of this tamarin has now reached 1,000 animals, about half of them in the wild. Unfortunately, there is little room for expansion of the wild population due to habitat fragmentation and deforestation. Most of the details of the biology and habitat needs of marmosets and tamarins have been learned from intense studies of the endangered golden lion tamarin.

There are three other species of lion tamarins—the black-faced lion tamarin L. caissara, the golden-rumped or black lion tamarin (L. chrysopygus ) and the golden-headed or gold-and-black lion tamarin (L. chrysomelas ). Each has an extremely tiny range and is endangered.

The pygmy marmoset (Cebuella pygmaea ) is the smallest New World primate. It is only 5 in (13 cm) in head and body plus an 8 in (20 cm) tail, which is banded in shades of black and tan. Its hands and feet may have an orange hue. It feeds on the sap of trees, which it obtains by gouging the bark with its sharp lower canine teeth. It roams a range of not

much more than an acre, which must supply a comfortable sleeping tree plus several trees suitable for tapping for sap. The father takes care of the young except when they need to be nursed by the mother. The twins ride on his back until they are grown. The pygmy marmoset is relatively adaptable and can survive low-density selective harvesting of trees from its forest habitat.

Goeldi’s monkey or marmoset (Callimico goeldii ) has long, black hair and a full black tail. It lives in open, second-growth forest. It has 36 teeth like the New World monkeys (Cebidae ), instead of 32 like other marmosets and tamarins. It also has a considerably longer gestation period of 150-165 days and gives birth to only one young at a time, instead of twins. The mother cares for the newborn for about two weeks, and then the father takes over. Goeldi’s monkey is rare, and lives only near several small rivers in the Amazon basin. It is protected in Manu´ National Park in Peru.