status: Endangered, IUCN Endangered, ESA
Description and biology
The white-eared marmoset, also known as the buffy-tufted ear marmoset, is a small monkey, about 7 to 9 inches (18 to 23 centimeters) long and weighing only about 9 to 11 ounces (257 to 314 grams). The white-eared marmoset is a member of the Callitrichidae family, which includes 26 species of marmosets and tamarins from the tropical forests of Central and South America. They are some of the world's smallest primates. The white-eared marmoset is black with white spots on the forehead and tail and very long white hair coming out of its ears. The species is diurnal (active during the daytime) and arboreal (lives in the trees). Its diet consists of fruit and insects, such as ants, termites, and caterpillars, and some small animals. It may also eat tree gum when other foods are not available. It has claws instead of nails on its fingers
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and toes for climbing in trees. It moves about on all four limbs when on the ground. The white-eared marmoset can also leap through the forest.
The white-eared marmoset is a social animal. It usually lives in a small group consisting of two to thirteen members. Each group has its own territory, which may be 1 to 13 acres in diameter. The group sleeps together in the branches of a tree or in dense vegetation (plant life) on the ground. The white-eared marmoset is monogamous—males and females remain partners for life. Living groups are centered around one dominant monogamous couple; other members tend to come and go over the course of time. Only the dominant female in the group breeds. She will give birth to one to four offspring—but usually twins—after a gestation (pregnancy) period of 140 to 148 days. The young are then raised cooperatively by the members of the living group. Males as well as females care for the young in this family arrangement. Marmosets' life spans are about 11 to 17 years.
The white-eared marmoset has several means of communication. It makes high-pitched trills to signal alarm. It opens and closes its mouth, making a lip-smacking sound, to initiate sexual behavior or to convey aggression. Sometimes it puts its tongue in and out of its mouth rhythmically along with the lip smacking. When threatened, it will raise its eyebrows. Scent is also used by a female to mark a male before mating takes place.
Habitat and current distribution
The white-eared marmoset occurs in coastal mountain rain forest regions, above 3,000 feet in altitude, along the Atlantic coastline of southeastern Brazil. The area includes parts of Minas Gerais, Rio de Janeiro, and Sao Paulo. Marmosets in the wild are difficult for humans to observe, and their current population numbers are not known.
History and conservation measures
The largest threat to the white-eared marmoset is the deforestation (cutting down of trees) in the Brazilian rain forests and tropical forests. Brazil's Atlantic rain forest region has long been home to hundreds of thousands of species. It is a huge area of more than a half million square miles. In the last five centuries, however, the area has been overwhelmed by an overflowing human population. Into the 1970s, the Brazilian government promoted clearing the forests to harvest the lumber and to make way for sugar, coffee, and cocoa plantations, cattle grazing, and industry. Nearly 93 percent of the natural forests and wilderness have been lost. White-eared marmosets live, therefore, in small, fragmented areas. They are at risk from human capture as well, as they are prized as pets in Europe and elsewhere, and they are used for testing in medical and scientific laboratories. During the 1990s, with severely declining populations, it appeared that the white-eared marmoset would be extinct within 20 years. Breeding-in-captivity programs were thought to be the greatest hope for the preservation of the species.
DID YOU KNOW?
The Atlantic rain forest in Brazil has an average rainfall of 78 inches (2,000 millimeters) per year. Before being cleared, it teems with life and has an extraordinarily high level of biodiversity (variety of life forms). The luxuriant growth is due to tiny micro-organisms, or fungi, from which the plant-life gets its nutrients.
When farmers clear the rain forest to make room for coffee plantations, there is rich growth there. But after the land has been cleared, the fungi that feeds the vegetation dies, and the soil is too poor to keep up the coffee harvests for long. The farmers then have to clear more land to grow coffee. This cycle gets particularly bad in poor economic times, such as the 1980s and the early 2000s. Although the Brazilian government prohibited clearing of rain forests in 1988, the rate of cutting has actually accelerated. From 1990 to 1995 1,235,000 acres (500,000 hectares) were cleared in the Atlantic rain forest.
Since the 1980s, the Brazilian government changed its policies. Concerned citizen groups have made a tremendous difference in conservation efforts. Marmosets are now protected by the government, and cutting down the rain forests has been prohibited. To assure enforcement of these new laws, one nongovernmental organization, SOS Atlantic Forest, launched a satellite survey of the rain forests, to reveal and record illegal forest clearing. Another Brazilian group, the Pro-Bocainan Association, has championed restoring the management of Bocaina National Park, which had been only been protected by unenforced laws and had for years been subjected to great exploitation. Bocaina has 275,000 acres (111,336 hectares) of coastal mountain rain forest and is part of the largest remaining stretch of the marmoset's original habitat. With many organizations and private citizens working on behalf of the tiny primates, there was reason to hope that the marmoset populations were on the road to recovery in the early 2000s.