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Sunday, September 13, 2009

Common Marmoset or the Brazilian Monkey: a least concerned animal

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A common marmoset or Brazilian monkey(Callithrix jacchus) is an arboreal small and omnivorous animal which is mainly found in the tropical forests of Eastern Brazil. Taxonomically, it is the first order mammal belonging to family Cebidae or Callithricidae of the sub-class Eutheria and class Mammalia.

Marmoset is an old French word which means a “grotesque figure”. This animal was first seen in the wild in 1929 in Rio de Janeiro and was considered an invasive species as it predates upon bird-nestlings and their eggs. It is differently called in different languages like – Ouistit in French, Penseelaapje in Dutch, Sagul-comum or Sagui-de-nordest in Portuguese, and Silkesmarmosett in Swedish.

A common marmoset on the branch of a tree

Being small in size, as big as a squirrel, cleaver and active most of the time, these animals are hard to be recognized in the wild. These are kept in captivity in many countries for exhibition, observation and research purposes. Deserving for themselves the status of least concerned animals, and being endemic to Brazil, these are still neglected and no specific attempt for their conservation is done so far anywhere in the world in proper direction. However, these animals have been treated as specific materials for research and a lot of papers have been published relating to their behavior, mating, reproduction, adaptations etc.

A common marmoset ranges in size from a pigmy marmoset (about 20 cm), tamarins (of the size of a house rat), to golden lion marmoset (a little bigger).

A big network of smugglers of these animals across the world came to be suspected after the theft of eight Brazilian marmosets from the captivity in Alipore Zoological garden Kolkata, the capital city of Bengal state of India(go to http://www.ecosensorium.org/2009/09/theft-of-brazilian-monkeys-from-alipore.html).

Morphological features
A common marmoset is a small animal measuring on an average up to 188 mm. Both the male and female are more or less similar in size. The average weight of a male marmoset 256g is slightly higher than that of a female about 236g. The animal appears brown, grey or yellowish in colour with white ear tufts, long tail with coloured bands, and a blaze on the forehead. A common marmoset with white tufts of hair around the ears is called as Cotton Eared Marmoset.

A Brazilian monkey or Callithrix jacchus

1. Marmosets have claw like nails called tegulae that help them in squirrel like pattern of locomotion like clinging to trees vertically, running and leaping across branches etc. by the help of all the four legs.

2. Marmosets have large chisel shaped incisors and specialized caecum. The chisel shaped incisors help them in feeding on plant exudates like gum, sap, latex, and resins. They gnaw the bark of plants with lower incisors and stimulate the flow of edible exudates while clinging vertically by the help of their claw like nails. Most of the marmosets spend from 20 to 70 percent of their time in exudativory. However, they eat fruits and go for exudativory only when fruits and or other food items are not available. This feeding habit enables marmosets to live even in very high population densities.

3. Marmosets sleep in groups. They adopt sprawling positions while sleeping. They sleep in some dense areas so that no predator can identify them. Mustelids, felids, arboreal snakes, owls, raptors, etc. are common predators of marmosets. However, these animals remain most vigilant and have specialized alarm calls when in danger.

The habitat of marmosets ranges from the edge of forest to the deep forests and even fields and scrubs. These animals are excellent jumpers. The site of their home range varies from 0.005 to 0.065 km2, selected by them on the basis of diversities of gum trees. These animals do not travel great distances during day time and go to sleep about one hour before dark. Most of the time in a day, they remain active leaping from one branch to the other in the middle story of trees.

The Pigmy marmosets

Behavior, reproduction and life expectancy
Common marmosets live together in groups of ten to fifteen with a strict ranking ordered by the dominance and aggressive behavior of the group leader. These are monogamous, polygamous to polyandrous. Adults take care of the young. The gestation period ranges from 140 -150 days. The female gives birth to un- identical twins. Males usually mate after about one year while females become sexually mature within a period of 20 to 24 months. A common marmoset can survive up to 10 years in the wild. However, in captivity it is reported to survive up to 16 years.

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