Pgymy Marmoset
They are one of the world's smallest primates, being the smallest true monkey, with a head-body length ranging from 117-152 mm and a tail of 172-229 mm. The average adult body weight is just over 100 grams with the only sexual dimorphism of females being a little heavier. The fur colour is a mixture of brownish-gold, grey, and black on its back and head and yellow, orange, and tawny on its underparts. Its tail has black rings and its face has flecks of white on its cheeks and a white vertical line between its eyes.
It has many adaptations for arboreal living including the ability to rotate its head 180 degrees and sharp claw-like nails used to cling to branches and trees. Its dental morphology is adapted to feeding on gum, with specialised incisors that are used to gouge trees and stimulate sap flow. Its cecum is larger than usual to allow for the greater period of time gum takes to break down in the stomach. The pygmy marmoset walks on all four limbs and can leap up to 5 m between branches. There are two species of pygmy marmoset; Western Pygmy Marmoset and the Eastern Pygmy Marmoset. There are few morphological differences between these species, as they may only differ slightly in colour, and they are only separated by geographical barriers, including large rivers in Central and South America.
Habitat
Pygmy marmosets are endemic to South America, where they occur in the western part of Amazon Basin. These animals exhibit two well-defined sub-species: Western pygmy marmosets, occupying the state of Amazonas in Brazil (more precisely, the territory north of the Rio Solimões), eastern Peru (south to the Río Maranõn), southern Colombia, northern Bolivia and north-eastern parts of Ecuador; and Eastern pygmy marmosets occur from the state of Amazonas (Brazil) to eastern Peru and southwards to northern Bolivia as well as south of the Rio Solimões and Río Maranõn. Preferred type of habitat is lowland, tropical evergreen forest with river floodplains. Overall, these monkeys favour forests that remain flooded for over 3 months per year.
Diet
This monkey has a specialized diet of tree gum. It gnaws holes in the bark of appropriate trees and vines with its specialized dentition to elicit the production of gum. When the sap puddles up in the hole, it laps it up with its tongue. It also lies in wait for insects, especially butterflies, which are attracted to the sap holes. It supplements its diet with nectar and fruit. A group's home range is 0.1-0.4 hectares, and feeding is usually concentrated on one or two trees at a time. When those become depleted, a group moves to a new home range. Pygmy marmosets have adapted insect-like claws, known as tegulae, to engage in a high degree of claw-clinging behaviours associated with plant exudate exploitation. Exudate is any material that oozes out of a plant, including gum, sap, resin, and latex. Claw-clinging is primarily used during feeding, but also during plant exudate foraging.
Breeding
These primates mainly exhibit a monogamous mating system, where individuals of both genders have only one mate. The dominant male usually restricts access of other males to the breeding females of its group. However, Pygmy marmosets are also known to display polyandrous breeding, where single females mates with multiple males. This typically takes place in troops, containing several males. These animals don't have a specific breeding season and instead breed at any time of the year. The dominant female of a troop yields young at intervals of 5 - 6 months. Group members display a cooperative system of infant care, mating during the female’s postpartum estrus, about 3 weeks upon giving birth. The gestation period lasts for 4.5 months, producing 1 - 3 infants with an average of 2. The babies are mainly cared for by their father, who carries them on its back, while the mother is only responsible for cleaning as well as feeding her offspring during the nursing period, which lasts for 3 months. The age of reproductive maturity is 1 - 1.5 years old.
Population
The Eastern Pygmy Marmoset is classed as Least Concern(LC) on the IUCN Red List and their population trend is classed as stable. The number of mature individuals is unknown.
The Western Pygmy Marmoset is classed as Least Concern(LC) on the IUCN Red List and their population trend is classed as decreasing. The number of mature individuals is unknown.
Threats
Although the Pygmy marmosets presently face habitat destruction, this factor doesn't have a noticeable impact on their population as a whole. However, these animals are still threatened by some localized factors. For example, the population in Putumayo (Colombia) currently suffers from the pet trade. On the other hand, those in touristy areas occasionally display unusual behaviour, which is believed to negatively affect their breeding capabilities.
Conservation
There are many protected areas in Brazil, Bolivia, Columbia, Ecuador, and Peru where pygmy marmosets live. For example, in Bolivia, there is the Manuripi Health Nature Reserve, which protects pygmy marmosets from being hunted or captured and prevents their habitat from being destroyed. In Ecuador, Stella de la Torre and Pablo Yépez developed classes to educate children who live near pygmy marmosets' habitat about the importance of protecting and respecting these tiny primates.