Emilia’s Marmoset, Mico emiliae
EMILIA’S MARMOSET
Mico emiliae
Geographic Distribution and Habitat
Emilia’s marmosets, also called Snethlage’s marmosets, are endemic to the Brazilian states of Para and Mato Grosso in the Amazon basin, living near river banks, inland forests, and Atlantic coastal forests. Their home territory is about 24 to 98 acres (10 to 40 hectares). They can live near human communities, suggesting that they are adaptable to different environments and habitats. Their home territory size and location are primarily based on proximity to food sources.
The Emilia’s marmoset was taxonomically named in 1920 after the German-born Brazilian ornithologist, Emiliae Snethlage. There are sixteen primates in the genus Mico. The Emilia’s marmoset eluded researchers for decades because of its similar appearance to other marmosets in the area, namely the silvery marmoset (M. argentatus), white marmoset (M. leucippe), gold-and-white marmoset (M. chrysoleucos), and Munduruku marmoset (M. munduruku).
Size, Weight, and Lifespan
The Emilia’s marmoset is a petite primate, weighing in at 10 to 14 ounces (300 to 400 grams). They are 8.5 inches (21.6 cm) in length. Their tails add another 13.5 inches (34.1 cm). Emilia’s marmosets can live to be fifteen to eighteen years old in the wild.
Appearance
Although similar in appearance to other Mico marmosets from a distance, observing the Emilia’s marmoset up close reveals a distinct appearance. Their facial skin is a light pink color and their coat ranges from cream to white to gray. Most distinct in their appearance is their ears, which protrude far from their head and give them the appearance of a mythical creature, hopping around the jungle. Most primates’ fingers and toes have nails; however, the Emilia’s marmoset, like other marmosets, has claws (with the exception of the large toe) to better help them jump and grasp tree branches. As mentioned before, marmosets’ tails are longer than their bodies, but unlike many other South American monkeys it is not prehensile—meaning they use their tails for balance, rather than grasping.
Diet
Marmosets are the sweet-tooths in the primate world. Emilia’s marmosets’ diet consists largely of fruit, nectar, tree gums, and flowers. They are also known to eat insects and small amphibians. They, along with other small monkeys such as tamarins, have a reduced number of molars when compared to other primates, although the exact reason for this development is still being researched. As mentioned earlier, marmosets have retained claws on their fingers, which aid in their ability to extract sap and gum from trees. The marmoset will chew bark from a tree, occasionally using their claws to help gouge the tough exterior and, after a couple of days, they will return to this location and eat the sap that has started to pour out. This behavior highlights their cognitive ability as well since it takes mental-mapping skills to remember where the gouged tree is!
Behavior and Lifestyle
Emilia’s marmosets spend most of their time in trees, rarely descending to the forest floor. Because of their small size, they are much safer when in the canopy. They are diurnal, meaning they are awake during the day and sleep at night. They are territorial and will defend their home ranges by vocalizations, displaying, and aggressive biting. They are, however, considered to be a more timid primate so they generally shy away from physical fights with other members. When they encounter predators they will flee, swiftly jumping from tree to tree to escape.
The word marmoset comes from the French word marmouset, meaning shrimp or dwarf!
Emilia’s marmosets live in relatively small groups of about 4 to 15 individuals. These groups have a hierarchy consisting of a dominant breeding pair at the top, which is a unique social system that is generally only seen in smaller bodied primates. Many other primates hierarchies are established on the basis of sex, while Emilia’s marmoset groups are led on the basis of age and maturity. These two individuals maintain order in their groups; however, they will rarely use violence within their groups.
Males will migrate right before or just after reaching sexual maturity, while females stay in the troop. Because of this, most females within a troop are related and have strong social bonds. In the common marmoset (Callithrix jacchus), a close relative to Emilia’s marmoset, females are known to synchronize the hormone that induces the feeling of trust and attachment—this is thought to aid in the close bonds they form with one another.
Scent is of key importance to Emilia’s marmosets. They use a tactic called scent-marking to communicate many different things to their group and those outside their group. Scent-marking involves rubbing their chest and backside on trees and branches in order to establish their presence in their home range.
Males have dichromatic vision, meaning they can see shades of green-red. Females, like many other Central and South American monkeys, have trichromatic vision—allowing them to see the world as humans do.
Their vocalizations are high pitched and used to communicate in similar ways to other primates, such as warning others of danger, displeasure, and excitement. The calls that sound like high-pitched bird calls generally relate to in-group tensions, while lower pitched calls are to warn others of danger. Danger-calls are often accompanied by swishing of the tail to indicate fear.
Emilia’s marmosets are socially monogamous primates, preferring to be sexually paired with just one individual. As mentioned earlier, the pair that is most senior in age holds dominance in the groups. It is thought that olfactory and visual cues given by the dominant female represses estrus in other females. This is perhaps to avoid mating with close relatives and the occurrence of infanticide.
A female becomes sexually mature at around one year old. When they become pregnant they gestate for close to five months and almost always give birth to twins. Two infants involves a high level of investment from the mothers, as they must eat enough to sustain their young. It is thought that this is why marmosets have a perfectly unique family structure, in which family members take care of the infants almost full time so they mother can eat and feed them. Family members do all the grooming and soothing and holding of the infants so the mother can focus on feeding them. This structure is referred to as alloparental care.
The full extent of the Emilia’s marmoset’s ecological role is still unknown. They feed on gums, saps, and insects—the latter could aid in parasite protection for trees and other plant species. They are predated by large cats and birds of prey. These two roles make them essential in their environment. More research is needed to discover the extent of their role, though.
The International Union for Conservation of Nature lists Emilia’s Marmoset as Least Concern (IUCN, 2015), appearing on the IUCN Red List of Threatened Species. Their current population numbers are unknown.
Emilia’s marmosets’ biggest threat is, as with so many of our other primate relatives, deforestation. Agricultural deforestation is creeping to their northern Mato Grosso and South Para habitats from the south. Habitat fragmentation is also a threat to these tiny primates, with roads obstructing their home ranges and limiting their ability to maintain genetic diversity in their species. More research is needed on the consequences of habitat fragmentation for this species. It is no surprise that, additionally, Emilia’s marmosets are pursued for the pet trade. The appeal of their small size and cute faces are what attract potential pet-owners and results in them being hunted and captured from the forests to be kept in cages.
The Emilia’s marmoset is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.
Luckily, the Emilia’s marmoset occurs in protected areas. There are populations living in Kuruáya Indigenous Land, Serra do Cachimbo Ecological Station, Cristalino State Park, and Sinop Urban Park, and they are also thought to be living in Terra do Meio Ecological Station. More research is needed to understand their ranges and where they are found. The IUCN advises that local education is needed for this species to better help with conservation efforts. They are included in international legislation as well as international management and trade controls.
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Written by Robyn Scott, October 2023