Schneider’s Marmoset, Mico schneideri
SCHNEIDER'S MARMOSET
Mico schneideri
Geographic Distribution and Habitat
Schneider’s marmoset is endemic to Mato Grosso State in Brazil. This monkeys’ habitat is in the ‘arc of deforestation’ which is a section of land that spans over 193,000 miles (500 km2), and is experiencing the highest rates of deforestation in the Amazon. Their range is limited, as it is bordered by the Juruena River in the west, and the Teles Pires River to the east and to the north where the two rivers meet. This marmoset’s southern range is not well defined, but we do know that they do not live any further south than Lucas do Rio Verde.
This monkey is experiencing profound rates of habitat loss every day. It is estimated that in the past three generations, they have lost approximately 32% to 38% of their habitat, and another 54% or more is expected in the next three generations. This rapid deforestation is largely due to growing agricultural demand, including logging, cattle ranching, and soybean production.
While the Schneider’s marmoset was described in 1995, it was mistaken to be a neighboring species, the Emilia’s marmoset (Mico emiliae), until 2021. The Schneider’s marmoset is considered pseudo-cryptic, which means that it was considered relatively indistinguishable from the Emilia’s marmoset until new morphological and molecular data was gathered. Since this species has only recently been described, there is more research needed to learn about the ways in which it may differ from other Mico species.
The species was named after Horacio Schneider, a Brazilian primatologist and professor.
Size, Weight, and Lifespan
Schneider’s marmosets are sexually monomorphic, meaning that there is not a notable difference in the body size of males and females. They weigh approximately 10 to 14 ounces (200 to 400 grams) and are 8-9 inches (20.32 to 22.86 cm) long. Their tails are longer than their bodies, at 13.5 inches (34.1 cm) in length. Their lifespan is estimated to be fifteen to eighteen years in nature.
Appearance
There is a reason that the Schneider’s marmoset was mistakenly identified as Emilia’s marmoset for so many years. Indeed, these two species share many morphological similarities! They are both light cream or white primarily, however, Schneider’s marmosets have some distinguishing factors. This marmoset has light rust-colored pelage on the forearms, shins, and knees. Their lower back and hind legs are grayish-tan. Their chest and upper backs vary from cream to light gray, and they have a dark gray ‘cap’ on the crown of their head. Their tails show a gentle progression of light gray to dark gray, with that gradient starting at their rear. Their faces are pink, as are the ears that protrude from their petite heads.
Diet
Schneider’s marmosets have an incredibly specialized diet. They consume fruit, nectar, tree gums and saps, flowers, and sometimes insects. Unlike many other primates, marmosets have claws on most of their fingers, instead of nails. This allows them to efficiently extract sap from trees, by gouging a hole in the bark and patiently waiting for the sap to leak out, which sometimes takes up to two days. They help the process along by peeling away layers of the bark with their teeth and hands. This particular method of food-gathering highlights the marmosets’ intelligence since it takes a strong memory and mental mapping skills to remember the location of the gouged tree! While they are experts in extracting exudates such as sap and gum, they do rely heavily on fruit as well when it is in season.
Luckily, they do not have to compete with many other animals in their particular niche. However, their particular diet makes the deforestation rates all the more harrowing, as they are unable to adapt to other foods and are considered inflexible in their diet.
Behavior and Lifestyle
All marmosets, including Schneider’s marmosets, spend the majority of their time in the canopy. Their small size makes them especially vulnerable to predation, and venturing down to the forest floor is particularly risky for them. Male marmosets protect their territory by vocalizing and by ‘displaying’, a term used to describe the behavior that accompanies no-contact aggression, such as branch shaking. It’s been found that male marmosets will also leave behind a specific scent mark on the trees that they gouge, and this is thought to signal dominance to other males within the group. This is an effective communication tool, and marmosets are generally averse to physical altercations with one another, so posturing is their primary mode of settling dominance disputes.
Schneider’s marmosets are diurnal, which means that they are awake during the day and sleep at night.
The word marmoset comes from the French word marmouset, meaning shrimp or dwarf!
Schneider’s marmosets wake with the sun and begin their busy day of foraging and defending their territory. They spend the majority of their day in the canopy, safe from predators lurking on the forest floor. They are largely prey for big cats and birds, so by staying in the trees they avoid the vulnerabilities of being out in the open.
Their daily range is dependent on the time of year, with the late dry season to early wet season being the time when they explore more widely. The season also influences which part of the forest they spend the most time in. In the wet season, flooded areas are abundant with insects and small amphibians. In the dry season and early wet season, they may prioritize fruit trees in their area.
In the evenings, the marmosets will hunker down as a group and may sleep in a variety of locations within their range.
Schneider’s marmosets live in groups of 4 to 15 individuals. While many primates have a dominance hierarchy based on sex, marmosets (and some other small-bodied primates) have a system based on maturity and age. Another way in which these small monkeys differ from larger cousins is that their hierarchy contains a dominant breeding pair, rather than a single individual. Group members look to this pair for security and stability, and the breeding pair maintains order in the group.
Females are the philopatric sex, meaning they stay in the group they were born in their whole lives, while males disperse to find other groups. This dispersal process is essential for maintaining genetic diversity and health in their populations. Because females are the sex that stay, they tend to have strong bonds with group members, since they are often related!
Many primates have the same or similar scent capabilities as humans, which is to say they are not quite as sensitive as many other animals. Schneider’s marmosets, along with other marmosets, have a more sensitive nose than many other monkeys. As mentioned earlier, marmosets use scent marking to convey different messages within their group, and between other groups. Marmosets will rub their chest and rear-end on trees and branches in order to mark their territory.
In addition to scent marking, they communicate through a variety of vocalizations. These high-pitched vocalizations sound like chirps, much like the ones you might expect to hear from birds. They use these calls to communicate a variety of messages, such as fear or excitement. High-pitched calls more often relate to group tensions, while lower-pitched calls warn group members of danger. Calls that warn of danger are often accompanied by quick flicks of the tail, acting as a visual warning as well.
Male marmosets are only able to see in shades of green and red, which is referred to as dichromatic vision. Females, on the other hand, are able to see the full spectrum of colors that humans see, referred to as trichromatic vision.
Schneider’s marmosets’ hierarchy contains a dominant breeding pair. This breeding pair is generally, as the name may suggest, the only couple that produces offspring. It is not fully understood how this happens, though researchers believe that fertility is suppressed through olfactory and visual cues produced by the dominant female. While the mechanism of knowing how is still somewhat of a mystery, the purpose behind this reproduction system is well theorized. Having a single fertile couple prevents the possibility of inbreeding as well as infanticide — which may happen when a male wants to increase his chances of copulating with a female. This couple monopolizing fertility also allows for alloparenting. Alloparenting is when an adult individual who is not the biological mother takes on a parental role.
Females become sexually mature around one year of age. She will gestate for around five months, and give birth to twins. Many larger-bodied primates do not routinely give birth to twins, as it requires a very high maternal investment. The marmosets’ alloparenting comes in handy here, as it allows the twin infants to be cared for by others while the mother focuses on eating and producing milk for the young ones.
While it is unknown the full extent of this marmoset’s ecological role, their consumption of fruit and flowers puts them in the seed disperser category, like many other primates. It is thought that their consumption of insects also acts as an antiparasitic for trees. They are a part of the food web and are predated on by other animals, which contributes to the delicate homeostasis of the forest.
The International Union for Conservation of Nature lists Schneider’s marmoset as Endangered (IUCN, 2022), appearing on the IUCN Red List of Threatened Species.
The arc of deforestation is a profound divet in the Amazon rainforest. This area of deforestation constitutes almost ⅓ of all global deforestation. Schneider’s marmosets, along with 51 other monkey species, are deeply affected by this loss of habitat. Deforestation is caused by cattle ranching, slash-and-burn agriculture, mining, human settlement expansion, and subsistence farming. Unfortunately, there is only one area where Schneider’s marmosets occur that is protected. This leaves the vast majority of their habitat at risk of further destruction and fragmentation.
Additionally, many marmosets are caught and sold for the pet trade. While this is not incredibly common for Schneider’s marmosets on the national or international level, it has been reported on the local level.
The Schneider’s marmoset is currently not listed in an Appendix for 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.
The individual who first cataloged the Schneider’s marmoset as a separate species, Dr. Rodrigo Costa-Araújo, is in the process of creating a conservation project for this monkey. Dr. Costa-Araújo is focused on developing a framework that will benefit and help conserve all Amazonian marmosets, not only Schneider’s marmosets. While this is valuable for education, outreach, and potentially policy enactment, there is much more to be done. More research is needed to establish population size and trends, life history, management plan for the area, long-term monitoring, and the establishment of more protected areas. On a higher level, advocacy and education regarding the arc of deforestation is vital in creating change and preserving the unique, treasured species that inhabit the Amazon.
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Written by Robyn Scott, June 2024