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20 Things You Didn’t Know About Bald Monkeys (Bald Uakari)
What do know about Bald monkeys? Giving the fact that you might have seen these species no doubt, but there are few things you still don’t know about bald monkeys. The bald uakari (Cacajao calvus) or bald-headed uakari is a small New World monkey characterized by a very short tail; bright, crimson face; a bald head; and long coat. The bald uakari is restricted to várzea forests and other wooded habitats near water in the western Amazon of Brazil and Peru. There are four recognized subspecies of the bald uakari, each of which is considered vulnerable to extinction. Just continue reading further cos we’ve prepared for you in this article things you didn’t know about bald monkeys.
The conservation status of this species was changed from near threatened to vulnerable in the 2008 World Conservation Union (IUCN) Red List because the species has declined at least 30% over the past 30 years (three generations) due to hunting and habitat loss. This is considerably better than the 1994 assessment which found it to be endangered, followed by the 2003 assessment which found the species to be near threatened. Although the conservation status has improved, actual population numbers are on a decreasing trend. Since it only lives in white water flooded forests, it is very susceptible to human impact (i.e.: land acquisition for agriculture and/or pastures).
Key Facts You Need to Know About Bald Monkeys
We’ll be detailing you on everything you need to know about bald monkeys below:
- The bald uakari weighs between 2.75 and 3.45 kg (6.1 and 7.6 lb), with head and body lengths average 45.6 cm (18.0 in) (male) and 44.0 cm (17.3 in) (female).
- The bald uakari has a long, shaggy coat ranging from white in color to red and its head is bald.
- The tail of a bald monkey is bob-like and rather short for a New World monkey (about 5.9 inches (15 cm)), at only half the length of the body and head combined.
- Its scarlet red face is due to the lack of skin pigments and plentiful capillaries that run under its facial tissue.
- The bald uakari prefers to reside in seasonally flooded forests in the area of the Amazon River Basin, in the countries of Peru and Brazil.
- The uakari is arboreal (lives in the treetops) because of the flooding of the forests and the water rising to great heights during the rainy season.
- During the dry season, the bald uakari returns to the ground to look for seeds and other food material.
- A study of the diet of the uakari found it to consist of 67% seeds, 18% fruit, 6% flowers, 5% animal prey, and buds.
- The powerful lower jaw forms a pseudodental comb, which allows the uakari to open the hard surfaces of unripe fruits and eat the nuts that most other primates would not be able to open.
- This specie also eats insects that happen to cross its path, however, it does not specifically pursue this type of food.
- The bald uakari can be found traveling up to 4.8 kilometers per day in multi-male/multi-female groups of 5 to 30 individuals, and even up to 100.
- Female uakaries are also philopatric. This means that males leave the natal group.
- The total size of the group’s home range is between 500 and 600 hectares. This requires efficient territorial defense mechanisms. A few of these include specific vocalizations, wagging of the tail, and erection of the hair.
- The bright red facial skin of bald monkeys is a sign of good health and allows for the determination of a healthy mate.
- The breeding season of these species is between October and May.
- The gestation period of the bald uakari is approximately six months.
- Both sexes have a sternal gland, which might be involved in olfactory communication, especially during mating, when the female encourages the male to mate by releasing an attractive scent.
- The bald uakari lives approximately 30 years and has been known to live over 30 years in captivity.
- Due to the uakari’s location, it is extremely common for these animals to contract malaria. Primates who have contracted the disease are noticeably paler and are not chosen as sexual partners as they do not have the desired natural immunity to malaria.
- A skull of male Red uakari (C. c. rubicundus) at Zoology Museum of the University of São Paulo.
Bonus Tip – About the Smallest Monkey (Pygmy Marmoset)
The smallest monkey, otherwise known as the pygmy marmoset is a small species of New World monkey native to rainforests of the western Amazon Basin in South America. The species is notable for being the smallest monkey and one of the smallest primates in the world. It is generally found in evergreen and river edge forests and is a gum-feeding specialist or a gummivore. The pygmy marmoset has been viewed as somewhat different from typical marmosets, most of which are classified in the genera Callithrix and Mico, and thus is accorded its own genus, Cebuella, within the family Callitrichidae.
- About 83% of the population of Pygmy marmoset lives in stable troops of two to nine individuals, including a dominant male, a breeding female, and up to four successive litters of offspring. The modal size of a standard stable troop would be six individuals. Although most groups consist of family members, some may also include one or two additional adult members.
- Members of the group communicate using a complex system including vocal, chemical, and visual signals. Three main calling signals depend on the distance the call needs to travel. These monkeys may also make visual displays when threatened or to show dominance. Chemical signaling using secretions from glands on the chest and genital area allows the female to indicate to the male when she is able to reproduce. The female gives birth to twins twice a year and the parental care is shared between the group.
- The pygmy marmoset is one of the world’s smallest primates, being the smallest true monkey, with a head-body length ranging from 117 to 152 mm (4.6 to 6.0 in) and a tail of 172 to 229 mm (6.8 to 9.0 in). The average adult body weight is just over 100 grams (3.5 oz) with the only sexual dimorphism of females being a little heavier.
- 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 to 0.4 hectares (0.25 to 0.99 acres), and feeding is usually concentrated on one or two trees at a time.
- Young marmosets typically remain in the group for two consecutive birth cycles. The pygmy marmoset uses special types of communication to give alerts and warnings to its family members. These include chemical, vocal, and visual types of communication. It is believed to serve to promote group cohesion and avoidance of other family groups.
- Infant pygmy marmosets, along with their parents, twin, and other siblings, form cooperative care groups. Babbling, or vocalizing, by the infant marmoset is a key part of its relationships with its family members and is a major part of its development. As the infant develops, the babbling gradually changes to resemble and eventually become adult vocalization.
- Infant marmosets require the most attention, so having more family members participating in the care decreases the cost for any individual and also teaches parenting skills to the juvenile marmosets. Members of the group, usually female, may even put off their own reproduction through a temporary cessation of ovulation in order to care for the offspring of others in the group.
- The pygmy marmoset is usually monogamous though there is some variation within the species in terms of breeding systems. Polyandry also occurs as male marmosets are responsible for carrying the infants on their backs. Having a second male to carry the offspring can be beneficial as marmoset litters are often twins and decrease the cost to any particular male.
- Male and female pygmy marmosets show differences in foraging and feeding behavior, although male and female dominance and aggressive behavior varies within the species. Males have less time to search out food sources and forage due to the constraints of their infant caring responsibilities and predator vigilance. Without an infant to carry, female pygmy marmosets have greater freedom to forage, giving them an apparent feeding priority.
- The pygmy marmoset is well known for its communication abilities including an intricate system of calls. The trill is used during feeding, foraging, and when traveling and the group is close together. The J-call is a series of fast notes repeated by the caller and is used at medium distances. The long call is used when the group is spread out over distances greater than ten meters or in response to a neighboring group. The pygmy marmoset uses the trill for short-distance communication, J-calls for intermediate distances, and long calls for long distances; these have respectively decreasing frequencies.
- Environmental factors play a role in communication by affecting the frequency of the signal and how far the signal can travel and still be audible to communicate the desired message. Since the pygmy marmoset is often found in the rain forest, plant life and the humid atmosphere add to the normal absorption and scattering of sound. Because low-frequency calls are affected less by the disturbances than their high-frequency counterparts, they are used for communication across long distances.
- The pygmy marmoset has other ways to communicate information about matters such as the female’s ovulatory state. New World monkeys do not show genital swelling during ovulation as female Old World monkeys do. Instead, a lack of female aggression towards males can serve as a signal of ovulation. Scent glands on its chest, anus, and genitals are also rubbed on surfaces that leave chemical signals about the reproductive state of the female.