The mating system of sloths indicates that males compete with one another for access to females, suggesting that female sloths choose larger and more powerful males with which to mate. Mane size and darkness of male sloths may reflect health and vitality. Males may mate with multiple females. Maned three-toed sloths have been observed copulating while locked in a tight embrace high in the canopy of the forest.
Mating System: polygynous
Maned three-toed sloths are seasonal breeders, with breeding occurring between September and November, near the end of the dry season and the beginning of the wet season. Reproduction may occur at this time of year so that gestation and lactation can occur when temperatures are more favorable and food items are more abundant. Maned three-toed sloths give birth during the first 6 months of the year, between the months of February and April, during the final 2 months of the rainy season and initial month of the dry season. Females produce a single young after a gestation period of approximately 6 months. Young B. torquatus weigh approximately 300 grams at birth and cling to the mother for the first 6 to 9 months of life. Within two weeks of birth, infant maned sloths begin to ingest leaves. Lactation bears a high cost to the mother of newborns and the early development of folivory in infants may be an adaptation to lessen the cost of lactation. Although leaves are a portion of their diet, newborns suckle until they reach 4 months of age. Infants will remain with the mother for 8 to 11 months. Maned three-toed sloths achieve adult size (>60 centimeters) within 1 to 3 years of birth. Females can become sexually active after reaching adult size, and when the vaginal opening is apparent. For males, once the penis is well-developed at 1.5 centimeters or larger, they are considered sexually mature.
Breeding interval: Three-toed sloths bradypus torquatas are seasonal breeders, giving birth once yearly.
Breeding season: Maned three-toed sloths breed between September and November, near the end of the dry season and the beginning of the wet season.
Range number of offspring: 1 (high) .
Average number of offspring: 1.
Average gestation period: 6 months.
Range weaning age: 4 (high) months.
Range time to independence: 8 to 11 months.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average number of offspring: 1.
Maned three-toed sloth young are precocial and begin consuming leaves just two weeks after their birth. Knowledge regarding preferred leaves to eat is passed from mother to young. This is critical as they must be able to efficiently recognize food. Weaning occurs after 4 months but juveniles typically stay with their mother for 8 to 11 months, being carried while the mother eats and travels. After this time juvenile disperse from their mother's home range and are considered sub-adults, not yet sexually mature. There is no evidence of male parental investment.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female); extended period of juvenile learning
Maned three-toed sloths occasionally produce long, high pitched "eee" calls, as has been documented in other sloths. Sloths do not call regularly and cannot be detected by their vocalizations in a methodical way. Adults and infants will call when under duress, when captured, or when handled. Mating calls of any kind have only been observed once over thousands of hours of observation. Maned three-toed sloths have poor vision, but little is known about other modes of perception or communication in these sloths.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
According to the International Conservation Union (IUCN), maned three-toed sloths are listed as endangered due to deforestation. Their occurrence in the highly threatened Brazilian Atlantic forest makes them especially vulnerable to habitat changes and isolation.
US Federal List: endangered
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: endangered
There are no adverse effects of maned three-toed sloths on humans.
Maned three-toed sloths are important, endemic members of Brazilian Atlantic forest ecosystems.
Maned three-toed sloths are prey for avian predators, such as harpy eagles (Harpia harpyja) and rainforest cats (Puma yagouaroundi and Leopardus pardalis). They may impact the growth of trees through their folivory.
Maned three-toed sloths are most numerous in dense forests that contain secondary-growth trees and an abundance of young leaves. They are strictly arboreal folivores with a highly selective diet: 99% leaves and 1% soft twigs and buds. Maned three-toed sloths prefer leaves from Mandevilla, Micropholis venulosa, and Ficus trees. They eat fewer liana leaves than tree leaves, as they prefer to stay camouflaged in the canopy. Remaining in dense foliage allows them to avoid predation by harpy eagles (Harpia harpyja) as well. Maned three-toed sloths digest leaves by bacterial fermentation in a complex stomach consisting of multiple chambers. A preference for young leaves is related to their easy digestion, as mature leaves contain structural carbohydrates that are difficult to digest. They spend twice as much time feeding during the dry season than the wet season. This is attributed to an increase in the demand for food and energy during the dry season.
Plant Foods: leaves; wood, bark, or stems
Primary Diet: herbivore (Folivore )
Bradypus torquatus occurs in patches of the coastal Brazilian Atlantic rain forest within the states of Bahia, Espirito Santo, and Rio de Janeiro.
Biogeographic Regions: neotropical (Native )
Maned three-toed sloths are found at altitudes as high as 1000 meters. The highest concentration of individuals is found in Espirito Santo, Brazil. Habitats in this state are mostly secondary and are classified as dense ombrophilous. In this region, maned three-toed sloth populations are between 100 and 200 individuals. The topography of Espirito Santo is hilly with average altitudes ranging from 600 to 800 meters. Given a lack of published data regarding the climate of Espirito Santo state, scientists have used nearby Santa Lucia, which is 18 kilometers from Espirito Santo state and boasts similar topography, altitude, and canopy cover. Santa Lucia receives heavy rainfall, with an annual average precipitation of 1868 millimeters, and an annual average temperature of 19.9 degrees Celsius. Santa Lucia has a wet and hot season between October and March with a drier and cooler season between April and September.
Range elevation: 0 to 1000 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Other Habitat Features: riparian
There is very little information regarding the longevity of wild maned three-toed sloths. They do not survive well in captivity, but wild lifespans are estimated at 20 years or more. An individual Choloepus didactylus (Linnaeus's two-toed sloth) was still alive after 28 years in captivity and a captive Choloepus hoffmanni lived for 32 years. However, Choloepus species consume a wider array of food than Bradypus species.
Status: wild: 20 (high) years.
Species in the genus Bradypus all have fur with a greenish tint, which is due to the growth of algae on the hairs. The fur grows from the hind legs towards the head. This unique growth pattern helps to accommodate their upside-down lifestyle, shedding water from the fur, as sloths are strict arboreal mammals who spend the vast majority of their time in a suspensory position. From the nape of the neck to the shoulder region, maned three-toed sloths have fur that is approximately 15 centimeters in length and projects as shaggy plumes, giving them a maned appearance. Bradypus torquatus males possess an emblematic black mane around the dorsal region of the neck, this black mane is absent in females and infants. The black mane might be a visual signal that helps females recognize males.
Maned three-toed sloths are brown on the face and chin and the head can rotate beyond 90 degrees. They have long limbs that range in size from 100 to 115 millimeters in length. From the tip of the nose to the inflection point of the tail, individuals measure 450 to 500 millimeters. They have short, stubby tails that ranges in size from 48 to 50 millimeters. Maned three-toed sloths are the largest of three-toed sloth species, from 3.6 to 4.2 kg. Females tend to be larger and heavier than males. However, it is difficult to distinguish sexes externally, the only reliable method is karyotype analysis. Geographical variation exists among both sexes; maned female sloths that live in low altitude regions (0 to 350 meters) are smaller than females that live in colder and higher altitudes (600 to 1000 meters). This is similar to Bradypus variegatus in Bolivia, where larger body sizes are common in high altitude forests, whereas smaller body sizes are found in warmer lowlands of the Amazon. Female sloths of the species Bradypus tridactylus are also heavier and larger than males. Maned three-toed sloths have feet without any free toes. They have 3 long, curved claws that form a hook, allowing them to suspend from branches. The claws also allows them to grasp objects against the palm of the hand with a pincer-like grip. The dentition of B. torquatus consists of five peglike teeth on each side of the maxilla and four teeth in the mandible. Maned three-toed sloths have no true canines or incisors, but rather, a set of cheek teeth that are not clearly separated into premolars and molars resulting in a dentition of 0-0-5 and 0-0-4-5. This dentition is effective in shearing and mashing of leaves. Three toed sloths are characterized by a low metabolic rate and a low core body temperature. This may be an adaptation for feeding on leaves that contain low nutrients. Aside from this, there is little available information regarding the basal metabolic rate of any species in the genus Bradypus.
Range mass: 3.6 to 4.2 kg.
Range length: 450 to 500 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger; sexes colored or patterned differently; male more colorful
Maned three-toed sloths spend the majority of their time camouflaged in the forest canopy. Young maned three-toed sloths develop and grow rapidly, an adaptive response to greater predation levels in early life stages. Three-toed sloths are active during sporadic periods of both day and night, which may be an adaptation to avoid predators. Sloths are preyed on by harpy eagles (Harpia harpyja) as well as large cats such as jaguarundis (Puma yagouaroundi) and ocelots (Leopardus pardalis).
Anti-predator Adaptations: cryptic
The maned sloth is now found only in the Atlantic coastal rainforest of southeastern Brazil, although it was once also found further north. It has been identified predominantly from evergreen forests, although, being able to eat a wide range of leaves, it can also inhabit semi-deciduous and secondary forest. It is typically found in hot, humid climates without any dry season, and with annual rainfall of at least 120 centimetres (47 in). There are no recognized subspecies.
Maned sloths have a pale brown to gray pelage. Long outer hair covers a short, dense, black and white underfur. The coarse outer coat is usually inhabited by algae, mites, ticks, beetles, and moths. The maned sloth's small head features fur-covered pinnae and anterior oriented eyes that are usually covered by a mask of black hair. The sides of the maned sloth's face and neck feature long hair covering the short hair of the sloth's snout. Facial vibrissae on the maned sloth are sparse. The maned sloth earns its name from a mane of black hair running down its neck and over its shoulders. The mane is usually larger and darker in males than in females, and in the latter, may be reduced to a pair of long tufts. Other than the mane, the fur is relatively uniform in color, and, in particular, the males lack the patch of bright fur found on the back of other, closely related, sloths.
Adult males have a total head-body length of 55 to 72 centimetres (22 to 28 in), with a tail about 5 centimetres (2.0 in) long and a weight of 4.0 to 7.5 kilograms (8.8 to 16.5 lb). Females are generally larger, measuring 55 to 75 centimetres (22 to 30 in), and weighing 4.5 to 10.1 kilograms (9.9 to 22.3 lb). Like all other sloths, the maned sloth has very little muscle mass in comparison to other mammals its size. This reduced muscle mass allows it to hang from thin branches.
Maned sloths are solitary diurnal animals, spending from 60–80% of their day asleep, with the rest more or less equally divided between feeding and travelling. Sloths sleep in crotches of trees or by dangling from branches by their legs and tucking their head in between their forelegs.
Maned sloths are folivores, and feed exclusively on tree and liana leaves, especially Cecropia. Although individual animals seem to prefer leaves from particular species of tree, the species as a whole is able to adapt to a wide range of tree types. Younger leaves are preferred to older, and tree leaves are preferred to liana leaves. Individual maned sloths have reported to travel over a home range of 0.5 to 6 hectares (1.2 to 14.8 acres), with estimated population densities of 0.1 to 1.25 per hectare (0.040 to 0.506/acre).
Maned sloths rarely descend from the trees because, when on a level surface, they are unable to stand and walk, only being able to drag themselves along with their front legs and claws. They travel to the ground only to defecate or to move between trees when they cannot do so through the branches. The sloth's main defenses are to stay still and to lash out with its formidable claws. It can swim well but does not move well on the ground.
Although some reports indicate that maned sloths are able to breed year round, others have observed that the majority of births occur between February and April. The mother gives birth to a single young, which initially weighs around 300 grams (11 oz) and lacks the distinctive mane found on adults. The young begin to take solid food at two weeks, and are fully weaned by two to four months of age. The young leave the mother at between nine and eleven months of age. Although their lifespan has not been studied in detail, they have been reported to live for at least twelve years.
In 1955, the maned sloth occurred only in Bahia, Espírito Santo and Rio de Janeiro in eastern Brazil, in the Bahia coastal forests. It has declined since then as these forests have dwindled. The major threat to the maned sloth is the loss of its forest habitat as a result of lumber extraction, charcoal production, and clearance for plantations and cattle pastures. Excessive hunting is also a threat.