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Bradypus torquatusmaned three-toed sloth

By Brady Bullinger

Geographic Range

Bradypus torquatus occurs in patches of the coastal Brazilian Atlantic rain forest within the states of Bahia, Espirito Santo, and Rio de Janeiro. (Eisenberg and Redford, 1999)

Habitat

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. (Dias, 2008; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

  • Range elevation
    0 to 1000 m
    0.00 to 3280.84 ft

Physical Description

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. (Chiarello, 2006; Eisenberg and Redford, 1999; Emmons and Francois, 1990)

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. (Chiarello, 1998; Chiarello, 2006; Eisenberg and Redford, 1999; Emmons and Francois, 1990)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • male more colorful
  • Range mass
    3.6 to 4.2 kg
    7.93 to 9.25 lb
  • Range length
    450 to 500 mm
    17.72 to 19.69 in

Reproduction

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. (Dias, 2008; Eisenberg and Redford, 1999; Emmons and Francois, 1990; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

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. (Dias, et al., 2008; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

  • 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 number of offspring
    1
    AnAge
  • 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

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. (Chiarello, et al., 2003; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

  • 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

Lifespan/Longevity

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. (Chiarello, 2008; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

  • Typical lifespan
    Status: wild
    20 (high) years

Behavior

Three-toed sloths, are known for their incredibly slow movement and cryptic coloring. Maned three-toed sloths spend most of their day resting and feeding. They typically move and feed during mid-morning. During the dry season, they spend more time feeding in comparison to the wet season. Sloths are strictly arboreal, spending the majority of their time in the forest canopy. However, they can move quickly on the ground and swim well to travel between forest stands. Maned three-toed sloths move quietly and can also be active at night, making it difficult to observe behavior. (Chiarello, 1998; Chiarello, 2008; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

  • Range territory size
    8,000 to 109,000 m^2

Home Range

Home range size varies with the diversity and density of tree species in a forest stand. Maned three-toed sloths have average daily movements of 23 to 28 meters. Adult females have home ranges of 0.8 to 4.5 hectares. Adult males have home ranges of about 7.6 hectares. Maned three-toed sloths range twice as far during the dry season as during the wet season. (Chiarello, et al., 2003; Chiarello, 1998; Chiarello, 2008; Dias, et al., 2008)

Communication and Perception

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. (Chiarello, 2008; Dias, 2008)

Food Habits

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. (Chiarello, 1998; Chiarello, 2006; Emmons and Francois, 1990)

  • Plant Foods
  • leaves
  • wood, bark, or stems

Predation

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). (Chiarello, 1998; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

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. ("Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

Economic Importance for Humans: Positive

Maned three-toed sloths are important, endemic members of Brazilian Atlantic forest ecosystems.

Economic Importance for Humans: Negative

There are no adverse effects of maned three-toed sloths on humans.

Conservation Status

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. (Chiarello, 2008; "Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus", 2005)

Contributors

Brady Bullinger (author), University of Oregon, Stephen Frost (editor, instructor), University of Oregon, Tanya Dewey (editor), Animal Diversity Web.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

young precocial

young are relatively well-developed when born

References

The Zoological Society of London. 2005. Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus. The Zoological Society of London, 267: 63-73.

Anderson, R., C. Handley. 2001. "A new species of three-toed sloth from Panama, with a review of the genus Bradypus" (On-line). Accessed March 03, 2009 at http://web.sci.ccny.cuny.edu/~anderson/publications/AndersonHandley2001ProceedingsBiologicalSocietyWashington.pdf.

Barros, M., I. Sampaio. 2003. "Phylogenetic analysis of 16S mitochondrial DNA data in sloths and anteaters" (On-line). Accessed March 03, 2009 at http://www.scielo.br/scielo.php?pid=S1415-47572003000100002&script=sci_arttext&tlng=en.

Chiarello, A. 1998. Activity budgets and ranging patterns of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae). Journal of Zoology, 246: 1-10.

Chiarello, A. 2006. Diet of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae). Journal of Zoology, Volume 246, Issue 1: 11-19.

Chiarello, A. 2008. Sloth ecology: An overview of field studies. Pp. 269-280 in S Vizcaino, W Loughry, eds. The Biology of the Xenarthra. United States: The University Press of Florida.

Chiarello, A., D. Chivers, C. Bassi, M. Maciel, L. Moreira. 2003. A Translocation Experiment for the Conservation of Maned Sloths, Bradypus torquatus. Biological Conservation, 118: 421-430.

Dias, B. 2008. First observation on mating and reproductive seasonality in maned sloths Bradypus torquatus. Journal of Ethology, Volume 27, Number 1: 97-103.

Dias, B., L. Dias dos Santos, P. Lara-Ruiz. 2008. First observation on mating and reproductive seasonality in maned sloths Bradypus torquatus. Japan Ethological Society and Springer, 27: 97-103.

Eisenberg, J., K. Redford. 1999. Mammals of the Neotropics. London: The University of Chicago Press.

Emmons, L., F. Francois. 1990. Neotropical Rainforest Mammals. Chicago: University of Chicago Press.

Gilmore, D., C. Da Costa, Duarte. 2001. "Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses" (On-line). Accessed March 03, 2009 at http://www.scielo.br/pdf/bjmbr/v34n1/3877m.pdf.

Martins, D. 2003. "Morphology of the male reproductive system in three-toed sloth (Bradypus torquatus - Illiger, 1811)" (On-line). Accessed March 03, 2009 at http://www.biotaneotropica.org.br/v5n1/en/fullpaper?bn02305012005+en03/03/09.

Moraes-Barros, N., C. Miyaki. 2007. "Identifying management units in non-endangered species: the example of the sloth Bradypus variegatus" (On-line). Accessed March 03, 2009 at http://www.srcosmos.gr/srcosmos/showpub.aspx?aa=10554.

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