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Bradypus variegatusbrown-throated three-toed sloth

By Hee-Jin Jung

Geographic Range

Brown-throated three-toed sloths are native to South America and southern Central America. Their geographic range includes Bolivia, Brazil, Columbia, Ecuador, Honduras, Nicaragua, Panama, Paraguay, Peru, and Venezuela. Although once present in Argentina, it is now thought to be extinct. (Chiarello, 2008)

Habitat

Brown-throated three-toed sloths can be found in many new-world tropical forests, though some have also been discovered in semi-deciduous forests and subtropical lowlands and swamps. They live in the canopy for the majority of their lives and are capable swimmers. They seldom travel on the ground. They can be found at elevations ranging from sea level to 2400 m. Although not selective about the species of tree they choose to inhabit, they tend to seek out trees with crowns that are highly exposed to sunlight. This preference has been attributed to the sloths using sunlight to fulfill their thermoregulatory needs. ("Brown-throated three-toed sloth (Bradypus variegatus)", 2008; Chiarello, 2008)

  • Aquatic Biomes
  • rivers and streams
  • Range elevation
    0 to 2400 m
    0.00 to 7874.02 ft

Physical Description

As indicated by their common, brown-throated three-toed sloths have brown coloration on their throat and head. Their coat consists of a layer of short, soft, and fine fur and a layer of thick, woolly fur. Algae often resides on outer layer, giving some individuals a greenish appearance. They have long forelimbs with three clawed-toes on each limb. They also have approximately 10 cervical vertebrate that enable them to rotate their necks up to 270 degrees. Their teeth are cylindrical and lack enamel. Similar to many ungulates, their stomachs are multi-compartmentalized, with intestinal microfauna that help digest cellulose from their exclusively vegetarian diets. Even as endotherms, brown-throated three-toed sloths have difficulty regulating their body temperature in cold environments and in cooler ambient temperatures. This is likely due to sparse muscle mass, their relatively small heart, and low-ranging heart rate. Adults range in mass from 3.49 to 5.19 kg, with an average of 4.34 kg. Average length is 60 cm, and they have a basal metabolic rate of 147 cm^3 oxygen/hour. Although size-dimorphism is not present in this species, males have a mid-dorsal speculum that is not present in females. (Feldhamer, et al., 2007; Gilmore, et al., 2001; Gilmore, et al., 2000)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Range mass
    3.49 to 5.19 kg
    7.69 to 11.43 lb
  • Average length
    60 cm
    23.62 in
  • Average basal metabolic rate
    147 cm3.O2/g/hr

Reproduction

Brown-throated three-toed sloths are thought to be monogamous. Females vocalize to attract males when they are ready to mate. Females typically mate with the first male they encounter. Although it is unclear if they have a defined breeding season, evidence suggests mating occurs just prior to the rainy season. Copulation lasts 10 to 15 minutes and takes place in the female's tree, approximately 15 m above the ground. During copulation, the male positions himself behind the female. Once mating is complete, the male leaves shortly there after. (Bezerra, et al., 2007)

Once copulation is finished, males immediately leave and do not provide any parental care to young. Bradypus variegatus gives birth to a single offspring once a year. During gestation, which lasts for 5 to 8 months, the mother does not make any preparations, such as nest-building. After birth, neonates are held ventrally, which is thought to help provide protection for young, including attack from predators. Neonates weigh less than 1 kg at birth. Most individuals become independent once weaning is complete, which takes approximately 4 months. Females become reproductively mature by 3 years of age, and males become reproductively mature between 3 and 5 years of age, with an average of 4 years of age. (Bezerra, et al., 2007; SOARES and CARNEIRO, 2002)

  • Breeding interval
    Brown-throated three-toed sloths breed once yearly
  • Average number of offspring
    1
  • Range gestation period
    5 to 8 months
  • Average weaning age
    4 months
  • Range time to independence
    2 to 4 months
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Range age at sexual or reproductive maturity (male)
    3 to 5 years

Brown-throated three-toed sloths give birth on the ground or in trees. During birth, the mother pulls the infant between her hindlegs, and other sloths aid in the birthing process by cleaning the mother and infant and by ensuring that the infant doesn't fall. Mothers help young establish motor behavior, posture, learning development, and independent exploration in young. Paternal care is thought to be non-existent in this species. (Gilmore, et al., 2000)

  • Parental Investment
  • female parental care
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

In the wild, the lifespan of adult brown-throated three-toed sloths is typically between 30 and 40 years. There is no other information available regarding the lifespan of this species. (MORAES-BARROS, et al., 2011; MORAES-BARROS, et al., 2011; MORAES-BARROS, et al., 2011)

  • Range lifespan
    Status: wild
    30 to 40 years
  • Typical lifespan
    Status: wild
    30 to 40 years

Behavior

Brown-throated three-toed sloths sleep approximately 14 to 16 hours a day and are both diurnal and nocturnal. They are active for approximately 8 to 10 hours a day, which is typically partitioned into discrete 2 to 3 hour periods. They are most active between 1200 and 1800 hours, and most individuals sleep between 0600 and 1200. Brown-throated three-toed sloths exhibit two different resting modes. The first is that of an "awake-alert" state during which the animal's eyes are actively open and blinking; the second is that of a "behavioral sleep", during which the animal's eyes are closed but still remains suspended from a tree. Adults have never been observed in the same tree with another adult. Agnostic behavior is relatively rare between conspecifics; however, they readily protect territory, food, or other resources. (Duarte, et al., 2003; Gilmore, et al., 2001; Greene, 1989)

  • Average territory size
    20000 m^2

Home Range

The average home ranges of brown-throated three-toed sloths is less than 2 hectares. There is no further information on the home range of this species. (Gilmore, et al., 2001)

Communication and Perception

Social interactions between Bradypus variegatus adults are relatively rare. However, communication between mothers and their young is significant, particularly in the form of vocalization. Vocalizations are also used to communicate with other conspecifics during breeding season, as females call out to attract a potential mate. Bradypus variegatus lack a ciliary muscle in their eyes and have very few ganglion cells and nerve fibers, which result in poor eyesight and visual acuity. Evidence suggests that vision functions optimally at low light intensities. Defecation and urination occur on the ground, and both have been suggested to function as a means of communicating with other conspecifics. (Bezerra, et al., 2007; Gilmore, et al., 2000; SOARES and CARNEIRO, 2002)

Food Habits

Bradypus variegatus is a strict herbivore that feeds primarily on trees in the genus Cercropia (e.g., embauba). They consume various parts of the tree, including leaves, flowers, and fruits. Bradypus variegatus is a facultative drinker and receives most of its water from ingested plant materials. (Bezerra, et al., 2007; Duarte, et al., 2003; Gilmore, et al., 2000)

  • Plant Foods
  • leaves
  • fruit
  • flowers

Predation

Brown-throated three-toed sloths are highly camouflaged and slow-moving, both of which help decrease risk of predation via decreased visibility. Major predators of this species include spectacled owls, harpy eagles and a variety of felid species. Brown-throated three-toed sloths descend from the canopy to defecate and urinate on the ground. Although they only descend from teh canopy once every 3 to 8 days, this behavior greatly increases vulnerability to predation. (Gilmore, et al., 2001; Touchton, et al., 2002; Voirin, et al., 2009)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Brown-throated three-toed sloths have are mutualists with algae, which reside in the coats of sloths. The presence of algae confers a greenish tint to the outermost fur coat, which is hypothesized to function as camouflage. It has also been suggested that algae provides essential trace elements and nutrients. In exchange, algae receives shelter in the coats of their host and sunlight, as sloths prefer sections of sun-exposed canopy. Brown-throated three-toed sloths are primary prey for a number of vertebrate predators including harpy eagles and many species of felid; however, they do not make up a large portion of any one species' diet. Known parasites of this species include Leishmania and Pneumocystis carinii. (Gilmore, et al., 2001)

  • Ecosystem Impact
  • creates habitat
Mutualist Species
  • algae, (Chlorophyta)
  • algae, (Chrysophyta)
  • algae, (Cyanophyta)
  • algae, (Rhodophyta)
Commensal/Parasitic Species
  • trypanosomatid protozoans, (Leishmania)
  • fungus, (Pneumocystis carinii)

Economic Importance for Humans: Positive

There are no known positive effects of Bradypus variegatus on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Bradypus variegatus on humans.

Conservation Status

Bradypus variegatus is classified as a species of least concern on the IUCN's Red List of Threatened Species. Although precise population trends are unknown, is has been estimated that densities ranging from 2.2 to 8.5 animals per hectare occur throughout their geographic range. Although some populations in the Brazilian Amazon are thought to be declining due to deforestation, there are no major threats to the long-term persistence of this species. (Chiarello, 2008)

Contributors

Hee-Jin Jung (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, John Berini (editor), Animal Diversity Web Staff.

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.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

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.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

monogamous

Having one mate at a time.

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

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).

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

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

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.

year-round breeding

breeding takes place throughout the year

References

2008. "Brown-throated three-toed sloth (Bradypus variegatus)" (On-line). World Association of Zoos and Aquariums - United For Conservation. Accessed March 12, 2011 at http://www.waza.org/en/zoo/visit-the-zoo/sloths-anteaters-armadillos-pangolins-and-aardvark/bradypus-variegatus.

Bezerra, B., A. Souto, L. Halsey, N. Schiel. 2007. Observation of brown-throated three-toed sloths: mating behaviour and the simultaneous nurturing of two young. Japan Ethological Societ, 26: 175–178.

Chantelois, M. 2009. "Bradypus variegatus: Brown-throated sloth" (On-line). Accessed February 22, 2011 at http://www.eol.org/pages/328518.

Chiarello, A. 2008. "Bradypus variegatus" (On-line). The IUCN Red List of Endangered Species. Accessed March 12, 2011 at http://www.iucnredlist.org/apps/redlist/details/3038/0.

Duarte, D., A. Jaguaribe, M. Pedrosa, A. Clementino, A. Silva, A. Barbosa, D. Gilmore, C. Da Costa. 2004. Cardiovascular responses to locomotor activity and feeding in unrestrained three-toed sloths, Bradypus variegatus. Brazilian Journal of Medical and Biological Research, 37: 1557-1561.

Duarte, D., V. Silva, A. Jaguaribe, D. Gilmore, C. Da Costa. 2003. Circadian rhythms in blood pressure in free-ranging three-toed sloths (Bradypus variegatus). Brazilian Journal of Medical and Biological Research, 36: 273-278.

Feldhamer, G., L. Drickamer, S. Vessey, J. Merritt. 2007. Mammalogy: Adaptation, Diversity, Ecology. Maryland: Johns Hopkins University Press.

Gilmore, D., C. Da Costa, D. Duarte. 2001. Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses. Brazilian Journal of Medical and Biological Research, 34: 9-25.

Gilmore, D., C. Da-Costa, D. Duarte. 2000. An update on the physiology of two- and three-toed sloths. Brazilian Journal of Medical and Biological Research, 33: 129-146. Accessed February 22, 2011 at http://www.scielo.br/pdf/bjmbr/v33n2/3528c.pdf.

Greene, H. 1989. Agnostic Behavior by Three-toed Sloths, Bradypus variegatus. Biotropica, Volume 21, Issue 4: 369-372. Accessed February 23, 2011 at http://www.jstor.org/stable/2388289.

MORAES-BARROS, ., J. SILVA, J. MORGANTE. 2011. Morphology, molecular phylogeny, and taxonomic inconsistencies in the study of Bradypus sloths (Pilosa: Bradypodidae). Journal of Mammalogy, 92: 86-100.

SOARES, C., R. CARNEIRO. 2002. SOCIAL BEHAVIOR BETWEEN MOTHERS ´ YOUNG OF SLOTHS Bradypus variegatus SCHINZ, 1825 (XENARTHRA: BRADYPODIDAE). Brazilian Journal of Biology, Volume 62, Issue 2: 249-252.

Touchton, J., Y. Hsu, A. Palleroni. 2002. FORAGING ECOLOGY OF REINTRODUCED CAPTIVE-BRED SUBADULT HARPY EAGLES (HARPIA HARPYJA) ON BARRO COLORADO ISLAND, PANAMA. ORNITOLOGIA NEOTROPICAL, 13: 365–379.

Urbani, B., C. Bosque. 2007. Feeding ecology and postural behaviour of the three-toed sloth (Bradypus variegatus flaccidus) in northern Venezuela. Mammalian Biology, Volume 72, Issue 6: 321-329.

Voirin, J., R. Kays, M. Lowman, M. Wikelski. 2009. Evidence for Three-Toed Sloth (Bradypus variegatus) Predation by Spectacled Owl (Pulsatrix perspicillata). Edentata, 8-10: 15-20.

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