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.
- Biogeographic Regions
- neotropical
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.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- forest
- rainforest
- Aquatic Biomes
- rivers and streams
- Wetlands
- swamp
- Other Habitat Features
- riparian
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.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes colored or patterned differently
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.
- Mating System
- monogamous
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.
- Key Reproductive Features
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- viviparous
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.
- Parental Investment
- female parental care
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
provisioning
- female
-
protecting
- female
-
provisioning
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.
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.
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.
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.
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.
- 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.
- 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
.
- Ecosystem Impact
- creates habitat
- algae, ( Chlorophyta )
- algae, ( Chrysophyta )
- algae, ( Cyanophyta )
- algae, ( Rhodophyta )
- 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.
Additional Links
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.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- 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.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- 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.
- 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.
- monogamous
-
Having one mate at a time.
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- female parental care
-
parental care is carried out by females
- arboreal
-
Referring to an animal that lives in trees; tree-climbing.
- diurnal
-
- active during the day, 2. lasting for one day.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- 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.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- frugivore
-
an animal that mainly eats fruit
References
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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.
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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.
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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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