Bradypus pygmaeuspygmy three-toed sloth

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Geographic Range

Bradypus pygmaeus, commonly called monk, dwarf, or pygmy three-toed sloth, is found only on the Isla Escudo de Veraguas of Bocas del Toro, which is located off the coast of Panama. This island is small, only about 5 square kilometers in area. (Anderson and Handley, 2001; Hayssen, 2008)

Habitat

Pygmy three-toed sloths have been found living only in coastal, red mangroves at sea level. (Anderson and Handley, 2001; Hayssen, 2008)

Physical Description

Bradypus pygmaeus is similar to Bradypus variegatus but smaller. Pygmy three-toed sloths have buff-colored faces with dark circles that surround the eye and go outwards to their temples. Clay-orange fur covers the face, starting underneath the dark eye circles. The hair on the head and shoulders is long and bushy, distinctive against the shorter facial hair and making it look as if these sloths have a hood. The throat is brown-gray and the dorsum is speckled and has a dark mid-sagittal stripe. Males differ in that they have a dorsal ginger speculum with fuzzy hair following the margin. Pygmy three-toed sloths have in total 18 teeth, 10 from the upper jaw which consists of 2 anterior chisel-shaped teeth and 8 molariform teeth. On the bottom jaw there are 8 teeth; 2 anterior chisel-shaped, and 6 molariform teeth. The skull is small in comparison to other closely related species, lacks foramina in the anterodorsal nasopharynx, and doesn't have pterygoid sinuses that are inflated. The zygomatic arch is incomplete with slim roots, and the process of the jugal descends long and thin. Bradypus pygmaeus also have large external auditory meatus. Like other sloths, body temperature regulation is likely to be imperfect, making them heterothermic. (Anderson and Handley, 2001; Hayssen, 2008)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Range mass
    2.5 to 3.5 kg
    5.51 to 7.71 lb
  • Average mass
    2.9 kg
    6.39 lb
  • Range length
    485 to 530 mm
    19.09 to 20.87 in
  • Average length
    505.4 mm
    19.90 in

Reproduction

There is little information on the Bradypus pygmaeus mating system. However, in other Bradypus species, there is evidence that males compete for access to mating opportunities with receptive females. (Hayssen, 2008)

Reproduction in Bradypus pygmaeus has not been researched enough to report details. Bradypus torquatus has been studied more extensively. They copulate towards the end of the dry season and early wet season, which occurs from August through October, which results in gestation and lactation occurring during times of plenty of food. Births occur from February to April, marking the end to the wet season and start of the dry season. One infant is born after a gestation period of 6 months. The interbirth interval is 1 year for maned sloths. (Bezerra, 2008; Dias, 2009)

  • Breeding interval
    A close relative, Bradypus torquatus, breeds once yearly, but the breeding interval for B. pygmaeus is not known.
  • Average number of offspring
    1

Female pygmy three-toed sloths invest heavily in young through gestation and lactation, as do females in other sloth species. Details of parental care are not reported for pygmy three-toed sloths, but related species care for their young for up to 6 months. (Lynch, 2006)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

Little information is known at this time about the lifespan or longevity for Bradypus pygmaeus. Other species of sloths have been known to live 30 to 40 years in captivity. (Beall, 2009)

Behavior

Pygmy three-toed sloths are mainly arboreal, although they can walk on the ground and also swim. Like other sloths, they can be active at any time of the day and spend much of their time sleeping or sedentary. They are generally solitary and do not tend to travel far. (Anderson and Handley, 2001; Hayssen, 2008)

  • Range territory size
    4.3 (low) km^2

Home Range

Pygmy three-toed sloths have home ranges that are small, on average 1.6 ha. (Anderson and Handley, 2002)

Communication and Perception

There is little information on communication in Bradypus pygmaeus. Like other sloths, pygmy three-toed sloths are likely to have relatively poor eyesight. They may use vocalizations and are likely to use chemical cues in communication.

Food Habits

Pygmy three-toed sloths are arboreal folivores. They eat leaves from many different kinds of trees and have low metabolic rates. (Anderson and Handley, 2001)

  • Plant Foods
  • leaves

Predation

Predators of pygmy three-toed sloths have not been reported. However, like other sloths, they are very slow-moving animals with long, hair that often grows algae, allowing them to blend in well in their leafy habitats. Other sloth species are preyed on by harpy eagles (Harpia harpyja), jaguars (Panthera onca), jaguarundis (Puma yagouaroundi) and ocelots (Leopardus pardalis). (Anderson and Handley, 2001)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Because pygmy three-toed sloths are a recently described species, little is known about their ecosystem roles. They are hosts to various parasites, may influence vegetation through their browsing, and act as prey for larger, arboreal predators. (Lynch, 2006)

Economic Importance for Humans: Positive

There are no known benefits to humans from Bradypus pygmaeus at this time.

Economic Importance for Humans: Negative

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

Conservation Status

Because of their extremely restricted range, habitat degradation in that area, increasing tourism, and illegal hunting, Bradypus pygmaeus has been listed as Critically Endangered by the IUCN. ("IUCN Red List of Threatened Species", 2009; Hayssen, 2008)

Other Comments

Bradypus pygmaeus was recently discovered in 2001, which is why a lot of information is lacking for the species. Compared to Bradypus variegatus Pygmy three-toed sloths are 15% smaller in total length, and 40% smaller in their mass. (Anderson and Handley, 2001)

Contributors

Farryn Guarino (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point, 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

coastal

the nearshore aquatic habitats near a coast, or shoreline.

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.

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.

island endemic

animals that live only on an island or set of islands.

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

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.

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

2009. "IUCN Red List of Threatened Species" (On-line). Accessed August 10, 2009 at http://www.iucnredlist.org/search.

Anderson, R., C. Handley. 2001. A New Species of Three-toed Sloth (Mammalia: Xenarthra) from Panama, with a Review of the Genus Bradypus. Proceedings of the Biological society of Washington, 114: "1-33". Accessed July 27, 2009 at http://web.sci.ccny.cuny.edu/~anderson/publications/AndersonHandley2001ProceedingsBiologicalSocietyWashington.pdf.

Anderson, R., C. Handley. 2002. Dwarfism in Insular Sloths:Biogeography,Selection,and Evolutionary Rate. Evolution, 56/5: "1045-58".

Beall, L. 2009. "Animal facts: Sloth" (On-line). Helium. Accessed August 17, 2009 at http://www.helium.com/items/990653-animal-facts-sloth.

Bezerra, B. 2008. Observation of Brown-Throated Three Toed Sloths, Mating Behavior and Simultaneous Nurturing of Two Young. Journal of Ethology, 26/1: "175-178".

Dias, B. 2009. First Observation on Mating and Reproductive Seasonality in Manned Sloths Bradypus torquatus ( Pilosa: Bradypodidae). Journal of Ethology, 27/1: "97-103".

Hayssen, V. 2008. Bradypus pygmaeus (Pilosa:Bradypodidae). Mammalian Species, 812: "1-4". Accessed July 26, 2009 at http://www.bioone.org/doi/pdf/10.1644/812.1.

Lynch, W. 2006. Slowpokes. Wildlife Conservation, 109/1: "44-49".