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.
Biogeographic Regions: neotropical (Native )
Other Geographic Terms: island endemic
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.
Range mass: 2.5 to 3.5 kg.
Average mass: 2.9 kg.
Range length: 485 to 530 mm.
Average length: 505.4 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently
Catalog Number: USNM 579179
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Female; Adult
Preparation: Skin; Skull
Collector(s): C. Handley & E. Nelson
Year Collected: 1991
Locality: Isla Escudo de Veraguas, N quarter W point, Bocas Del Toro, Panama, North America
Microhabitat: Ecological remarks by collector(s): yes
Bocas del Toro-San Bastimentos Island-San Blas Mangroves Habitat
This taxon is found in the Bocas del Toro-San Bastimentos Island-San Blas mangroves ecoregion, but not necessarily exclusive to this region. The Bocas del Toro-San Bastimentos Island-San Blas mangroves is one of the ecoregions of Panama, situated on the Caribbean coast of northern Panama. Precipitation in this region, entirely in the form of rainfall, amounts to approximately 6000 mm per annum. This ecoregion is largely comprised of mangrove swamps and contains an extensive coral reef system that protects the mangroves by moderating ocean wave action; in turn the mangroves trap sediment and promote water clarity than enhance coral reef development. Extensive submerged areas of this ecoregion are considered seagrass meadows, a highly biodiverse marine ecosystem that has high primary productivity as well as considerable species richness In the shallower waters are found manatee along with numerous corals, sponges, pipefishes and baracuda. The deeper coastal waters are habitat for dolphins, most notably at Dolphin Bay, somewhat south of Bastimentos Island.
The dominant shoreline ecoregion feature is the presence of Red Mangrove trees, whose submerged roots stabilize the shoreline. The near coastal zone and low elevation upland areas of this ecorefion also support a host of other flora, as well as birds, mammals, amphibians and arthropods.
Birdlife at the coastal upland and rich coastal riparian zone and other near shore upland habitats is quite diverse. A notable terrestrial bird endemic to the Bocas del Toro region is the Brown Parakeet. Another notable bird found in this ecoregion is the Pale-billed woodpecker, Campephilus guatemalensis, a large bird, who is found at the southern limit of his range here. The White-fronted nunbird, Monasa morphoeus, is a near passerine species found at the moist lowland forest edge, including secondary growth. Another bird found here that is tolerant of degraded forest is the Crimson-fronted parakeet, Aratinga finschi. A specialist bird to the mangroves and also dense somewhat upland areas of Bocas is the Rufous-necked wood-rail, Aramides axillaris. The Bare-necked umbrella bird is normally found at the higher elevation margin of the Bocas area, but can often be found in the near coastal fringe in non-breeding season.
Mammalian species include the Collared-peccary, who may be found in mainland Bocas del Toro lowland moist forest or grasslands. Also found here is the critically endangered Pygmy three-toed sloth, Bradypus pygmaeus, whose extant population of no more than a few hundred animals is restricted to the tiny (3.4 km2) island of Isla Escudo de Veraguas. There are also Central American red brocket, Mazama temama, a species of forest deer widespead in Mesoamerica.
Pygmy three-toed sloths have been found living only in coastal, red mangroves at sea level.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest
Aquatic Biomes: coastal
Habitat and Ecology
Pygmy three-toed sloths are arboreal folivores. They eat leaves from many different kinds of trees and have low metabolic rates.
Plant Foods: leaves
Primary Diet: herbivore (Folivore )
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.
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).
Anti-predator Adaptations: cryptic
Life History and Behavior
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.
Perception Channels: visual ; tactile ; acoustic ; chemical
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.
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.
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.
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.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
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.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
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.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: critically endangered
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2013Critically Endangered
- 2006Critically Endangered(IUCN 2006)
- 2006Critically Endangered
Despite having been designated as a protected landscape through a governmental resolution in 2009, a number of domestic and international efforts have been mounted to develop tourism infrastructure on the island. This includes plans for an eco-lodge, a casino, a marina, and a banking centre. The current status of the island’s custody is vague; a governmental resolution, and thus the protected status of the island, cannot be revoked, but no government staff has been appointed specifically to enforce protection of the island. Ongoing disagreements between the local Ngäbe bugle Comarca, regional politicians, and the Panamanian government are further complicating long-term protection of the island and the pygmy sloths. Additionally, as pygmy sloths have become more widely recognized internationally, there is growing interest in collecting them for captivity.
The pygmy sloth is listed on CITES Appendix II (Notification to the Parties 2013/052, 20 November 2013).
Relevance to Humans and Ecosystems
There are no known adverse effects of Bradypus pygmaeus on humans.
There are no known benefits to humans from Bradypus pygmaeus at this time.
Pygmy three-toed sloth
The pygmy three-toed sloth (Bradypus pygmaeus), also known as a monk sloth or dwarf sloth, is a small three-toed sloth, endemic to Isla Escudo de Veraguas, a small island off the coast of Panama, which separated from the mainland nearly 8900 years ago. Only described as a separate species in 2001, they are thought to have originated from isolation of individuals of the mainland population of brown-throated three-toed sloths. The population became a distinct species through insular dwarfism on the island.
Studies suggest an inverse, linear relationship between mean body sizes and age of the island for island populations of sloths in this region.
Pygmy three-toed sloths have a tan face with a dark brown band across the brow and orange eye patches. The back can exhibit either uniform or blotchy color distribution, but is usually dark brown with an obvious dorsal stripe. Pygmy sloths are unique in that they have long hairs on the crown and the sides of the head, giving the distinct impression of a hood. Compared to the related brown-throated three-toed sloth, the pygmy species is, on average 40% smaller in body mass, weighing 2.5 to 3.5 kilograms (5.5 to 7.7 lb), and 15% smaller in body length. Adults measure 48 to 53 centimetres (19 to 21 in), with a 4.5 to 6.0 centimetres (1.8 to 2.4 in) tail.
They have a relatively small skull, with a large external auditory meatus, narrow squamosal and mandibular processes, no foramina in the anterodorsal nasopharynx, a minuscule stylomastoid foramen, and they usually lack foramina for the external carotid artery. They have eighteen teeth, ten in the upper jaw and eight in the lower. Two of the teeth in each jaw are incisor-like, although those in the upper jaw are small or may be absent. The incisor-like teeth in the lower jaw are compressed anteroposteriorly. Many of the features found in pygmy sloths are thought to be indicative of a relatively rapid evolution of a new species in an isolated, island, habitat.
Pygmy sloths are also 12–16% smaller in cranial dimensions than the mainland species (length: 67.5 to 72.2 millimetres (2.66 to 2.84 in); width: 38.8 to 45.7 millimetres (1.53 to 1.80 in).
All three-toed sloths are arboreal mammals that feed on leaves; the pygmy sloth is unique in that it is found exclusively in the red mangroves, and feeds on coarse leaves. Red mangrove leaves are a relatively poor source of nutrients, in comparison with the tender leaves of the Cecropia tree eaten by brown-throated sloths on the mainland.
The smaller size of pygmy sloths reduces their energy requirements for survival and reproduction, making them an apparent example of insular dwarfism. No predators of pygmy three-toed sloths have been documented.
Mating, gestation, birth and post-birth dynamics have not been observed for pygmy sloths, but these features may be inferred from studies of other species in the genus.
Individuals of other species reach sexual maturity around three years of age and typically give birth after twelve months gestation, although captive bred sloths can give birth as early as six months after mating. Mammary glands are found near the armpits of the female and infants cling to the mothers’ underside. Captive-bred young of other species are independent of their mothers around six months of age. Some reports suggest that female sloths give birth to a single offspring, but observations of a female brown-throated sloth in the wild with two infants suggest that they are capable of producing twins.
The behavior of pygmy three-toed sloths has not been reported, but can be inferred from the behavior of its close relative, the brown-throated sloth.
Two male brown-throated sloths were observed fighting in the wild by striking one another using their forefeet. This observed dispute probably took place over access to new greenery and fruits in a Cecropia tree. In other cases, disputes between male sloths may be for rights to mate. Captive females will fight for resources. Like other sloths, the pygmy sloth is a good swimmer. 
Population and threats
A 2011 study found only 79 pygmy three-toed sloths on Escudo de Veraguas. While their population has presumably always been low due to their restricted range, this census found far lower population numbers than had been estimated (around 300). Although the island has no human population, the World Conservation Union stated in 2006 that visiting fishermen poach the sloth, which is an easy target because it lives in the mangrove forests by the sea. However, this claim has not been substantiated. Although protected as a wildlife refuge, the enforcement is lax.
|Wikispecies has information related to: Bradypus pygmaeus|
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