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Isla Escudo, where the pygmy sloth is found today, only became isolated from mainland Central America 8900 years ago, as sea levels rose after the end of the last Ice Age glaciation. The pygmy sloth has therefore undergone extremely rapid body size evolution following the isolation of its founder population in the early Holocene Epoch.
The smallest of the three-toed sloths, the pygmy three-toed sloth is characterised by pale grey-brown fur that is often blotchy and a tan-coloured face with a distinctive dark band around the eyes. Long, shaggy hair hangs over the face, giving a hooded appearance. Male adults have a bright orange patch on their back through which a black band runs vertically. Sloths have an unusual means of camouflage to avoid predation; their outer fur is often coated in algae, giving the hair a greenish colour that helps conceal them in their forest habitat. Three-toed sloths (Bradypus) can be distinguished from their distant relatives, the two-toed sloths (Choloepus), by the three digits on their forelimbs, blunter muzzle, and simpler, chisel-shaped teeth.
Sloth fore-arms are much longer than their thighs, so when on the ground they crawl on their elbows rather than their hands and their thighs are spaced so widely that they cannot bring their knees together. Although this makes it difficult for the pygmy three-toed sloth to move along on the ground their hands and feet have long, curved claws that let them hang upside down in trees all day long with ease. Their specialised neck allows them to turn their head approximately 270o horizontally and observe all around without having to move the rest of their body. A further adaptation to living upside down is that sloth hair grows in the opposite direction of the hair of most animals, which makes it easier for water to run off away from the skin when the animal is upside down.
Their small home ranges average 1.6 Ha which is suitable for their lives as solitary individuals. Adults only come together to mate, finding each other using loud calls. Although the gestation period for the pygmy three-toed sloth is unknown, other species of three-toed sloth are pregnant for between 4 and seven months before giving birth. The mother bears one infant at a time, and will care for it between six months or a year during which time she will carry the young sloth with her everywhere she goes.
The green algae found in the fur of the pygmy three-toed sloth is a unique species of Trichophilus algae which is thought to be symbiotic, providing camouflage to the sloth at no detriment to the sloth’s health. Algae begin to grow on the pygmy three-toed sloth during childhood and are probably transferred from mother to child.
Isla Escudo de Veraguas has been designated as a protected area and is located within the Ngobe-Bugle comarca which means the local indigenous people have strong administrative power.
A group of scientists from ZSL went out to Escudo to conduct an extensive population survey of the pygmy sloths in March 2012. In total they encountered 72 sloths and observed a lot of mangroves that had been cut down: it is thought that now there are less than 100 individuals left on the island. At present a campaign is being run to raise funds to implement conservation plans that include socioeconomic work with local communities and schools to stop poaching and reduce mangrove harvesting.
This project supports in-country EDGE Fellows to help conserve relevant EDGE species
To significantly increase the protection and awareness of Isla Escudo de Veraguas as a unique habitat using pygmy three-toed sloths as a flagship species through long-term collaborations with Panamanian authorities and local communities.
Law enforcement within the reserve is inadequate and needs to be strengthened to protect this species. Conservation could also be improved through local awareness programmes, specifically those promoting sloths as conservation flagship species. Education of local communities is vital to stopping poaching problems as well as reducing deforestation and increasing law enforcement within the reserve.
Marine and freshwater programme coordinator at ZSL with a passion for mangroves and corals
Craig recently co-led the Negros Interior Biodiversity Expedition in the Philippines
I am veterinarian and I am working with the pygmy three-toed sloth on Escudo de Veraguas Island in Panama.
Anderson, R.P. and Handley, C.O. Jr. 2002. Dwarfism in insular sloths: biogeography, selection, and evolutionary rate. Evolution 56: 1045-1058.
Anderson, R.P. and Handley, C.O. Jr. 2001. A new species of three-toed sloth (Mammalia:Xenarthra) from Panamá, with a review of the genus Bradypus. PBiol Soc Wash. 114(1):1-33.
Bezerra, B.M. et al. 2008. Observation of brown-thraoted three-toed sloths: mating behaviour and the simulataneous nurturing of two young. J. Ethol 26:175-178
De Moraes-Barros, N. et al. 2006. Comparative phylogeography of the Atlantic forest endemic sloth (Bradypus torquatus) and the widespread three-toed sloth (Bradypus variegatus)(Bradypodidae, Xenarthra). Genetica 126:189–198.
Diniz, L. and Oliveira, P. 1999. Clinical problems of sloths (Bradypus sp. And Choloepus sp.) in captivity) 30:1:76-80
Hanging with the Sloth Guidebook
Hayssen, V. 2008. Bradypus pygmaeus (Pilosa: Bradypodidae). Mammalian Species 812: 1-4.
Robert P., et al. 2001. A new species of three-toed sloth (Mammalia: Xenarthra) from Panama, with a review of the genus Bradypus. Proceedings of the Royal Soc of Washingtion 114(1):1-33.
Samudio, R. & Members of the IUCN SSC Edentate Specialist Group 2008. Bradypus pygmaeus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. <www.iucnredlist.org>. Downloaded on 09 November 2010.
Suutari, M. et al. 2010. Molecular evidence for a diverse green algal community growing in the hair of sloths and a specific association with Trichophilus welckeri (Chlorophyta, Ulvophyceae).10:86
Taube, E. et al. 2001. Reproductive biology and postnatal development in sloths, Bradypus and Cholepus: review with original data frm the field (French Guiana) and from captivity. Mammal Rev. 31:3:173-188
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