Species of the Week SPECIAL EDITION: Pygmy Three-Toed Sloth

The pygmy three-toed sloth was officially recognised as a distinct species in 2001. Along with armadillos and anteaters, sloths are members of the superorder Xenarthra, and today there are six living species from two genera: Bradypus (three-toed sloths) and Choloepus (two-toed sloths).

Pygmy three-toed sloths are sadly only found on Escudo de Veraguas, a very small island 17km off the coast of Panama which has been separated from the mainland for around 9,000 years because of the rise in sea levels after the last Ice Age. As a result of the long-term isolation the sloths underwent an extremely rapid body size change, and they are now the smallest sloth in the world. Most people would recognise the typical brown and hairy sloth face, but interestingly unlike other species adult males all have two bright orange patches on their back.

Pygmy sloths are the only known animals to use Trichophilus algae to avoid predation: green-coloured fur can hide them amid the trees. This alga begins to grow when they are young and is probably transferred from mother to child. Sloths survive attacks from predators with tough skins, strong grips and a remarkable ability to heal quickly.

It is very difficult for pygmy three-toed sloths to move along on the ground, but their hands and feet have curved claws that allow them to hang onto trees, where they are much more comfortable. Sloths usually only descend to the ground for toilet purposes and amazingly can halt their bowel movements for up to a week!

Pygmy sloths can turn their head approximately 270 degrees horizontally without having to move the rest of their body, and strangely their hair grows in the opposite direction of the hair of most animals, so water drips off their coat when they are upside down. Pygmy sloths have small home ranges of about 1.6 hectares, and live a solitary life except during the mating season. Females are assumed to be pregnant for 4-7 months like other three-toed sloths, and they look after their single baby for up to one year after giving birth. The pygmy three-toed sloths only feed on the leaves of red mangrove trees, which cover approximately 1.5 sq km of Escudo Island.

The sloths' red mangrove habitat on Escudo

This species is classified as Critically Endangered on the 2011 IUCN Red List, and there is evidence to suggest that just in the last decade they have suffered an 80% population loss.

The most serious threat to the pygmy three-toed sloth is the destruction of their mangroves: there has been cutting of trees on Escudo for local livelihoods and to make space for human residents. If more people move to the island, this deforestation will only increase. Escudo is a protected area within the Ngöbe-Buglé Comarca, which means the local people have strong governing power, but this may not be enough to protect the remaining population of pygmy sloths.

David Curnick holding a pygmy sloth

Two ZSL EDGE scientists (Dr Craig Turner and Mr David Curnick) went to Escudo in March this year to carry out a thorough population census of the pygmy sloths, and conduct an investigation into their ecology and health. They have just submitted a paper on their findings and have released some exclusive photographs of the sloths they encountered on the island.

Learn more about the EDGE Campaign for the pygmy three-toed sloth.

We need YOUR help to implement long-term conservation actions for this unique species!

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