Pygmy three-toed sloth  (Bradypus pygmaeus)

With only a small population confined to a single tiny island off the coast of Panama, the pygmy three-toed sloth is the most endangered of all Xenarthra. As its name suggests, this recently discovered species is a dwarf compared with its mainland relatives (4). In addition to its small size, the pygmy three-toed sloth is characterised by usually blotchy, pale grey-brown fur and a tan-coloured face with a distinctive dark band across the forehead, from which long, shaggy hair hangs over the face, giving a hooded appearance. Sloths have an unusual means of camouflage to avoid predation; their outer fur is often coated in algae, giving the pelage a greenish tint that helps hide 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, peg-like teeth (3).

Known only from Isla Escudo de Veraguas in the archipelago of Bocas del Toro, Panama (1) (3).

Known exclusively in red mangrove forests surrounding the island at near sea level (1) (3).

Very little is known about the biology of the pygmy three-toed sloth, although much can be inferred from what is known about three-toed sloths generally. Three-toed sloths are arboreal folivores that eat the leaves of a variety of trees. This is an energy-poor diet, and these animals have a very low metabolic rate (3). Their main defences are camouflage, stealth and stillness, whereby they avoid predation largely by avoiding detection (3) (5). However, should they be attacked, sloths also have a remarkable capacity to survive due to their tough hides, tenacious grips and extraordinary ability to heal from grievous wounds (5).

The pygmy three-toed sloth has an extremely restricted range on one very small island. Although the island is uninhabited, fishermen, farmers, lobster divers and local people are all seasonal visitors, and are thought to hunt the sloths illegally. The growing tourism industry is also a potential threat to the species, by degrading its habitat (1).

Isla Escudo de Veraguas is protected as a wildlife refuge and is contained within the Comarca Indigenous Reserve. However, law enforcement within this protected area is currently inadequate, and needs to be improved (1).

For more information on the pygmy three-toed sloth see:

• Anderson, R.P. and Handley Jr., C.O. (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): 1 - 33.

Reviewed (23/02/2007) by Robert, P. Anderson, Assistant Professor, Department of Biology, City College of New York, and Research Associate, American Museum of Natural History.
http://web.sci.ccny.cuny.edu/~anderson/