Wildlife Wednesday: South America’s Brown-throated Sloth

Rainforest Trust

Nov 4, 2015


  • Brown-throated sloths are noted for their characteristic smiles. Photo by Stefan Laube

Think you’re overworked and sleep-deprived? Maybe you should take a tip from the brown-throated sloth. So laid-back that algae grows on their fur, these sloths are the epitome of taking it easy. They spend up to eight consecutive days hanging from trees, eating at their leisure, and sleeping up to 18 hours a day. Infrequent trips to the ground offer protection from predators. After all, why leave the canopy when you have all the leaves you can eat?

  • The green tinge to the sloth's fur is due to algae. Photo by Charlie Jackson

Despite its apparent laziness, the brown-throated sloth is highly adaptable, with the ability to swim and a hardiness that allows it to live in a variety of different ecosystems, from evergreen forests to highly disturbed natural areas. It is the most widespread and common of the three-toed sloths, ranging from Honduras to Brazil. Though it is common throughout Latin America, individuals seldom travel, usually occupying only 12 acres. As you can imagine, it took a long time for the sloth’s ancestors to spread throughout South America, considering the slow pace at which they move.

  • The brown-throated sloth's diet consists of leaves. Photo by Christian Mehlfuhrer

You may think a sloth’s life is dull, but things liven up between January and March. The usually solitary Brown-throated sloths come together during mating season. Their long claws are both useful for clinging to trees and as weapons when males skirmish. Even the females become rowdy, emitting shrill mating calls. Young cling to their mothers for five months or more, nursing until they are old enough to eat leaves.

Famed for their constant smiles, brown-throated sloths are cute, but don’t let that grin trick you. Under their soft fur are unique anatomical features that distinguish them from other species. They lack a gall bladder and appendix, but have large segmented stomachs and a slow metabolism, adaptations to a low nutrient diet. Instead of viewing sloths as lazy, we can admire them for their calculated expenditures of energy.