The Brown Throated Sloth (Bradypus variegatus)

brown throated sloth in a tree
Photo Credit



With its adorable super-hero style mask over its eyes, the Brown Throated Sloth is probably the one that most people think of when you tell them how much you LOVE sloths.

They have greyish brown to beige fur on their body, with darker brown fur on their throat, forehead and the sides of their face.

Their face is paler, with the well recognised dark strip running accross their eyes.

They have very cool haircuts. Their hair tends to form a fringe across their foreheads.

Males have an interesteing patch of short orange fur with a black strip and spots on their upper back. This is called a speculum. Females have long back hair with spots and stripes, but no orange colorings for the poor ladies.

The markings on their back are unique to each sloth, a bit like our fingerprints. This makes it much easier for researchers to identify individual sloths.

Their fur hangs backwards, to allow the water to run off them as they hang upside down from the trees.

Their fur is generally inhabited by a species of moth called Cryptoses choloepi (known as a sloth moth). This moth produces a fertile environment in the sloth’s coat which allows algae to grow. This can give the sloth a green tinge and a handy camouflage, but it also provides the sloth with a nutritious plant food growing right there on their back!

Arms and legs

As you can see in the picture, the Brown Throated Sloth is a three toed (or fingered) sloth. Both its forearms and hindlegs have three claws.

Their claws can grow to be 7-8 cm long on their hands, and 5 – 5.5 cm long on their feet.

Brown Throated Sloths have arms that are twice as long as their legs.


Both male and female brown throated sloths grow to about 42 – 80 cm in height. Adults weigh 2.25 – 6.3 kg (again – no difference between the boys and the girls).

Their heads are small in relation to their body and their mouth is an ever-appealing smile shape.

Skeletal features

They have a stumpy tail, about 4 inches (10cm) long.

Most mammals have 7 vertebrae, but three toed sloths have 9. This allows them a much greater rotation – they can turn their neck about 270 degrees. This comes in very handy when they’re going for a swim as it allows them to keep their head out of water much more easily. It also allows them to scan for predators, like harpy eagles and jaguars, without using too much energy in moving their body position.

Brown Throated Sloths have 12 sets of ribs (24 in total).


Brown throated sloths have no gall bladder, appendix or cecum.


Brown Throated sloths live in the neotropical ecozone of Central and South America. They can be found in Honduras, Nicaragua, Panama, Venezuela, Costa Rica, Bolivia, Ecuador, Brazil and eastern parts of Peru.

They can be found in a variety of environments. Dry forests and evergreen ones.

1200m (3,900ft) is about as high above sea level as they’ll get, but some adventurous individuals have been found up even higher.


Bradypus sloths are strict vegetarians and are pretty selective about which leaves they eat. Overall, they can eat up to 96 different types of leaves, but each individual sloth usually chooses from just 5 or 6 different tree species.

They are thought to change trees every couple of days.

Ten upper and eight lower molars, which are simple and peg like, help them slowly chew their leaves each day. They don’t have any incisors.


Brown throated sloths sleep between 15 to 18 hours each day. They are active for only brief periods of time.

They are solitary creatures who inhabit the high canopy of the forest and only come down to the ground about once a week to visit the lavatory. They don’t travel very far in their lifetimes – their range is about 0.5 to 9 ha (1.2 to 22.2 acres). Within a typical range, a sloth might visit 40 trees but it tends to specialise in one type – perhaps even spending one fifth of its time in that type of tree.

They are capable swimmers who are active in both the day time and the night time.

Mating and Breeding

Brown throated sloths have no external genitalia.

The female lets out a loud shrill scream during mating season to attract the boys. It apparently sounds like a woman screaming – an ‘AY AY’ sound.

The life expectancy of a Brown Throated Sloth is about 30 years, and both males and females reach sexual maturity at 3 years of age.

No one knows exactly – but they think that the gestation period is about six months.

A single baby is born, and hangs on to mom for the next 8 to 12 months. Baby learns how to select the right type of tree and mom passes on her preferences for specific trees to her offspring.

Babies are weaned at about 4-5 weeks, then they start learning about leaves by licking their mom’s mouth.

After about a year, mom moves far away from her baby, but stays within her territory.

Threats and Conservation

Brown Throated Sloths are classified as least concern, but some populations are threatened by the destruction of their habitat. In the Atlantic Forest of Brazil, for example, the Brown Throated Sloths have a very low genetic diversity and are at risk from hunting. In Colombia there is a growing illegal pet trade. These amazing fringed friends are also at risk from being killed on the roads.

Recommended Reading

Brown Throated Sloth – Wikipedia

World Land Trust

Sloth Sanctuary Costa Rica