Brown-throated Sloth: where and when to see them

The brown-throated sloth is a three-toed sloth of Central and South American forests, including both lowland coasts of Costa Rica. Its slow movements, rounded face and shaggy coat make it distinctive, yet remarkably easy to overlook among leaves. Greenish algae growing on the fur can strengthen its resemblance to surrounding vegetation. Although globally widespread, it is vulnerable locally to forest fragmentation, road traffic, dog attacks and electrocution while moving between disconnected patches of canopy.

Size

42-80 cm body length

Weight

2.3-5.5 kg

Lifespan

Not reliably established

Status

Least Concern

Brown-throated sloths spend most of their lives suspended from branches, resting and feeding within relatively small areas. Activity occurs during both day and night and varies with weather, temperature and individual routine. They conserve energy through slow movement and a low metabolic rate rather than sleeping continuously. Mothers carry dependent young against the body as they travel. Adults descend infrequently to defecate, when ground-level hazards become especially important, and they can swim when necessary. They maintain a stable body temperature using behavioral thermoregulation, often sunning themselves or moving into cooler shade as needed. Despite their generally solitary nature, mothers and young exhibit a strong, prolonged bond during the offspring's first year.

• Males have an orange-yellow back patch marked with a dark central stripe.
• Algae can grow within the specialized structure of its outer hairs.
• Its forelimbs have three claws, unlike those of two-toed sloths.
• Despite its slow movement in trees, it is capable of swimming.

Sloths are resident and can be observed throughout the year where suitable forest remains. December through April generally offers easier walking on Costa Rica's Pacific side, while Caribbean rainfall follows a different pattern. Guide skill, canopy visibility and recent animal movements matter more than a single seasonal peak. While sloths are visible year-round, experienced local guides are invaluable for locating these camouflaged animals, regardless of the month. Their slow movements mean they often stay in a general area for extended periods, which can aid in repeat sightings.

Lowland and foothill tropical forests, secondary woodland and connected wooded landscapes provide habitat. In Costa Rica, coastal forest can support animals close to established trails, but canopy continuity matters. Isolated ornamental trees may expose sloths to dangerous ground crossings, dogs, vehicles and electrical infrastructure. They are highly arboreal, rarely descending from the canopy, preferring dense, well-connected tree cover over fragmented patches. A healthy understory and mid-story provide crucial food sources and cover for their specific dietary needs.

Leaves form the bulk of the diet, with tender shoots and some flowers or fruit also eaten. Individuals select particular tree species rather than consuming every available leaf. A specialized, multi-chambered stomach and microbial fermentation help process fibrous food, but digestion is very slow. Despite their slow metabolism, adult sloths can consume a considerable volume of leaves daily relative to their body weight. Their diet is low in calories, which further contributes to their sedentary lifestyle.

Common name

Brown-throated Sloth

Scientific name

Bradypus variegatus

Animal group

Mammals

Size

42-80 cm body length

Weight

2.3-5.5 kg

Lifespan

Not reliably established

Status

Least Concern

Identification

Three claws on each forelimb, a dark eye mask and a brown throat distinguish this species from Costa Rica's larger, longer-faced Hoffmann's two-toed sloth. The brown-throated sloth typically has a more rounded head and a distinct, darker brown patch on its throat, which is absent in the two-toed sloth. Males also possess a dorsal speculum, a bright orange patch with a black central stripe on their back, not present in females or other species.