Brownthroated threetoed sloth

Bradypus variegatus


Bradypus variegatus Schinz, 1825, Brazil. The genus name Bradypus comes from the Greek bradus for "slow" and pous, for "foot," podos.


Portuguese: Preguica-de-bentinho (Brazil); Spanish: Perezoso de tres dedos (European Spanish), perico (Bolivia, Colombia, Ecuador), pelejo (Peru).


Color varies over wide geographical range, long coarse body fur brownish gray with white patches on hindlegs and lower part of back. Extent of white patches highly variable, some populations are nearly all white. Others are a deep foxy red-brown. Fur may have a greenish tinge due to algae. Fur on head shorter and denser. Head with a black "mask" across the eyes extending back to the ear region (ears are hidden in fur and not easily visible). Throat and chest brown. Adult males have a "speculum," a patch of short deep orange fur between the shoulder blades that is bisected by one of more deep brown-black horizontal lines. Distinguished from the two-toed sloth by the number of forefoot claws and a shorter dark muzzle (bigger, paler and more pig-like in Choloepus).


Southern Mexico to northern Argentina, to elevations of at least 3,610 ft (1,100 m).


Evergreen and seasonally dry forests. A natural tolerance of disturbance and secondary growth also allows them to survive in isolated trees in deforested pastures, and even in city parks.


Active at any time of day, though generally more active at night. Drops its body temperature each night (an energy-conserving strategy) and must warm up each morning by basking. This is the time when harpy eagle predation most frequently occurs. When not basking or feeding, likely to be sleeping curled up in a ball in the crook of a tree. Hard to see under such circumstances. Spends up to 18 hours a day asleep to conserve energy. Adults are solitary but home ranges may overlap. Neighbors rarely feed in the same tree, and males may fight each other. Individuals may spend many days in the same tree, and can pass their entire 20- to 30-year life span in home ranges of less than 4.9 acres (2 ha). One of the most common animals in the South American rainforest, Bradypus sloths can occur at densities of six or seven per 2.5 acre (1 ha). When not hanging suspended, may rest in a fork of a branch with head between forelimbs. May be very difficult to see under such conditions. Vocalizations, a shrill whistle and a low reptilian hiss, are given only under duress. The shrill "ai, ai" sounds whistled through the nostrils, are the basis for the name for this animal in the indigenous Guarani language.


Within home range, a sloth may use up to fifty trees of thirty different species. To avoid toxification by the tannins, phenols and other chemicals in the leaves it ingests, sloths change trees (and tree species) on average once every 1.5 days. Passage of food through the gut is measured in days, rather than the hours usual for most mammals. This is necessary to extract all possible energy from the low-quality forage. Diet preferences are inherited from mother during several months of a "social weaning" process. Since these differ considerably, several sloths may coexist in the same area, but not compete.


Breeding occurs throughout the year. A single young is born, though twins have been reported once or twice. Gestation is 5 to 6 months. Young weigh 0.44-0.55 lb (0.20-0.25 kg) at birth. Young are weaned within 4 weeks, but are carried by the mother for another five months. Babies are carried resting on their mother's abdomen, graduating to dorsal carriage as they get older and larger. Once the young has learned the location of the trees in the maternal patch, the female leaves, bequeathing the young one all or part of her foraging area. This highly unusual arrangement is thought to minimize energetically wasteful conflict between individuals. Probably polygynous.


CITES Appendix II. Not threatened.


Hunted for meat in certain parts of their range. ♦

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