# Sloth — Facts, Threats & Conservation

*Bradypus & Choloepus spp.*

> A sloth is a slow-moving, leaf-eating mammal that lives hanging upside down in the trees of Central and South American rainforests. There are six living species in two groups, the three-toed sloths (Bradypus) and two-toed sloths (Choloepus), and they are the slowest mammals on Earth.

**IUCN status:** Mixed across species: most Least Concern; maned sloth Endangered; pygmy three-toed sloth Critically Endangered  ·  **WARN range:** Brazil, Colombia

## Quick facts
| Fact | Value |
| --- | --- |
| Lifespan | ~16 years median in care; some two-toed sloths reach 30-49 years |
| Weight | Two-toed ~4-9 kg (9-20 lb); three-toed ~3.5-6 kg |
| Length | ~50-75 cm (about 20-30 in) |
| Diet | Folivore; leaves and buds (two-toed also fruit, occasionally small animals) |
| Gestation | Three-toed ~6 months; two-toed ~10-12 months |
| Young per birth | Usually a single cub |
| Top speed | ~3 m per minute on the ground (slowest mammal); faster swimming |
| Baby name | Cub or pup |
| Group name | Largely solitary; no standard collective noun |
| CITES | Bradypus and Choloepus species listed on CITES Appendix II |

## Scientific classification
- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Mammalia
- **Order:** Pilosa
- **Suborder:** Folivora (sloths)
- **Families:** Bradypodidae (three-toed) and Choloepodidae (two-toed)
- **Genera:** Bradypus Linnaeus, 1758 and Choloepus Illiger, 1811
- **Species:** 6 living species (group entry, not a single species)

## Conservation status
- **Status:** Mixed by species: 4 of 6 living species Least Concern; maned sloth Endangered; pygmy three-toed sloth Critically Endangered
- **Population:** No single reliable total for all sloths; pygmy three-toed sloth estimated at only a few hundred to a few thousand individuals
- **Trend:** Stable for widespread species; decreasing for the threatened maned and pygmy three-toed sloths
- **Assessed:** 2022-2024 (species assessed individually by the IUCN)
- **CITES:** Appendix II (Bradypus and Choloepus species)
- The IUCN does not assess "sloth" as one taxon; each species has its own status, so a single category would be misleading.

## Key facts: Sloth
- "Sloth" covers six living species in two genera: three-toed sloths (Bradypus, four species) and two-toed sloths (Choloepus, two species).
- They are the slowest mammals on Earth, with a metabolism only 40-45% of what is expected for their size, an adaptation to a low-energy leaf diet.
- Their fur hosts symbiotic green algae and specialised sloth moths, giving older animals a greenish tinge that aids camouflage.
- Most sloth species are Least Concern, but the maned sloth (Bradypus torquatus) is Endangered and the pygmy three-toed sloth (Bradypus pygmaeus) is Critically Endangered.
- In Brazil and Colombia, the main pressures are Atlantic Forest loss, the illegal pet trade, and road and power-line deaths.
- Despite their slowness in trees, sloths are surprisingly capable swimmers and can hold their breath for long periods.

## What a sloth is and how it lives
Sloths belong to the order Pilosa, the same group as anteaters, and form the suborder Folivora ("leaf-eaters"). Six living species are recognised, divided between the three-toed sloths of the genus Bradypus and the two-toed sloths of the genus Choloepus. Despite the common names, all sloths have three toes on their hind limbs; the difference is in the forelimbs, where three-toed sloths have three front claws and two-toed sloths have two. They spend almost their whole lives suspended in the rainforest canopy, gripping branches with long, curved claws, and descend to the ground only about once a week, usually to defecate. Their leaf-heavy diet yields very little energy, so sloths conserve it through low body temperatures, long digestion times, and minimal movement.

## Behaviour, ecology and the algae in their fur
A sloth's slowness is its survival strategy. Moving little makes it almost invisible to predators such as harpy eagles and big cats that hunt by detecting movement. Their coarse outer fur grows the opposite way to most mammals, running from belly to back so rain sheds off while they hang upside down, and it provides a home for symbiotic green algae and specialised sloth moths. The algae can give the coat a greenish cast that improves camouflage and may even offer a minor nutritional supplement. Three-toed sloths are almost entirely leaf-eaters, while two-toed sloths are more omnivorous, also taking fruit and occasionally small animals. Both groups are surprisingly strong swimmers, using their long arms to cross rivers far faster than they ever move on land.

## Why some sloths are threatened
At the group level sloths are not assessed as a single unit, and four of the six living species are listed as Least Concern. The picture is far more serious for two species. The maned sloth (Bradypus torquatus), endemic to Brazil's heavily fragmented Atlantic Forest, is assessed as Endangered, with a small and declining area of suitable forest. The pygmy three-toed sloth (Bradypus pygmaeus) is Critically Endangered, restricted to a single tiny island off Panama with an estimated population of only a few hundred to a few thousand animals. Across the wider range, habitat loss, the illegal pet trade, electrocution on power lines, and road traffic are recurring threats, particularly where forest meets expanding towns and farmland.

## What sloth rescue involves
Rescue and rehabilitation work focuses on animals orphaned, injured, or seized from the illegal pet trade, as well as those electrocuted on power lines or hit by vehicles where forest is fragmented. Care is slow and specialised: sloths need precise diets, careful handling of stress-prone infants, and gradual reconditioning before any release into protected forest. Longer-term protection depends on keeping forest connected, installing wildlife crossings and insulating power lines, and reducing demand for sloths as pets and tourist photo props. Because so much sloth habitat lies in countries with limited conservation funding, local shelters and rescue teams are often the front line.

## Three-toed vs two-toed sloths
| Feature | Three-toed sloth (Bradypus) | Two-toed sloth (Choloepus) |
| --- | --- | --- |
| Front claws | Three on each forelimb | Two on each forelimb |
| Living species | Four | Two |
| Diet | Almost entirely leaves | More omnivorous: leaves, fruit, occasional small animals |
| Activity | Mainly active by day | Mainly active at night |
| Gestation | About 6 months | About 10-12 months |
| Most threatened member | Pygmy three-toed sloth (Critically Endangered) | Both Choloepus species currently Least Concern |

## What WARN does
The World Animal Rescue Network (WARN CIC) is a registered global not-for-profit animal welfare organisation that funds local partner shelters, sanctuaries and rescue teams rather than running its own facilities. Two of WARN's five focus countries, Brazil and Colombia, sit squarely within the sloth's range, where partners take in animals orphaned by deforestation, injured on roads and power lines, or confiscated from the illegal pet trade. WARN's funded focus is on supporting that hands-on local care, while its wider role is education and awareness, helping people understand why a wild sloth should never be kept as a pet or used as a tourist prop. WARN is honest that several sloth species also live beyond its five countries, where its contribution is information and advocacy rather than direct funding.

A donation to WARN helps fund the local partner shelters in Brazil and Colombia that rescue, treat and rehome sloths orphaned by deforestation or taken from the illegal pet trade.

## Frequently asked questions: Sloth
### How long do sloths live?
In human care, sloths typically live around 16 years, and some two-toed sloths have reached their 30s and 40s, with one recorded near 50. Reliable lifespans in the wild are not well documented but are thought to be shorter.

### What do sloths eat?
Sloths are mainly folivores, eating leaves, buds and shoots. Three-toed sloths eat almost only leaves, while two-toed sloths are more omnivorous and also take fruit and occasionally insects or small animals.

### How big are sloths?
Most sloths are roughly 50 to 75 cm (about 20 to 30 inches) long. Two-toed sloths usually weigh about 4 to 9 kg (9 to 20 lb); three-toed sloths are a little smaller, generally around 3.5 to 6 kg.

### Are sloths dangerous?
Sloths are not aggressive toward people and pose little danger, but they are wild animals with long, sharp claws and strong teeth that can inflict serious wounds if they feel threatened. They should never be handled as pets or for photos.

### How many sloths are left?
There is no single reliable total because "sloth" covers six species. Most are still widespread, but the pygmy three-toed sloth numbers only a few hundred to a few thousand on one island, and the maned sloth is Endangered with a small, declining range in Brazil.

### What is a baby sloth called and how are sloths grouped?
A baby sloth is called a cub or pup, born singly after a long gestation. Sloths are mostly solitary and have no widely used collective noun, though informal terms such as a "bed" of sloths are sometimes used.

## Sources
- [IUCN Red List - Bradypus variegatus (brown-throated three-toed sloth)](https://www.iucnredlist.org/species/3038/210442893)
- [IUCN Red List - Bradypus pygmaeus (pygmy three-toed sloth)](https://www.iucnredlist.org/species/61925/207941457)
- [IUCN Red List - Bradypus torquatus (maned sloth)](https://www.iucnredlist.org/species/3036/210442853)
- [IUCN SSC Anteater, Sloth and Armadillo Specialist Group](https://xenarthrans.org/species/sloths/)
- [Smithsonian's National Zoo - Two-toed sloth](https://nationalzoo.si.edu/animals/two-toed-sloth)
- [CITES species database](https://cites.org/eng/disc/species.php)
- [Britannica - Sloth](https://www.britannica.com/animal/sloth)

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Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/sloth