Sloth Kukang

Sloth bones and claws

All four species of ground sloth had very large claws and small, blunt teeth. They all were herbivores and probably used the teeth for browsing on trees and shrubs. The shape of their hip bones indicates that they could stand up on their hind legs. This would allow them to reach high up into trees for the best leaves and twigs.

The bone on the left is the finger bone (phalanx) that supports the claw on the thumb of a Jefferson's ground sloth. The specimen on the right is a tooth, also from a Jefferson's ground sloth.

Both of these specimens were recovered from Heinze Cave, Jefferson County, Missouri. Radiocarbon dating indicates that both specimens are more than 40,000 years old.

All four species of ground sloth became extinct in North America approximately 10,000 years ago. The reason for their extinction is being studied by paleontologists.

Conservation Status of Sloths and Sloth Bears

IUCN is the International Union for Conservation of Nature. Under their Red List of Threatened Species, sloth bears are listed as vulnerable as of 2016 during their last assessment. Their population is decreasing, with an estimated of fewer than 20,000 individuals spread across the Indian subcontinent.

Some sloth species are in a similar situation; IUCN has the Maned Sloth listed as vulnerable with the population decreasing. Pygmy Sloths are listed as critically endangered, with a population size of around 2,000-2,500 individuals.

The Brown-Throated Sloth is listed as Least Concern, though there is evidence indicating the population is decreasing as well; for this reason, it is urgent to determine the species’ population trends.

Reconstruction of Harlan's Ground Sloth

Harlan's ground sloth is reconstructed as looking quite similar to Jefferson's, but was a grazing form. This reconstruction of a Harlan's ground sloth is in the museum at Mastodon State Historic Site near Kimmswick, Missouri. The Historic Site is located at the Kimmswick Site. This archaeological site is one of the most intriguing sites known dating from the time of the Clovis people.

Evidence found at the Kimmswick Site has been used by some researchers to suggest that the Clovis People may have used the hides of the Harlan's ground sloth (Graham and Kay, 1988).

Ground sloths were large relatives of the modern two-toed sloths (Choloepus spp.) and three-toed sloths (Bradypus spp.). Unlike modern sloths, which spend most of their time in trees, the ground sloths spent all of their time on the ground. This is fortunate because Jefferson's and Harlan's ground sloth were each about the size of an ox.

Sloth bears….and sloths and bears

Sloth bears got their name in 1791 by English zoologist George Shaw, who encountered the bear and believed the species was related to actual sloths since they shared similar traits, naming them “bear sloths”. Shaw named them Bradypus ursinus, which means something like ‘slow feet bear,’ using the family name of three-fingered sloths, the Genus Bradypus.

The sloth bear goes by many different names throughout the region depending on the language, and once Europeans got involved, the name changed once again. Confusion over whether the bear is a bear or a sloth made it challenging for scientists to classify it under the Latin-based binomial naming system. Once it was indeed determined that it was a bear, they changed the Genus but kept the common name, so “bear sloth” changed to “sloth bear.”

The modern scientific name of the sloth bear, Melursus ursinus, combines Greek and Latin elements. “Melursus” is derived from the Greek “melas” (meaning “black”) and the Latin “ursus” (meaning “bear”), referring to the bear’s dark fur. The specific name “ursinus,” from Latin, translates to “bear-like.”

To add more confusion to the subject, the most common name for sloths in Latin America is ‘oso perezoso’, which means, as you might guess, sloth bear.

What do sloth bears eat?

Despite being in the order Carnivora, sloth bears are myrmecophagous, meaning they consume termites and ants. Occasionally, during monsoon season, they are known to dine on fruit in trees such as mango, fig, ebony, etc., as well as flowers. Termites, ants, beetles, and other insects are also of interest to sloth bears year-round, and they are 95% of their diet.

Aside from digging out mounds, they are capable climbers and can climb trees to knock down honeycombs to collect the honey from the ground.

Scientists study sloth bears around India through GPS collars that communicate through satellites and allow them to collect data from the exact location of the animals at any given time. Scientists have studied and collected data on sloth bear attacks, threats to sloth bears, sloth bear denning, relocation of sloth bears, and sloth bear densities. The sloth bear is the least studied and understood bear in the Indian subcontinent.

Here at SloCo, we similarly study sloths through VHF/GPS collars, backpacks, and data loggers. VHF and GPS collars allow scientists to locate sloths and collect information about the sloth and its habitat.

The overall goal of scientists studying sloths is the same for sloth bears: to ensure long-term survival, conservation, and coexistence.

What is a sloth bear?

A Sloth bear is a type of bear species native to India, Sri Lanka, Nepal, and Bhutan. Known for its long snout and long lower lip used for sucking up insects, it’s officially named Melursus ursinus. Despite the name referring to them as ‘lazy’, sloth bears are anything but lazy!

These bears have a distinctive shaggy black coat with a whitish-yellow ‘U’ or ‘Y’ shaped mark on their chest. And although they share a resemblance, sloth bears should not be confused with the Asian Black Bear (Ursus thibetanus)

Finally, sloth bears! We seized the opportunity to compare sloths and sloth bears to clarify the confusion surrounding their common names and delve into their lifestyles, the threats they face, and ways we can help in their conservation!

Sloth Ranges, Then and Now

This map shows some of the important ground sloth finds in the region. Green dots represent Jefferson's ground sloth finds, and yellow triangles represent Harlan's ground sloth finds.

More information on Ground Sloths can be found at the La Brea Tarpits Web site, and at the Academy of Natural Sciences Museum.

How Slothy are Sloth Bears?

Sloth bears adapt their sleep cycle to their environment, which may be a nocturnal, diurnal, or crepuscular schedule depending on other bears, people, or predators in their habitat. Sloth bears may forage for food at night and sleep during the day to avoid potential conflicts with humans. They typically sleep 10 to 14 hours a day and do not hibernate.

Sloths, contrary to popular belief, do not sleep more than the average 10 to 12 hours, and from our last published research, we know that their activity varies depending on the individual and even differs across the same population; some sloths are more diurnal, others nocturnal.

What can we do to protect both species?

These extraordinary creatures’ continued existence hinges significantly on our actions today. This involves adopting more sustainable farming practices and endorsing conservation initiatives that safeguard the natural habitats of these animals from further degradation.

You can support organizations working with this species, like Wildlife SOS, founded in 1995; it has a strong track record in India for rescuing wildlife in distress, including sloth bears, elephants, leopards, and others. Free the Bears is an organization that works to rescue and rehabilitate bears in various Asian countries.

Four species of ground sloths inhabited the United States at the end of the last Ice Age. These were Jefferson's ground sloth (Megalonyx jeffersonii), Laurillard's ground sloth (Eremotherium laurillardi), the Shasta ground sloth (Nothrotheriops shastensis), and Harlan's ground sloth (Glossotherium harlani). Of these four only two, Jefferson's and Harlan's ground sloths, are found in the midwestern U.S.

Ground sloths were large relatives of the modern two-toed sloths (Choloepus spp.) and three-toed sloths (Bradypus spp.). Unlike modern sloths, which spend most of their time in trees, the ground sloths spent all of their time on the ground. This is fortunate because Jefferson's and Harlan's ground sloth were each about the size of an oxen.

All four species of ground sloth had very large claws. However, all were herbivores. They had relatively small, blunt teeth, which they probably used for browsing on trees and shrubs. The shape of their hip bones indicates that they could stand up on their hind legs. This would allow them to reach high up into trees for the best leaves and twigs.

The picture above shows a reconstruction of Jefferson's ground sloth from the University of Iowa Museum of Natural History.