CORPUS CHRISTI, Texas — Workers over at the Texas State Aquarium are mourning as they announced the loss of a very special resident. Chico, their Linnaeus' two-toed sloth, died Tuesday morning. Sloth themed cake with a personalized NR Treats cake topper for a very special birthday girl!拾.

Happy International Sloth Day! In addition to my role as a Digital Imaging Technician, I am also an avid and self-professed lover of sloths. As such, that also means I find myself advocating for this often-misunderstood animal. And there is no better day than today to spread the slothfulness word far and wide by seeing what I could find within our own collections. I learned about the past and present roles the Smithsonian has played in studying and caring for sloths.

First, a few facts about sloths. While I first fell in love with them about two years ago by disappearing down a sloth-based YouTube rabbit hole, I soon graduated from adoring their fixed smiles and instinct to hug to wanting to learn everything I could about their unique biology and evolution story. Presently, there are two families of sloths—two-toed (Choloepus) and three-toed (Bradypus). This is a misleading name as all sloths have three toes on their rear limbs. They are distinguishable by the number of “fingers” they have on their forelimbs. Between the two families are six different species of sloth.

Wild sloths can be found mainly in the tropical rainforests of Central and South America. Their natural state involves being suspended upside down from a tree, and they only descend to the jungle floor when they need to use the bathroom (the reasons why have still not been fully figured out by scientists). Their diet as tree-dwellers naturally consists primarily of tree leaves and their favorite snack, hibiscus flowers. This low-nutrient diet, combined with the slowest metabolism of any mammal (three-toed sloths have the slowest, followed by the giant panda, and then two-toed sloths) are the main causes of their supposedly “lazy” disposition. Sloths have evolved, unlike so many other animals, to consume less and therefore move less. They can survive on around only 100 calories a day! All movement is done with purpose and care to avoid using up precious energy stores. Being leaders in energy conservation has gifted them various survival advantages. Their extremely low metabolism means they only have to use the bathroom (i.e. leaving the safety of the trees) about once a week. Their lack of movement, along with the humid tropical climate they call home, promotes symbiotic algae growth on their thick fur, which aids in camouflage protection from predators. Ironically, due to not moving much at all, sloths can evade attack since most predators (in a sloth’s case, jaguars and eagles) are often focused on signs of movement to spot their prey.

In addition to natural threats, increased human activity has also proved detrimental to the sloth. Human-based threats they face include deforestation, electrocution from hanging wires, being hit by cars, and animal trafficking for the exotic pet trade. Their photogenic faces and increasing popularity on social media can be a double-edged sword as sloths are often captured from the wild and used for exploitative purposes in the ecotourism industry. To remedy these human-generated issues, there are many organizations in the countries where sloths live and internationally that are dedicated to the care, rehabilitation, and re-release of wild sloths into the rainforest.

The Smithsonian’s National Zoo in Washington, D.C. currently cares for two adult male two-toed sloths, Howie and Vlad, and their newest addition, Athena, a young female two-toed sloth that was debuted just last year. I hope you get a chance to visit them (Athena and Vlad live in the Small Mammal House; Howie in Amazonia), and you can also catch videos of them on the Zoo’s social media.

The Smithsonian has a long history of studying, caring for, and educating the public about sloths, both past and present! In the late 1800s, the United States National Museum (USNM) displayed skeletal remains of various extinct giant sloth species that used to roam North and South America. The curators annual report for the USNM Department of Mammals for 1885-1886 describes the placement of sloth bones and two sloth specimens for public exhibition. A similar report covering 1894-1895 describes a chestnut-headed sloth as “one of the laziest of mammals.” Geez, that’s harsh!

Then there is the famous (infamous?) Megatherium Club – an informal group of nineteenth- century Smithsonian naturalists who were known for working hard and playing hard. The name Megatherium refers to an extinct species of ground sloth. It is the largest sloth species ever discovered with a size equivalent to that of a modern elephant! This topic has already been extensively covered by my colleagues in past blog posts and an online exhibit, which I encourage you to check out.

Records show that the first living sloths at the National Zoo were introduced around 1900. In 1942, USNM Assistant Director A. Remington Kellogg and Smithsonian field collector Watson M. Perrygo travelled to the American Southwest to collect fossil specimens of large ground sloth species that roamed North America until about 11,000 years ago. Details of their travels and efforts are described in their field books. In a 1940 field book, sixth Secretary of the Smithsonian and ornithologist Alexander Wetmore describes excavating sloth bones in Costa Rica. In a photo album from 1963 from when he was working in Panama, Wetmore describes and includes a photograph of a two-toed sloth that decided to visit the camp site one evening!

In some of our more recent collections (mid-twentieth century to present), there are many references to Smithsonian staff caring for sloths and studying and documenting their behavior. In the mid-1960s, National Zoological Park zoologist Marion P. McCrane became the first person ever to successfully hand-rear a two-toed sloth, which included having the baby sloth attached to her for long periods of time, reminiscent of the months that baby sloths remain attached to their mothers in the wild. She later published her experiences to assist those who might find themselves in a similar situation in the future. From 1971-1977, resident scientist at the Zoo John F. Eisenberg directed a long-term project on sloth research in Panama.

During her nearly 30-year career as a biologist with the Zoo, Dr. Devra Kleiman dedicated her professional career to researching animal behavior, most famously in her work with giant pandas and golden lion tamarins. An extensive documenter of her work in both written and audiovisual formats, Kleiman also participated in several field studies from the 1970s through the mid-2000s. Some of her field books from these trips can be viewed in the Smithsonian Transcription Center. They describe her time spent in Brazil and the Peruvian Amazon, including her observations of wild sloths, efforts to track and collar them, and collect medical information. It’s not always dry research data though—on a few occasions she describes finding sloths that had climbed their way into her bunkbed!

The Smithsonian Tropical Research Institute (STRI) in Panama is also very active in the scientific study of sloths, which only makes sense given its geographic location. Some of STRI’s recent topics in sloth research include the potential uses of fungi that grows on sloth hair to treat cancer and tropical diseases like malaria. Another research area is studying the symbiotic relationships between sloths and the multiple species of moths and other insects that have evolved specifically to live on sloths.

There’s still a lot we don’t know about sloths. More research remains to be done to fully understand sloths’ physiology and behavior. But at least we can say we’ve come a long way from considering them “one of the laziest of mammals,” right?

Sloths made the evolutionary decision to consume less and therefore do less, accepting all the advantages and disadvantages that came along with it. Consequently, they have carved out a niche for themselves in today’s animal kingdom, which has suited them well. I hope this has been an entertaining and educational introduction to this fascinating and unique animal!

RELATED COLLECTIONS

• Watson M. Perrygo Papers, circa 1880s-1979, Record Unit 7306, Smithsonian Institution Archives
• Smithsonian Institution, National Museum of Natural History, Department of Paleobiology Collection, Remington Kellogg field books, 1918-1942
• National Zoological Park. Department of Zoological Research, Animal Research Records, 1969-1979, Accession 08-045, Smithsonian Institution Archives
• John F. Eisenberg Papers, circa 1960-1982 and undated, Record Unit 7411, Smithsonian Institution Archives
• Marion P. McCrane Papers, 1962-1989, Accession 01-157, Smithsonian Institution Archives
• United States National Museum, Curators’ Annual Reports, 1881-1964, Record Unit 158, Smithsonian Institution Archives

RELATED RESOURCES

• “The Archival Legacy of Devra Kleiman,” by Jennifer Wright, The Bigger Picture, Smithsonian Institution Archives
• “The Megatherium Club,” Featured Topics, Smithsonian Institution Archives
• “The Mischievous Megatherium Club: After Hours,” by Candice Driver, The Bigger Picture, Smithsonian Institution Archives
• “The Substitute Mother,” by Jennifer Wright, The Bigger Picture, Smithsonian Institution Archives

Bears are a curious subject. On the one hand, they look adorable, but on the other hand, they are capable of such destruction that approaching a real live bear is almost never wise.

In Sri Lanka, as well as around the world, despite looking cuddly in photos, bears are very cautiously approached in real life. The chances of surviving being mauled by a bear are slim, and even if you do survive, you could end up blinded, disfigured, or losing a limb or two. Despite this, when looking at human-bear conflict, it is most often the bears who end up dying.

Sri Lanka has its own endemic subspecies of the sloth bear. The Sri Lankan sloth bear is small-sized and is fairly specialised, with long steel-like claws they use to break the termite mounds, their jaws don’t have incisors, and their snouts enable them to suck ants of these termite mounds easily.

The International Union for Conservation of Nature (IUCN), the global authority on the status of the natural world and the measures needed to safeguard it, deemed the sloth bear to be a vulnerable species in 2004. Despite this, research suggests that sloth bear populations are still declining.

So what is happening with these mysterious creatures? Why are they declining and what can we do about it?

The Sri Lankan sloth bear

There have been confrontations and deadly fights recorded between sloth bears, but mainly they avoid physical conflict. Leopards especially avoid conflict because they need to hunt to survive and can’t afford to get injured.” Naturalist and Environmental Foundation Ltd. (EFL) Director Rukshan Jayawardene

The sloth bear is a South Asian bear that can easily be confused with other bears despite its smaller size, especially in India which has three species of bear – the Asiatic black bear, the sloth bear, and the sun bear. The sloth bear is also found in Bangladesh (though they are possibly extinct there), Bhutan, India, Nepal, and Sri Lanka.

Though not endangered, the sloth bear is a vulnerable creature, which means that care needs to be taken in conserving populations. Omnivorous, sloth bears do not actively hunt, preferring to scavenge, and sometimes taking over kills from leopards, especially female leopards.

Naturalist and Environmental Foundation Ltd. (EFL) Director Rukshan Jayawardene shared that leopards and sloth bears have somewhat of a messy co-existence.

“There have been confrontations and deadly fights recorded between sloth bears,” Jayawardene said, adding: “But mainly they avoid physical conflict. Leopards especially avoid conflict because they need to hunt to survive and can’t afford to get injured.”

The threats faced by sloth bears

A Sloth

From a natural standpoint, the Sri Lankan sloth bear doesn’t have any major threats. “In Sri Lanka, the sloth bear has no enemies, “Jayawardene said. “The leopard is an enemy but it isn’t hunted. There is no record of young bears and cubs having been killed, though I feel it must be happening and we just don’t know about it. I’ve seen an unusual amount of interest from leopards in young bears. Predators like the leopard automatically react to small mammals like that. Although, in the case of sloth bears, they’re inseparable from their mothers for the first few months of life, so danger from leopards is relatively low because they’re under their mother’s protection,” explained Jayawardene.

The IUCN lists the main threats to sloth bears as habitat loss and poaching. In a Sri Lankan context, poaching is not a major threat to the sloth bear. Biodiversity Education and Research (BEAR) Founder and Principal Scientist Ranil P. Nanayakkara explained that habitat destruction and deforestation are the biggest threats the Sri Lankan sloth bear faces. “They are a species that prefers monsoon thick forest. They’re termite eaters and ant-eaters, food that is highly forested habitats. Habitat destruction is a major threat they face on a global scale.”

From a human perspective, Nanayakkara explained that the threat of people is there to a certain extent when people go into the forest to collect bee honey and firewood. “It’s not that common in Sri Lanka where people get mauled by sloth bears,” he said, adding: “It has a very keen sense of smell but comparatively poor hearing and eyesight, and they like to lie up in caves or under trees. It’s possible to unexpectedly come across them in deep slumber, and in this case, they either retreat or charge. Females with cubs are especially likely to charge.”

Jayawardene expanded on the impact that human interference can have on sloth bears. “They’re very intolerant of human disturbance in their forest habitats and withdraw from areas where humans are entering.” They don’t adjust to humans the way other animals like leopards do. They change to become less frequently seen in the wilderness where humans are present. The density of bears in a given area will reduce if you have human activity as opposed to where there is no human activity.”

Jayawardene also talked about the impact of firewood collection, explaining that it has a direct bearing on sloth bear populations. “Rotting wood forests are primarily the food of termites. If people are going into the forest and bringing out dead wood that termites convert into food, then termite activity will lessen and this will have a knock-down effect on the sloth bear population.”

Jayawardene and Nanayakkara both noted that poaching is not a major threat to sloth bears, because there is no real demand for their meat, fur, or teeth. However, poachers do frequently kill a sloth bear on sight for fear of attack, and finding sloth bear carcasses with gunshot wounds or that have been hacked to death by either poachers or villagers who have unexpectedly come across them is not uncommon.

The sloth bear and awareness: Why so mysterious?

“They’re often overlooked. This is one reason my research team at BEAR and I have been researching sloth bears for over 11 years. Even in terms of publicity too, leopards and elephants get a lot more attention” BEAR Founder and Principal Scientist Ranil P. Nanayakkara

Weighing in on awareness about sloth bears, Nanayakkara explained that sloth bears tend to fly under the radar because they’re not as charismatic a species as popular animals like elephants and leopards, especially when visiting national parks. “They’re often overlooked. This is one reason my research team at BEAR and I have been researching sloth bears for over 11

years,” Nanayakkara said. “Even in terms of publicity too, leopards and elephants get a lot more attention.”

Jayawardene shared the view that part of the aura of mystery that surrounds sloth bears is because there haven’t been enough comprehensive studies. This is in part because the sloth bear is such a shy animal who retreats from humans. “Bears are very unpredictable, which makes them hard to study. Leopards, for instance, have predictable timing and activities. If you leave them alone and are not affecting their daily routine, they’re actually very predictable. There is no discernible pattern with bears. Research poses a bit of a challenge. I don’t personally know of any instance of casual observers where they have seen a bear cub playing in the absence of their mother, for example. I’ve seen bear cubs with their mothers but these have always been fairly brief sightings. Because it’s a difficult animal to observe, there is not enough knowledge.”

Protecting the Sri Lankan sloth bear

When it comes to conservation, the elusiveness of the sloth bear becomes a challenge. The actual population of sloth bears in Sri Lanka is not confirmed. Through his research with BEAR, Nanayakkara has identified 61 individual bears within the Wilpattu National Park. Nanayakkara stressed the importance of safe spaces when it comes to conservation.

A Sloth Treats A Sloth Coloring Page

“The main thing is to have protected areas like Wilpattu, Wasgamuwa, and so on,” Nanayakkara explained. “But they need to dry monsoon forests to survive because their diet consists of insects like termites and ants. A lack of that will cause an imbalance, and we don’t know what defects that will bring about,” he said, adding that the research BEAR carries out looks to be able to inform sustainable and measurable conservation management plans on bears in the long term.

Jayawardene also highlighted the need for more research, stressing that conservation cannot take place blindly based on assumptions – we need to know why sloth bears are declining and map the reasons for this. “We can’t do anything serious to conserve the sloth bear other than things we do to conserve animals within protected areas. I would urge the Department of Wildlife Conservation to try and understand what ails sloth bears and why they specifically are declining when other animals don’t seem to be affected.”

Looking to the future

The Sri Lankan sloth bear is endemic to Sri Lanka and while not as charismatic as the other animals Sri Lanka is known for, is evidently a unique animal with a lot of depth. Despite its elusive nature, it’s vital that we protect the sloth bear.

Globally, the IUCN notes there are likely less than 1,000 sloth bears in the wild, which rightly enough makes it an animal that is vulnerable to becoming endangered and possibly even dying out. They are part of the vast natural resource that makes Sri Lanka a force to be reckoned with on the world map. Do we really want to imagine a Sri Lanka without bears?

Photos by Ranil P. Nanayakkara