By the definition in the title of this article, I consider myself a close relative of the much-maligned, but ever-smiling Sloth. In Costa Rica they are known colloquially as lazy (lazy). In fact, if you come across one in the wild, your first impression is that they are perfect lazy bums. His movements are painfully slow, yet deliberate.

In 1749 the great French naturalist George-Louis Leclerc, Comte de Buffon made the most detailed description of the sloth up to that time. But he had never seen one alive! He described his long list of “faults” and concluded that they were “imperfect sketches of Nature,…imperfect and grotesque…”cast “[one more] defect added to the number would have totally prevented its existence…”. However, they are one of the most successful mammals on our planet. Here are some interesting facts about sloths:

• It takes them a month to digest their food, so 2/3 of their weight is in their stomach.
• Because they subsist solely on a diet of low-energy, hard-to-digest Cecropia leaves, their metabolic rate is low, but varies over a wide range. Your body temperature can change by 10 degrees F. in one day.
• Sloths sleep less than 10 hours a day, not 15 to 18 as was long believed.
• They come down from their tree once a week to defecate (they bury the feces). They rarely move from one tree to another.
• The common ancestor of the two-toed and three-toed sloth (both reside in Costa Rica) lived more than 35 million years ago, making the close resemblance of the two animals an excellent example of parallel evolution.

On the last day of a recent trip to the Caribbean side of Costa Rica, we were lucky enough to take the last tour of the day at the Aviarios Sloth Sanctuary north of Cahuita. We did it with a minute to spare, but needn’t have worried as we were the only people who showed up for that tour! We were taken to an auditorium with capacity for about 100 people where, alone, we watched a humorous 15-minute video about the life of the sloth.

Rebecca (Becky) Cliffe, a final year zoology student at the University of Manchester, England, was our guide for the land portion of the tour. We first visited 3 open pens for adult sloths, both two-toed and three-toed. They tend to stay in their open front “cages”, but even if they do manage to escape, they don’t get very far at the speed at which they move. Most cages held two or more sloths together, sometimes shared by two different species. They are normally completely solitary animals in the wild, but because some arrived at the sanctuary at a very young age, they bonded with other residents in no time.

Our next stop was the Sloth Nursery where the youngest animals begin their rehabilitation. Sloths have several predators to worry about, including eagles and jaguars, but the majority of documented injuries and deaths occur due to power lines or poaching. Sometimes the wrong locals keep babies as pets. Since keeping sloths as pets is illegal in Costa Rica, if the police find out, they confiscate the animal and take it to Aviarios.

I don’t think there is anything cuter than a lazy baby. They are simply adorable. The little ones usually sleep together, clinging to each other’s fur. Some have their own stuffed toys that they have bonded with. A two-fingered boy named Ubu receives physical therapy every day from Becky for his two hind legs, which are partially paralyzed. The treatment seems to be doing some good.

All of the sloths in the nursery have a wonderful golden brown coat color, which is not the dull gray and green of wild sloths. The reason for their repellent appearance in the wild is that sloths carry an entire “ecosystem” in their fur consisting of two types of symbiotic cyanobacteria (responsible for the greenish tint) plus a host of other non-parasitic insects. There is a species of moth whose entire life cycle depends entirely on the environment of a sloth’s fur. In exchange for providing a home for these other organisms, sloths receive camouflage and resistance to skin diseases like mange.

However, these bacteria and insects do not survive when a sloth is kept in captivity and bathed. Resistance to scabies and other diseases cannot be replaced by antibiotics, since sloths have a fatal reaction to such drugs. So, to replace the “ecosystem” of their fur, a mix of achiote (annatto) and coconut oil is used on his coat daily. This is what gives the baby sloths in Aviaries their strikingly beautiful color.

By the way, if you’re wondering why sloths come down from their trees to poop (I know you were!), well so is Becky. In fact, while she volunteers at Aviarios she is also working on her Ph.D. in Zoology, whose thesis will be that defecation is a key part of her mating process. In the year that she has been at the center, she has collected a large number of observations of sloths in the wild that support her theory.

After the tour of the land facilities (an excellent cafe and gift shop on the second floor, by the way), we were given a canoe tour of the canals on the east side of the property. Dark, mysterious green canals surround the central island. We all kept our comments to a minimum and to whispers so as not to scare away wildlife. we saw one congo monkey (howler monkey) crashing through the trees, a small bat hanging under a broken tree inches from our noses, and a variety of fish in the cool, slightly murky water.

In more open water we saw many birds, including three species of kingfishers, one of which dive-bombed the water next to our canoe and came up with a small silverfish. The great egret was my favorite. There is a short video of that bird on the YouTube channel linked from my blog in Costa Rica.

I highly recommend that if you plan to visit the eastern side of Costa Rica, make sure to include the Aviarios Sanctuary on your itinerary (and the nearby Cahuita National Park). You will not be disappointed.