Sloth – "A Habitual Disinclination to Exertion"


By the definition in the title of this article I consider myself a close kin of the much maligned, but ever smiling, Sloth. In Costa Rica they are known colloquially as a perezoso (lazy one). Indeed, if you encounter one in the wild your first impression is to think they are perfect slackers. Their movements are achingly slow, though deliberate.

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

  • It takes a month for them to digest their food, thus 2/3rds 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. Their body temperature can change by 10 degrees F. in a day.
  • Sloths sleep less than 10 hours a day, not 15-18 as was long believed.
  • They climb 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 of which reside in Costa Rica) lived over 35 million years ago, thus 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 very fortunate to catch the last tour of the day at the Aviarios Sloth Sanctuary north of Cahuita. We made it with a minute to spare, but we needn’t have worried as we were the only folks who showed up for that tour! We were led to an auditorium with seating for about 100 where we, alone, watched a 15 minute humorous video about the life of the sloth.

Rebecca (Becky) Cliffe, a final year zoology student from Manchester University (England), was our guide for the land-based portion of the tour. We first visited 3 open pens for the adult sloths, both two-toed and three-toed. They tend to stay put in their open front “cages”, but even if they do happen to escape they don’t get far at the rate they move. Most cages held two or more sloths together, sometimes shared by the two different species. Normally they are completely solitary animals in the wild, but because some came to the sanctuary at a very tender age they bonded with other residents in a short time.

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

I don’t think there is anything cuter than a baby sloth. They are simply adorable. The youngest ones often sleep together, clinging to each other’s fur. Some have their own stuffed toys to which they have bonded. One two-toed youngster, named Ubu, is given physical therapy every day by Becky for his two hind legs, which are partially paralyzed. The treatment seems to be doing some good.

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

These bacteria and insects don’t survive, however, when a sloth is kept in captivity and bathed. Resistance to mange and other diseases can’t be replaced by antibiotics, either since sloths have a fatal reaction to such drugs. So, to replace their fur’s “ecosystem” a mixture of achiote (annato) and coconut oil is used on their fur daily. This is what gives the baby sloths at Aviarios their strikingly beautiful color.

By the way, if you’re wondering why sloths climb down from their trees to defecate (I know you were!), well, so does Becky. In fact, while she is volunteering at Aviarios she is also working on her Zoology doctorate, whose thesis will be that the defecation is a key part of their mating process. In the year she’s 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-based facilities (great café and gift shop on the second floor, by the way), we were given a tour by canoe of the canals on the east side of the property. The green, dark, and mysterious canals surround a center island. All of us kept our comments to a minimum and in whispers in order to not spook the 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 Kingfisher, one of which dive bombed the water by our canoe and came up with a small silver fish. The Great Egret was my favorite. There is a short video of that bird on the YouTube Channel linked from my blog on Costa Rica.

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

Source by Casey Bahr