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Ecology

A Lazy Life

These wonderful animals have made laziness their best defensive weapon. For all their lethargy, sloths –placental mammals– have managed to stay alive on the planet for thousands of years. Their oldest relative, thought to have lived about 8,000 years ago, is the American megatherium, which measured between 20 and 25 feet.

Text and Photos: Javier A. Pinzón

Moving slowly, very slowly, through the tropical forest, this mammal has made slow motion a way of life. The sloth, which is not a bear, spends up to 18 hours a day dozing. Sloths live a quiet life thanks to a green lichen that grows on their fur and the way they hang from trees, which makes them nearly invisible to predators. But the sloth’s sluggish nature works in its favor. When enjoying a succulent snack of leaves, or even when faced with a disturbance, it can turn its head almost 360 degrees, thus saving the energy required to move its entire body. The sloth is, without a doubt, nature’s own Bob Marley. 

Néstor Correa, a member of the Pan-American Association for Conservation (APPC), is an expert on the wonderful world of these animals, which have made sluggishness their best defensive weapon. For all its slowness, the sloth –a placental mammal of the Pilose order and the Xenarthra superorder– has survived on Earth for many years; its oldest relative, thought to have lived about 8,000 years ago, is the American megatherium, which measured between 20 and 25 feet. 

Of the four families of sloths that once existed, only two remain: Megalonychidae, which includes the oldest two-toed species of sloths, and the Bradypodidae family, with four species known as the “new” or three-toed sloths. The first family is divided into Choloepus hoffmanni, which inhabits Central America, Colombia, Ecuador, and Peru and Choloepus didactylus, in South America. The Pan-American or hermit sloth, which has a long tail and measures up to sixteen feet long, is thought to have evolved from the second family. Among the species in this family are the B. torquatus, which lives in Rio de Janeiro and Bahia; the B. tridactylus from the Amazon; the B. Variegatus in Central America, Mexico, and South America; and, finally, the B. Pygmaues, which is endemic to Panama and now on the critically endangered list.

When hanging from trees, these three-toed masters of sluggishness can move at about 0.15 miles per hour and their two-toed relatives manage a lightning 0.16 mph! On the ground, they are even slower because their bodies are designed for moving through trees and their long claws make walking difficult, so they prefer to crawl across the terrain. Forest clearing and habitat fragmentation due to road construction forces sloths to travel on the ground, where they are most vulnerable, from one patch of forest to another. In fact, cars are their main cause of death, according to Correa.

Sloths are slow, but curious. Correa has documented how common it is to find orphaned sloths: the intrepid offspring let go of their mother, grab hold of a weak branch, fall to the ground, and lose their mother forever. The more deteriorated the forest, the more prone they are to injury, as the lack of trees decreases the chances of being able to grab another branch before falling. 

In a healthy forest, with vines, lush trees, and strong branches all around, a sloth will catch hold of another branch. The APPC has also noted many cases of sloths orphaned when the mother falls from the tree. If a baby sloth doesn’t separate from its mother in time, it will continue to breastfeed until the milk becomes toxic and it will die from the poison.

Due to the animal’s popularity, illegal trafficking and poaching of the species, especially the young, have increased considerably. The APPC works to raise awareness of these illegal practices among tourists. To assist them, a neighbor and ally, the Gamboa Rainforest Resort, has built facilities that let tourists become familiar with the sloth rehabilitation process while respecting the animals’ spaces and routines. 

A new enclosure at the center allows volunteers to observe young sloths to see if they are ready to return to their pleasant life in the treetops. Unfortunately, certain guests of the APPC program will never have the luxury of returning to the forest; without the opportunity to develop survival instincts with their mothers, they become so docile that they would be easy prey for other species.

Like the sloth, many animals need trees to survive, but indiscriminate felling is destroying our forests. According to a study in Nature magazine, an estimated 15.3 billion trees are cut down annually. Humans have reduced the number of trees by 46% since the origins of agriculture 12,000 years ago. A change of direction is necessary, to move toward a planet where we can all coexist.