January 18, 2011

Ai Ai Ai

The slow-moving, smiling brown-throated sloth

by Tim McSorley

The Dominion - http://www.dominionpaper.ca

The brown-throated three-toed sloth inhabits a wide swath of Central and Latin America. The long-limbed mammal can sleep up to 20 hours per day and has a mouth in the permanent shape of a smile. cc Photo: MicroMacroMicro

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The brown-throated three-toed sloth inhabits the upper branches of the tropical forests of Central and Latin America. Spending up to three days in a single tree before moving on to the next, this long-limbed critter feeds on leaves, twigs and fruit. Brown-throated sloths can sleep up to 20 hours per day and move at a maximum speed of about 0.3 miles per hour. Their slow movement and low metabolism means they can take up to a month to digest just one meal.

Its incredibly slow movement makes it easy prey, especially on the ground. But lengthy arms with long, sharp claws provide a significant defense from larger animals. In the rainy season, its long, wiry brown and grey fur develops patches of green algae, which helps it camouflage itself among the foliage.

The most common of the four species of three-toed sloths, the brown-throated sloth is distinguished by brown fur around its throat and on its chest, a "mask" of black fur around the eyes and, on males, an orange or yellow patch of fur between their shoulder blades. Like other sloths they can turn their heads 90 degrees, and their mouths naturally take the shape of a smile. While they are mammals, they also have the reptilian characteristic of having a body temperature that fluctuates as the external temperature goes up or down. Weighing 0.2 to 0.25 kilograms at birth, adults grow to the size of a cat—about four kilograms.

The brown-throated sloth is a primarily solitary animal, coupling only to mate. To attract males, the female makes an "ay" cry, which many say sounds like a woman screaming. It is also very similar to the sound both male and female sloths make when they are in danger. This noise has led the animal to also be referred to as the "ai" by the Guarani people of South America.

While the sloth moves with difficulty on the ground, it still descends from its perch in the humid canopy once every week. The terrestrial trek is made in order to dig a small hole into which it defecates, covering the hole with leaves. It is a precarious venture for the sloth, as it might need to descend 30 metres to reach the ground, putting it at the mercy of jaguars and other carnivores.

While its habitat has suffered from deforestation and fragmentation, its wide habitat (from Honduras in the north to parts of southern Brazil) and adaptability have allowed the brown-throated sloth to thrive.

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