A sloth that springs into action does not even seem possible, given the creature’s notorious lethargy, but one of the two sloth species in Costa Rica is fast as well as fierce. “Like a lion!” says Encar García, a conservationist. This unusual species, which is called the Hoffmann’s two-toed sloth, doesn’t hesitate to deploy teeth or its two large foreclaws when threatened. The other species, which has three forefingers and is called the brown-throated sloth, is, she reassures us, more typical—“the one that’s smiling.”

Despite their striking differences, both the Hoffmann’s two-toed sloth and the brown-throated sloth face the same problems when people encroach on their forest habitat. They climb power lines in search of a mate and often get electrocuted. If they come down from the trees, they may be attacked by dogs. Rapid development of forested areas has led to more deaths and injuries, says García. “We rescue a sloth almost every day.”

The organization she co-founded, the Jaguar Rescue Center, in Playa Chiquita, takes in orphaned and injured sloths and other mammals such as monkeys and opossums, along with birds and reptiles. (Not jaguars, though; the name is a winking acknowledgment of an early effort to rehabilitate a misidentified ocelot.) The center provides its patients with food, shelter and medical care, with the goal of returning animals to the wild.

baby two-toed sloth
A baby Hoffman’s two-toed sloth lies in a basket during rehabilitation at the Jaguar Rescue Center in Costa Rica.   Annie Marie Musselman

Nursing a helpless baby sloth, which weighs only 10 or 11 ounces—about the size of a grapefruit—requires almost constant attention for several months. Infants are fed goat’s milk every three hours throughout the day and night until they’re ready for a leaf-based diet, usually by 11 months. All the blankets and bottle-feeding in the world, though, don’t make up for not having a real parent. A baby sloth in the wild will cling to its mother’s fur for about six months while learning to find leaves that are nutritious and low in toxins. “We are not perfect sloth mothers,” says García. “I mean, we cannot eat leaves, we cannot teach them how to climb in the trees.”

The rescue center releases one-third to one-half of the sloths it cares for. Once an animal has recovered from an injury or has grown big enough to survive on its own, it’s outfitted with a microchip, painted nails and a colorful braid to identify it. According to the center’s latest records, 90 percent of the sloths released into the wild over the past couple of years are still alive today and thriving in their natural, if shrinking, habitat. 

juvenile Hoffman's two-toed sloth
A juvenile Hoffman’s two-toed sloth plays in an enclosure during rehabilitation at the Jaguar Rescue Center in Costa Rica. Annie Marie Musselman

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This article is a selection from the September issue of Smithsonian magazine